the petrogenesis of the station creek igneous … · igneous complex and associated volcanics,...

THE PETROGENESIS OF THE STATION CREEK IGNEOUS COMPLEX AND ASSOCIATED

VOLCANICS, NORTHERN NEW ENGLAND OROGEN

JOSEPH ENG HOO TANG

School of Natural Resource Sciences, Queensland University of Technology

This thesis is submitted in partial fulfillment of the requirements of the Doctor of Philosophy (Geology)

2004

KEYWORDS: Petrogenesis; petrography; geology; Station Creek Igneous Complex; Mount

Mucki Diorite; Gibraltar Quartz Monzodiorite; Woolooga Granodiorite; Rush

Creek Granodiorite; Woonga Granodiorite; Wratten Igneous Suite; andesitic

volcanics; Highbury Volcanics; Neara Volcanics; North Arm Volcanics;

evolution of magma; geochemistry; stable isotopes; radiogenic isotopes; trace

elements; modelling; fractional crystallisation; differentiation; mineral

chemistry; geothermometry; geobarometry; emplacement conditions; mantle

and lithospheric mantle sources; mantle melting; mafic underplating;

continental margin; calc-alkalic; crustal assimilation; magma evolution;

39Ar/40Ar dating; tectonic classification

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ABSTRACT

The Station Creek Igneous Complex (SCIC) is one of the largest Middle-Late Triassic

plutonic bodies in the northern New England Orogen of Eastern Australia. The igneous

complex comprises of five plutons - the Woonga Granodiorite (237 Ma), Woolooga

Granodiorite (234 Ma), Rush Creek Granodiorites (231 Ma) and Gibraltar Quartz

Monzodiorite and Mount Mucki Diorite (227 Ma respectively), emplaced as high-level or

epizonal bodies within the Devonian-Carboniferous subduction complex that resulted from a

westward subduction along the east Australian margin. Composition of the SCIC ranges from

monzogabbro to monzogranite, and includes diorite, monzodiorite, quartz monzodiorite and

granodiorite.

The SCIC has the typical I-type granitoid mineralogy, geochemistry and isotopic

compositions. Its geochemistry is characteristics of continental arc magma, and has a

depleted-upper mantle signature with up to 14 wt% supracrustal components (87Sr/86Srinitial =

0.70312 to 0.70391; εNd = +1.35 to +4.9; high CaO, Sr, MgO; and low Ni, Cr, Ba, Rb, Zr,

Nb, Ga and Y). The SCIC (SiO2 47%-76%) has similar Nd and Sr isotopic values to island-

arc and continentalised island-arc basalts, which suggests major involvement of upper mantle

sourced melts in its petrogenesis. SCIC comprises of two geochemical groups - the

Woolooga-Rush Greek Granodiorite group (W-RC) and the Mount Mucki Diorite-Gibraltar

Quartz Monzodiorite group (MMD-GQM). The W-RC Group is high-potassium, calc-alkalic

and metaluminous, whereas the MMD-GQM Group is medium to high potassium, transitional

calc-alkalic to tholeiitic and metaluminous. The two geochemical groups of the SCIC magmas

are generated from at least two distinct sources - an isotopically evolved Neoproterozoic

mantle-derived source with greater supracrustal component (10-14 wt%), and an isotopically

primitive mafic source with upper mantle affinity. Petrogenetic modeling using both major

and trace elements established that the variations within respective geochemical group

resulted from fractional crystallisation of clinopyroxene, amphibole and plagioclase from

mafic magma, and late fractionation of alkalic and albitic plagioclase in the more evolved

magma.

Volcanic rocks associated with SCIC are the North Arm Volcanics (232 Ma), and the

Neara Volcanics (241-242 Ma) of the Toogoolawah Group. The major and trace element

geochemistry of the North Arm Volcanics is similar to the SCIC, suggesting possible co-

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magmatic relationship between the SCIC and the volcanic rock. The age of the North Arm

Volcanics matches the age of the fractionated Rush Creek Granodiorite, and xenoliths of the

pluton are found within epiclastic flows of the volcanic unit. The Neara Volcanics (87Sr/86Sr=

0.70152-0.70330, 143Nd/144Nd = 0.51253-0.51259) differs isotopically from the SCIC,

indicating a source region within the HIMU mantle reservoir (commonly associated with

contaminated upper mantle by altered oceanic crust). The Neara Volcanics is not co-

magmatic to the SCIC and is derived from partial melting upper-mantle with additional

components from the subducting oceanic plate.

The high levels emplacement of an isotopically primitive mantle-derived magma of

the SCIC suggest periods of extension during the waning stage of convergence associated

with the Hunter Bowen Orogeny in the northern New England Orogen. The geochemical

change between 237 to 227 Ma from a depleted-mantle source with diminishing crustal

components, to depleted-mantle fractionate, reflects a fundamental change in the source

region that can be related to the tectonic styles. The decreasing amount of supracrustal

component suggests either thinning of the subduction complex due to crustal attenuation,

leading to the late Triassic extension that enables mantle melts to reach subcrustal levels.

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TABLE OF CONTENTS CHAPTER 1: INTRODUCTION 1

GRANITOIDS AND ARC MAGMATISM 1 REGIONAL GEOLOGICAL SETTING OF THE NEW ENGLAND OROGEN 5

Outline of the tectonic evolution for the NNEO 7 Plutonism of southeast Queensland of the eastern Australian continental margin 13

AIMS OF THE STUDY 16 The specific objectives of this research 18

CHAPTER 2: RESEARCH METHODOLOGY 19

Fieldwork and geophysics data 19 Petrography 19 Geochemistry 20 Mineral Chemistry 22 Ages 23

CHAPTER 3: THE GEOLOGICAL SETTING OF THE STATION CREEK IGNEOUS COMPLEX 24

Introduction 24

Structure and tectonics 31 THE PALAEOZOIC STRATIGRAPHY 33

The Lower Plate Assemblage 33 The Upper Plate Assemblage 37 The Wratten Igneous Suite, associated hornfels aureole and foliated diorite 39 Early Permian Highbury Volcanics 41 Early Triassic Neara Volcanics 43

MIDDLE TO LATE TRIASSIC VOLCANICS AND HYPABYSSAL ROCKS 45 The North Arm Volcanics 45 Middle-Triassic to Jurassic intrusions 47 Andesitic to rhyolitic dykes 47

CHAPTER 4: THE STATION CREEK IGNEOUS COMPLEX 51

Introduction 51 DEFINITION OF THE STATION CREEK IGNEOUS COMPLEX 51

Mount Mucki Diorite 52 Gibraltar Quartz Monzodiorite 53 Woolooga Granodiorite 57 Rush Creek Granodiorite 58 Woonga Granodiorite 59 Structure of the Station Creek Igneous Complex 60

PETROGRAPHY AND MINERAL CHEMISTRY 62 Petrography of the Mount Mucki Diorite 66 Petrography of the Gibraltar Quartz Monzodiorite 68 Petrography of the Woolooga Granodiorite 69 Petrography of the Rush Creek Granodiorite 73 Petrography of the Woonga Granodiorite 74

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MINERAL CHEMISTRY 76 Amphiboles 76 Biotite 83 Pyroxenes 87 Feldspars 91 Fe-Ti oxides 95 Accessory phases (titanite, apatite and epidote) 96

CHAPTER 5: GEOCHEMISTRY 101

Integrity of geochemical data and the calculation of ferrous-ferric ratios 101 THE STATION CREEK IGNEOUS COMPLEX 101

Geochemical classification 101 Major element geochemistry 108 Trace elements geochemistry 111 Element ratio diagrams 114 REE geochemistry 118 Spider diagram 122

VOLCANIC ROCKS AND DYKES 125 Geochemical classification of volcanic and hypabyssal rocks 125

The Neara Volcanics 125 The North Arm Volcanics and Late Triassic dykes 128 The Highbury Volcanics 128

Geochemistry 129 The Neara Volcanics 129 The North Arm Volcanics 129 The Highbury Volcanics 132

THE FOLIATED GRANODIORITES OF THE WRATTEN IGNEOUS SUITE 132 ISOTOPE CHEMISTRY 136

Radiogenic isotopes 136 Rb/Sr radiometrics 136 Sm/Nd radiometrics 139 The Sm/Nd and Rb/Sr systematics 139

STABLE ISOTOPES 140 Background 140 Oxygen Isotopes 140 Hydrogen-oxygen isotopic systems 141

CHAPTER 6: DISCUSSION 145

PETROGENESIS OF THE STATION CREEK IGNEOUS COMPLEX 145 Tectonic environments 145

Geochemical signatures 145 Tectonic classification 146

The intrusive timing between plutons of the Station Creek Igneous Complex 148 Crystallisation and emplacement constraints 148

Depth of emplacement and geobarometry 148 Geothermometry and temperature of crystallisation 154

Hornblende-plagioclase and magnetite-ilmenite geothermometry and oxygen fugacities 154

Geothermometry based on P2O5 solubility 156 Water content 156

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Geochemical diversity and variation within the Station Creek Igneous Complex 160 The Woolooga-Rush Greek Granodiorite group (W-RC Group) 163 The Mount Mucki Diorite-Gibraltar Quartz Monzodiorite Group (MMD-GQM Group) 164 The Woonga Granodiorite Group 165

Petrogenetic modeling 165 Definition of components 167

The least-evolved magma of the MMD-GQM group and the Station Creek Igneous Complex 167

The least-evolved magma of the Woolooga-Rush Creek group 167 Possible contaminant: supracrustal melts (the foliated granodiorite of the

Wratten Igneous Suite) 167 Possible sources 168

Intraplutonic models: Close-system fractional crystallisation (FC) modelling 168 Interplutonic models 171

Fractional crystallisation (FC) modelling 171 Magma-mixing models 172 Assimilation-crystal fractionation (AFC) models 173

Magma source characterisation 174 Geochemical constraints 174 Isotopic constraints 175

Parental magma 184 Partial melting versus fractional crystallisation models 185 Interpreted source regions 189

A GEOCHEMICAL COMPARISON BETWEEN THE SCIC AND THE NEARA AND NORTH ARM VOLCANICS 190

PETROGENETIC SUMMARY 193 The MMD-GQM group (227 Ma) 194 W-RG group (231-234 Ma) 195 Comparing the SCIC with the Lower Triassic Neara Volcanics 196

CHAPTER 7: GEOLOGICAL SYNTHESIS AND CONCLUSIONS 199 Magmatism: implications for growth and evolution of the eastern Australian continental margin 199

The Early Triassic 201 The Middle Triassic 202 The Late Triassic 204 Summary 204

CONCLUSIONS 205

REFERENCES 208

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LIST OF FIGURES

Figure 1.1: Simplified map of the New England Orogen showing major geologic blocks and the palaeo-tectonic settings.

6

Figure 1.2: A time-space plot of the Gympie-Yarraman area, southeast Queensland, Australia. 8 Figure 1.3: Locality map of the research area in relation to the geological framework, tectonic terranes and

previous regional mapping in the central New England Orogen, southeast Queensland, Australia. 17

Figure 3.1: The geologic elements of southeast Queensland highlighting the relationship between the North D’Aguilar Block to surrounding geology (including major Carboniferous to Jurassic plutons)

25

Figure 3.2: Schematic tectonostratigraphy showing the 3 rock assemblages of the northern North D’Aguilar Block in southeast Queensland.

26

Figure 3.3: The solid geology of the Station Creek Igneous Complex of the northern North D’Aguilar Block, southeast Queensland.

34

Figure 3.4: The geology of the Gibraltar Rock area, southeast Queensland. 46 Figure 4.1A: The total magnetic image (reduced to pole) of the Station Creek Igneous Complex. 54 Figure 4.1B: Radiometric image of the Station Creek Igneous Complex. 55 Figure 4.2: Rose diagrams comparing the orientations of intrusive contacts of the Station Creek Igneous

Complex to bedding planes and foliations of the Palaeozoic basement rocks. 61

Figure 4.3: Streckheisen classification of plutonic rocks of the Station Creek Igneous Complex based on modal mineralogy.

63

Figure 4.4: Modal variation within component plutons of the Station Creek Igneous Complex. 64 Figure 4.5: Modal variation of major rock-forming minerals in relation to whole-rock silica content in the

Station Creek Igneous Complex. 65

Figure 4.6: Textural variations in the Station Creek Igneous Complex. 70 Figure 4.7: Leake (1978) classifications of magmatic amphiboles from the Station Creek Igneous Complex,

and associated volcanic and intrusive rocks based on: a. Mg/(Mg+Fe2+) versus T(Si), and b. A(Na+K) versus T(Si).

78

Figure 4.8: Molar chemical variations in amphiboles from the Station Creek Igneous Complex and associated volcanic and intrusive rocks.

81

Figure 4.9: Geochemical comparison of biotite from the SCIC and associated intrusions with biotite of the various granite types.

85

Figure 4.10: Compositional classification of biotite from the various plutons of the Station Creek Igneous Complex and associated intrusions.

85

Figure 4.11: Chemical variations in biotite from the Station Creek Igneous Complex and monzodiorite intrusions.

86

Figure 4.12: Variation of SiO2 versus Al2O3 in pyroxene from the Station Creek Igneous Complex and associated rocks.

89

Figure 4.13: Classification of pyroxenes from the Station Creek Igneous Complex and the monzodioritic intrusions.

89

Figure 4.14: Molar cationic variations in pyroxenes from the Station Creek Igneous Complex and associated intrusive and volcanic rocks.

90

Figure 4.15: Variations in feldspar composition from plutons of the Station Creek Igneous Complex and associated hypabyssal and volcanic rocks.

93

Figure 4.16: Variation of Na+ versus Ca2+ in feldspars from the Station Creek Igneous Complex and associated rocks.

94

Figure 4.17: Variation of Al3+ versus Ca2+ in feldspars from the Station Creek Igneous Complex and associated rocks.

94

Figure 4.18: Composition variations of Fe-Ti oxides plotted on a FeO-TiO2-Fe2O3 ternary diagram for plutonic rocks of the Station Creek Igneous Complex and volcanic and hypabyssal rocks.

98

Figure 4.19: Fe3+-Al-Ti cationic variations in magnetites from the Station Creek Igneous Complex, monzodiorite intrusions and volcanic rocks.

98

Figure 4.20: Variations of Mn versus Fe2+ cations in ilmenite from the Station Creek Igneous Complex and associated rocks.

98

Figure 5.1: The geochemistry of the Station Creek Igneous Complex plotted on a molar (Na2O+CaO)-Al2O3-K2O diagram shows little deviation from a variation trend from average gabbro to granite compositions.

104

Figure 5.2: Geochemical classification of pluton rocks based on normative quartz, plagioclase and alkali- 104

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feldspar. Figure 5.3: Subdivision of plutonic rocks of the SCIC into low-, medium- and high-K fields based on the K2O

versus SiO2 diagram. 106

Figure 5.4: Geochemical classification of plutonic rocks of the SCIC into calc-alkaline and tholeiite associations.

106

Figure 5.5: AFM diagram shows the chemical variation trends of intrusive rocks of the SCIC. 107 Figure 5.6: Plot of alumina saturation versus alkalinity for the SCIC. 107 Figure 5.7: Calcic-alkali ratio versus silica trends for intrusive units of the Station Creek Igneous Complex. 109 Figure 5.8: Harker variation diagrams for major element geochemistry of the Station Creek Igneous Complex. 110 Figure 5.9: Harker variation diagrams for trace element geochemistry of representative samples from the

Station Creek Igneous Complex and associated intrusions. 112

Figure 5.10: Cation ratios versus SiO2 plots of the SCIC highlight three geochemical variation trends: the Woolooga-Rush Creek Granodiorite group, the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group and the Woonga Granodiorite.

115

Figure 5.11: Ti/K versus Si/K element ratio diagram of the SCIC highlights four variation trends of different element ratio-ratios.

115

Figure 5.12: Variation diagrams of bivariant trace elements and incompatible elements ratios. 117 Figure 5.13: Chondrite normalised rare earth element abundances for representative samples from plutons of

the Station Creek Igneous Complex. 120

Figure 5.14: The europium anomaly or Eu/Eu* of the Station Creek Igneous Complex. 121 Figure 5.15: Rare earth element ratio diagrams for the Station Creek Igneous Complex. 121 Figure 5.16: Spider diagrams for selected samples from plutons of the Station Creek Igneous Complex. 123 Figure 5.17: Normalised trace element abundances for representative samples of the Station Creek Igneous

Complex. 124

Figure 5.18: TAS classification of volcanic rocks of the northern North D’Aguilar Block. 124 Figure 5.19: The subdivision of subalkalic volcanic rocks of the northern North D’Aguilar Block into low-,

medium- and high-K fields based on the K2O versus SiO2 diagram. 126

Figure 5.20: Geochemical classification of volcanic rocks of the northern North D’Aguilar Block into calc-alkaline and tholeiite associations.

126

Figure 5.21: AFM diagram shows the geochemical variation trends for volcanic rocks. 127 Figure 5.22: Plot of alumina saturation versus alkalinity for volcanic rocks. 127 Figure 5.23: Harker variation diagrams for volcanic rocks of northern North D’Aguilar Block. 130 Figure 5.24: REE patterns of volcanic rocks of the northern North D’Aguilar Block. 131 Figure 5.25: Spider diagrams of volcanic rocks of the northern North D’Aguilar Block. 131 Figure 5.26: QAP classification of cataclastic or foliated granodiorite of the Wratten Igneous Suite using

normative mineral compositions. 133

Figure 5.27: The geochemical classification of foliated granodiorite of the Wratten Igneous Suite in the Woolooga area.

133

Figure 5.28: Alumina saturation versus alkalinity for the foliated granodiorite of the Wratten Igneous Suite compared to domains of the SCIC.

134

Figure 5.29: Harker variation diagrams of foliated granodiorite of the Wratten Igneous Suite. 134 Figure 5.30: REE pattern of foliated granodiorite of the Wratten Igneous Suite. 135 Figure 5.31: Spider diagram of foliated granodiorite of the Wratten Igneous Suite, northern North D’Aguilar

Block. 135

Figure 5.32: Rb-Sr data for whole-rock samples from the SCIC, foliated granodiorite, Black Snake Porphyry and Neara Volcanics.

138

Figure 5.33: 143Nd/144Nd versus 147Sm/144Nd data for whole-rock samples from the SCIC, the Black Snake Porphyry, the Neara Volcanics and the foliated granodiorite.

138

Figure 5.34: Initial 143Nd/144Nd versus 87Sr/86Sr ratios recalculated to 246 Ma. 143 Figure 5.35: The δ18O isotopic values of the Station Creek Igneous Complex, associated volcanic and country

rocks and mineralisation. 143

Figure 5.36: Plot of δD versus δ18O for plutons of the SCIC and proximal intrusions (the Black Snake Porphyry and Yorkeys Diorite).

144

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Figure 6.1: Granite and tectonic discrimination diagrams for the Station Creek Igneous Complex. 147 Figure 6.2: The geologic reconstruction of intrusive history of the Station Creek Igneous Complex. 149 Figure 6.3: The interpreted P-T environment for the emplacement of the Station Creek Igneous Complex

(shaded area <1.5 Kbar and <375oC). 151

Figure 6.4: The pressures of crystallisation calculated using the aluminium-in-hornblende barometry of Hammarstrom and Zen (1986).

151

Figure 6.5: Plot of Log fO2 versus temperature for co-existing magnetite-ilmenite pairs from the Station Creek Igneous Complex and monzodiorite intrusions.

155

Figure 6.6: The variation of P2O5 versus SiO2 contents in the Station Creek Igneous Complex. 155 Figure 6.7: Crystallization pressures and temperatures of plutons of the Station Creek Igneous Complex. 158 Figure 6.8: Inter-element plots comparing geochemical variations within the Station Creek Igneous Complex to

the major fractionating phases (mineral-vector diagram). 162

Figure 6.9: Major elements least square modelling within and between plutons of the SCIC 169 Figure 6.10: The 87Sr/86Sr initial ratios of the Station Creek Igneous Complex (SCIC) compared to volcanic arc

magmas derived from a variety of tectonic environments 176

Figure 6.11: The 143Nd/144Ndinitial versus 87Sr/86Srinitial data of the Station Creek Igneous Complex (SCIC) plotted against potential crustal contaminants of the NEO.

177

Figure 6.12: The 143Nd/144Nd versus 87Sr/86Sr ratios of the Station Creek Igneous Complex compared to isotopic fields of island-arc and ocean island basalts, and continentalised arc system.

179

Figure 6.13: Two-component isotopic mixing model between ‘subduction zone mantle’ derived melt (MMD) and the extrapolated upper crustal component (CR)

183

Figure 6.14: The compatible-element versus incompatible-element diagrams comparing fractional crystallisation and partial melting models for the Station Creek Igneous Complex.

186

Figure 6.15: Major elements plotted against MgO for the Neara and North Arm Volcanics. 192 Figure 6.16: Sr/Ba versus Ba plot comparing geochemical variations within the Neara and North Arm

Volcanics to partial melting and crystal fractionation trends. 192

Figure 6.17: A petrogenetic summary of the Station Creek Igneous Complex. 198 Figure 7.1: Temporal geochemical changes in magmas of southeast Queensland of the northern New England

Orogen between 320 and 120 Ma. 200

Figure 7.2: The Early-Late Triassic tectonic evolution of the eastern Australian continental margin 203

LIST OF TABLES

Table 1.1: A petrogenetic comparison of Late Carboniferous to Late Triassic intrusive units in New England Orogen

14

Table 3.1: Stratigraphy of the North D’Aguilar Block of the Northern New England Orogen, southeast Queensland.

27

Table 3.2: Intrusive units in the North D’Aguilar Block of the Northern New England Orogen, southeast Queensland.

30

Table 3.3: Tectonic and magmatic history of the northern region of the North D’Aguilar Block of the NNEO, southeast Queensland.

32

Table 4.1: Radiometric ages of plutons in the Station Creek Igneous Complex 52 Table 4.2: Representative samples for mineral chemistry analysis by electron microprobe 77 Table 4.3: Representative amphibole analyses from the various units of Station Creek Igneous Complex,

volcanic rocks and monzodiorite intrusions. 79

Table 4.4: Semi-quantitative Fe2O3 and FeO results for biotite separates determined by titrametric method (weight percent)

83

Table 4.5: Representative biotite analyses from the various plutons of the Station Creek Igneous Complex. 84 Table 4.6: Representative pyroxene analyses from the various plutons of the Station Creek Igneous Complex,

volcanic units and monzodiorite intrusions. 88

Table 4.7: Selected feldspar analyses to represent the different units of the Station Creek Igneous Complex, volcanic rocks and monzodiorite intrusions.

92

Table 4.8: Representative magnetite and ilmenite analyses from plutons of the Station Creek Igneous Complex, associated volcanic rocks and monzodiorite intrusions.

97

Table 4.9: Apatite analyses from the various plutons of the Station Creek Igneous Complex and monzodiorite 100

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intrusions. Table 4.10: Epidote analyses from the various units of the Station Creek Igneous Complex and volcanic rocks. 100 Table 4.11: Representative sphene analyses from the various units of the Station Creek Igneous Complex and

volcanic rocks and monzodiorite intrusions. 100

Table 5.1: Major, trace and isotopic element data for representative samples of the Station Creek Igneous Complex and associated rocks, southeast Queensland.

102

Table 5.2: Titrametric results of ferrous and ferric iron in representative whole-rock plutonic and volcanic rock samples.

101

Table 5.3: Radiogenic and stable isotopic data for the Station Creek Igneous Complex and associated volcanic and country rocks.

137

Table 6.1: A comparison of the calculated pressure of crystallisation using the various Al-in-hornblende geobarometers for igneous rocks.

152

Table 6.2: Representative pressure of crystallisation (kbar) calculated using the aluminium-in-hornblende barometer of Hammarstrom and Zen (1986).

152

Table 6.3: Comparison of the temperatures of crystallisation using geothermometers of Blundy & Holland, (1990) and Spencer & Lindsley (1981).

153

Table 6.4: Representative results of magnetite-ilmenite geothermometry and oxygen fugacity using the thermometer of Spencer & Lindsley (1981) and the new constants of Anderson & Lindsley. (1985).

153

Table 6.5: Summary of fractional crystallization models within plutons and between plutons in a geochemical group of the SCIC.

172

Table 6.6: Calculated percentages of crustal component (CR) for the various plutons of the SCIC based on two-component isotopic mixing model (Langmuir et al., 1978)

182

LIST OF PLATES

Plate 3.1: Foliated Karandah Granodiorite of the Wratten Igneous Suite. 40 Plate 3.2: An outcrop of the Wide Bay Creek Gneiss, east of Kilkivan. 40 Plate 3.3: An andesitic flow within epiclastic rocks of the Neara Volcanics. 49 Plate 3.4: Epiclastic rock of the Neara Volcanics with sub-angular, poorly sorted lithic fragments (andesite,

trachyandesite, tuff, minor components of foliated granitoid, siltstone and chert) in a groundmass of volcanogenic detritus.

49

Plate 3.5: Polylithic conglomerate of the Neara Volcanics. 50 Plate 3.6: Flow-banded rhyolitic dyke intruding the Woolooga Granodiorite, east of Kilkivan. 50 Plate 4.1: Net-vein complex of inter-mingled diorite and quartz monzodiorite at the contact between the

Mount Mucki Diorite and Gibraltar Quartz Monzodiorite. 56

Plate 4.2: Intrusive contact between the Gibraltar Quartz Monzodiorite and the Neara Volcanics. 56 Plate 4.3: Sub-ophitic chilled margin of the Mount Mucki Diorite (Sample SC936). 67 Plate 4.4: Hornblende replaces poikilitic augite (Fe-Ti oxides and apatite inclusions) in the Mount Mucki

Diorite 67

Plate 4.5: Plagioclase-dominated porphyritic and hypidiomorphic-granular granodiorite (Rgw1) of the Woolooga Granodiorite.

71

Plate 4.6: Interstitial granophyric groundmass in the Woolooga Granodiorite. 71 Plate 4.7: Compositional zonation in hornblende of the Rush Creek Granodiorite, from magnesio-hornblende

core to actinolitic-hornblende rim. 75

Plate 4.8: Intensely cracked plagioclase cores enclosed in undeformed oligoclase rims, Rush Creek Granodiorite.

75

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LIST OF MAPS IN ATTACHED FOLDER

1. The geologic fact map of the Station Creek Igneous Complex 2. The solid geology of the Station Creek Igneous Complex

APPENDICES

APPENDIX 1: ANALYTICAL METHODOLOGIES

I. SILICATE ROCK ANALYSIS BY ICP 1 II. LOSS ON IGNITION 3 III. DETERMINATION OF FERROUS AND FERRIC IRON 4 IV. DETERMINATION OF S, CO2 AND H2O+ 6

APPENDIX 2: WHOLE ROCK GEOCHEMICAL DATA

I. WHOLE ROCK GEOCHEMISTRY 8 II. STABLE ISOTOPE DATA FOR ORE DEPOSITS 22 III. RADIOMETRIC DATA 22 IV. COMPARISON OF GEOCHEMICAL RESULTS USING THE DIFFERENT

ANALYTICAL TECHNIQUES 22 V. GENERIC GEOCHEMISTRY (RECALCULATED) 23

APPENDIX 3: PHASE CHEMISTRY DATA 30 APPENDIX 4: PETROGRAPHIC DATA 38

MODAL COMPOSITION (POINT COUNTING) APPENDIX 5: PETROGENETIC MODELLING

MATHEMATICAL EQUATIONS USED IN PETROGENETIC MODELLING 40 FRACTIONAL CRYSTALLISATION MODELS 41 MIXING AND ASSIMILATION MODELS 49 ASSIMILATION-CRYSTAL FRACTIONATION MODELS 56 PARTIAL MELTING MODELS 60 AVERAGE GEOCHEMISTRY OF MAJOR SOURCE REGIONS 67 PARTITION COEFFICIENTS 68

APPENDIX 6: REPRESENTATIVE PETROGRAPHY 70 APPENDIX 7: RADIOMETRIC AGES, SOUTHEAST QUEENSLAND

AGES OF LITHOLOGIC UNITS 77 GEOCHEMISTRY VERSUS AGES OF PLUTONIC ROCKS

IN SOUTHEAST QUEENSLAND 79 APPENDIX 8: MINERALISATION POTENTIALS 83

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STATEMENT OF ORIGINAL WORK

The work contained in this thesis has not been previously submitted for a degree or diploma at any other higher education institution. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made. Signed: ___________________________ Date: _________________

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ACKNOWLEDGEMENT

This research was undertaken at the School of Natural Resource Sciences with

Queensland University of Technology under the Australian Postgraduate Award (APA)

sponsorship. Gratitude is extended to all the staff of the school for the fellowship and

assistance rendered that made my stay very pleasant. Particularly, deep appreciation is

extended to my principal supervisor- Associated Professor David Gust for his guidance,

assistance and contributions throughout the research, and for the critical editorial and

scientific criticisms that improved the manuscript. I also thank my co-supervisors- Dr

Alwyn Grenfell and Associated Professor Rodney Holcombe for their encouragement

and guidance. Laboratory assistance by Mr William Kwiecien and Ms Sharon Price, and

sample preparation by Mr David Keith are greatly appreciated.

I also extend my thanks to the Geological Survey of Queensland of the Natural

Resources and Mines department, for allowing time-off, material support and the

relevant database used in this thesis. Sincere gratitudes are extended to Mr Leonard

Cranfield and Dr John McKellar for proof-reading and their scientific contributions. Mr

Cranfield’s assistance in the publication of the Goomeri 1:100,00 map, the Goomeri

map commentary and a Queensland Government Mining Journal article arising from

this research, is gratefully acknowledged.

Field-assistance and material supports by my sister Lynne and brother-in-law

Chong Seang are greatly appreciated. I have been encouraged greatly by the support of

my family, and friends- Kenrick Van Noord and Associate Professor Lloyd Hamilton. I

thank my wife Josephine and my son Chok-Liang for their ongoing support, tolerance

and faith.

Finally, I dedicate this thesis to the memory of my beloved son - Chok-San.

Chapter1: Introduction

1

CHAPTER 1: INTRODUCTION

GRANITOIDS AND ARC MAGMATISM

The primary aims of granitoid research are to identify the magma source

(crustal igneous, sedimentary or mantle material), tectonic environments of magma

genesis, magma-generation and differentiation processes, and conditions of

emplacement. Such information requires the interpretation of major elements, trace

elements and isotopic geochemistry, radiometric ages, petrography, geology and the

distribution of granitoids in relation to plate-tectonic settings. The established links

between magma chemistry, arc maturity and plate tectonics are used as primary

petrogenetic tools to ascertain the tectonic setting and geologic history of a region (e.g.

Gill, 1981; Brown, 1982; Batchelor & Bowden, 1985; Arculus, 1987; Wang & Glover,

1992; Gust et al., 1996; Allen et al., 1998). Granitoids act as probes into the

subterranean geology, image their sources and provide information about the upper

mantle and/or lower crust (Chappell & White, 1992; Miller et al., 1992; Zen, 1992;

Chappell, 1996). Changes in magma chemistry related to variations in the nature of

magmatic source provide critical clues to tectonic styles, and are vital in the

interpretation of the tectono-magmatic history of continental evolution.

Late Permian to Late Triassic magmatism is voluminous throughout the

northern New England Fold Belt of eastern Australia. The New England Fold Belt or

New England Orogen (Day et al., 1978) was an active continental margin from the mid-

Carboniferous through to the early Mesozoic. It was formed by repeated cycles of

convergent and extensional tectonics related to active subduction and subsequent slab

roll-back (Holcombe et al., 1993, 1997a,b). The contractional tectonics were in part

related to the Hunter-Bowen Orogeny, the termination of which occurred in the latest

Middle – early Late Triassic. Significantly, the orogeny was succeeded by Late Triassic

extension that was a prelude to the break-up of Gondwana (Gust et al., 1996).

A detailed petrogenetic study of plutonic rocks of the Station Creek Igneous

Complex emplaced during the transition from the contractional tectonism to the

extensional tectonism cited above, is the subject of this thesis. Investigation of its

emplacement during the latest Middle - Late Triassic period of transitional tectonism,


2

provides the opportunity to employ the study of magmatic rocks to improve our

understanding of the tectonic evolution of the eastern Australian continental margin.

Arc-type magmas have contributed to the evolution and growth of the

continental crust for the last two billion years. Commonly known as the calc-alkalic

series, arc magmas occur exclusively above subduction zones along plate-margins in

regions of compressive stress. Calc-alkalic magmas are characterised by andesite and

granodiorite, and minor tholeiitic rock, rhyodacite, rhyolite and shoshonite.

Granodiorite occurs in composite suites comprising smaller constituent plutons

emplaced in the crust by diapiric intrusion. Brown (1982) proposed that a magmatic arc

matures by the progressive thickening of the volcanic pile on oceanic crust, until the

pile is thick enough to support plutonism; hence evolving from an island-arc to a

continentalised island-arc and subsequently to a continental-margin arc system. In this

thesis, the term tholeiite refers strictly to basaltic rock that has low K, low LIL elements

and exhibits initial Fe-enrichment with magmatic fractionation, whereas tholeiitic rock

refers to low-K rock having tholeiite characteristics.

The composition of arc-associated plutonic and volcanic rocks varies laterally

along an arc system, as well as with arc maturity and the vertical distance above the

subduction zone (Jakes & White, 1972; Ewart, 1976; Perfit et al., 1980a; Brown, 1982;

Kay & Kay, 1982; Thorpe et al., 1984). Tholeiite and andesite typically occur in island-

arcs and immature arcs (Fujinawa, 1988; Green, 1980). Calc-alkalic magmas are typical

of mature and continental-margin arcs (Brown, 1982; Thorpe et al., 1984). In a

continental-margin subduction setting, the volcanic-plutonic front begins 100-200 km

inland from the oceanic trench, trending almost parallel to the trench, with the volume

of the magmatism decreasing inland from the volcanic front (Thorpe, 1982). The

composition of the magma changes from tholeiite (close to the trench) to calc-alkalic

and alkalic compositions distally.

Basic magmas are generated by 10-30% partial melting of the upper mantle

(100+50 km depth) (Wyllie, 1979; Jaques & Green, 1980). The melt composition

depends on the chemical and mineralogical compositions of source rocks, melting

process and the degree of partial melting (Bergantz & Dawes, 1994). The three primary

island-arc basalts are the olivine tholeiite, high-alumina tholeiite and alkali olivine

basalt (Yoder, 1979; Tatsumi et al., 1983; Gust & Perfit, 1987). Although primitive


3

island-arc basalt and primitive mid-ocean-ridge basalt (MORB) are both derived from

similar upper mantle source (Perfit et al., 1980b), the chemical differences between

their evolved lavas resulted from different fractionating mineralogy and conditions

(Gust & Perfit, 1987). Island-arc tholeiite differs from MORB by having a relatively

high Al2O3 and Ba content and a lower content of Ni and Cr.

Magma evolves within magma chambers by high-level differentiation

processes such as fractional crystallisation, magma mixing, wall-rock assimilation and

crustal contamination, or a combination of these processes (e.g. Perfit et al., 1980a;

Bailey, 1981; Eggins & Hensen, 1987; Driver et al., 2000). Continental-margin andesite

differs from island-arc andesite by having higher K2O, Rb, Ba, Sr, U and Th contents; a

higher Rb/Sr ratio; lower CaO; a lower K/Rb ratio; enrichment of light rare earth

elements (LREE) and large-ion lithophiles (LIL); higher 87Sr/86Sr ratios (0.702-0.704),

and changes in mineralisation styles from Fe-Cu, Ag-Pb-Zn to Sn-Mo. The geochemical

differences are attributed to increased involvement of subducted sediments in the

mantle-derived melts and/or the addition of hydrothermal fluids (eg. Arculus &

Johnson, 1981; Chappell & Stephens, 1988; Arculus, 1994; Wyllie & Ryabchikov,

2000). Post-solidus interaction with meteoric water further modifies the stable isotope

and rock geochemistry.

Granitoid petrogenesis has been debated between schools of “graniters” and

“magmatists” since the 18th Century (Whitney, 1988; Atherton, 1993; Wilson, 1993;

White, 2002). Read’s (1948, 1949) “graniter model” for granite origin follows a series

of metamorphism and melting from granulite to granite. The “magmatist model” of

Bowen (1922, 1928) favours a closed-system fractional crystallisation of mantle-

derived basalt to form the diversity of granitic rocks. The simplistic granite

classification suited for the broad divisions between sedimentary and igneous sources

are the S-type and I-type granites respectively (Chappell & White, 1974). The I-type

granite is further subdivided into high-temperature and low-temperature granites

(Chappell et al., 1999a), M-type granites with predominantly mantle-sourced magma

(Pitcher, 1979), and A-type or anorogenic granites (Loiselle & Wones, 1979).

In continental-arcs, gabbros, syn-plutonic mafic dykes and mafic inclusions in

granitoids may represent parental magmas (Tepper, 1996), whereas diorite, granodiorite

to granite are differentiates of the parental magmas (Perfit et al., 1980a; Kay & Kay,


4

1982; Thorpe et al., 1984). Calc-alkalic granitoids consist of two groups: a low-K

tonalite group (e.g. Clarence River Supersuite of eastern Australia, Peninsular Ranges

of the USA, and granitoids in Japan and Nicaragua-Panama arcs) and a high-K

granodiorite and quartz monzonite group (e.g. major plutonic suites of the New England

Fold Belt, Andes, and western America). The low-K tonalitic group has primitive initial 87Sr/86Sr (0.702-0.707), and is derived from dehydration partial melting of basaltic or

amphibolitic sources with limited differentiation (e.g. Gromet & Silver, 1987; Rapp et

al., 1991; Wyllie & Wolf, 1993; Rapp & Watson, 1995; Bryant et al., 1997). The high-

K granodioritic group has varied initial 87Sr/86Sr (0.704-0.710); it is enriched in K2O,

Rb, Cs, Ba, Zr, U and Th, and has higher ratios of Fe3/Fe2, Fe/Mg and Rb/Sr. The

geochemical signatures suggest either an undepleted continental lithospheric source, or

a crustal-contaminated depleted mantle magma (e.g Chappell & Stephens, 1988;

Hildreth & Moorbath, 1988, Robert & Clemens, 1993, Driver et al., 2000; Wyllie &

Ryabchikov, 2000). Suggested mechanisms for crustal involvement range from magma

mixing (hybridisation) process to multi-stage melting of a multi-component source that

comprises both mantle and crustal constituents (e.g. Arculus & Johnson, 1981;

McCourt, 1981; Pitcher, 1983; Hickey et al., 1986; Hildreth & Moorbath, 1988; Taylor

& McLennan, 1997; Passmore & Sivell, 1998; Arculus, 1999). Models for multi-

components/multi-stage melting that produce intermediate rocks with mantle-like

isotopic compositions are partial melting of the mantle wedge, oceanic crust, juvenile

lower crust, basaltic underplates and meta-igneous sources in subduction zones (e.g.

Shaw & Flood, 1981; Hensel et al., 1985; Stephens, 1991; Landenberger & Collins,

1996; Bryant et al., 1997, Clemens, 1998).

Trace-element and isotope compositions of plutonic rocks enhance

understanding of magma origin and distribution in terms of plate tectonics (i.e. magma

associations) (e.g. Dewey, 1980; Shaw & Flood, 1981; Hensel et al., 1985; Whalen et

al., 1987; Miller et al., 1992; Norman et al., 1992; Pitcher, 1983 & 1993; Chappell,

1996; Chappell et al., 1999b). Since the 1970s, considerable advances in geochemistry

have increased understanding of magmatic processes through modern modelling

techniques (Allegre et al., 1977; Minster et al., 1977; Allegre & Minster, 1978; Minster

& Allegre, 1978;) and better definition of the partition coefficient of trace elements in

minerals (e.g. Hanson, 1978; Irving, 1978; Miller & Mittlefehldt, 1982; Dostal et al.,

1983; Fujimaki, 1986; Green & Pearson, 1983, 1987). Rare-earth elements (REE) are


5

used in the modelling, and evaluating magmatic history and magmatic processes. Three

types of REE variation (changes in total REE abundance, changes in relative abundance

of heavy and light REE, and fractionation of Eu) occur during magmatic processes. The

various REE variations identify different magmatic processes, and different crystallising

mineralogies and conditions. Mobile elements (U, K, Rb, Cs, Ba, Si, Ca, Al) are

sensitive to fractional crystallisation and secondary processes such as alteration and

low-grade metamorphism. Immobile elements (Ti, Fe, Y, Zr, Nb, Ta, Hf, Co, Sc, REE)

elements are most useful for tectonic classification.

Experimental petrology contributes significantly towards comprehension and

interpretation of granitoid petrogenesis and melt production. Classic experiments on

granitic systems (Tuttle & Bowen, 1958; Whitney, 1988; Ebadi & Johannes, 1991;

Holtz et al., 1992a, 1995) and andesitic systems (e.g. Eggler, 1972a,b; Eggler &

Burnham, 1973) provide pressure, temperature and compositional constraints, as well as

approximation of water, oxygen and fluid fugacities. The physiochemical conditions of

magma determine the texture, mineralogy, crystallisation sequence, and the

geochemical evolution of plutons (tholeiitic or calc-alkalic). Magmatic rheology and the

ability of magma to segregate determine the formation of plutonic bodies (Vignersse et

al., 1996). Experiments by van der Molen & Paterson (1979) have established that a

critical melt fraction of 26-36% is required for melt-source separation and segregation.

The type of melting, depth of melting, and the accompanying tectonism govern melt

segregation (Wickham, 1987).

REGIONAL GEOLOGICAL SETTING OF THE NEW ENGLAND OROGEN

The New England Orogen (Day et al., 1978) is the easternmost and youngest

part of the Tasman Orogen, extending over 1500 km from Bowen in Queensland to

Newcastle in New South Wales. It comprises three provinces: the Yarrol Province

(referred to herein as the Northern New England Orogen or NNEO), the New England

Province (also referred to as the Southern New England Orogen or SNEO) and the

Gympie Province (Figure 1.1).


6

SOUTHERN NEO(NEW ENGLANDPROVINCE)

NORTHERNNEO (YARROLPROVINCE)

GYMPIEPROVINCE

152 Eo

20 So

146 Eo20 S

o

24 So

24 So

28 So

28 So

32 So

148E o

32 So

Bowen

Rockhampton

Brisbane

Newcastle

0 100 200 300 km

NEW ENGLANDOROGEN

Newcastle

Bowen

1000 km

152 Eo

146 Eo

20 So

24 So

24 So

28 So

32 So

152 Eo148 E

o

0 100 200 Km

Devonian magmatic arc

Devonian to mid-Carboniferous forearc basin

Devonian to mid-Carboniferous subduction complex

Permian, presumed exotic terrane

Legend

ThomsonFold Belt

Galilee Basin

Bowen Basin

Gunnedah Basin

Lachlan Fold Belt Sydney Basin

Connors Arch

Campwyn Block

Bowen

Coastal BlockWandilla

SlopeA

ndBasin

Coastal Block

Gympie BlockYarrol Block

Gogango Overfolded Zone

Rockhampton

Auburn Arch

Good Night Block

Yarraman BlockEsk Trough

North D’AguilarBlock

South D’Aguilar Block

Beenleigh Block

Emu Creek Block

Coffs Harbour Block

Nambucca Basin

Hastings Block

Tamworth Block

Texas-Woolomin Block

Newcastle

Silverwood Block

MoretonClarence Basin

Brisbane

GoondiwindiFaults M

ooki FaultHunter

Thrust

Yarrol FaultG

reat Moreton Fault

Dem

on F ault

Peel Fault

N o r t h

Figure 1.1 : Simplified map of the New England Orogen showing the major geologic

blocks and the palaeo-tectonic settings. The three provinces of the NEO (Northern NEO or Yarrol, Gympie and Southern NEO or New England Province) are shown in the insert.


7

The NEO resulted from a mid-Devonian to mid-Carboniferous subduction

along the eastern Australian margin of Gondwana (Leitch, 1975; Murray, 1997;

Murray et al., 1987; Korsch et al., 1988). The conceptual model for the NEO was a

Californian-style, west-dipping oceanic plate that subducted beneath eastern Australia

(Blake & Murchey 1988; Korsch et al., 1990). The subduction produced three tectonic

regimes that included a magmatic arc in the west, a fore-arc basin, and a subduction

complex in the east (Leitch, 1974; Henderson et al., 1993). The volcanic arc and the

fore-arc basin are separated from the subduction complex by a belt of serpentinised

ultramafic and metamorphic rocks. In the northern part of the NEO, the Connors-

Auburn magmatic complex and the Yarrol basin are interpreted as the Palaeozoic arc

and the fore-arc, with the subduction complex being the Wandilla Complex (Murray et

al., 1987).

The Gympie Province is regarded as by some an exotic terrane (e.g.

Harrington, 1983, 1987; Cawood, 1984; Waterhouse & Sivell, 1987) that docked with

the NNEO in the Middle-Late Triassic (Harrington & Korsch, 1985b; Murray, 1990;

Cranfield et al., 1997). The province comprises arc-related basic to intermediate

volcanics, volcaniclastic sediments, and marine to non-marine sediments of Early

Permian to Early Triassic age. Its unique structural history does not correlate with the

adjacent North D’Aguilar Block of the NEO (Cranfield, 1999).

A tectonic nomenclature used within Queensland (C. G. Murray, personal

communication) renamed the three tectonic regimes of NNEO as tectonic provinces

(the Connors-Auburn Province, Yarrol Province and the Wandilla Province). The

geological entity/block (e.g. North D’Aguilar Block) within each province was

assigned a subprovince status. Though the new classification has been quoted in

publications within Queensland (e.g. Cranfield, 1999; Cranfield et al., 2001), it lacks

formal definition. The scheme consequently has not been widely adopted and is not

used in this thesis. The term Northern New England Orogen (NNEO) is used in

preference to Yarrol Province in order to avoid confusion with the new nomenclature.

Outline of the tectonic evolution for the NNEO (Figure 1.2)

Pre- Late Carboniferous convergence

During the period of mid-Devonian to mid-Carboniferous convergence, deep


8

L

M

E

R

N

C

L

A

SN

G

T

K

UK

A

S

A

S

W

N

V

T

U

M

L

Figure 1.2: A time-space plot of the Gympie-Yarraman area,

R am m utt F m


9

M A R Y B O R O U G H T E C TO N IC S A N D M A G M AT IS M PLUTONIC UNITS

Southeast Queensland, Australia (Tang, 2003).

25

Extension, faultingand dyking

Minor contraction, calc-alkaline magmatism, may be related to collision between Gympie and the New England provinces

Eastward thrust and associated folding (Claddagh Thrust), related to the Hunter Bowen Orogeny

Ex

ten

sio

na

l

b

asi

ns

M o u n t M ia fau lt (d e tac h m e n t)an d e x h u m a tio n o f c o re co m p le x

Ext

ensi

on

Co

ntr

act

ion

Th

rus

tin

gE

xte

nsi

on

Det

ach

me

nt

Act

ive

wes

twar

d s

ub

du

ctio

nTr

ans

pre

ssi

on

E sk tro u g h a n d v o lca n is m

Ext

ens

ion

?

?

Cla

ddag

h T

hrus

t

Core Complex (Lower plate Assemblage)

Extensional basinsand volcanism, possibly back-arc extension associated with the offshore Gympie arc

Upper plateAssemblage

Syntectonic magmatism

Accretionary wedgesediments

Subduction plate

Formation of accretionary complexduring active subduction (D1) and blueschist metamorphism (M1)

1. Gallangowan Granodiorite (319 Ma)2. Claddagh Granodiorite (307 Ma)3. Karandah Granodiorite (Late Carb.)4. Coppermine Creek Granodiorite (5. Capsize Creek Granodiorite (311 Ma)6. Yabba Creek Granodiorite (289-311 Ma)7. Woonga Granodiorite (237 Ma)8. Woolooga Granodiorite (234 Ma)9. Rush Creek Granodiorite (231-232 Ma)10. Mount Mucki Diorite (227 Ma)11. Gibraltar Quartz Monzodiorite (227 ma)12. Kingaham Granodiorite (220, 239, 242 Ma)13. Black Snake Porphyry (233 Ma)14. One Mile Creek Granite (Late Triassic)15. Calgoa Granodiorite (233 Ma)16. Tungi Creek Granodiorite (226 Ma)17. Native Creek Granite (Late Triassic)18. Monsildale Granodiorite (232, 253 Ma) 19. Kimbala Granodiorite (Early Triassic)20. Avoca Granodiorite (255 Ma)21. Goomboorian Igneous Complex (234, 240 Ma)22. Eerwah Vale Tonalite (Early-Middle Triassic)23. Woondum Granite (223, 226 Ma)24.Cedar Pocket Porphyry (Middle-Late Triassic)25. Noosa Quartz Diorite (140-146 Ma)26. Woolshed Mountain Granodiorite (258 Ma)27. Kenewah Granodiorite (Late Permian)28. Melrose Igneous Complex 29. Hivesville Granite (260.5 Ma)30. Wooroolin Granite (258 & 274 Ma)31. Stuart River Granite (250, 256 Ma)32. Boondooma Igneous Complex (237-260 Ma)33. Taromeo Igneous Complex (233-250 Ma)34. Memerambi Granite (254 Ma)35. Canoe Creek Granite (Late Triassic)36. Toondahra Granite (Late Triassic)37. Woroonden Granodiorite (Late Triassic)39. Unnamed diorite (Early-Late Permian)40. Unnamed granitoids (Late Permian)

Late Carb.)

LITHOLOGY

Granite

Granodiorite

Diorite

Gabbro

Transitional blueschist facies metasediments

Sub-greenschist facies metasediments

Intrusive rocks

Stratigraphy

Basic volcanics (basalt to basaltic andesite)

Basic-intermediate volcanics, volcaniclatics and sediments

Intermediate-acid volcanics and sediments

Limestone

Turbidite

Conglomerate, sandstone and mudstone

Intermediate volcanics, volcaniclastics and sediments

Acid-intermediate volcanics, tuff and sediments

Sandstone, mudstone and phyllite

Lacustrine- coal measure

Fluviatile deposits

Acc

retio

nary

wed

ge

Exte

nsio

nal

basi

n de

posi

tsM

arin

eC

ontin

enta

l

* S-type granites

* Tholeiitic magma

* Bimodal magmatism

* Calc-alkalic magma

* Calc-alkalic to alkalic magmas


10

marine sediments overlying an oceanic plate were subducted westward beneath

oceanic crust and upper mantle rocks that formed basement to the NEO. The rocks of

the subduction complex (the Wandilla Complex) were thrust-imbricated against the

continental-margin lithospheric plate, being deformed and regionally metamorphosed

during the subduction process. Deeper level mafic and pelitic rocks were underplated

to a depth of about 20 km (Holcombe & Little, 1994). These rocks were subjected to a

high-pressure– low-temperature, transitional epidote-blueschist facies, which has been

referred to as M1 (Little et al., 1992, 1993a; Holcombe & Little, 1994). Deep marine

sediments and volcanic rocks are the predominant higher-level rocks in the subduction

complex. These are regionally metamorphosed to a sub-greenschist facies.

Late Carboniferous extension

By the Late Carboniferous, the earlier subduction regime was replaced by

extensional tectonism that attenuated the subduction complex (Blake & Murchey,

1988; Veevers et al., 1993; Fergusson & Leitch, 1993). Deeper-level accreted rocks

and ophiolitic basement were exhumed along a detachment fault (the Mount Mia

Fault) and juxtaposed against the higher-level rocks. The transitional epidote-

blueschist-facies rocks at depth were overprinted by a subsequent retrograde

greenschist facies (M2) during the exhumation. The ophiolitic basement was exposed

to erosion and subsequently redeposited as a sedimentary serpentine-matrix melange

on the ocean floor. Tectonic plucking incorporated higher-grade mafic blocks (e.g.

exotic blueschist and greenschist blocks) and metasedimentary fragments (e.g. biotite-

muscovite schist) into sheets of serpentinitic melange (Little, 1993; Donchak et al.,

1995). The serpentinitic unit includes both sedimentary ophiolitic debris and

serpentinised ophiolite basement, as evident in the Marlborough terrane (Bruce & Niu,

2000; Bruce et al., 1998).

In the southern region of the NNEO, synkinematic S-type granitoids

(Claddagh, Gallangowan and Karandah Granodiorites; Tang & Gust, 2000) were

intruded along the Mount Mia detachment zone (Sliwa, 1994). An approximate 306

Ma Ar/Ar (hornblende) age from the Claddagh Granodiorite (Little et al., 1992)

indicates the probable timing of the extensional event. The enveloping country rocks to

the synkinematic granitoids were thermally metamorphosed to hornblende hornfels

facies.


11

Early Permian back-arc extension

In the Early Permian, a subduction front associated with the Gympie volcanic

arc back-stepped further to the east of the earlier Devonian - Late Carboniferous

subduction system (Sivell & Waterhouse, 1988). At this time, the Wandilla terrane

became a region of back-arc extension, subjected to block faulting, graben formation

and uplift (Holcombe et al., 1993). Volcanic-derived sediments associated with the

back-arc extension (Marumba beds, Kandanga Creek Megabreccia, Cambroon beds,

Cedarton Volcanics) were preserved in the down-faulted extensional basins (Sliwa et

al., 1993b; Donchak et al., 1995). The embryonic stage of the Esk Trough may also

have formed at this time along the western margin of the North D’Aguilar Block

(Campbell et al., 1999).

Middle Permian thermal subsidence phase

Campbell et al. (1999) attributed a widespread marine transgression in the

Middle Permian to a phase of thermal subsidence that followed the Early Permian

extension. This event produced clastic offshore marine shelf and coastal plain

sediments that included minor carbonate sedimentation. These deposits are currently

preserved along the periphery of the North D’Aguilar Block-Esk Trough as the

Cressbrook Creek Group and the Northbrook beds.

Late Permian thrust-dominated contraction

The Late Permian was characterised by a major period of thrust-dominated

contractional tectonics assigned to the Hunter-Bowen Orogeny (Leitch, 1969;

Holcombe et al., 1993, 1997a). Thrusting in the southern part of NNEO has an

opposite sense of movement to the rest of the NNEO, and is characterised by a west-

over-east sense of displacement, with a possible dextral strike-slip component

(Donchak et al., 1995). In the northern NNEO, movement along these fault zones

exhumed deep crustal rocks such as the Marlborough terrane (Henderson et al., 1993).

In the southern NNEO, Late Carboniferous syntectonic granodiorites with their

associated metamorphic aureoles were thrust eastward over the accretionary-wedge

sedimentary rocks, along a thrust sheet termed the ‘Claddagh Thrust’ (Little et al.,

1993a; Holcombe et al., 1993). I-type calc-alkalic plutons were widely emplaced in the

subduction complex during the Late Permian (Henderson et al., 1993, Gust et al.,


12

1993). Examples of plutons of this age include: the Monsildale Granodiorite (253 Ma,

K/Ar hornblende; Sliwa, 1994), Avoca Creek Granodiorite (255 Ma, K/Ar hornblende;

Grayson 1995) and the Kimbala Granodiorite.

Triassic episodes of alternating contraction and extensions

The NEO orogeny had mainly ceased by the Early Triassic (Landenberger &

Collins, 1996; Landenberger et al., 1995) and was followed by minor episodes of

alternating contraction and extension (Korsch & Totterdell, 1996; Holcombe et al.,

1993). The result of episodic contraction and extension was that the Palaeozoic rocks

were faulted into numerous geologic blocks. Some blocks were readjusted by

movements on north and northwest trending faults (Cawood & Leitch, 1985; Aitchison

& Flood, 1990; Coney et al., 1990). Dextral wrenching (transpressional) movements

during the Early Triassic opened up the Esk Trough to further deposition of rift

sediments (Tooloogawah Group). These sediments are gently to moderately folded.

Post-orogenic I-type calc-alkalic magmatism is widespread in the Late

Permian - latest Middle Triassic (Gust et al., 1993), coincidental with the transitional

period between the terminal stages of arc magmatism and the beginning of extensional

magmatism (Gust et al., 1996). An example of such a plutonic mass is the Station

Creek Igneous Complex. Magmatism of the Late Triassic is mostly anorogenic,

reflecting predominantly extensional tectonics (e.g. the Mungore Granite and the

Aranbanga Volcanics).

Post-Late Triassic tectonics

Following a period of extension in the Late Triassic, episodic reactivation of

NNW trending faults (e.g. Bracalba and North Pine Faults) occurred through dip-slip

and strike-slip movements (Donchak et al., 1995). An extension period in the Early

Cretaceous lasted approximately from 100-130 Ma, with placement of extension-

related volcanics and plutonics (Stephens et al., 1994). A period of contraction in the

Late Cretaceous caused folding, thrusting and uplift. Post-Cretaceous tectonics are

associated with the opening of the Coral and Tasman Seas and led to the development

of the oil-shale bearing grabens along the eastern Queensland coast. Although faults of

this era are not major structural features, they are significant in defining many

boundaries between tectonic units in Queensland.


13

Plutonism of southeast Queensland of the eastern Australian continenal margin

Continental margin plutons are abundant in the Tasman Orogen (Palaeozoic

mobile belt) on the eastern fringe of the Australian plate. The eastern Australian craton

was expanded and thickened through accretion of oceanic crust, deep marine

sedimentary rocks (quartz-rich turbidites, cherts) and mafic volcanics. Successive fold

belts from the Delamerian Fold Belt (550-410 Ma), Lachlan Fold Belt (450-340 Ma) to

the New England Fold Belt (310-210 Ma) represent an outstepping migration of

deformation fronts associated with various subduction systems (Gray & Foster, 1998).

Granitoids intrude the subduction complexes, stabilising the continental margin by

‘stitching’ tectonic terranes and contributing to the volume of the continental crust. An

intimate connection between plutons and plate tectonics allow their radiometric ages

and field relationships to be used as time constraints to tectonic events (McCulloch &

Gamble, 1991; Sivell & McCulloch, 1993, 1997).

Plutonic suites in the New England Orogen (NEO) show progressive

compositional changes from peraluminous granite in the Carboniferous, metaluminous

granite in Early-Middle Triassic, to metaluminous and alkalic granites in the Middle-

Late Triassic (Table 1.1). The compositional changes reflect diminishing crustal

contributions, from predominantly meta-sedimentary origin in the Carboniferous to

dominantly mantle-derived melts in the Triassic. The Early-Middle Triassic

metaluminous granitoids have typical continental-arc signatures over a range of both

isotopic and geochemical compositions. These plutons are sourced from depleted

mantle or primitive lower crustal sources. Their initial Sr ratios are generally higher

than mantle values, which suggests involvement of substantial crustal components

(Hansen, 1997), primitive lower crust (Bryant et al. 1997; Shaw & Flood, 1981) or

meta-sediments (Hensel et al., 1985). The (Middle-) Late Triassic granitoids are

mantle fractionates with crustal contamination (Stephens, 1991; Landenberger &

Collins, 1996). The granites are dominated by A- and I-types, yet both have similar

parentage or are partially melted from the same source. The I-type granite is

interpreted as disequilibrium with dry but not refractory partial melts that leave behind

a charnokitic


14

Chapter 1: Introduction

15

lower crustal composition. Partial melting of these charnokitic residues at

temperatures above 900oC yields co-magmatic A-type granites (Landenberger et al.,

1995; Stephens, 1991). Pyroxene geothermometry of primitive Late Triassic magmas

calculated temperatures up to 1100oC. These mantle-derived magmas represent major

heat influxes that could induce partial melting (Kleeman, 1988).

In southeast Queensland (central NEO), approximately 18% of the basement

geology is granitoid (mainly diorite, granodiorite to granite) (data from Cranfield et

al., 2002; Day et al., 1983). The predominantly calc-alkalic, high-K plutonism is

associated with westward subduction along the east Australian margin (Gust et al.

1996). Calc-alkalic magmatism was active until 300 Ma followed by a thirty to forty

million years hiatus. Magmatism recommenced at 265 Ma, and the magmatism

between 265 to 250 Ma was bimodal in character and spatially restricted. Widespread

calc-alkalic magmatism recurred between 250-220 Ma, peaking at 240 Ma, but

gradually became more geographically restricted after 230 Ma. The Early-Middle

Triassic plutons are typical of continental-margin arcs, being dominated by diorite,

granodiorite to granite and consisting of significant mantle component as shown by

their primitive isotopic signatures (Holcombe et al., 1997a; Passmore & Sivell, 1998).

Magmatism between 230 and 220 Ma is distinct in composition, comprising dominant

granodiorite to granite with A-type affinities. It was derived from underplating

mantle-material that had been replenished by previous melting episodes. The

plutonism between 220 and 210 Ma was mostly anorogenic.

The variation in magmatism coincides with a major change in tectonic style

from Palaeozoic convergence to Mesozoic extension. The termination of calc-alkalic

magmatism at 300 Ma and its recommencement at 265 Ma reflect the cessation of

mid-Palaeozoic subduction and the development of a new west-dipping subduction

zone: the Gympie arc to the east at 270 Ma (Sivell & McCulloch, 1993; Passmore &

Sivell, 1998). Magmatism after 265 Ma shows progressive changes from magmatic

arc (up to ∼ 240 Ma; residual from subduction in the Late Permian) to extension and

rift-related volcanism and intrusion (Ashley et al., 1996). The Palaeozoic-early

Mesozoic plutonism of the NEO ended between 230 and 210 Ma with intrusion of

sub-volcanic cauldrons and ring complexes often linked with peralkaline granites of

A-type (post-tectonic regime). Anorogenic-styled plutonism between 220 to 210 Ma


16

is related to extensional tectonics.

The interval between 240 and 220 Ma represents a period of major changes in

tectonic style (from convergence to extension) and source characteristics (from a

depleted mantle source with diminishing crustal components, to mantle fractionate). It

represents the transitional period between the end of arc magmatism and at the

beginning of extensional magmatism in the central NEO. There is little previous

information about the magma sources, the tectonic setting of the source region, or the

mechanism of magma genesis for the Middle-Late Triassic granitoids.

The Station Creek Igneous Complex (SCIC), 30 km west of Gympie, is one of

the largest Middle-Late Triassic plutonic bodies in the central NEO (Figure 1.3). This

intrusive complex, emplaced during the 240-220 Ma tectonic transitional period,

occupies an important spatial and temporal position in the tectonic framework of the

NEO. Critical examination of its petrogenesis will reveal crucial information about its

magmatic source, tectonic setting, geologic history, conditions of crystallisation, and

thus about the development of the eastern Australian plate margin.

AIMS OF THE STUDY

This thesis presents new petrologic and geochemical (major, trace and isotopic

element) data and petrogenetic interpretations for the SCIC of the northern New

England Orogen. Results of mapping within this thesis have redefined the geology

and petrochemistry of the SCIC, and the geology of the subduction-complex (Crouch

et al., 1997; Tang & Gust, 2000; Tang & Pascoe, 2002). The research focuses on

geochemistry, petrography and mapping in order to:

• define the origin of intraplutonic geochemical variation;

• define interplutonic magmatic variations either as products of sub-crustal

processes (e.g. crystal fractionation, partial melting, contamination) or source

heterogeneity; and

• identify the nature of magmatic source region and tectonic setting, and establish

possible changes in tectonic styles during the Middle-Late Triassic interval.


17

Maryborough 1:250,000 map SG 56-6(Cranfield, 1994; Ellis , 1968)et al.

Donchak , 1995et al.

Crouch , 1995et al.

Little, 1993

E a rly to M idd le Triassicgran ito idTe rrane boun daryTow nsh ip

L e g e n d

Road

1 0 2 0 3 0 k m

Scale

Previous regional mapping

25 00’So

Gympie

Kingaroy

Murgon

25 00’So

Maryborough

EskTrough

Yarraman Block

NambourBasin

Gympie Block

GympieBlock

N o r t h

W o olo og a

U ppe r W idgee

K ilk ivan

N o rthD ’A g u ila rB lo c k

27 00o

27 00o

Little, 1993

Crouch . (1995)et al

Donchak . (1995)et al

Geological Survey Maryborough Sheet SG 56-6

Geological Survey Gympie Sheet SG 56-10

1

3

2

1 Previous petrogenetic studies12

3

. Mungore Granite (Stephens, 1991),

. Monsildale Granodiorite (Kwiecien, 1996) and

. Goomboorian Diorite (Hansen, 1997)

1:100,000 geological mapDonchak , 1999;Tang & Pascoe, 2002

et al.Goomeri

1:250,000 geological map SG 56-10 (Cranfield 1999; Murphy ., 1976) et al

N E W E N G L A N DO R O G E N

1 0 0 0 k m

N e w c a s t le

B o w e n

Enlarged area

Study area

Figure 1.3: Locality map of the research area in relation to the geologic framework, tectonic terranes and previous regional mapping in the central New England Orogen, southeast Queensland, Australia.


18

The youngest intraplutonic high-level differentiation processes are examined first,

and derived arguments are then applied to older interplutonic variations and source

characterisation. The SCIC is a suitable choice for petrogenetic study because of:

• its central position with respect to the Devonian-Carboniferous subduction

complex of eastern Australia.

• its Middle-Late Triassic age encompassing the transition from compressional

to extensional tectonics.

• its I-type, predominant depleted mantle-derived and calc-alkalic composition

in a subduction setting.

• its composite nature, diverse composition (monzogabbro to monzogranite) and

wide geographical coverage over an area of more than 800km2.

The specific objectives of this research were:

• To map the composite plutons of the SCIC and the adjoining subduction complex

geology, with an emphasis on contact relationships, lithologic variations within

and between plutons, xenolith types and tectonic structures. The intentions were

to identify individual intrusions and intrusive timing, and to seek physical

evidence for magmatic processes such as fractional crystallisation, partial melting,

mixing and assimilation (Chapters 3-4; Tang & Pascoe, 2002; Tang, 2003).

• To undertake petrological, geochemical and petrogenetic studies in order to model

conditions of crystallisation and genesis of magma, and to determine the nature

of the source of the igneous complex. The research also plans to assess the

causes of both interpluton and intrapluton geochemical diversity, either as

products of sub-crustal processes (e.g. crystal fractionation, contamination) or

source heterogeneity. The petrogenetic study further aims to determine changes

in tectonic styles and the timing of such changes (Chapters 4–6; Crouch et al.,

1997; Tang & Gust, 2000).

• To compare geochemistry of the SCIC with contemporaneous volcanics (Neara

Volcanics, North Arm Volcanics) and to test the likelihood of any co-

magmatism (Chapters 5-6).

Chapter2: Research Methodology

19

CHAPTER 2: RESEARCH METHODOLOGY

Fieldwork and geophysics data

Geological field mapping of the Station Creek Igneous Complex covered

approximately 800 sq. km, of which 480 sq. km area was mapped in detail.

Approximately 350 km of field traverse was covered, and 839 geochemical and

petrological samples were collected. The Station Creek Igneous Complex was

systematically sampled to collect a representative suite for each pluton, encompassing

both textural and compositional variants, contact zones, xenoliths and cross-cutting

dykes. Field classification of plutonic rocks uses the IUGS classification scheme (Le

Maitre, 1989) and enclaves classification is based on Barbarin & Didier (1991)

definition.

The field relationship between the various country rock units and plutonic

rocks were examined to establish the timing of intrusions and different fault events

and to determine the stratigraphy. Within each pluton, intrusive contacts, lithologic

zonation, rock texture and fabric, foliations, enclaves, faults and alteration were noted.

A total of 1133 structural readings of fault orientations, fractures, folds, bedding,

schistosity, foliations and lineations were recorded.

Airborne geophysics (magnetic and U-Th-K radiometrics surveys) from the

Geological Survey of Queensland and Gympie Eldorado Exploration Ltd. (Kilkivan

survey) assisted in refining the compilation of the geological map. An additional 800

magnetic susceptibility readings (expressed as SI units) of plutonic, volcanic and the

country rocks were determined in the field using a Geo Instrument magnetic

susceptibility meter (model GMS-2).

Petrography

Petrographic studies of plutonic, volcanic, hypabyssal and country rocks

were based on thin-sections (170 sections), hand specimens (732 samples) and sodium

cobaltinitrite stained-slabs and thin-sections. Medium- to coarse-grained rocks were

etched with hydrofluoric acid and stained with sodium cobaltinitrite to enable accurate

point counting and modal approximation of plagioclase and orthoclase. Modal mineral


20

compositions were point counted from stained thin sections (5 cm x 2 cm) and rock

slabs (>10 square cm area) with a minimum number of counts per sample being 400.

Plagioclase compositions were determined using optical extinction angles (Mitchel-

Levy) method (Deer et al., 1992). The compositions of pyroxene and hornblende were

determined by electron microprobe. Classification of amphiboles is based on Leake

(1978) scheme. An ‘accessory phase’ refers to a mineral phase that makes up less than

0.25 modal percentage in a rock.

Geochemistry

Two hundred and six whole-rock samples (130 plutonic rocks of the Station

Creek Igneous Complex, 15 Late Carboniferous foliated granodiorite of the Wratten

Igneous Suite, 21 volcanic rocks, 11 dykes, 12 intrusive stocks, 7 xenoliths and 10

representative country rocks) were analysed for major element chemistry. The

volcanic samples include the Highbury Volcanics (7 samples), the Neara Volcanics

(11 samples) and the North Arm Volcanics (3 samples). All plutonic rocks are slightly

altered (deuteric and/or thermal overprinted), although their geochemistry plotted on a

molar Al2O3-(CaO+Na2O)-K2O triangular plot (Nesbitt & Young, 1984) showed

minimal deviation from the standard granitoid compositions.

Major element geochemistry (as well as Ba and Sr) of whole-rock samples

was analysed by inductive coupled plasma-atomic emission spectrometry (ICP-AES,

Liberty 200) in the School of Natural Resource Sciences of the Queensland University

of Technology. Details of sample preparation and silicate rock analysis (including loss

on ignition, S and CO2 determinations) are presented in Appendix 1. The ICP-AES is

standardised on two USGS standards (G-2 and W-2), with each analytical batch

checked against four in-house standards (QUT No. 2769, 1552, 446 and 353) and a

Station Creek Igneous Complex sample (SC550) for precision. The acceptable

deviations in results for SiO2 and Al2O3 is 1.5 wt %, for Na2O and K2O is 0.5 wt %

and 0.2 wt % for other major elements. The ferrous and ferric iron contents of selected

whole-rock samples were determined by titrametric methods. The major element

geochemistry is normalised to 100% on an anhydrous basis for graphic presentations

and in discussions.

Trace and rare earth element analyses included 19 samples determined by X-


21

ray fluorescence (XRF) method (Chappell, 1991) at the Australian National

University, and 49 samples by instrumental neutron activation analysis (INAA;

Meucke, 1980) at Becquerel Laboratories, Lucas Heights. The analytical method for

INAA was based on “Au plus 20 elements” commercial scheme with slightly longer

counting times and multiple counting episodes. Twenty whole rock samples were also

analysed for trace and rare earth elements by ICP-MS method (Jenner et al., 1990) at

the Department of Earth Sciences of the University of Queensland. Analyses by the

ICP-MS method have accuracies to 0.01 ppm whereas the INAA and XRF methods

have accuracies to 0.1 ppm and 1 ppm respectively. Duplicate samples tested using

the different geochemical techniques indicated similar precisions (within 20%

variance) except for the Tb (30-60% variance for the INAA results) and Zn (17-80%

variance for the INAA results) (Appendix 2).

Eighteen whole-rocks and five mineral separates were analysed for oxygen

isotopes; ten rock samples for deuterium-hydrogen isotopes and nine sulfide separates

were analysed sulphur isotopes at the Isotope Laboratory of the Department of Earth

Sciences, University of Queensland. For the oxygen isotopic determination, samples

were reacted with BrF5 at 650°C in nickel vessels for 12 hours to liberate oxygen. The

liberated oxygen (converted to CO2 by reaction with an internally heated carbon rod)

was analysed on Micromass 602E mass spectrometer, and oxygen isotopes were

reported in ‰ relative to VSMOW (analytical uncertainities ±0.2‰, one-σ). For the

deuterium determination, whole-rock samples were heated under vacuum conditions

to produce water. The liberated water was reduced to hydrogen by reaction with Zn

metal at 450°C, and the δD content was analysed on Micromass 602E mass

spectrometer (reported in ‰ relative to VSMOW, analytical uncertainities ±3‰ at

one-σ). Sulfide samples were combusted in a Fisons elemental analyser (NA-1500

NC) coupled to a Micromass IsoPrime ‘continuous flow stable isotope ratio mass

spectrometer’ or CF-IRMS. The δ34S and δ33S were analysed on the Micromass

Isoprime CF-IRMS, and reported in ‰ relative to VCDT (analytical uncertainities

±0.2‰, one-σ).

A selection of twelve rock samples representing a variety of rocks was

analysed for radiogenic isotopes (Rb-Sr and Sm-Nd) at the radiogenic isotope

laboratory of the Department of Earth Sciences, University of Queensland. Initial

ratios for Nd and Sr were calculated using decay constants of 1.42 X 10-11 (Steiger &


22

Jager, 1977) and 6.54 X 10-12 (Lugmair & Marti, 1977) respectively based on the ages

of individual units.

Mineral Chemistry

Mineral chemistry in the thesis was determined using a JEOL 840 electron

microprobe equipped with energy dispersive spectrometry (EDS) (accelerating

voltage of 15 kV; current of 2.5 nano-amperes; 100 seconds counting time). Both core

and rim compositions were analysed for each mineral grain with the simultaneous

analysis of Si, Ti, Al, Cr, Fe, Mn, Ca, Mg, Na, K, and P. Fluorine and chlorine were

analysed using wave-dispersal spectrometric analysis (WDS) (accelerating voltage of

15 kV; 20 nano-amperes current; 60 seconds counting time) using a defocused beam

(5x5 microns area). The fluorine and chlorine results represent an average

composition of the analytical area. ASTIMEX Scientific Ltd. mineral standards

(plagioclase, diopside and almandine for silicates; obsidian, fluorite and tugupite for

halogens) were analysed before and between sample changes.

Fe2+/Fe3+ ratios in biotite were calculated using ratios established by

analytical chemistry. Biotite from the different plutons were separated and

concentrated by L-1 model Frantz isodynamic magnetic separator (250 µm fraction;

18o side-slope; 6.25A current; vibration speed of 9). The mineral separates were

analysed for Fe2+ and Fe3+ by titrametric method (Appendix 1) and these ratios were

used to calibrate the Fe2+/Fe3+ ratio of biotite from respective plutons.

Mineral stoichiometric recalculation and classification were done using the

MINPET (1997) program. Structural formulae of hornblende, feldspars, pyroxenes,

magnetite, ilmenite and biotite are based on 23, 32, 6, 32, 6 and 22 oxygens,

respectively. All mineral chemistries presented in this thesis (Appendix 3) have the

appropriate mineral stoichiometry. The abbreviations of cationic sites in the mineral

stoichiometry are adopted from Deer et al. (1992) (T for tetrahedral site and C, B, A

for octahedral sites and in biotite and feldspars, Z represents tetrahedral site and Y for

octahedral site). The allocation of Fe2+ and Fe3+ in pyroxenes is based on cation

balance stoichiometric calculation of Droop (1987), in hornblende by combined

methods of Droop (1987) and Leake (1978), and in Fe-Ti oxide minerals by method

of Buddington & Lindsley (1964).


23

Ages

Three magmatic biotite separates from the SCIC were dated by argon-argon

method (Deino & Potts, 1990) at the University of Berkeley in the USA. The biotite

crystals were extracted from fresh rocks that have not undergone subsolidus reaction

or recrystallisation. The plateau ages from these single-biotite crystals yielded

precision of + 0.5 Ma (one-σ, Table 4.1).

Two hornblende separates were dated by K-Ar method at the University of

Queensland using the isotope dilution method of Dalrymple & Lanphere (1969). The

argon isotopes were analysed on a VG Gas Analysis 8-80 mass spectrometer, and the

K2O content of the samples were determined by ICP-OES. Ages are calculated using

the decay constants of Steiger & Jager (1977) with quoted errors at one-σ.

Chapter3: Geological Setting

24

CHAPTER 3: THE GEOLOGICAL SETTING OF THE STATION CREEK

IGNEOUS COMPLEX

Introduction

The Station Creek Igneous Complex consists of multiple plutons intruded

into the Devonian-Late Carboniferous accretionary wedge (termed the Wandilla

Complex) of the North D’Aguilar Block. The North D’Aguilar Block (NDB) is a

fault-bounded tectonic fragment of the northern New England Orogen (NNEO) that

has been extensively mapped by the Geological Survey of Queensland (Ellis, 1968,

Brooks et al., 1974; Murphy et al., 1976; Murray et al., 1979; Cranfield, 1999;

Donchak et al, 1995, 1999; Tang & Pascoe, 2002). The NDB is a significantly

mineralised, NNW-trending block that extends for approximately 160 kilometres in

length and less than 40 kilometres in width (Figure 3.1). The Electra Fault separates

the NDB from the more eastern Gympie Block (Cranfield et al., 1997). In the west,

the NDB is separated from the Lower Triassic Esk Trough by the steep west-dipping

Perry Fault (Ellis, 1968). Small Early Permian extensional marine basins are located

on or near the boundary between the Esk Trough and the NDB (Northbrook and

Marumba Blocks), or within the NDB (Cambroon Block) (Sliwa et al., 1993b). The

NDB is separated from correlative accretionary complex rocks of the South D'Aguilar

Block by the North Pine Fault. The Nambour Basin (Late Triassic-Jurassic) partly

overlies the NDB to its north and to the southeast and locally conceals the contact

between the NDB and the Gympie Block.

The NDB was subjected to the complex tectonic history of the Palaeozoic

rocks within NNEO to form three tectonostratigraphic assemblages- Lower Plate

Assemblage, Upper Plate Assemblage and a Late Permian thrust sheet (Figure 3.2;

Little, 1993; Holcombe et al., 1993). Units within respective assemblages are

summarised in Table 3.1.

During the Late-Carboniferous extensional phase, crustal detachment along a

low angle detachment fault (the Mount Mia Fault), juxtaposed deeper level rocks

(Lower Plate Assemblage) against the higher level rocks (Upper Plate Assemblage).

The Lower Plate Assemblage has a unique two-stage metamorphic history of an

earlier transitional epidote-blueschist facies (M1), which retrogressed to a greenschist

facies (M2). The Lower Plate Assemblage comprises mafic schists (Widgee


25

Figure 3.1: The geologic elements of southeast Queensland highlighting the relationship between the North D'Aguilar Block to surrounding geology

. Major research area is highlighted. Plutons: 1. Station Creek Igneous Complex, 2.Boonara Granodiorite, 3. Calgoa Diorite, 4. Boogooramunya Granite, 5. Yorkeys Diorite, 6. Black Snake Porphyry, 7. Kingaham Creek Granodiorite, 8. Kimbala Granodiorite, 9. Monsildale Granodiorite, 10. Neurum Tonalite, 11. Dayboro Tonalite 12. Mt Samson Granodiorite, 13. Eerwahvale Tonalite, 14. Woondum Granite, 15. Cedar Pocket Porphyry, 16. Goomboorian Diorite, 17. Mungore Granite, 18. Musket Flat Granodiorite, 19. Broomfield Granite, 20. Tawah Granite, 21. Degilbo Granite, 22. Hogback Granite, 23. Wonbah Granodiorite, 24. Mt Urah Granodiorite, 25. Tungi Creek Granodiorite, 26. Briggs Granodiorite; 27. Wolca-Tenningering Granitoids, 28. Chowey-Mingo Granites, 29. Wigton Granite, 30. Boondooma Igneous Complex, 31. Taromeo Tonalite,32. Claddagh Granodiorite, 33. Gallangowan Granodiorite

(compiled from 1:250,000 Maryborough, Gympie and Ipswich geology maps) Carboniferous to Jurassic plutons and the

N

Electra Fault

Perry Fault

North Pine Fault

Great Moreton Fault

Bracalba Fault

Maryborough

26 00’So

26 30’So

27 00’So

27 30’So

Brisbane

Gympie

Jimna

Murgon

Kingaroy

Nanango

152

30’E

o 153

00E

o

25 00’So

26 00’So

26 30’So

152

30’E

o

153

00’E

o

153

30’E

o15

330

’Eo

Clarence-Moreton Basin

Cressbrook Creek Group

Northbrook Beds

Ipswich Basin

Nambour Basin

CambroonBeds

Marumba Beds

GympieBlock

Yarraman Block

EskTrough

Maryborough Basin

Gympie Block

GoodnightBlockCoastal

Block

Station CreekIgneous Complex

SouthD’Aguilar Block

NorthD’AguilarBlock

1

2

34

5

7

8

9

10

11

12

6

13

1415

16

17

17

1

18

19

20

21

22

23

24

25

2726

28

29

29

30

3031

32

33

2500’So

28 So28 S

o

26 So

26 So

24 So

152 00’o

1 5 2 0 0 ’ Eo

D’Aguilar Blocks

Bowen Basin

Area enlarged

Brisbane

Gympie Block

Northern NEO

0 200 km

GympieProvince

Study Area

TarongBasin

Plutonic and subvolcanic unitsLate Jurassic to Early Cretaceous intermediate to acid intrusion (138-140 Ma)

Late Triassic granites and felsic subvolcanic intrusions (210-228 Ma)

Early to Middle Triassic granites to diorites (231-238 Ma)

Permian to Early Triassic granites, diorites and gabbros (254-244 Ma)

Late Carboniferous S-type granites (297-307 Ma)

Early to Middle Triassic volcanics and continental sediments (+ Permian?)

Permian marine sediments and volcanics

1 0 2 0 3 0 k m

?Permian to Carboniferous sediments andvolcanics

Mid Devonian-Carboniferous accretionaryrocks (basement rocks)

LEGEND

Basement rocks

Fault


26

Fault with sense of movement indicated

UNITS LITHOLOGY ASSOCIATION

Mount Mia Serpentinite (DCs) 3. Talamy Schist 4. Greenschist 5. Marble 6. Blueschist

Gobongo Metamorphics (DCg), Kurwongbah beds

Widgee Metamorphics (Dce), Wongella Metamorphics [Rocksberg Greenstone and Peters Creek Greenstone]

Phyllite, schist and metasiltstone.

Tremolite-actinolite-chlorite schist, serpentine, greenschist.

Serpentine, reworked serpentinitic sediment, lenses of 3biotite-muscovite schist, 4greenschist blocks, 5rounded marble clasts, and 6crossite-albite schist.

Undifferentiated andesitic and rhyolite, epiclastic sediments.

Late Triassic andesite and rhyolite (Ra)

North Arm Volcanic Group & Aranbanga Volcanic Group

Early Triassic Esk Trough sediments (Rn)

Volcanics, volcanogenic sediments, conglomerate, arkose and mudstone.

Neara Volcanics, Esk Formation, Gayndah Formation and Bryden Formation.

1Highbury Volcanics and Rammutt Formation; 2[Cedarton Volcanics, Marumba beds, Kandanga Creek Megabreccia and Cambroon beds]

1Volcanic flows and 2intrabasinal volcanogenic sediments and siltstone.

Early Permian volcanogenic sediments (Pgh)

Wratten Igneous Suite (Cgd); Manumbar Metamorphics and Wide Bay Creek Gneiss (Cm)

Late Permian syntectonic granitoids and associated metamorphic aureole, mylonitised.

CLADDAGH THRUST SHEET ASSEMBLAGE

Amamoor beds, Undifferentiated Carboniferous sediment and greenstone lenses (Dcab); [Boolouma beds]

Mudstone and slate, phyllite, chert, jasper, siltstone and intervening greenstones.

UPPER PLATE ASSEMBLAGE (DCa)

~~~~~~~~~~~~~~~~~~~~~~~~~~~ Unconformity ~~~~~~~~~~~~~~~~~~~~~~

Anderson Creek Phyllite (DCan), [Jimna Phyllite ]

Polydeformed phyllite

LOWER PLATE ASSEMBLAGE (DCs, DCg, Dce)

~~~~~~~~~~~~~~~~~~~~~~~~ Claddagh Thrust ~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~~~~~~~~~ Mount Mia detachment fault ~~~~~~~~~~~~~~~~~~~~

SCHEMATIC STRATIGRAPHIC SECTION (Not to scale)

Ra

Rn

Pgh

Cgd

Cm

DCan

DCs

DCe

DCg

DCa

DCab

Claddagh Thrust

Mount Mia Fault

3 4

5

6

Figure 3.2: Schematic tectonostratigraphy showing the 3 rock assemblages of the

northern North D’Aguilar Block in southeast Queensland. Each association comprises of numerous units, and unit(s) in parenthesis are stratigraphic- or age-equivalent units. (Tectonostratigraphy is modified from Little et al., 1993a, unit descriptions from Cranfield, 1994; Crouch et al., 1995; Donchak et al., 1995; Ellis, 1968; Little, 1993; Murphy et al., 1976; Sliwa, 1994; Tang & Gust, 2000 and Tang (2003).


27

Table 3.1: Stratigraphy of the North D’Aguilar Block of the Northern New England Orogen, southeast Queensland.

STRATIGRAPHIC UNIT DESCRIPTIONS REFERENCES

North D’Aguilar Block

Upper Plate Assemblage - Zeolite to greenschist facies metamorphism, accretionary wedge sequences

Undifferentiated Carboniferous sediments

Mudstone with subordinate siltstone, chert layers, jasperoid and manganiferous bands, and basaltic flows. Mineralogy reflects zeolite to sub greenschist facies with the incipient recrystallisation of clay.

Ellis (1968); Murphy et al. (1976); Donchak et al. (1995); Fuller (1988)

Amamoor Beds (Late Devonian to Early Carboniferous)

Massive and thin-bedded jasper, chert, slate and altered volcanics, and siliceous arenite and shale with or without chert lenses

Scott et al. (1991); Holcombe et al. (1993); Cranfield & Scott (1993), Little et al. (1993a); Sliwa et. al. (1993a)

Booloumba Beds (Late Devonian to Early Carboniferous)

Rhythmically interbedded quartzose and slate with interbeds of green and haematitic slate, quartzite and pillow basalt

Holcombe et al. (1993); Sliwa et. al. (1993b)

Jimna Phyllite (Late Devonian to Early Carboniferous)

Slate, Phyllite, metachert and mafic greenschist Holcombe et al. (1993); Sliwa et. al. (1993a)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ FAULT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Assemblage between Upper Plate and Lower Plate assemblages - Low grade metamorphism, polydeformed unit between the Upper and

Lower Plate Assemblages Anderson Creek Phyllite

(Late Devonian to Early Carboniferous)

Phyllite Holcombe et al. (1993); Little et al. (1993b)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ FAULT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Lower Plate Assemblage – Two-stage (blueschist followed by retrograde greenschist) metamorphism, polydeformed, accretionary wedge sequences

Talamy schist (Late Devonian to Early Carboniferous)

Mica schist, albite-rich blueschist (retrograded) and quartzite.

Donchak et al. (1995)

Mount Mia Serpentine (Late Devonian to Early Carboniferous)

Serpentine-matrix melange containing clasts of phyllite, massive serpentine and less common mafic greenschist, marble and epidote blueschist.

Holcombe et al. (1993); Little et al. (1993a & b); Cranfield & Scott (1993)

Gobongo Metamorphic (Late Devonian to Early Carboniferous)

Interbedded phyllite and schist. Tang (2003); Donchak et al. (1995)

Kurwongbah beds (Late Devonian to Early Carboniferous)

Feldspathic phyllite and siliceous phyllite with minor greenschist and metasiltstone

Dobos et al. (1993); Holcombe & Little (1993); Holcombe et al. (1993)

Widgee Metamorphic (Late Devonian to Early Carboniferous)

Blastoporphyriric greenschist. Donchak et al. (1995)

Wongella Metamorphic (Late Devonian to Early Carboniferous)

Clast-in-matrix melange, greenschist and serpentine. Donchak et al. (1995)

Peters Creek Greenstone (Late Devonian to Early Carboniferous)

Mafic greenschist, volcanoclastic greenstone and metagabbro

Sliwa et al. (1993a), Sliwa (1994)

Rocksberg Greenstone (Late Devonian to Early Carboniferous)

Augite-bearing greenschist and transitional blueschist with minor volcanoclastic greenschist, black graphitic schist, mafic metasandstone, serpentine and peridotite

Dobos et al. (1993); Holcombe & Little (1993); Holcombe et al. (1993)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ FAULT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Assemblage 3: Foliated synkinematic granodiorite and metamorphic aureole

Wratten Igneous Suite (Late Carboniferous syntectonic granodiorites)

Coarse to medium grained, foliated biotite granodiorite Tang & Gust (2000); Donchak et al. (1995); Murphy et al. (1976); Brook et al. (1974)

Manumbar Metamorphic (Carboniferous)

Reddish brown, fine- to medium-grained, mafic gneiss to schist, amphibolite, greenschist and phyllite.

Tang (2003); Donchak et al. (1995)

Wide Bay Creek Gneiss (Carboniferous)

Fine- to medium-grained quartzo-feldsphatic gneiss Donchak et al. (1995)

Footnote: Detailed descriptions of units mapped within this thesis are documented in Tang (2003).


28

Metamorphics), phyllites (Gobongo Metamorphics), biotite-schist (Talamy Schist),

clast-in-matrix melange (Wongella Metamorphics), and an overlying sheet of

serpentinite-matrix melange (the Mount Mia Serpentinite). The Mount Mia

Serpentinite contains metres-to-kilometre sized exotic blocks of blueschist,

greenschist and metasediment (Donchak et al., 1995). The mafic schists and phyllite

of the Lower Plate Assemblage are correlative with the Rocksberg Greenstone and

Kurwongbah beds of the South D’Aguilar Block respectively. A thin, discontinuous

layer of polydeformed phyllite (Anderson Creek Phyllite) which occurs on the Mount

Mia Serpentinite sheet may correlate with the Jimna Phyllite in the southern part of

the NDB and the Bunya Phyllite of the South D’Aguilar block.

The Upper Plate Assemblage includes the Amamoor Beds, the Booloumba

beds and an undifferentiated Carboniferous sedimentary unit (Donchak et al., 1995).

The accretionary wedge rocks consist mainly of interbedded shale and ribbon chert,

with minor fault-bounded lenses of massive or pillowed greenstone. The rocks have a

single-stage regional metamorphic history with regional metamorphic grades ranging

up to greenschist facies. Rocks of the Upper Plate Assemblage are correlative with the

greywacke-poor, eastern part of the Neranleigh-Fernavale beds in the South

D’Aguilar Block.

An assemblage of Late Carboniferous syntectonic granodiorites - the Wratten

Igneous Suite of Tang & Gust (2000), Wide Bay Creek Gneiss of Donchak et al.

(1995) and associated contact metamorphic aureole rocks (Manumbar Metamorphics)

form the Late Permian Claddagh thrust sheet. The Wratten Igneous Suite comprises

the Claddagh Granodiorite, Gallangowan Granodiorite, Karandah Granodiorite and

outliers of an unnamed foliated granodiorite. The Manumbar Metamorphics defines a

zone of thermal metamorphosism that surrounds the syntectonic granodiorites. Within

this zone, hornblende hornfels facies metamorphism overprints regionally

metamorphosed amphibolite, phyllite and quartzite. The Claddagh thrust sheet

overlies the Upper Plate Assemblage near the western edge of the NDB.

Early Permian extensional basins containing the Marumba beds, Cambroon

beds, Kandanga Creek Megabreccia and Cedarton Volcanics occur on the margin and

within the NDB (Sliwa et al., 1993b; Donchak et al., 1995). Coarse mass-flow clastic

deposits derived from the surrounding basement rocks, and intrabasinal marine

volcanogenic sediments, andesite to rhyolite, and volcaniclastic rocks fill these basins.


29

Early Triassic volcanic rocks of the Toogoolawah Group comprise

volcanoclastic rocks, volcanogenic sedimentary rocks, interbedded fluvial

sedimentary rocks and conglomerates (Murphy et al., 1976; Day et al., 1983;

Bischoff, 1986). The Toogoolawah Group consists of equivalent basal units- the

Gayndah Formation in the north and the Bryden Formation in the south. The Neara

Volcanics and the Esk Formation (in ascending stratigraphic order) overlie the basal

unit, and their combined thickness is approximately 6000 metres (Campbell et al.,

1999). The main volcanic sequence, the Neara Volcanics, is confined mainly to Esk

Trough, but has isolated erosional outliers on hilltops and in down-faulted depressions

within the NDB (Murphy et al., 1976, Bischoff, 1986). The thickness of the Neara

Volcanics on the North D’Aguilar Block is estimated at <300 metres (Murphy et al.,

1976; Bischoff, 1986), whereas within the Esk Trough, this unit attains a total

thickness of approximately 2170 metres (Cranfield & Murphy, 1983). The ages of the

volcanic rocks from the Neara Volcanics are 240 + 3 Ma (K/Ar whole rock) (Sliwa et

al., 1993a), 241 + 11 Ma (Ar/Ar whole rock) (Cranfield et al., 1976) and 242 + 8 Ma

(K/Ar hornblende) (Murphy et al., 1976).

Orogenic and post-orogenic plutons intrude the NDB (Table 3.2). These

intrusive units range in age from Late Carboniferous to Late Triassic, with minor

Early Jurassic intrusions. Gust et al. (1993, 1996) identified several magmatic epochs

in south-east Queensland that reflected the oscillating signatures of extensional and

contractional tectonics. An earlier pre-300 calc-alkalic magmatism was followed by

bimodal magmatism between 265 to 250 Ma. Widespread calc-alkalic magmatism

recurred between 250-220 Ma and subsequent plutonism between 220 to 210 Ma was

mostly anorogenic. Tang & Gust (2000) identified two distinct peraluminous and

metaluminous groups in the Late Carboniferous plutons of the NDB. The Permian to

Middle Triassic plutons in the NDB are metaluminous and calc-alkalic, and they include

the Station Creek Igneous Complex, which intrudes both the Upper and Lower Plate

Assemblages (Crouch et al., 1997; Tang & Gust, 2000).

A flat-lying sequence of Middle-Late Triassic andesite to dacite,

volcanoclastic and epiclastic rocks unconformably overlies the Palaeozoic rocks and

the Neara Volcanics (Little, 1993). Murphy et al. (1976) dated a volcanic rock from

this sequence as 232 Ma (K/Ar, whole rock). This age is similar age to that of the

North Arm Volcanics and the Station Creek Igneous Complex. NW, NS and


30

Table 3.2: Intrusive units in the North D’Aguilar Block of the Northern New England Orogen, southeast Queensland.

UNIT AGE (Ma) LITHOLOGY REFERENCES Mount Mee Granophyre

Mid-Late Triassic? Granophyre Cranfield et al. (1976)

Boogooramunya Granite

214-226 (Mid Triassic) Biotite granite, granophyre Cranfield & Murray (1989a, 1989b)

Neurum Tonalite 228 + 2 (K/Ar; Mid Triassic) Biotite-hornblende tonalite and granodiorite, porphyritic tonalite

Moultrie (1995); Day et al. (1983); Murphy et al. (1976); Webb & McDougall (1967)

Station Creek Granodiorite

231+ 7, 236 (K/Ar biotite; Early -Mid Triassic

Hornblende-biotite granodiorite to quartz monzodiorite, hornblende diorite, biotite granite, hornblende-biotite monzonite

Crouch et al. (1997); Cranfield & Murray (1989a; 1989b); Day et al. (1983); Murphy et al. (1976); Brooks et al. (1974); Webb & McDougall (1967)

Black Snake Porphyry

233 (K/Ar biotite; Early Triassic)

Porphyritic, hornblende-biotite diorite to quartz diorite.

Herbert (1983); Murphy et al. (1976)

Boonara Granodiorite

233 + 3 (K/Ar hornblende; Early Triassic)

Hornblende-biotite granodiorite, granodiorite, porphyritic augite quartz microdiorite

Cranfield & Murray (1989a, 1989b)

Calgoa Diorite 234 + 2 (K/Ar hornblende; Early Triassic)

Hornblende-biotite granodiorite, hornblende diorite, pyroxene diorite

Cranfield & Murray (1989a, 1989b); Trezise & Graham (1984)

Kingham Creek Granodiorite

239+8 (K/Ar biotite); 220; (Late Permian-Mid Triassic)

Biotite-hornblende granodiorite Day et al. (1983); Murphy et al. (1976); McNaughton (1973); Webb & McDougall (1967)

Tungi Creek Granodiorite

226 (biotite; Late Permian? - Mid Triassic)

Hornblende-biotite granodiorite Day et al. (1983); Murphy et al. (1976)

Dayboro Tonalite 238 (Late Permian-Early Triassic)

Pyroxene-biotite tonalite, biotite-pyroxene quartz diorite

Day et al. (1983); Cranfield et al. (1976)

Kimbala Granodiorite

Late Permian-Early Triassic? Medium to coarse grained, hornblende-biotite granodiorite

Day et al. (1983); Murphy et al. (1976); McLeod (1954)

Monsidale Granodiorite

234 + 3; 253 + 3 (K/Ar Hornblende; Late Permian-Early Triassic)

Hornblende-biotite granodiorite, hornblende diorite, olivine gabbro, orbicular gabbro

Kiewcien (1996); Sliwa (1994); Day et al. (1983); Murphy et al. (1976); McLeod (1954)

Avoca Creek Granodiorite

255 + 5 (K/Ar hornblende; Late Permian-Early Triassic)

Fine-medium grained, porphyritic hornblende-biotite granodiorite to diorite.

Grayson (1995); Crouch et al. (1995)

Mount Warrawee Intrusive Complex

Late Permian-Early Triassic? Gabbro, microgabbro, biotite-pyroxene tonalite, biotite tonalite

Scott & Cranfield (1993); Cranfield & Scott (1993); Murphy et al. (1976)

Yorkeys Diorite Late Permian-Early Triassic? Hornblende diorite, hornblende gabbro, quartz diorite, granodiorite, granite

Cranfield & Murray (1989a)

Capsize Creek Complex

Carb. to Permian Fine-medium grained biotite-hornblende diorite, biotite granodiorite, biotite-hornblende granodiorite, foliated.

Crouch et al. (1995)

Coppermine Creek Granodiorite

Late Carboniferous Medium-coarse grained, biotite-hornblende (augite) granodiorite to diorite, foliated

Crouch et al. (1995); Harris (1986)

Claddagh Granodiorite

307 + 1 (Ar/Ar hornblende; Late Carboniferous)

Medium-coarse grained, porphyritic biotite granodiorite, foliated, syntectonic and mylonitic.

Sliwa (1994); Little et al. (1993a); Little et al. (1992); Day et al. (1983); Murphy et al. (1976); Hayden (1971); Smith (1964)

Yabba Creek Granodiorite

317 + 3 (K/Ar hornblende; Late Carboniferous)

Fine-medium grained hornblende-biotite granodiorite, slightly foliated.

Sliwa (1994); Sliwa et al. (1993a)

Gallangowan Granodiorite

320 + 10 (K/Ar biotite; Late Carboniferous)

Porphyritic biotite granodiorite, foliated, S-type granite affinity

Sliwa (1994); Day et al. (1983); Murphy et al. (1976); NcNaughton (1973)

Karandah Granodiorite

Late Carboniferous Porphyritic biotite granodiorite, foliated and mylonitic.

Cranfield & Murray (1989a); Brooks et al. (1974)


31

NE-trending andesite and rhyolite dykes of Late Triassic age (Roberts, 1992) intrude

the Neara Volcanics, the Station Creek Igneous Complex and the Palaeozoic

basement.

Structure and tectonics

The major regional structure in the North D’Aguilar Block is a gently folded,

doubly plunging, NNW-trending antiform named the Talamy Arch (Little, 1993). The

Talamy Arch exposed a Late Carboniferous low angle detachment fault (the Mount

Mia Fault) which has an underlying metamorphic core complex. The rocks below the

detachment fault (i.e. the Lower Plate Assemblage) are characterised by two

metamorphic events (Holcombe et al., 1993). The earlier Middle Carboniferous

metamorphism is related to subduction tectonics (D1), and attained a transitional

blueschist facies (M1). The M1 mineralogy is overprinted by a latter regional

greenschist facies metamorphism (M2) associated with the exhumation of deep level

rocks (Little et al., 1993b). The resulting structural fabrics produced within the Lower

Plate Assemblage are tight north-plunging recumbent folds, steeply dipping NNW and

NE foliations (S1), and a subhorizontal crenulation foliation (S2). Table 3.3 summaries

the tectonic and structural history of the NDB.

The Upper Plate Assemblage rocks have attained a sub-greenschist facies

metamorphism and contain only a single steeply-dipping slaty cleavage (S1). The

original bedding is commonly preserved and typically disrupted into boudins.

The Late Permian thrust-dominated deformation generated a NNW foliation

and was accompanied by a low grade burial metamorphism to prehnite-pumpellyite

facies (Sliwa et al., 1993b). In the Kilkivan area, thin-skinned thrusting of the Upper

Plate Assemblage (Amamoor beds) formed a series of imbricate wedges with the

Lower Plate Assemblage rocks (e.g. Mount Mia Serpentinite) (Donchak et al., 1995).

Along the Mount Clara Fault, the Amamoor beds were thrusted over the Lower Plate

Assemblage rocks (the Mount Mia Serpentinite, Gobongo Metamorphics), the

Karandah Granodiorite and the Manumbar Metamorphics along part of the Mount

Mia detachment fault.

In the post-Mid Triassic period, the geologic blocks of the NDB were

readjusted and/or tilted. Some faults were reactivated at this time - in particular the


32

Table 3.3: Tectonic and magmatic history of the northern region of North D’Aguilar Block of the NNEO, southeast Queensland.

ERA MAJOR EVENTS 11, 12, 13, 20

TECTONISM AND GEOLOGICAL FABRICS

MAGMAT ISM 10

IGNEOUS UNITS

JURASSIC

Faulting

Sinistral movement17

Minor intrusions

TRIASSIC

205 Ma LATE TRIASSIC MID TRIASSIC 230 Ma EARLY TRIASSIC

Faulting ??Docking of Gympie Block4 229 Ma: Andesite dykes and volcanoclastics flows; faulting11

Plutonism

Volcanism

Extension 18, 19, 20 WNW dextral fault and enchelon quartz veins; down to west high angle normal fault, NNW (F3) and NE upright kinks and folds (F4)11, 12 Andesite dykes along E-W, NW-SE8, 12 Tilting and folding of Neara Volcanics along NNW axial planes12 Esk Trough formed and infilled11, 18, 20

Post 220 Ma: I- and A-type granites 220 to 230 Ma: Widespread magmatism 230 to 250 Ma: Widespread calc-alkaline magmatism

E.g. Mungore Granite (215-228 Ma) North Arm Volcanics and dykes (232-229 Ma)9,22 Station Creek (227-231 Ma)21, Boonara (233 Ma)6, 7; Black Snake (233 Ma)1,

3; Calgoa (234 Ma)6, 7

Neara Volcanics (240-242 Ma)1, 15

250 to 260 Ma: Limited bimodal magmatism.

PERMIAN

251 Ma LATE PERMIAN EARLY PERMIAN

Hunter-Bowen Orogeny20

260-262 Ma: Uplift and folding (Texas-Coff Harbour orocline)5

270 Ma: Gympie arc14

Claddagh Thrust: Eastward thrusting of the foliated peraluminous granodiorite and associated metamorphic aureole over the Upper Plate Assemblage; ductile deformation to mylonitisation, uplift, block faulting and erosion, dextral movement, N-S wrenching, Esk Trough formed and filled-in, NNW folding2, 11, 12, 13 New Gympie arc formed to the east14. Formation of extensional Permian basins e.g. Marumba and Cambroon basins16, embroyic stage of the Esk Trough.

260 to 300 Ma: Limited magmatic activity.

Avoca Creek Granodiorite (255 Ma)22, Monsidale Granodiorite (253 Ma)22

CARBONIFEROUS

298 Ma UPPER CARB MID CARB. 340 Ma EARLY CARB. 354 MA

296-299 Ma: Uplift/ exhumation and extension since 318 Ma8, 16 320 to 340 Ma: Change from subduction to extension. Ceased active accretion at ~320 to 340 Ma. Up until Lower Carb: Subduction and thrusting only in accretionary complex decoupled from craton.

Uplift, juxtaposition of the Lower Plate against the Upper Plate Assemblages along the Mount Mia detachment fault, greenschist facies metamorphism (M2), east-west extension, subhorizontal crenulations (S2), NNW trending upright folds and the formation of the Talamy Arch.11, 12, 13 Westward thrust-imbrication and subduction underplating (D1), blueschist facies metamorphism (M1) of the Lower Plate Assemblage11,13, NNW to NE schistosity (S1), northward reclining folds2, 5, 8

300 to 350 Ma: Calc alkalic magmatism

Foliated peraluminous granitoids e.g. Claddagh Granodiorite (306 Ma)8

1Murphy et al. (1976); 2Murray (1997); 3Herbert (1983); 4Harrington & Korsch (1985a); 5Korsch et al. (1988); 6Cranfield & Murray (1989a); 7Cranfield & Murray (1989b); 8Little et al. (1992); 9Roberts (1992); 10Gust et al. (1993, 1996); 11Holcombe et al. (1993); 12Little (1993); 13Little et al. (1993a, b); 14Sivell & McCulloch (1993, 1997); 15Sliwa et al. (1993a); 16Sliwa et al. (1993b); 17Veevers et al. (1993); 18Ashley et al. (1996); 19Nash & Jones (1996); 20Holcombe et al. (1997a & b); 21Brooks et al. (1974); 22Geological Survey of Queensland database, Cranfield et al., 2002.

Abbreviations: EXT = Extensional tectonics, CON = Contractional tectonics, TR = Transpression

C

O

N 20

?

?

305 Ma

SUB

DU

CT

ION

E

X

T

R11

E

X

T20


33

WNW-striking brittle faults have a dextral-slip motion. The Neara Volcanics is folded

and tilted by at least two episodes of deformation (Little, 1993). The post-Mid

Triassic structural fabric includes at least two upright sets of kinks and folds, along a

NNW trend (F3) and a NE trend (F4).

THE PALAEOZOIC STRATIGRAPHY

The results of geological mapping of the Station Creek Igneous Complex as part of

this research (Figure 3.3) have been published in the Goomeri 1:100,000 geology

map, second edition (Tang & Pascoe, 2002). The new findings enable the

simplification of the geology by combining stratigraphic equivalent units as well as

the recognition of new units. Previously defined units such as the Murdering Creek

Metamorphics, the Mount Clara beds and the Oakview Metamorphics were combined

into the Gobongo Metamorphics, the Amamoor beds and the Manumbar

Metamorphics respectively. The presence of Early Permian volcanics (the Highbury

Volcanics and Rammutt Formation of the Gympie Group) has been identified on the

North D’Aguilar Block. The ‘Wratten Igneous Suite” was introduced to group the

various Late Carboniferous syntectonic granodiorites based on similar

tectonostratigraphy, age and geochemistry (Tang & Gust, 2000). A Late Triassic

andesitic to rhyolitic volcanic unit equivalent to the North Arm Volcanics and

Aranbanga Volcanic Group, was mapped overlying unconformably on the Neara

Volcanics in the Mount Sinai region. The detailed description of units in the study area

is documented in the accompanying geological map commentary (Tang, 2003).

The Lower Plate Assemblage

Mapping within this thesis indicates the Gobongo Metamorphics is a

structurally coherent unit of interlayered phyllite and siliceous quartz-mica schist. Rare,

thin layers of mafic greenschist occur within the sequence. The phyllite weathers to

reddish-brown colour and forms flaggy outcrops, whereas the quartz-mica schist

weathers to a lighter grey colour and forms more massive, erosionally resistant outcrops.

Layers of phyllite, schist, and white-coloured quartz laminae 1 millimetre thick that

form subparallel to the compositional layerings, give the unit a conspicuously striped

appearance. The Rush Creek Granodiorite intrudes the


34

DCs

DCs

DCs

DCs

DCs

DCs

DCs

DCs

DCs

DCe

DCe

DCe

DCe

DCe

DCe

DCe

DCe

DCeDCe

DCeDCe

DCe

DCt

DCt

DCg

DCg

DCg

DCg

DCg

DCg

DCg

DCg

Dcg

DCg

DCg

DCg

DCg

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCa

DCac

DCa1

DCa1

DCab

DCab

DCab

DCac

DCac

DCac DCac

Pzj

Cgc

Cgc

Cgc

Cgc

Cgc

Cgc

Cgd

Cgd

Cgd

Cgd

Pgh

Pgh

Pgh

Pgh

Pgh

Pgh

Pgh

Pgha

Pgha

Pgha

Pgr

Pmt

Pmt

Pmt

Pmt

Pch

Pch

Pch

Pch

Cma

Cma

Cma

Cma

Cmp

Cmp

Cmp

Cw

Cq

Jt

Jm

Jm

Jm

MOUNT MUCKI DIORITE

WOONGA GRANODIORITE

Rgmm

Rga

Rg

Rg

Rg

Rg

Rg

Rg

Rg

Rg

Rr

Black SnakePorphyry

Neureum Porphyry

Mountain

Rgl

Rgl

Rgl

Rnc

Rnc

Rnc

Rnc

Rnc

Rn

Rn

Rn

Rn

Rn

Rn

Rn

Rn

Rn

Rn

RaRa

RaRa

71290 0 0 m N

2615’So

2600’So 2600’S

o

152

30’E

o

71000 0 0 m N

70900 0 0 m N

450

00

0m

E

422

00

0m

E

450

00

0m

E

2615’So

152

15’E

o

152

15’E

o

Pch

DCa

Rg

Native CreekMicrogranite

WOOLOOGAGRANODIORITE

Rgw

RUSH CREEKGRANODIORITE

Wratten's camp

DCs

Ra

Kilkivan

Gibraltar Rock

MountMucki Ghrooman

Bille MountainMount Sinai

Woolooga

DevilsMount

WidgeeMountain

Widgee

Mount Clara Thrust

Claddagh ThrustLong Tunnel Thrust

Rgg g

Rgg g

Mount Mia

Rgw

GIBRALTAR QUARTZMONZODIORITE

71100 0 0 m N

71200 0 0 m N

71000 0 0 m N

70900 0 0 m N

440

00

0m

E

430

00

0m

E

71100 0 0 m N

71200 0 0 m N

430

00

0m

E

440

00

0m

E

Ra

DCn

Mou

nt M

ia D

etac

hmen

t Fau

lt


35

Figure 3.3: The solid geology of the Station Creek Igneous Complex and the surrounding stratigraphic units of the northern North D'Aguilar Block, southeast Queensland.

DCaDCa

1

DCabDCac

DCs

SCALE 1: 150,000

0 2 4 6 8 10 km

Quartz arenite with minor layers of shale, siltstone and conglomerate.Myrtle Creek Sandstone

Hornblende quartz monzodiorite, monzogranitegranodiorite and Unnamed intrusive

LEGEND

Kilkivan

Thrust fault, triangle points down-dip

SymbolsGeological boundary

Fold axis

Fault

Inferred fault

Dykes

Road and tracks

Township

Lower Permian

Early Triassic

Late Triassic

Upp

er P

late

Late Triassic to Early Jurassic

Shale, mudstone, siltstone and minor sandstone Tiaro Coal Measures

Andesite, trachyandesite and volcanoclastic rocks with polylithic xenoliths. Ra North Arm Volcanics

Stratified rhyolite and dacite tuff, siltstone and sandstone.Rammutt Volcanics

Pch

Grey-green, brown mudstone with minor laminae of chert and metabasalt.

Grey, green, black fragmental chert and silicic mudstone.Oakview Mudstone

ManumbarMetamorphics

Slate, phyllite, chert with lenses of greenschist and silicified metavolcanics.

Jasperoid and haematitic chert, fragmental.

Chert and cherty mudstone

Metabasalt lenses

Hornblende-albite-epidote amphibolite, strong mineral lineation, upper greenschist facies.

Garnet bearing finely laminated quartzite, metasandstone, and metasiltstone.

Cma

Pelitic phyllite, silicified, fragmental and contains numerous quartz veins.

Amamoor beds

Basic to intermediate volcanics and volcanoclastic sediments with intervening layers of siltstone, mudstone and conglomerate.Neara Volcanics

Pyroclastic volcanics with minor epiclastic sediment with polylithic component.

Serpentine, foliated and schistose, localised shearing, comprises greenschist and marble lenses .

Tremolite-actinolite-chlorite schist, schistose, crenulation cleavages, interlayered with minor serpentine, c and pelitic schist.

rossite-albite-chlorite schist

Biotite-muscovite schist.

Low

er P

late

Phyllite with minor lenses of greenschist.

DCt

DCg

Phyllite, slate and mudstone with lenses of greenschist and altered volcanogenic sediment.

Mount Mia Serpentine

Late CarboniferousMedium grained, hypersthene-augite diorite; foliated, deformed and chloritised.Foliated diorite

Porphyritic biotite granodiorite with K-feldspar megacrysts; syn-kinematic foliation, schistose and may be cataclastic, chloritised and silicified. Foliated granodiorite

Middle to Late Triassic

Biotite-hornblende granodiorite

Porphyritic hornblende granodiorite, hornblende-biotite granodiorite, diorite, quartz monzodiorite

Leucocratic, fine to medium grained, flow aligned augite-hornblende monzodiorite (hatched) to quartz monzodiorite.

Stat

ion

Cre

ek Ig

neou

s

Com

plex

Melanocratic, fine to medium grained, hornblende-augite diorite to leucodiorite (monzodiorite). Rgm m

Mount Mucki Diorite

Gibraltar Quartz Monzodiorite

Medium grained, hornblende-biotite granodiorite.sucrosic Woonga Granodiorite

Boonara Granodiorite

Unnamed intrusive

Rgg g

Rush Creek Granodiorite

Porphyritic, fine to medium grained, biotite-hornblende augite granodiorite to monzogranites; granophyre. Stripped insert represents monzogranite composition.

+Rgs

Porphyritic, fine to medium grained, biotite-hornblende augite quartz monzodiorite (stripped insert) to granodiorite; granophyre.+Woolooga Granodiorite

Rgw

Middle Devonian to Late Carboniferous

Basaltic flows with intervening layers of rhyolite tuff, mudstone, siltstone and metabasalt. Insert represents area of layered volcanogenic sediments and andesitic flows.

well stratified, indurated andesite, Highbury VolcanicsPgha

Wide Bay Creek Metamorphics

DCnAnderson Creek Phyllite

Gobongo Metamorphics

Talamy Schist

Widgee Metamorphics

Poly-deformed phyllite.

Rga

Wra

tten

Igne

ous

Su

ite


36

Gobongo Metamorphics east of Wratten’s Camp, and west of Wratten State Forest

forming a dark grey contact metamorphic zone of albite-epidote to hornblende

hornfels facies from 100 to 200 metres in width. The hornfels is indurated and much

of the original compositional banding was obliterated through recrystallisation. In the

Black Snake area, the Gobongo Metamorphics is interlayered with the Widgee

Metamorphics, and juxtaposed against the Mount Mia Serpentinite by steep-dipping

faults. Along the Mount Clara Fault, the Gobongo Metamorphics are faulted against

the structurally overlying Amamor beds. The Neara Volcanics unconformably overlie

both units.

The Widgee Metamorphics occur as massive blocks of light to dark green,

fine- to coarse-grained, massive to schistose mafic greenschist within the Mount Mia

Serpentinite. Exposures west of the Wratten Camp contains blastoporphyritic and

blasto-ophitic textures (SC1225 AMG 434825E-7093741N). These exposures contain

euhedal crystals of clinopyroxene that are almost completely replaced by coarse-

grained tremolite-actinolite, with the cores of clinopyroxene being preserved. South of

Mount Mia, the Widgee Metamorphics form a breccia of pebble and cobble-sized

clasts of greenschist (and minor metaserpentinite and metagabbro) in a finer-grained

matrix of similar composition. The Rush Creek Granodiorite intrudes a slab of the

Widgee Metamorphics west of Wrattens camp, causing localised bleaching along a

zone less than 10 metres wide adjacent to contact of the two units.

The Talamy Schist occurs as meter to kilometre size slabs within the

Mount Mia Serpentinite. A road exposure immediately south of the Rush Creek

Granodiorite (AMG 433500E, 7089300N) comprises gradations of quartz-mica schist,

quartzite and albite-rich schist. Coarse-grained quartz-mica schist is the most common

rock type. It is silvery-grey when fresh and weathers to orange-tan colour. Grey-coloured

metachert occurs as a discontinuous layer ranging from 1 to 5 cm within the quartz-mica

schist. Albite-rich schist (containing abundant blue amphibole/actinolite) is difficult to

distinguish from the mafic blueschist, with which it is gradational with an increasing

basaltic component in bulk composition.

The Wongella Metamorphics is a clast-in-matrix tectonic melange (Donchak et

al., 1995) that has massive to strongly foliated textures. An exposure of the unit east of

Kilkivan (SC1283, AMG 424975E-7115175N) consists of a block greater than 3 metres

wide of a crossite-albite-muscovite schist in a foliated matrix of quartz-muscovite-


37

actinolite.

The most widely exposed unit of the Lower Plate Assemblage is the Mount Mia

Serpentinite. The unit comprises of pebble to cobble sized, subangular to subrounded

fragments of serpentinite and lesser mafic greenschist, in a fine-grained serpentinitic

matrix. Minor clast types include blueschist, quartz-mica schist, marble, and quartzite.

The rock fragments are plastically deformed or stretched and enveloped within a scaly

serpentinitic matrix. The serpentinite has a moderate to strongly schistose fabric,

which is crenulated in shear zones. In the Kilkivan area, the Mount Mia Serpentinite

has been thrust over the Amamoor beds by the Long Tunnel Thrust (Donchak et al.,

1995), which is synchronous with the Late Permian Claddagh Thrust. The serpentinite

is also faulted against the Late Carboniferous Karandah Granodiorite (AMG 428700E,

7114200N). The Mount Mia Serpentinite is intruded by the Rush Creek Granodiorite,

and is unconformably overlain by the Early Triassic Neara Volcanics and the Late

Triassic North Arm Volanics.

The Upper Plate Assemblage

The Upper Plate Assemblage comprises shale of the Amamoor beds and an

unnamed mudstone unit referred to as the Oakview Mudstone in this thesis.

The Amamoor beds are a metasedimentary sequence of shale, fine arenite,

subordinate ribbon chert and jasper, greenstones and minor volcaniclastic

metagreywacke. A single dominant cleavage (S1) commonly parallel to bedding is

evident throughout the Amamoor beds. The unit structurally overlies the Mount Mia

Serpentinite and the Anderson Creek Phyllite along the Mount Mia fault. It is

overthrusted by the Late Carboniferous Claddagh Granodiorite along the western

margin of the NDB. Contacts between the Amamoor beds and the Permian Highbury

Volcanics are predominantly tectonical, though this contact relationship is unclear to the

southeast of the Woolooga Granodiorite due to strong masking by thermal metamorphic

overprints. Outliers of the Early to Middle Triassic Neara Volcanics and the Late

Triassic North Arm Volcanics unconformably overlie the Amamoor beds. In the

Widgee Creek area, the Amamoor beds are locally faulted against the Mount Mia

Serpentinite and Widgee Metamorphics along high-angle NW and ENE trending

faults. These faults cut and offset the older, more gently dipping Mount Mia Fault


38

producing down-to-the-east movements along the NW faults, and a graben-like off-set

along the ENE faults. In the Kilkivan area, the Mount Mia Serpentinite overthrust the

Amamoor beds along the Long Tunnel Thrust.

The Station Creek Igneous Complex and several small Permo-Triassic stocks

intrude the Amamoor beds. The width of thermal metamorphic aureole increases from

100-200 metres in width marginal to the Rush Creek Granodiorite, to 500-2000

metres around Woolooga Granodiorite, to approximately 1000 metres at the margins

of the Mount Mucki Diorite. The thermal metamorphic grade in all these aureoles

ranges from albite-epidote hornfels facies to hornblende hornfels facies.

The Oakview Mudstone comprises grey to black, laminated mudstone with

subordinate siltstone, chert layers, jasperoid and manganiferous bands, and basaltic

flows. Ellis (1968), Murphy et al. (1976), Cranfield (1994) and Donchak et al. (1995)

differentiated this unit from the Amamoor beds based on lower grade metamorphism

and the absence of a foliated fabric. The Oakview Mudstone shows little evidence of

metamorphism, except for incipient recrystallisation of clay to microscopic tabular

clay mineral(s). The mudstone strata (1-10 cm thick) have intervening siltstone and

siliceous argillite laminae. The siltstone layers are commonly wispy or discontinuous,

and are defined by lenticles or rotated blocks. Chert layers are brownish-white;

haematite stained and interfinger with mudstone and volcanic flows. The chert is

recrystallised and commonly occurs as lenticles, or rarely as thinly-bedded sequences

with cumulative thickness of up to 20 metres. The jasperoid lenses are finely

crystalline and laminated (hematite and manganiferous laminae), and are commonly

associated with metabasalts. Thick layers of metabasalt (greater than 50 metres in

thickness) occur at a few localities south of Woolooga (e.g. AMG 437700-6119000).

The metabasalt or greenstone is green to black, massive, microsucrosic, and is cut by

numerous calcite and chlorite veins.

The Oakview Mudstone is overthrusted by the Karandah Granodiorite and

the associated metamorphic aureole of the pluton, and is faulted against the Amamoor

beds. The Woolooga Granodiorite and the Gibraltar Quartz Monzodiorite intrude the

unit. A 1000-2000 metre wide zone of thermal metamorphism at the margins of the

Woolooga Granodiorite consists of black, indurated, massive, and fractured

metapelite. The greenstone within this zone is recrystallised, forming a dark green and

fine-grained rock with anastomising chlorite, calcite and epidote veinlets. An outlier


39

of the Neara Volcanics unconformably overlies the Oakview Mudstone.

The Wratten Igneous Suite, associated hornfels aureole and foliated diorite

The highly cataclastic rocks east and north-east of Kilkivan township

comprise foliated granodiorite of the Wratten Igneous Suite, Wide Bay Creek Gneiss,

and amphibolite, greenschist and phyllite of the Manumbar Metamorphics. Fine-

grained, cataclastic diorite (up to 5 km2) forms part of the thrust-sheet in the Kilkivan

area. The granodiorite-metamorphic assemblage correlates stratigraphically with a

similar assemblage associated with the Claddagh thrust-sheet in the Manumbar area

(Little, 1993). Foliated granodiorite in the vicinity of Kilkivan is named the Karandah

Granodiorite (Brooks et al., 1974). Similar rocks in the Manumbar area are termed

Claddagh and Gallangowan Granodiorites (Crouch et al., 1995 and McNaughton,

1973 respectively). Foliated granodiorite (up to 2 Km2) is also mapped on eastern edge

of the North D’Aguilar Block (south of Woolooga).

The Karandah Granodiorite is a coarse-grained, hypidiomorphic-granular

biotite granodiorite with orthoclase megacrysts (~1 cm long) and minor amounts of

hornblende and biotite. Plagioclase (An32-40), hornblende, orthoclase and biotite are

weakly aligned parallel to the flow-laminations (Plate 3.1). Subhedral hornblende (1-2

mm) comprising less than 5 modal % of the rock is generally poikilitic with rounded

quartz inclusions. Plagioclase phenocrysts exhibit undulose extinction and kinked

twins but generally lack fractures. Red-brown biotite crystals (1-3 mm) constitute up

to 20 modal % of the rock and have kinked cleavage planes and/or show undulose

extinction. Apatite is an accessory mineral.

Cataclastised Karandah Granodiorite is strongly foliated and contains

plagioclase and quartz fragments in a green, lacy, microcrystalline chlorite-epidote

groundmass. The foliation is defined by the ribbon quartz and chlorite-haematitic clay

lamellae, which are wrapped around crystal fragments. Plagioclase fragments have

kinked twins and were embayed against each other to produce interlocking grains

with sutured boundaries and cherty intergrowths. Quartz occurs as anhedral-

polycrystalline and amoeboid shaped grains with chlorite and opaque mineral

inclusions.

The Wide Bay Creek Gneiss is a pinkish-white coloured quartzofeldspathic


40

Plate 3.1: Foliated Karandah Granodiorite of the Wratten Igneous Suite. Orthoclase megacrysts (~0.5-1 cm long), plagioclase, + hornblende and biotite are weakly aligned parallel to the flow-laminations. (Width of view ~4 cm)

Plate 3.2: An outcrop of the Wide Bay Creek Gneiss, east of Kilkivan. The medium-grained, granoblastic, quartzofeldspathic gneiss (leucocratic bands) interlayer with greenish-brown schistose layers (biotite-chlorite rich).


41

gneiss that occurs below the foliated granodiorite. Its thickness is estimated at 200

metres. The gneiss is granoblastic, fine- to medium-grained and consists of quartz,

oligoclase, microcline, biotite, hornblende with accessory garnet (almandine), opaque

oxide, apatite, sphene, and zircon. The gneiss is thinly laminated with a greenish-

brown schistose layering defined by biotite-chlorite rich and sericitic clay (biotite-

poor) lamellae a few millimetres-thick, that are subparallel to the dominant foliation

(Plate 3.2).

The Manumbar Metamorphics have an estimated thickness of 400-metres,

and occur on the periphery of the Wide Bay Creek Gneiss. Amphibolite within the

unit is composed of interlocking, nematoblastic plagioclase, hornblende, actinolite

and tremolite, with minor chlorite, apatite, epidote, sphene and Fe-oxides. Greenschist

is light to dark green, fine-grained, and contains albite, actinolite, epidote, and chlorite. It

is characterised by laterally discontinuous epidote-rich bands and veins ranging from 1-3

cm thick. Phyllite occurs as strongly deformed, beige coloured layers within the

greenschist which contain quartz, white mica, chlorite, albite and biotite.

The cataclastic diorite is composed of plagioclase, augite, hornblende, and

minor amounts of quartz, opaque minerals and sphene. It has been altered and strongly

sheared to produce schlieren structures. Foliation is defined by chlorite-epidote-albite-

quartz lamellae, which form along shear surfaces. Alteration involved saussuritisation of

plagioclase, chloritisation and uralitisation of augite and hornblende, and partial

replacement of rocks by calcite and quartz.

The contact between foliated granodiorite-Manumbar Metamorphics

assemblage and the structurally underlying Upper Plate Assemblage rocks (Amamoor

beds and Oakview Mudstone) is a thrust fault. In the Woolooga area, erosion removed

the upper section of the thrust sheet, leaving the basal amphibolite juxtaposed against

the Oakview Mudstone.

Early Permian Highbury Volcanics

The Highbury Volcanics occurs to the east and southeast of Woolooga

Granodiorite. The unit is correlated to the Mary Volcanics of the Gympie Group

(Tang, 2003), and consists of massive basalts and porphyritic trachybasalt to andesitic

basalt with interbedded volcanogenic arenite and siltstone. Basalts, which occur


42

mainly at a lower stratigraphic level are succeeded by porphyritic trachybasalt and an

increasing proportions of tuffaceous interbeds, epiclastic lenses and siltstone.

Basalt is thermally metamorphosed to a black, micro-sucrosic rock with

lamellae of fine-grained crystalline bands and chertified patches (e.g. SC-574, AMG

443030-7121934). Trachybasalt contains plagioclase and pyroxene phenocrysts (1-5

modal %) in black, microcrystalline groundmass. The volcanic rocks are generally

fractured, epidotised and chloritised with quartz-calcite veins. Roof pendants of basalt

(e.g. SC-1097, AMG 441539-7105203) in the Woolooga Granodiorite are black,

micro-sucrosic and the banding is defined by recrystallised layers with an average

grainsize of approximately 0.5 mm. Amygdales were infilled with rhondonite, quartz

and calcite. Trachybasalt roof pendants (e.g. SCJT-1098, AMG 441487E-7104756N)

are dark grey, sucrosic and have a weak layering defined by the alignment of plagioclase

and pyroxene (after hornblende) phenocrysts.

The stratified volcanogenic sediments (0.1 to 3 m thick) consist of tuff,

rhyolitic ash-flow, pyroclastic flow and epiclastic rocks. The sediments are thermally

metamorphosed to form a grey-black, microcrystalline rock whose banding is defined by

the compositional difference between layers (e.g. SCJT-586 at AMG 441943-7122569).

Siltstone beds (0.1-0.3 metre thick) are buff to brown in colour, and commonly

display fining upward sequences from silt to clay. Detrital quartz was identified

within the coarser base of the siltstone layers. Along contacts with plutonic rocks,

siltstone is altered to a dull green, silicified and banded rock which is overprinted by

calcification.

The Highbury Volcanics is altered, locally brecciated and thermally

metamorphosed, but show little or no burial metamorphism other than incipient clay

recrystallisation. A maximum burial metamorphic facies for this unit is zeolite facies.

Andesine and labradorite phenocrysts are saussuritised, and chlorite, actinolite and

calcite replace clinopyroxene. Rare amygdales in basalts were infilled with chlorite,

actinolite, zeolite, epidote and calcite. Irregular veins of epidote, chlorite, calcite and

quartz formed along fracture planes or as irregular patches in brecciated rocks.

The Highbury Volcanics is faulted against the Amamoor beds and

unconformably overlain by the Neara Volcanics. The boundary with the Rammutt

Formation (west of the Devils Mountain) is faulted. The Woonga Granodiorite, the


43

Woolooga Granodiorites and the Mount Mucki Diorite intrude the Highbury

Volcanics. A localised thermal metamorphic aureole comprises of recrystallised

metabasalts of albite-epidote to hornblende hornfels facies and roof pendants that

were thermally metamorphosed to pyroxene hornfels facies.

Early Triassic Neara Volcanics

The Neara Volcanics (Hill & Tweedale, 1955) consist primarily of andesitic

volcanics (andesite flow, tuff, autoclasts) and volcanoclastic sediments (epiclastic,

volcanolithic conglomerate, greywacke), interbedded with mudstone, sandstone and

polylithic conglomerate. Although most of the Neara Volcanics are confined to the

Esk Trough, they also unconformably overlap the adjoining eastern margin of the

NDB. The thickness of the unit in the Mount Sinai area is estimated at 300 m

compared to ~6000 m in the Esk Trough (Campbell et al., 1999).

The andesite flows are dark-grey to black, massive, commonly fractured and

have haematite and calcite as joint-infilling minerals (Plate 3.3). The flows vary in

thickness from 0.5 metres to greater than 2 metres and interdispersed among the various

rock types of the Neara Volcanics. The flows comprise flow-aligned plagioclase and

hornblende phenocrysts (1-2 mm) in a trachytic-textured groundmass. Andesitic flows

also contain a varying amount of andesitic fragments from about 2 % to over 50 %

(forms layers of autoclastic andesite).

The epiclastic rocks consist of angular, poorly sorted (0.5 to 50 cm diameter)

lithic fragments in a groundmass of volcanogenic detritus (Plate 3.4). The lithic

fragments are predominantly of volcanic origin (>95 %) and include porphyritic

andesite, andesite, trachyandesite, tuff and pumice. Minor components of the clasts are

foliated granitoid and metasediments (mudstone, siltstone, phyllite and chert). The

groundmass contains fragments of plagioclase crystals and traces of angular quartz in a

silt-sized matrix. Thin horizons less than 10 cm thick of black glassy to spherulitic,

rhyolitic to trachyandesitic welded tuff occurs rarely in the epiclastic rocks.

Greywacke beds are medium to coarse-grained, and contain up to 10 %

angular andesitic lithic detritus (1-10 cm), 15% subrounded plagioclase (1-2 mm) and

<5% subangular quartz in a silt-sized matrix. They are intercalated with andesitic tuff

(0.3 to >2 m thick) and dark grey mudstone beds up to 30 cm thick.


44

Volcanolithic conglomerate (or andesitic boulder beds) consists of clast- to

matrix-supported cobbles and pebbles interbedded with thick lenses of coarse sandstone.

The cobbles and pebbles are moderately well-sorted and subrounded, and the

predominant rock type is a porphyritic andesite to basaltic andesite. Minor clast types

include quartzite, phyllite, siltstone, fine-grained arenite, jasper and occasionally

coarse-sandstone and coarse-grained biotite granite. The boulder beds form very

thick-layers (over 2 m) and have little internal structure. Arenaceous beds up to 30cm

thick and mudstone bands are locally present.

Polylithic conglomerate is clast- to matrix-supported, moderately sorted and

contains mainly rounded cobble-pebble sized clasts (Plate 3.5). This rock type occurs

mainly to the west of Kilkivan within the Esk trough, though small exposures were

mapped in the Bongmillerer Creek area on the NDB. The conglomerate is a

commonly poorly bedded and is composed dominantly of lithic detritus (sedimentary,

metamorphic and igneous rocks) in a volcanic-derived chloritic clay matrix. The main

clasts are quartzite, chert, jasper, fine-grained arenite and coarse-grained quartzose

sandstone. Igneous rocks including andesite, basalt, rhyolite and granite cobbles form

less than 25 % of the clasts. The finer conglomerates are matrix supported and contain

arenaceous bands. Lithic arenite layers containing about 70 % of non-volcanic clast

material (chert, silstone, mudstone, greywacke, monocrystalline and polycrystalline

quartz) are present between conglomerate beds. The volcanic-derived grains are basalt

and andesite. Quartz pebbles are scattered throughout or confined to bedding planes in

the arenite.

The Neara Volcanics shows little regional or burial metamorphism, other

than incipient clay recrystallisation. Its maximum burial metamorphic facies is the

zeolite facies. Neara Volcanics overlies the Palaeozoic Upper- and Lower Plate

Assemblages rocks, the Claddagh and Karandah Granodiorites and the Highbury

Volcanics. Scattered erosional-resistant remnants (<20 metres thick) of the volcanics lie

unconformably on the Palaeozoic rocks. These volcanic outliers consist of interbedded

porphyritic epiclastics andesite, greywacke and mudstone. The porphyritic epiclastic

andesite strata (referred to in the thesis as the ‘altered basal unit” or ABU) is weakly

chloritised and argillised. The Woolooga Granodiorite, Rush Creek Granodiorite,

Gibraltar Quartz Monzodiorite, Mount Mucki Diorite, and a Late Triassic-Early

Jurassic pluton intrude the Neara Volcanics. The volcanic rocks are thermal


45

metamorphosed to hornblende hornfels and albite-epidote hornfels facies. The North

Arm Volcanics unconformably overlies the Neara Volcanics. Post-Middle Triassic

high-angle, NW trending faults cut the Neara Volcanics and juxtapose the volcanics

against the Palaeozoic rocks and the plutons of the Station Creek Igneous Complex.

In the Gibraltar Rock area, the volcanic rocks in the contact zone to an Early

Jurassic intrusion are pervasively argillised, obliterating most of the original texture

and mineralogy and forming a white clayey rock (subunit Rtnal). Propylitised volcanic

rocks surround the intensely argillised zone in the Bongmillerer Creek and Serpentine

Creek areas. In the propylitised rocks, hornblende and augite were altered to fibrous

actinolite (uralite), epidote, iddingsite, pinnite biotite and chlorite. Sericite, kaolinite,

epidote, quartz and clay replace feldspars, and the groundmass is chloritised,

epidotised and argilllised. Hairline-fractures braiding throughout the green, sucrosic

rock are infilled by quartz-albite, epidote, calcite, clay, and may contain trace amounts

of pyrite and/or chalcopyrite. These infilled fractures form veinlets (0.5 to 5 mm

wide) which trend mainly NW, WNW and N-S, and have minor NE and ENE trends.

MIDDLE TO LATE TRIASSIC VOLCANICS AND HYPABYSSAL ROCKS

The North Arm Volcanics

The North Arm Volcanics covers approximately 15 km2 of the Mount Sinai

area. Rock types include andesitic debris-flow (epiclastic rock) and laterally

discontinuous horizons of porphyritic andesite and trachyandesite to dacite lavas. The

matrix-supported epiclastic strata are composed of poorly sorted, angular to

subrounded, pebble- to boulder-sized clasts in a fine-grained lithic arenite matrix. The

clasts comprise andesite to dacite (>75 % of the clasts), mudstone, phyllite, chert,

greywacke and granodiorite. The granodiorite fragments (1-2 % of the lithic

fragments) are subangular, fine- to medium-grained, and porphyritic with plagioclase

(An26-35) phenocrysts. Quantities of rock fragments in the epiclastic rocks decrease

progressively from south (50 %) to north (3 %) (Figure 3.4). The matrix consists of

rounded grains of quartz, feldspars, andesite and tuff in a greenish-grey, chloritised


46

Figure 3.4: The geology of the Gibraltar Rock area, southeast Queensland. NW and ENE faults modified the geology, and post-Late Triassic intrusions caused extensive alteration to the north of the Gibraltar Rock. The North Arm Volcanics shows progressive reduction of clastic components from south to north.

Scale 1:100,000

0 5KmLEGEND

Net-veining

Pluton and unit boundary.

Estimated percentage of clastic components in volcanogenic rock.

25

Radiometric age

Dyke (andesite, dacite and rhyolite).

Diorite, monzodiorite and granodiorite stocks.

North Arm Volcanics. Andesite and epiclastic andesite.

Mount Mucki Diorite


Woolooga Granodiorite


Woonga Granodiorite

Neara Volcanics.Rn = Epiclastics, volcanoclastics.

c

Highbury Volcanics. Basalt, mudstone, siltstone and tuff.

Oakview Mudstone.Ra

Rgmm

Rgg

Rsc

Rwo

Rwg

Late Triassicto Jurassic

Late Triassic

Rgl

Fine-grained, equigranular and homogeneous rock.

Mid-Triassic

Text

ure

Partially recrystallised, silicified and altered; pink coloration.

Early Triassic

193 Ma

Early Permian

Devonian-Carboniferous

Late Carboniferous

Pgh

Rn

Pmt

DCup

Cuc

DClp

Claddagh Thrust assemblage.

Upper Plate Assemblage of lower greenschist facies (Amamoor beds).

Lower Plate Assemblage of greenschist-amphibolite facies.

Zone of intense alteration .

Rnc

Fault, dashed-line is inferred fault

Rgl

Rwo

Rwo

Rwo

Rwo

Rsc

Rgmm

Rwg

MOUNT MUCKIDIORITE

WOOLOOGAGRANODIORITE

Rwo


Rgg

Rgg

50

3020

2015

10

7 3

Black Snake Plateau

Oakview

193 Ma

210 Ma

Rwo

5

Pmt

Rn

Rn

Rn

Rn

Altered zone

Ra

Ra

Ra

Rn

Rn

Rn

Rn

Pgh

Pgh

DCup

Pmt

Pgh

DCupDCup

CucRgg

Rn

Cuc

Cuc

DClp

DClp

DCup

Pgh

Pmt

DCup

1 0 K m

STATION CREEKIGNEOUS COMPLEX

AREAENLARGED

Rnc

Rnc

Rnc

Rnc

Gibraltar Rock

Rgl

W r a t t e n

S t a t e

F o r e s tRgl


47

and epidotised clayey matrix. Porphyritic andesite and trachyandesite are generally grey

to black, and contain 2-5 modal % phenocrysts of medium-grained quartz and

plagioclase with traces of hornblende and clinopyroxene. The microcrystalline

groundmass consists of felted textured plagioclase, hornblende, quartz, Fe-Ti oxides and

apatite. Locally, the andesite and trachyandesite flows may include autoclastic breccia

layers (up to a metre thick) between flows. Dacite flows consist of flow-aligned

plagioclase, K-feldspar, + quartz in a fine-grained aphanitic groundmass. Chloritisation,

sericitisation, epidotisation and calcification are the typical products of alteration of

rocks in the Mount Sinai area.

The North Arm Volcanics unconformably overlies or is faulted against

mainly Palaeozoic rock units in the NDB. Its basal contact with the underlying Neara

Volcanics is not exposed, and is presumably unconformable. The two volcanic units

are difficult to differentiate in the field due to similar textures, compositions and the

lack of well-defined bedding planes in both units. The North Arm Volcanics is

juxtaposed against the Rush Creek Granodiorite by high-angle NW trending faults.

Granodiorite and phyllite xenoliths occur in the volcanics. The granodiorite xenoliths

have a similar mineralogy and texture to the Rush Creek Granodiorite, whereas the

phyllite xenoliths are probably derived from the Amamoor beds.

Middle-Triassic to Jurassic intrusions

Porphyritic granodiorite to diorite bodies of Middle-Triassic to Jurassic age

intrude the Station Creek Igneous Complex or were emplaced near it. In the Gibraltar

Rock area, several diorite bodies and a Jurassic granodiorite intrudes the Woolooga

Granodiorite (Figure 3.4), causing pervasive hydrothermal alteration. The Jurassic body

is dated as 193 + 5 Ma (see table 4.1, this study), and is faulted by N-S faults. The Black

Snake Porphyry (233+8 Ma, K/Ar biotite; Murphy et al., 1976) is emplaced

approximately 1 km west of the Rush Creek Granodiorite, with associated Cu-Au-Ag

mineralisation. The Boonara Granodiorite (233+3 Ma, K/Ar hornblende; Cranfield &

Murray, 1989a) and the Calgoa Diorite (234+2 Ma, K/Ar hornblende; Cranfield &

Murray, 1989a) intrude the Oakview Mudstone west of the Woolooga Granodiorite. A

porphyritic trachyandesite called the Neureum Mount Porphyry (Early-Mid Triassic,

Crouch et al., 1995) intrudes along a NW-trending fault to the NE of Kilkivan.


48

Andesitic to rhyolitic dykes

Sub-vertical rhyolite, dacite and trachyandesite dykes varying in width from

2 to 10 metres intrude the Station Creek Igneous Complex, the Neara Volcanics and

the Palaeozoic rocks. These dykes occur either as an individual dyke or in subparallel

arrays typical of a dyke swarm. The strikes of the dykes are parallel to the ubiquitous

NW foliations of the basement rocks. A NW-trending trachyandesite to rhyolite dyke

swarm intruding along a 5 km-wide corridor has been traced from the Brooyar Forest

to Log Creek area for a distance of more than 30 km. The dyke swarm crosscuts most

major faults and the Woonga and Woolooga Granodiorites, but is generally absent in

the Mount Mucki Diorite. Nash (1986) traced this dyke swarm to Rosedale area,

extending over a 100 km to the north. Felsic (rhyolite to dacite) dykes resist erosion

and form subparallel ridges that weather to form aligned piles of blocky rubble.

Andesite and dacite dykes are porphyritic and have aligned phenocrysts of

plagioclase, hornblende and/or biotite in a microcrystalline groundmass. Generally,

rhyolitic dykes are less deformed, pink, aphanitic and display flow banding and flow-

banded folds with microspherulitic lamellae (Plate 3.6). Dykes that occur as

individuals vary in composition from andesite to rhyolite and in orientation (e.g. NE,

NW, N-S and E-W directions). The dykes mapped within the Mount Mucki Diorite

are dacitic to rhyolitic in composition.

Nash & Jones (1996) regarded the age of the dykes as Late Triassic. An

andesite dyke in the Fat Hen Creek was dated 229 Ma (Roberts, 1992), and andesite

dykes intruding the Neara Volcanics in the Esk Trough were dated at 222.6 (Ar/Ar,

hornblende) and 223.6 Ma (K/Ar whole rock) by Irwin (1973). Subparallel dacitic

dykes also intrude the Jurassic Mrytle Sandstone.


49

Plate 3.3: An andesitic flow within epiclastic rocks of the Neara Volcanics. The gently dipping, dark-grey to black andesite is massive and fractured, and normally resists erosion.

Plate 3.4: Epiclastic rock of the Neara Volcanics with sub-angular, poorly sorted lithic fragments (andesite, trachyandesite, tuff, minor components of foliated granitoid, siltstone and chert) in a groundmass of volcanogenic detritus.


50

Plate 3.5: Polylithic conglomerate of the Neara Volcanics. The poorly bedded conglomerate is composed of poorly sorted, well-rounded cobbles to pebbles (sedimentary, metamorphic and igneous rocks) in a volcanic-derived greywacke matrix.

Plate 3.6: Flow-banded rhyolitic dyke intruding the Woolooga Granodiorite, east of Kilkivan.

Chapter 4: The Station Creek Igneous Complex

51

CHAPTER 4: THE STATION CREEK IGNEOUS COMPLEX

Introduction

The Station Creek Igneous Complex is a north-south elongated lobate plutonic

masses that covers at least 265 km2 (see Figure 3.3). It was originally mapped as one

pluton and named the Station Creek Adamellite (Ellis, 1968; Brooks et al., 1974;

Murphy et al., 1976; Murray et al., 1979). The name was subsequently revised to

Station Creek Granodiorite in the Maryborough 1:250,000 Sheet area by Cranfield

(1994). Bloomfield (1990, 1991), Edgar (1992) and Crouch et al. (1995) undertook

limited geochemical sampling and mapping of the plutonic body. The previous

radiometric ages for the igneous complex are 227 Ma (K/Ar, biotite; Webb &

McDougall, 1967), 231 Ma (K/Ar, biotite; Brooks et al., 1974) and 226.8 +3 Ma

(K/Ar amphibole; Edgar, 1992).

DEFINITION OF THE STATION CREEK IGNEOUS COMPLEX

Mapping within this thesis identifies five discrete plutons and introduces the

term of “igneous complex” to represent the plutonic entity (Crouch et al., 1997). Tang

& Gust (2000) defined the component plutons of the Station Creek Igneous Complex

as the Woolooga Granodiorite, Rush Creek Granodiorite, Woonga Granodiorite,

Gibraltar Quartz Monzodiorite and Mount Mucki Diorite. The ages of these high level

plutons range from Mid- to Late Triassic (227 to 237 Ma, Table 4.1), and represented

close approximations to their emplacement ages. The errors of the Ar/Ar (biotite)

ages do not overlap the ages of respective plutons, and the concordance of Ar/Ar

(biotite) and K/Ar (biotite) ages in the Station Creek Granodiorite and similarities in

the K/Ar ages of hornblende and biotite from the Mount Mucki Diorite support the

precision of these radiometric ages.

Poor exposures and deep weathering mask the contacts between plutons. The

intrusive relationships are defined from a combination of field observations and

radiometric ages. Geophysical data was used to help define the contacts. The Mount

Mucki Diorite intrudes the Woonga Granodiorite and the Woolooga Granodiorite,

causing pervasive alteration and localised recrystallisation in the host units. The

Gibraltar Quartz Monzodiorite intrudes the Woolooga Granodiorite and the intrusive


52

contact is highly argillised and silicified. The contact between the Woolooga

Granodiorite and Rush Creek Granodiorite is poorly exposed and deeply altered but is

clearly defined by geophysics. A net vein complex of intermingled lithologies from

both the Mount Mucki Diorite and Gibraltar Quartz Monzodiorite defines their

contact.

The Station Creek Igneous Complex (SCIC) intrudes the Palaeozoic Upper

and Lower Plate rock assemblages of the North D’Aguilar Block, the Late

Carboniferous Wratten Igneous suite, the Lower Permian Highbury Volcanics and the

Early Triassic Neara Volcanics. The Late Triasic North Arm Volcanics overlies the

Station Creek Igneous Complex and andesitic dykes and small granidioritic to dioritic

bodies intrude the igneous complex.

Table 4.1: Radiometric ages of plutons in the Station Creek Igneous Complex (including age determinations from previous work)

Pluton Lithology Sample No.

AMG Zone 56

Age (Ma)

Method Laboratory Reference

Woonga Granodiorite

Granodiorite SC1129

447247-7109122

237 + 0.5 Ma

Ar/Ar biotite

Berkeley Uni., U.S.A

This study


Granodiorite to quartz monzodiorite

SC582

441398-7122346

234 + 0.4 Ma

Ar/Ar biotite


This study

SC1179 430615-7094268

232 + 0.3 Ma

Ar/Ar biotite


This study


Granodiorite- monzogranite K52 434735-

7100325 231 + 7 Ma

K/Ar biotite

Geochron Laboratory Inc.

Brooks et al., 1974

SC999

442100-7112875

210 + 21 Ma

K/Ar hornblende

Uni. Queensland, Australia

This study

SE158c 442500-7113800

226.8 +3 Ma

K/Ar amphibole

Uni. Queensland, Australia

Edgar, 1992

Mount Mucki Diorite

Monzogabbro, diorite, quartz diorite and leucodiorite

G56/10/4 448853-7113977

227* Ma

K/Ar biotite

- Webb & McDougall, 1967

Intrusion Granodiorite SC806 437783-7108115

193 + 5 Ma

K/Ar hornblende

Uni.Queensland, Australia

This study

* Recalculated using decay constants of Steiger & Jager, 1977

Mount Mucki Diorite

Mount Mucki Diorite is the youngest and the most mafic pluton of the

Station Creek Igneous Complex. It is a poorly exposed unit covering approximately

30 km2. Fresh rocks occur on ridges along its western margin. The pluton has been

dated as 226.8 +3 Ma (K/Ar amphibole; Edgar, 1992) and 227 Ma (K/Ar biotite;


53

Webb & McDougall, 1967). The latter age was recalculated using decay constants of

Steiger & Jager (1977). An age of 210+21 Ma (K/Ar hornblende, this study) has been

disregarded due to its high error range.

The Mount Mucki Diorite intrudes the Amamoor beds, Neara Volcanics,

Highbury Volcanics, foliated Carboniferous granodiorite (the Wratten Igneous Suite),

Woonga Granodiorite and Woolooga Granodiorite. A monzogabbroic chilled margin

approximately 5 metres wide occurs at the contact with the Neara Volcanics. The

contact zone between the Mount Mucki Diorite and Gibraltar Quartz Monzodiorite is

characterised by a net vein complex of intermingling rock types from each unit (Plate

4.1). Enclaves of the Mount Mucki Diorite are subrounded to subangular (or blobs),

plastically deformed, have chilled margins and are intruded by narrow dykes of the

Gibraltar Quartz Monzodiorite (Plate 4.1).

The Mount Mucki Diorite with magnetic susceptibilities ranging between

5,000-18,000 X 10-5 SI shows a complex, subconcentric internal zonation on a total

magnetic intensity (reduced to pole) image (Figure 4.1). The less magnetic zones may

correspond to the lower magnetic susceptible leucodiorite (magnetic susceptibilities

5,000 to 10,000 X 10-5 SI) and epidotised-chloritised rocks (magnetic susceptibilities

<5,000 X 10-5 SI). The magnetic image also shows that the highly magnetic Mount

Mucki Diorite extends beneath the low-moderately-magnetic Woolooga Granodiorite.

On the radiometric (K-Th-U) red-blue-green (rgb) image, the Mount Mucki Diorite

has darker (weaker K-Th-U radiometric responses) than both the Woolooga

Granodiorite and the Gibraltar Quartz Monzodiorite.


Gibraltar Quartz Monzodiorite covers approximately 20 km2. It intrudes the

Woolooga Granodiorite, Neara Volcanics, Oakview Mudstone, Manumbar

Metamorphics and a foliated Palaeozoic diorite. Exposures of the Gibraltar Quartz

Monzodiorite are poor and discontinuous, and the pluton is partly concealed beneath

west-dipping Neara Volcanics (Plate 4.2). A zone of intense hydrothermal alteration

and potassic metasomatism obscures its contact with the Woolooga Granodiorite. Its

contact to the Mount Mucki Diorite is characterised by a net-vein complex of inter-

mingled monzogabbro-diorite and quartz monzodiorite from both plutons.


54

Figure 4.1A: The total magnetic image (reduced to pole) of the Station Creek Igneous Complex. (Refer to figure 3.3 for geological units and boundaries). Geophysical image used with permissions from the Geological Survey of Queensland and Gympie Eldorado Gold Mines Pty. Ltd.

RaPzs

Pzp

Ra

PchCpRwo

PchCpPch

Pch Woolooga

Rwo

Pgh

PghPgh

t

Rnc

Jm

Jt

Jm

Rgl

Jm

Rgl

?Pght

Rg

Pgh

DCmv

Rg

DCmDCmv

Rmm

Pgh

Cuc

Rn

Rnc

RnRnc

Rgg

Rwo

Cucd

Cucd

Ca

Rgg

Pmt

Cp

Pmt

Rn

CucRn

Rn

Rr

Pmt

RgPzp Rg

Cp

Rg

Rnc

Pgh

Pch

Pch

CucDCm

DCmDCm

DCch

KilkivanPzs

Pzp

PzfCuc

Cucd

Cucd

DCm Pzp

PzsPzp

Ca

Pzf

DCm

Cq

Cuc

DCm

Pgh

DCm

Pch

DCmv

RwgRglRn

RaRa

Pzp

PzsPzf

Rg

Pzs

Pzp

Pzp

DCch

DCch

Pgh

DCm

Pmt

Rnc

Rwo

PghtPgh

Rn

Rwo

Pzp

Pzs

Pzp

Pzf

DCm

CaRn

Pzj

DCm

Pzp

CpCuc

Cq

Ca

Rg

Pzp

Pzs

PzsPzf

Rsc

DCm Rn

Pzs

Pzf

Pzf

DCv

DCch

DCs

Pzs

Pzf

Pzp

PzfPzf

DCm

Pzf

DCm

Pzp

Pzf

Rg

Pzp

DCmCuc

Rn

Pzf

RaRsc

Pzk

Pzp

RnRa

Pzs

Pzp

PzkRg

DCv DCm

Pmt

152

15’E

o

Nt

11o

26 00’So

430

00

0m

E

440

00

0m

E 71290 0 0 m N

450

00

0m

E

26 00’So

71200 0 0 m N

71100 0 0 m N

71000 0 0 m N

26 15’So

450

00

0m

E

70900 0 0 m N

152

30’E

o

71100 0 0 m N

71200 0 0 m N

422

00

0m

E

430

00

0m

E

152

15’E

o

70900 0 0 m N

71000 0 0 m N

26 15’So

440

00

0m

E


55

Figure 4.1B: Radiometric image of the Station Creek Igneous Complex. Geophysical image used with permissions from the Geological Survey of Queensland and Gympie Eldorado Gold Mines Pty. Ltd.

152

15’E

o

Nt

11o

26 00’So

430

00

0m

E

440

00

0m

E 71290 0 0 m N

450

00

0m

E

26 00’So

71200 0 0 m N

71100 0 0 m N

71000 0 0 m N

26 15’So

450

00

0m

E

70900 0 0 m N

152

30’E

o

71100 0 0 m N

71200 0 0 m N

422

00

0m

E

430

00

0m

E

152

15’E

o

70900 0 0 m N

71000 0 0 m N

26 15’So

440

00

0m

E


56

Plate 4.1: Net-vein complex of inter-mingled diorite and quartz monzodiorite at the contact between the Mount Mucki Diorite and Gibraltar Quartz Monzodiorite.

Plate 4.2: Intrusive contact between the Gibraltar Quartz Monzodiorite (left) and the Neara Volcanics (right). A narrow chilled-margin of the Gibraltar Quartz Monzodiorite incorporates angular andesitic xenoliths (indicated by arrows) derived from the Neara Volcanics.


57

Argillic and propylitic alteration overprints the Gibraltar Quartz

Monzodiorite. Intense bleaching, argillisation, silicification, chloritisation and

saussuritisation occur in the Gibraltar Rock region, proximal to an Early Jurassic

intrusion. Mafic minerals alter to actinolite, chlorite and epidote, plagioclase is

saussuritised, and orthoclase is sericitised. Fractures are infilled by quartz, calcite and

epidote to form systems of braided veins. Box work structures or cubic voids in the

rocks indicate the likely presence of crystals of pyrite that have been subsequently

oxidised.

The Gibraltar Quartz Monzodiorite contains both chilled cognate enclaves

and metamorphic xenoliths (Barbarin & Didier, 1991). The most common and widely

dispersed are cognate enclaves of quartz micromonzodiorite composition. These

enclaves which range in size from 1 to 5 cm in diameter, are partly resorbed,

chloritised, argillised and have faint flow orientation parallel to the NW-flow

alignment of the groundmass. Angular metamorphic xenoliths are localised along the

pluton margin and comprised of volcanics, metasediments, phyllite, chert and foliated

granitoid.

The moderate magnetic susceptibilities of the Gibraltar Quartz Monzodiorite

(3500 to 7200 X 10-5 SI) superimpose on both the Woolooga Granodiorite (magnetic

susceptibilities from 600 to 3700 X 10-5 SI) and the Mount Mucki Diorite (magnetic

susceptibility from 8,000 to 18,000 x 10-5 SI). On the radiometric (K-Th-U) images,

the Gibraltar Quartz Monzodiorite has moderate-high K-reponses but very low

response in the thorium and uranium channels.


Woolooga Granodiorite (234 + 0.4 Ma, Ar/Ar biotite) is the largest pluton of

the Station Creek Igneous Complex (106 square km). It intrudes undivided

Carboniferous rocks, Amamoor beds and Neara Volcanics. The central section of the

pluton is concealed below the Neara Volcanics, faulted by ENE faults and intruded by

the Gibraltar Quartz Monzodiorite, which results in northern and southern exposures

of the Woolooga Granodiorite. The northern part is well exposed whereas the

southern section is partly concealed below the Neara Volcanics, and faulted and

intruded by the Mount Mucki Diorite, Gibraltar Quartz Monzodiorite and Rush Creek


58

Granodiorite. Strong hydrothermal alteration occurs at contacts with other plutons of

the Station Creek Igneous Complex. All mafic minerals within the contact zone are

chloritised and most of the plagioclase and K-feldspars are argillised. Within the

intensely altered Gibraltar Rock area, the rock is totally replaced by sericite, clay and

quartz.

The northern part of the Woolooga Granodiorite is compositionally zoned

and has a wide rim of granodiorite and a narrow core of quartz monzodiorite. The

compositional change is gradational and the contact between granodiorite and quartz

monzodiorite is approximated. Lithologic zonation is poorly defined in the southern

part of the pluton due to multiple faulting events accompanied by westward tilting

along dextral NW-NNW faults.

The Woolooga Granodiorite contains microcrystalline cognate-enclaves of

dacite and andesite composition. The more common dacitic enclaves are composed of

augite, hornblende, oligoclase (An28-33), quartz and orthoclase. The dacitic xenoliths

are generally rounded but do not have reaction rims. The andesitic xenoliths with

diffuse boundaries and reaction rims are similar in composition to the quartz

monzodiorite of the Woolooga Granodiorite. They contain augite, hornblende and

andesine (An33-43).

Aerial geophysical surveys highlight the intrusive relationships between the

various plutons. The total magnetic intensity image (reduced to pole) shows that the

strongly magnetic Mount Mucki Diorite (magnetic susceptibility of 8,000 to 18,000 x

10-5 SI) extends below the Woolooga Granodiorite (magnetic susceptibility of 600 to

3700 x 10-5 SI). The weakly magnetic Woolooga Granodiorite contrasts with the

moderately magnetic Gibraltar Quartz Monzodiorite (magnetic susceptibilities

ranging from 3500 to-7200 x 10-5 SI). Zones of low magnetic intensity within the

Woolooga Granodiorite represent areas of pervasively altered rocks at the contacts

with Gibraltar Quartz Monzodiorite, Mount Mucki Diorite, Rush Creek Granodiorite

and an Early Jurassic intrusion. On the radiometric (K-Th-U) rgb image, the moderate

to high K response of the Woolooga Granodiorite differentiates it from the low

radiometric response of the Mount Mucki Diorite.


59


Rush Creek Granodiorite (231-232 Ma) covers approximately 73 km2, and

exposures are generally poor. It intrudes the Woolooga Granodiorite, Neara Volcanics

and Palaeozoic basement rocks. The pluton is cut by several NW and ENE faults and

has associated zones of shearing and brecciation. Lineations and slickensides on NW

trending faults indicate dominantly sinistral movements whereas those related to the

ENE faults showed mainly vertical displacement. Late orthoclase-quartz-tourmaline

veins (1-50 cm width) intrude the Rush Creek Granodiorite.

A hypersthene monzodiorite body (<1 km2) intrudes the centre of the Rush

Creek Granodiorite (see Figure 3.3). An intensely argillised and silicified halo forms

around the monzodiorite intrusion. All primary minerals within the alteration halo

have been completely destroyed and replaced by sericite-clay and quartz.

The Rush Creek Granodiorite contains enclaves of a grey microgranitoid

(containing An32-36 plagioclase) and rare metasediments xenoliths. The microgranitoid

cognate enclaves show no reaction rim to the host rock.

On the total magnetic intensity image (reduced to pole), the Rush Creek

Granodiorite with a magnetic susceptibility of 350 to 2,800 X 10-5 SI contrasts from

the low-moderate magnetic response of the altered and partially recrystallised

southern part of the southern Woolooga Granodiorite. A narrow zone of elevated

magnetism that concides with localised magnetite enrichment at the contact defines

the boundary of the Rush Creek Granodiorite. The Rush Creek Granodiorite has

higher K, Th and U radiometric responses than the Woolooga Granodiorite that has

only moderate K responses. The hypersthene monzodiorite intrusion in the Rush Creek

Granodiorite is highly magnetic (magnetic susceptibilities between 4,100 and 4,900 X

10-5 SI) and has low K, Th and U radiometric responses. The zone of argillised

granodiorite around this monzodiorite intrusion is weakly magnetic.

Woonga Granodiorite

Woonga Granodiorite (237 + 0.4 Ma, Ar/Ar, biotite) is an extremely poorly

exposed unit covering 36 km2. It intrudes the Amamoor beds, Highbury Volcanics

and the Neara Volcanics, and is intruded by the Mount Mucki Diorite and Gibraltar

Quartz Monzodiorite. Large expanses of the pluton are deeply weathered and eroded


60

to form a topographic depression overlain by colluvium and alluvium. The contact

with the Mount Mucki Diorite is thermally metamorphosed, recrystallised and

intensely altered (sericitisation and chloritisation). Erosional resistant ridges of the

Mount Mucki Diorite occur around the Woonga Granodiorite.

The Woonga Granodiorite has a consistently low magnetic response

(magnetic susceptibilities <1000 x 10-5 SI) and a moderate-high radiometric response

in the K channel, but very low responses in the thorium and uranium channels.

Geophysics suggests that the strongly magnetic and very low radiometric Mount

Mucki Diorite encircles the Woonga Granodiorite (Figure 4.1).

Structure of the Station Creek Igneous Complex

The Station Creek Igneous Complex intrudes the Palaeozoic rocks east to the

Talamy Arch, and also intrudes the Highbury Volcanics of the Gympie Group. The

intrusive contacts mimic the NW-WNW regional structural fabric (Figure 4.2). Most

contact zones consist of subparallel extensional partings intruded by plutonic rocks

(0.5 to ~2metres wide), and there is no evidence of forceful intrusion or intrusive

breccia.

Most plutons of the Station Creek Igneous Complex have homogeneous

structural fabrics with the exception of the Gibraltar Quartz Monzodiorite that shows

slight flow alignment along a NW trend, and internal-layering in Mount Mucki

Diorite.

Near-vertical NW, ENE and N-S faults intersect the Station Creek Igneous

Complex. In the Mount Sinai area, the Rush Creek Granodiorite (231-232 Ma) stitches

a NW trending fault, constraining this NW fault to a pre-Late Triassic age. The Mount

Mucki Diorite (226 Ma) and Gibraltar Quartz Monzodiorite were faulted by NW

trending faults, which imply that the NW faults are active from Middle to Late

Triassic. Striations on some NW fault planes indicate early dextral movements that

were reactivated with minor sinistral movements. In the Mount Mucki area, high-

angle NW-trending faults crosscut the Woolooga Granodiorite and its overlying roof-

pendants. These high-angle faults have associated westward tilting motions, and

juxtaposed medium-grained crystalline rock i.e. Rgw3 (to the west of the faults)

against roof pendants and their underlying chilled zones i.e. Rgw2 (to the east of the


61

Figure 4.2: Rose diagrams comparing the orientations of intrusive contacts of the Station Creek Igneous Complex to bedding planes and foliations of the Paleozoic basement rocks. The majority of intrusive contacts are oriented to NW to NNW, similar to the structures of the basement rocks. Most dykes within the SCIC trend along NW and NNW directions. Fractures and faults within the intrusive complex have preferred orientations along NW, N-S and ENE.

Orientation of the SCIC intrusive contacts with the country

rocks

N=30

Bedding planes of the Upper Plate Assemblage

N=52

Foliations of the Paleozoic basement rocks

N=38

Bedding planes of the Lower Plate Assemblage

N=14

Structures within the Station Creek Igneous Complex Fracture and fault orientations

N=93

Dyke

N=8

Structure of country rocks


62

faults). The net-vein complex contact between the Mount Mucki Diorite and the

Gibraltar Quartz Monzodiorite is slightly displaced sinistrally along the NW faults.

ENE faults crosscut the NW faults, Woolooga Granodiorite and Rush Creek

Granodiorite (231-232 Ma). The vertical displacements and minor sinistral motions

associated with these faults control the geologic expressions of the plutons. The

vertical downthrow juxtaposes rocks of different textures within the plutons, and

juxtaposes granitoids against the overlying volcanic rocks. The N-S faults crosscut the

NW faults and are minor structural features in the SCIC. A N-S fault in the Gibraltar

Rock area cuts a Jurassic intrusive (193 Ma).

PETROGRAPHY AND MINERAL CHEMISTRY

Petrographic study concentrates on the major rock-forming minerals and their

original igneous relationship in fresh rocks and as preserved in the weakly altered

rocks. The component plutons of the Station Creek Igneous Complex differ

significantly in composition, mineralogy, petrography and geologic history. The

changes in the mineral chemistry reflect the chemical evolution mechanisms within

crystals as well as their overall variation within the igneous complex. Mineralogic

comparison with associated hypabyssal and volcanic units aims to establish chemical

similarity between these units.

The overall composition of the SCIC ranges from augite-hypersthene-bearing

monzogabbro to biotite monzogranite (Figure 4.3). There is considerable

compositional overlap between individual plutons. The Woolooga Granodiorite and

Rush Creek Granodiorite have a broad range in composition that varies from quartz

monzodiorite to granite, and from granodiorite to monzogranite respectively. The

Mount Mucki Diorite, Gibraltar Quartz Monzodiorite and Woonga Granodiorite have

relatively uniform compositions.

Plutons of the SCIC differ in their mineral assemblages and mineral modes

(Figure 4.4). The mineralogic and compositional variations within a pluton are

gradual and there are no mappable boundaries between compositional end-members.

Within an individual pluton, mineralogical changes are related to bulk composition as

expressed by whole-rock silica content (Figure 4.5). The Mount Mucki Diorite and

Gibraltar Quartz Monzodiorite differ in their modal variation for pyroxene,


63

Figure 4.3: Streckheisen classification of plutonic rocks of the Station Creek Igneous Complex based on modal mineralogy (data in Appendix 3) The modal mineralogy was point counted from stained thin sections and rock slabs with a minimum number of counts per sample being 400.

Monzodiorite/ monzogabbroQuartz diorite/ gabbro

Diorite/gabbro

Quartz monzodiorite

1234

6 Tonalite7 Granodiorite

9 Granite

Lithologic fields

5 Monzonite

8 Monzogranite




Woonga GranodioriteMount Mucki Diorite

SYMBOLS

Silicified sample*

Alkali feldspar Plagioclase

Quartz


64 Figure 4.4: Modal variation within component plutons of the Station Creek Igneous Complex.

Data is tabulated in Appendix 3.

Woonga Granodiorite

Cum

ulat

ive

mod

al %

Sam

ple

Granodiorite

SC

1086

SC

1129

An east to west section across the pluton 2000 m


Cum

ulat

ive

mod

al %

Transect from the NW to SE section of the pluton (metres)0 15,000m

Textural group/compositionRgs

1 Rgs3 Rgs

2Rgs

2

GranodioriteGranite Granite

1149

1160

1185

1216

1148

Sam

ple

SC

-

Cum

ulat

ive

mod

al %

0 12,000 m0

2 0

4 0

6 0

8 0

1 0 0

Approx. transect from east to NW section of the pluton

P e r th i t ic K - f e ld s p a r

Q u a r t z

P la g io c la s e

H o r n b le n d e p y r o x e n e+

214

215D

223

243

145

400

472

497

590

614

617

Textural group/composition

Quartzmonzodiorite GranodioriteGranodiorite

Sam

ple

SC

-

Fe-Ti oxidesBiotite

Biotite

Rga1Rga

2 Rga3


Cum

ulat

ive

mod

al %

Approximate NE to SW transect of the pluton 2500 m

Quartz monzodiorite

Quartz monzodiorite

Monzo-diorite

Quartzmonzodiorite

Sam

ple


Cum

ulat

ive

mod

al % Quartz monzodioriteMonzodiorite

SC

936

SC10

01

SC

1000

SC99

9

Approx. west to east transect of the pluton (metres)QuartzK-feldspar

Plagioclase

HornblendeOxides

750 m

PyroxeneReplacement

Monzogabbro

Sam

ple

Mount Mucki Diorite

K-feldspar

Quartz

Plagioclase

Hornblende

Fe-Ti oxides

Biotite

Pyroxenes


65

20

40

60

70

MO

DA

L M

INE

RA

L % Plagioclase

30

50

10

MO

DA

L M

INE

RA

L %

MM

GQM

WG

RCG

MO

DA

L M

INE

RA

L %

Hornblende

Mount Mucki DioriteGibraltar Qtz Monz.

Woolooga GranodioriteRush Creek Granodiorite

Woonga Granodiorite

AG

E

SiO RANGE OF INDIVIDUAL PLUTON2

+

MM

MM

GQM

RCG

WG

Figure 4.5: Modal variation of major rock-forming minerals in relation to whole-rock silica content in the Station Creek Igneous Complex. The mineral modes are point counted from thin-sections and rock-slabs, and the whole-rock silica composition is determined by ICP-AES analysis (data in Appendices 2 and 3). The 'age' arrow sets out the relative ages of the pluton determined by K/Ar and Ar/Ar methods.

sodium-cobaltinitrite stained

The dashed-line on each graph represents the general modal variation trend of the mineral with respect to SiO content.

2

Mount Mucki DioriteGibraltar Qtz Monz.

Woolooga GranodioriteRush Creek Granodiorite

Woonga Granodiorite

AG

E

SiO RANGE OF INDIVIDUAL PLUTON2

+


66

hornblende and plagioclase. Inflections in the plagioclase and hornblende variation

trends occur at approximately 57% SiO2, and a biotite modal maxima forms at 71%

SiO2.

Petrography of the Mount Mucki Diorite

The texture of the Mount Mucki Diorite is relatively uniform, fine- to

medium-grained, equigranular and hypidiomorphic-granular (Figure 4.6). The chilled

margin of the pluton (e.g. sample SC936, AMG 440987, 7112354) is fine-grained

(0.2-1 mm) and sub-ophitic. Sub-ophitic augite and orthopyroxene crystallise between

labradorite crystals, and hornblende replaces the earlier pyroxenes (Plate 4.3). The

Mount Mucki Diorite is compositionally banded with melanocratic hornblende-

pyroxene monzogabbro to quartz monzodiorite and leucocratic quartz monzodiorite

layers (thickness ranges from 30 cm to several metres). The contacts between the

lithologic bands are gradational with a progressive decrease in hornblende and

pyroxene from the monzogabbro to leucodiorite. Augite and magnesio-hornblendes

are tightly packed in the melanocratic bands that are typical of cumulate fabric.

Hornblende grew with crescumulate texture from the monzogabbro into the

leucodiorite.

The monzogabbro layers are composed of weak aligned pyroxene, poikilitic

magnesio-hornblende, and subhedral plagioclase (An54-76) in a finer-grained

groundmass of andesine (An36-48), actinolitic hornblende, orthoclase, albite, quartz

(<5%) with traces of magnetite, ilmenite, sphene, calcite, apatite and zircon. The

earlier formed plagioclase (labradorite to bytownite) is zoned, subhedral, poorly

twinned with an undulose extinction and alteration of the core. Augite (~17%)

encloses bytownite and orthopyroxene chadacrysts, Fe-Ti oxides and apatite. Within

the fine-grained rocks along chilled margins, augite crystallises in the interstices of

the earlier plagioclase forming subophitic patches. Magnesio-hornblende (up to 30-

45%) forms mesostasis clusters that mantle resorbed augite, orthopyroxene,

labradorite-bytownite (<0.5 mm), and inclusions of Fe-Ti oxides and apatite.

Actinolitic hornblende (0.25-0.5 mm) envelops the earlier hornblende (Plate 4.4) and

is interstitial with oligoclase (An36-48), orthoclase, magnetite, ilmenite, sphene, apatite,

zircon and quartz. The brown actinolitic hornblende contains only inclusions of rare

andesine. Orthoclase, albite and quartz (anhedral) are late stage minerals in the


67

Plate 4.3: Sub-ophitic chilled margin of the Mount Mucki Diorite (Sample SC936). Pyroxene (lower right) encloses labradorite crystals, and magnesio-hornblende (left) replaces and/or crystallises around the earlier pyroxene. (Photomicrograph, crossed polarised light, width of view ~2.5 mm)

Plate 4.4: Hornblende replaces poikilitic augite (Fe-Ti oxides and apatite inclusions) in the Mount Mucki Diorite. The hornblende-mantle is zoned from tschermakitic- and magnesio-hornblende (pale green) to actinolitic hornblende (brown). (Photomicrograph, plane polarised light, width of view ~2.5 mm)


68

intercrystal spaces, and quartz, apatite and calcite crystallised in miarolitic cavities.

The leucocratic quartz monzodiorite layers are composed of

glomeroporphyritic clusters (3-5 mm) of magnesio-hornblende, augite and

orthopyroxene and labradorite (An54-64) set in a plagioclase-rich (An35-45) groundmass.

The labradorite has similar composition and texture to plagioclase of the gabbro-

diorite band (i.e. zoned, subhedral, poorly twinned with an undulose extinction).

Pyroxene clusters contain bytownite chadacrysts, Fe-Ti oxides and apatite inclusions.

Some pyroxene crystals are oxidised with precipitation of Fe-oxides along cleavage

planes. Magnesio-hornblende (12-15%) surrounds and replaces augite and

orthopyroxene. Actinolitic hornblende forms a brown mantle around the earlier

formed hornblendes and pyroxenes, which commonly contain inclusions of magnetite,

ilmenite and apatite. Orthoclase (12%) and micrographic textured quartz (<10%)

crystallise in the interstices of earlier minerals.

Petrography of the Gibraltar Quartz Monzodiorite

The Gibraltar Quartz Monzodiorite is leucocratic, fine- to medium-grained,

inequigranular, hypidiomorphic-granular with a weak NW-trending mineral alignment.

Its composition is gradational from monzodiorite to quartz monzodiorite. Monzodiorite

consists of medium-grained subhedral plagioclase (51-60%, 2-3 mm), orthoclase (11-

19%), augite (1-6%) and hornblende (3-17%) in a fine-grained (0.2-1 mm)

groundmass of actinolitic hornblende, titanomagnetite, albite, orthoclase, quartz,

apatite, epidote and chlorite. Plagioclase (An38-54) occurs as zoned, rounded and

fractured crystals rimmed by non-taxial adcumulus oligoclase and contains rare

inclusions of resorbed bytownite (An74). Orthoclase is sieved-textured or has a

corroded core. Augite is zoned and differs in colour and birefringence from core to

rim. It is poikilitic and contains inclusions of exsolved magnetite-ilmenite, apatite and

sphene. Magnesio-hornblende that crystallises with, and replaces augite, also contains

chadacrysts of embayed augite. Actinolitic hornblende, actinolite and chlorite partially

replace clinopyroxene and magnesio-hornblende, and crystallise with quartz, albite

and epidote in the interstices of earlier minerals. Magnetite contains apatite and

sphene inclusions and exsolved ilmenite lamellae. Epidote is an alteration mineral

derived from the breakdown of plagioclase.


69

The quartz monzodiorite end-member is composed mainly of plagioclase (53-

54%), K-feldspar (22-23%) and quartz (10-17%), with lesser amounts of hornblende

(~4.2%). Plagioclase (An35-37) and orthoclase form an interlocking fabric. Traces of

resorbed augite and pseudomorphs of pyroxene in actinolitic hornblende show

evidence of incomplete replacement. Quartz and granophyric perthite fill the

intercrystal spaces, and myrmekite occurs within some perthite crystals. Biotite,

actinolite and chlorite are secondary minerals derived from subsolidus reaction of

hornblende and augite.

Petrography of the Woolooga Granodiorite

The Woolooga Granodiorite is leucocratic, fine- to medium-grained,

inequigranular, perthitic and texturally heterogeneous. The unit is texturally

subdivided into 3 subunits- Rgw1 (most common texture), Rgw2 and Rgw3 (Figure

4.6). Rgw1 is pinkish-white, porphyritic and hypidiomorphic-granular and contains

phenocrysts of normally zoned subhedral plagioclase (2-5 mm), hornblende (1-4 mm,

commonly with augite chadcrysts) in granophyric groundmass (Plate 4.5). The

phenocrysts commonly have undulose extinction, form kinked twins, and are

internally stained. Rgw2 is localised along narrow zones adjacent to intrusive contacts

with the country rocks and below roof pendants. It is fine-grained, porphyritic and

contains zoned plagioclase (2-4mm, 15-30%) and hornblende (1-3mm, 10-15%)

phenocrysts in an aplitic groundmass of orthoclase-quartz with traces of biotite. Rgw3

is medium-grained, inequigranular, hypidiomorphic-granular and contains undulose

and polycrystalline quartz. It is associated with potassic alteration and is localised to

intrusive contacts zones with other plutons of the Station Creek Igneous Complex. In

the Mount Mucki area, NW-NNW faults juxtapose fine-grained rock of Rgw2 and

roof pendants against medium-grained rock of Rgw1.

The Woolooga Granodiorite is reversely zoned from a granodiorite rim to a

more calcic quartz monzodiorite centre (Figure 4.4). The quartz monzodiorite end-

member consists of primary augite, magnesio- to actinolitic hornblende and andesine

(An44-50) with rare embayed bytownite cores. Augite occurs as poikilitic, prismatic

crystals with inclusions of magnetite and ilmenite. Most augite crystals form mafic

aggregates, which are replaced or rimmed by hornblende, actinolite and iddingsite.


70

Figure 4.6: Textural variations in the Station Creek Igneous Complex.


Rgl

Rgw1

Rgw2

Pe

Gr

PeHy

Brooyar StateForest

Alteration halo

Pe Rgw1

Rgw3

Gr

??

?

Gr

Gr

Gr

Gr

Hy

Pe

Pe

Rgs1

RgS2

Rgs3

Rush CreekGranodiorite

Woonga Granodiorite

Mount Mucki Diorite

WooloogaGranodiorite

Gibraltar QuartzMonzodiorite

Rgw2

Neureum MountainPorphyry

Black SnakePorphyry

Log Creek

Kilkivan

Mf

Mf

Pe

STATION CREEK IGNEOUS COMPLEX

1 0 K


GibraltarQuartzMonzodiorite

Woonga Grano- diorite


Woolooga (south)

Mount MuckiDiorite

Mf

7110000 N

7120000 N

7129000 N

7120000 N

7110000 N

7100000 N

7090000 N

4300

00 E

4220

00 E

4300

00 E

4400

00 E

4500

00 E

26 15’So

26 00’So

152

30’E

o

152

15’E

o

152

15’E

o Fault (relative movement indicated)

Hornfelsic aureole

Net-veining comprising diorite enclaves in quartz monzodiorite.

Strike of igneous banding

Porphyritic with plagioclase and hornblende phenocrysts in microcrystalline groundmass.

Rgs1

Textural group

Holocrystalline, porphyriticmedium grained,

with zoned plagioclase laths in graphic quartz-and-perthite matrix.Hypidiomorphic medium grained , with rare plagioclase phenocrysts.

Hy

Mesocrystalline, g homogeneous rey, rock.

Granophyric, fine-grained p, ink, with <15% feldspar phenocrysts.

Gr

IGNEOUS TEXTURES

Inferred fault

Hypidiomorphic medium grained, melanocratic, may be banded with leucocratic layers.

, fine to Mf

Rgw3

Hy


71

Plate 4.5: Plagioclase-dominated porphyritic and hypidiomorphic-granular granodiorite (Rgw1) of the Woolooga Granodiorite. Subhedral plagioclase and hornblende crystallise in granophyric groundmass (quartz, perthite, albite, actinolitic-hornblende, biotite, apatite, sphene and opaque minerals). (Polished slab, width of view ~7 mm)

Plate 4.6: Interstitial granophyric groundmass in the Woolooga Granodiorite. The groundmass is composed of graphic-textured quartz, K-feldspar, albite, actinolitic-hornblende, biotite, apatite, sphene and opaque minerals. (Photomicrograph, crossed polarised light, width of view ~2 mm).


72

Hornblende (11-19 modal %) is subhedral, highly birefringent and poikilitic. It

contains magnetite, ilmenite and apatite inclusions. Early phase magnesio-hornblende

(green) is anhedral and forms agglomerated clusters with apatite and Fe-Ti oxides.

Actinolitic hornblende (brown-green) grows syntaxially on magnesio-hornblende and

pyroxene crystals. Many hornblende crystals have uralitised cores pseudomorphed

after pyroxenes, and these are mantled by secondary actinolite and biotite. Plagioclase

is subhedral to euhedral, twinned, rhythmically zoned and locally poikilitic and

contains inclusions of zircon, apatite and traces of opaque minerals. Granophyric

perthitic-orthoclase, graphic quartz, albite, biotite, apatite, sphene, magnetite and

ilmenite fill interstices between the earlier formed crystals. Minute subhedral crystals

of apatite and zircon form inclusions in the magnetite.

The granodiorite consists of primary magnesio- and actinolitic hornblendes,

biotite and plagioclase (andesine to oligoclase). Hornblende (2-10 modal %) occurs as

laths or glomeroporphyritic clusters and locally contains corroded chadacrysts of

augite. Mono-mineralic augite phenocrysts are not present in the granodiorite.

Idiomorphic and bladed actinolite and pinnite biotite replace most of the magmatic

hornblendes. Euhedral biotite (2-6%) crystallises with perthite and oligoclase.

Secondary pinnite biotite and chlorite replace most of the euhedral biotite late in the

crystallisation sequence. Within the potassic-altered rocks of subunit Rgw3, all mafic

minerals were replaced by interpenetrating platelets of biotite. These biotite platelets

overprint the original granitic fabric. Plagioclase (oligoclase-andesine) is euhedral to

subhedral, zoned and commonly hosts trace amounts of apatite and Fe-Ti oxides. The

groundmass (0.2-1 mm) is composed of graphic textured quartz, K-feldspar, albite,

hornblende, biotite, apatite, sphene, chlorite and opaque minerals. K-feldspar occurs

as exsolved, fine-grained, granophyric intergrowths with quartz, actinolite, biotite and

albite, and forms myrmekite and micrographic intergrowths within crystal interstices

(Plate 4.6). Turbid, brownish alterations of K-feldspar are common and pervasive.

Magnetite, ilmenite, sphene, zircon, apatite, and epidote are common accessory

minerals. A dark brown, poorly crystalline biotite common forms around haematite-

magnetite grains within interstices. Sphene occurs as overgrowths on the

titanomagnetite.

The Woolooga Granodiorite shows varying degrees of sub-solidus

argillisation, chloritisation and uralitisation. Cores of early plagioclase phenocrysts


73

are partially saussuritised, and augite, hornblende and biotite phenocrysts are partially

uralitised and chloritised.

Petrography of the Rush Creek Granodiorite

The Rush Creek Granodiorite is leucocratic, fine- to medium-grained,

inequigranular and hypidiomorphic-granular. It varies texturally from a

hypidiomorphic to a granophyric fabric (Figure 4.6). Exposures at higher topographic

elevations (Rgs1) are fine-grained, leucocratic-pink, porphyritic and granophyric. Rgs1

contains <5% mafic minerals (hornblende and biotite) and <10% feldspar phenocrysts

in a pink aplitic groundmass. The most common textures in subunit (Rgs2) are

porphyritic and hypidiomorphic-granular, with phenocrysts of plagioclase (1-3 mm),

hornblende (0.5-2 mm) and biotite (0.5-1 mm) in a granophyric groundmass of

perthite, quartz, biotite, magnetite, ilmenite, sphene and apatite. A medium-grained,

hypidiomorphic rock of subunit Rgs3 is present at the centre of the pluton around a

hypersthene monzodiorite intrusion. The unit is composed of equigranular

hornblende, biotite, unzoned plagioclase, orthoclase and quartz. All crystals in Rgs3

including interstitial quartz are strained and display undulose extinction and polygonal

pressure-solution suturing. ENE faults juxtapose the fine-grained rocks of Rgs1

against medium-grained rocks of Rgs2 and Rgs3.

The composition of the Rush Creek Granodiorite varies from monzogranite

to granodiorite. Monzogranite and granite occur mainly at the edge of the pluton

whereas granodiorite dominates the core. The boundaries between the two

compositional types are gradational, and are generally unrelated to textural variations.

Granodiorite is medium- to coarse-grained, porphyritic, with a granophyric to

hypidiomorphic-granular texture and is composed of magnesio- to actinolitic

hornblendes (5-10 modal %, 2-10mm), biotite (3-6 modal %), zoned subhedral

plagioclase (30-45 modal %, 2-5 mm), 15-30 modal % perthite and quartz. Poikilitic

magnesio-hornblende is subhedral, glomeroporphyritic and contains apatite, magnetite

and ilmenite, and corroded augite inclusions. A lower birefringent brown-green

actinolitic hornblende mantles and replaces the earlier magnesio-hornblende (Plate

4.7). Actinolitic hornblende crystallises contemporaneously with biotite, actinolite,

oligoclase, anhedral quartz, anhedral perthite and apatite. Plagioclase phenocrysts are


74

zoned (andesine An33-39 cores to oligoclase An16-24 rims). Some crystals enclose

inclusions of apatite and embayed bytownite and augite. Most plagioclase crystals are

fractured and have undulose extinction, kinked twin planes and pressure-solution

sutures. Orthoclase occurs as graphic perthite (with quartz) in Rgs1 and Rgs2, and as

exsolved anhedral orthoclase (1-2 mm) in Rgs3. Biotite, quartz, perthite and trace

amounts of apatite and Fe-Ti oxides form interstitial minerals between hornblende and

plagioclase phenocrysts.

Granite and monzogranite are texturally and mineralogically similar to

granodiorite, but differ in the modal percentages of minerals (Figure 4.4). They are

composed of 1.5-5 modal % hornblende, 4-7 modal % biotite, 19-31 modal % zoned

subhedral plagioclase (1-3 mm), 30-43 modal % anhedral perthite and quartz.

Plagioclase phenocrysts have intensely cracked cores enclosed in undeformed

oligoclase adcumulus rims (Plate 4.8). Poikilitic hornblende clusters (sphene, apatite

and Fe-Ti oxides inclusions) co-precipitate with biotite, and anhedral quartz and

perthite. Pinnite biotite (dark brown and poorly crystalline), actinolite and chlorite

replace magnesio-hornblende and magnetite. Sericite, epidote and chlorite are late

stage alteration products.

A hypersthene monzodiorite intrusion within the Rush Creek Granodiorite is

melanocratic, fine-grained, sub-ophitic and has a weak mineral alignment. Plagioclase

(1-2 mm), augite (0.2-0.5 mm) and orthopyroxene (0.2-0.5 mm) phenocrysts are

weakly aligned in a fine-grained groundmass composed of pyroxene, plagioclase and

Fe-Ti oxides.

Petrography of the Woonga Granodiorite

The Woonga Granodiorite is leucocratic, homogeneous, medium- to fine-

grained, inequigranular and hypidiomorphic-granular. The composition and texture

within the pluton is relatively uniform, though the contact aureole with the Mount

Mucki Diorite is slightly recrystallised to a sucrosic texture. The unit comprises

subhedral plagioclase (1-2 mm), magnesio- to actinolitic hornblendes (1-2 mm) and

biotite in fine granitic groundmass of quartz, orthoclase, plagioclase, biotite and

actinolite with traces of magnetite, ilmenite, apatite, zircon and sphene. The

hornblende and biotite content decreases slightly from the rim to core of the pluton.


75

Plate 4.7: Compositional zonation in hornblende of the Rush Creek Granodiorite, from magnesio-hornblende core (brown) to actinolitic-hornblende rim (brown-pale green). Mineral inclusions within the magnesio-hornblende cores are apatite, magnetite, ilmenite and resorbed augite. (Photomicrograph, plane polarised light, width of view ~2 mm)

Plate 4.8: Intensely cracked plagioclase cores enclosed in undeformed oligoclase rims, Rush Creek Granodiorite. (Photomicrograph, crossed polarised light, width of view ~2.5 mm)


76

Hornblende is subhedral and poikilitic and has inclusions of sphene, apatite and

magnetite. The earlier tabular magnesio-hornblende forms an interlocking fabric with

subhedral andesine (An32-41). Later formed actinolitic hornblende and actinolite

crystallise with anhedral oligoclase (An24-29), biotite, orthoclase and quartz into the

interstitices of earlier crystals. Actinolitic hornblende and actinolite also replace or

rim magnesio-hornblende. Biotite accounts for less than 2% of the granodiorite,

crystallising as a late magmatic phase with quartz and orthoclase. Biotite overprints

and replaces the earlier hornblende and opaque minerals, forming rim around these

minerals. Plagioclase content remains relatively constant throughout the pluton,

averaging 43 modal percent. Most plagioclase crystals are zoned from andesine cores

(An30-41) to oligoclase syntaxial rims (An24); with local sieve-textured cores.

Plagioclase is fractured and strained as evidenced by kinked twins and undulosed

extinction. Orthoclase crystallises as anhedral crystals in the interstitices and has an

average modal percentage of 18%. Albite, quartz, epidote, apatite and chlorite fill

interstices between earlier minerals. Quartz and albite are recrystallised to a

polycrystalline texture, and augite and hornblende are replaced by actinolite.

MINERAL CHEMISTRY

Quantitative mineral chemistry of plutonic, hypabyssal and volcanic units in

the thesis area were determined by electron microprobe (complete data in Appendix

3). The sample selection is representative of both the texural and compositional

variety of rock types (Table 4.2).

Amphiboles

Amphibole of the SCIC varies compositionally from magnesio-hornblende to

actinolite (Figure 4.7a). In the Gibraltar Quartz Monzodiorite and Woonga

Granodiorite, the actinolitic hornblende and actinolite are suggestive of late-stage

minerals from hydrothermal alteration and/or thermal metamorphic overprints. On an

A(K+Na) versus T(Si) plot (Figure 4.7b, alternative classification), the amphibole

composition varies from hornblende to tremolite (with exception of a pargasite in the

Mount Mucki Diorite). The overall compositional variation within the Station Creek

Igneous Complex is mimicked by variations within individual amphibole crystals

from core to its rim. Compositions of magmatic amphiboles in the Black Snake


77

Porphyry and Neureum Mount Porphyry are tschermakite to magnesio-hornblende,

and amphibole in the Neara Volcanics is ferro-tschermakite.

Table 4.2: Representative samples for mineral chemistry analysis by electron microprobe

Pluton/Unit Mappable unit Sample No. Woolooga Rgw1 Granodiorite SC235, SC328, SC382, SC588, Granodiorite Rgw1 Quartz monzodiorite SC494, SC497, SC582, SC816 Rgw2 Granophyric granodiorite SC215, SC1104 Rgw3 Hypidiomorphic granodiorite SC617, SC1037, SC1069 Gibraltar QM Quartz monzodiorite and monzodiorite SC710, SC791, SC792, SC794 Mount Mucki Diorite

Monzogabbro and quartz monzodiorite SC936, SC999, SC1000, SC1001

Woonga Grano. Granodiorite SC1086, SC1129 Rush Creek Rgs1 Granophyric monzogranite SC1153, SC1185 Granodiorite Rgs2 Porphyritic monzogranite-granite SC1144, SC1149 Rgs3 Hypidiomorphic granodiorite SC1148, SC1166 Porphyritic Neureum Mountain Porphyry SC901 intrusions Black Snake Porphyry SC1286 Monzodiorite intrusion in Rush Creek Gran. SC1204 Stocks in the Woolooga Granodiorite SC852, SC820 Dykes Andesite and dacite dykes SC450, SC1008 Highbury Volc. Basalt SC945, SC1098 Neara Volcanics Andesite and trachyandesite SC707, SC725, SC788, SC886 North Arm Volc. Andesite SC082, SC1030 Xenoliths Diorite and granodiorite SC1018D, SC1018F, SC1030Xe

Variation from magnesio-hornblende to actinolite accompanies a increase in

tetrahedral-site occupancy by Si (Table 4.3) which is compensated by Al, coupled by

Al or Fe3+ entering the C-site for the loss of Mg; summarised as C(Al,Fe3+)3+ +

T(Al)3+ <=> C(Mg)2+ +T(Si)4+. This coupled substitution is the tschermakitic

substitutions (Czamanske & Wones, 1973). Variation from hornblende to tremolite

accompanies an increase in tetrahedral-site occupancy by Si that is compensated by

Al, Ti or Fe3+, coupled by alkalis entering an otherwise empty A-site. This

substitution is the edenitic substitution, summarised as A(Na+K)+ + T(Al,Ti,Fe)3+

<=> T(Si)4+ (Czamanske & Wones, 1973). Therefore, the variation from magnesio-

hornblende to actinolite-tremolite in the Station Creek Igneous Complex involved

both edenitic and tschermakitic substitutions with the overall equation of A(Na+K)+ +

C(Al ,Fe3+)3+ + 2T(Al)3+ <=> C(Mg)2+ + 2T(Si)4+.

The relationship between T(Al) versus A(Na+K) is approximately linear with

a 3:1 ratio (Figure 4.8A) instead of a 2:1 expected for the ideal edenitic and

tschermakitic substitutions. This higher ratio (termed as Al-loss) may involve


78

Figure 4.7: lassifications of magmatic-amphiboles

and b.

Leake (1978) c from the Station Creek Igneous Complex and associated volcanic and intrusive rocks based on: a. Mg/(Mg+Fe ) versus

(Si), A(Na+K) versus (Si). The overall variation trend for the SCIC reflects the change from core to rim in individual crystals and the compositional change from early magmatic-hornblende phenocrysts to late-stage interstitial amphiboles.

2 +

T T

General variation trend from core to rim in individual crystal, and from early magmatic-hornblend to late interstitial amphibole.

Ferro-tschermakite Ferro-

hornblendeFerro-

actinolite

Fe- act.horn.

Fe-tsch.horn.

TSi0

8 5.566.577.5

Tremolite

Tschermakite Magnesio-hornblendeActinolite

Act.horn.

Tsch.horn.

Trem. horn.

a. Mg/(Mg+Fe ) versus (Si) classification of hornblende2 +

T

General variation trend from core to rim in crystals.

b. A(Na+K) versus T(Si) classification of hornblende

Mount Mucki Diorite

Woonga Granodiorite


Neureum Mount Porphyry

Highbury Volcanics

Neara Volcanics

SYMBOLS

Xenolith

Gibraltar Quartz MonzodioriteWoolooga Granodiorite

(Purple= Rgw Green= Rgw Red= Rgw )

1;2; 3

Rush Creek Granodiorite (Green Rgs ; Purple= Rgs ; Red= Rgs )

12 3

=

Porphyritic monzodioritic intrusion

Tremolite-actinolite field, sub-solidus modification, or late stage deuteric alteration.

C

hapter 4: The Station Creek Igneous C

omplex

79


80

additional coupled substitutions such as C(Ti)4+ + 2T(Al)3+ <=> C(Mg)2+ + 2T(Si)4+

(Czamanske & Wones, 1973) or B(Ca)2+ + T(Al)3+ <=> B(Na)+ + T(Si)4+ (Giret et al.,

1980). Couple substitution involving the later reaction produced an overall equation

of A(Na+K)+ + B(Ca)2+ + C(Al,Fe3+)3+ + 3T(Al)3+ <=> B(Na)+ + C(Mg)2+ + 3T(Si)4+

(Equation A) fitting the 3:1 T(Al) to A(Na+K) ratio.

The relationship between T(Al) versus A(Na+K) is approximately linear with

a 3:1 ratio (Figure 4.8A) instead of a 2:1 expected for the ideal edenitic and

tschermakitic substitutions. This higher ratio (termed as Al-loss) may involve

additional coupled substitutions such as C(Ti)4+ + 2T(Al)3+ <=> C(Mg)2+ + 2T(Si)4+

(Czamanske & Wones, 1973) or B(Ca)2+ + T(Al)3+ <=> B(Na)+ + T(Si)4+ (Giret et al.,

1980). Couple substitution involving the later reaction produced an overall equation

of A(Na+K)+ + B(Ca)2+ + C(Al,Fe3+)3+ + 3T(Al)3+ <=> B(Na)+ + C(Mg)2+ + 3T(Si)4+

(Equation A) fitting the 3:1 T(Al) to A(Na+K) ratio.

The T(Al) varies over a narrow range of C(Mg+Total Fe) (Figure 4.8B). The

relationship between T(Al) and Total (Al) is linear with a ratio of 1:1 (Figure 4.8C),

which means that most Al in magmatic amphiboles enters the tetrahedral site. For

amphiboles with T(Al) >0.5 (mole), the relationship between T(Al) and C(Ti) is

approximately linear with a ratio of 5:1 (Figure 4.8D), and involves the coupled

substitution C(Ti)4+ + 2T(Al)3+ <=> (Mg)2+ + 2T(Si)4+ (Czamanske & Wones, 1973).

The C(Ti) substitution is restricted to the tschermakitic-pargasitic amphiboles of the

Mount Mucki Diorite, the Neara Volcanics, monzodioritic intrusions and the quartz

monzodiorite of Woolooga Granodiorite. The limited variation of C(Mg+Total Fe)

and T(Al) and a linear ratio between Total(Al) and T(Al) suggest limited substitution

of Al into the octahedral sites. Mg and Total Fe dominate the octahedral sites in the

amphiboles with only minor substitutions from Al and Ti.

The Al-substitution in the tetrahedral site requires the coupled substitutions

of Na-K (Ca) and Ca in the A- and B-sites respectively (Equation A). The linear

relationship between A(Na) and B(Na) (Figure 4.8E) fits the richterite substitution,

summarised as A(Na) + B(Na) <=> B(Ca) (Czamanske & Wones, 1973). Amphiboles

from the Mount Mucki Diorite, the Black Snake Porphyry and the Mount Neureum

Porphyry (quartz monzodiorite) show Na-loss in A-sites. The mineral stoichiometry

shows calcium and potassium substitute for sodium in the A-sites (Table 4.3).

Richteritic substitution may result from hydrothermal alteration (Deer et al., 1992) but


81

Figure 4.8: Molar chemical variations in amphiboles from the Station Creek Igneous Complex and associated volcanic and intrusive rocks.

A. A positive relationship between T(Al) and A(Na+K) with an approximately 3:1 ratio suggests couple substitutions involving these cations. The 3:1 ratio is higher than the idealised edenite-tschermakite substitutions and implied additional "Al-loss" substitution.

B. The limited change in C(Mg + Total Fe) against T(Al) suggests constant cationic balance in the octahedral coordination site. Minor substitution occurs in amphiboles from the Black Snake Porphyry, Neureum Mountain Porphyry and Mount Mucki Diorite.

C. A linear relationship between Total(Al) and T(Al) suggests that most Al occurs in the tetrahedral site. Amphiboles from the Mount Mucki Diorite, Black Snake Porphyry and Neureum Mountain Porphyry have minor Al substitution in the B-site.

D. No systematic variation occurs between T(Al) and C(Ti) in amphiboles from granodiorite and granite of the Woonga Granodiorite, Woolooga Granodiorite and Rush Creek Granodiorite. Amphiboles from the Mount Mucki Diorite, Neureum Mountain Porphyry and from quartz monzodiorite of the Woolooga Granodiorite have positive correlation between T(Al) and C(Ti) that suggest coupled substitution between the two elements.

E. A linear variation trend between B(Na) and A(Na) in amphiboles from the Woonga Granodiorite, Woolooga Granodiorite and Rush Creek Granodiorite suggests richterite substitution. Amphiboles from the Mount Mucki Diorite, Black Snake Porphyry, Neureum Mountain Porphyry and from quartz monzodiorite of the Woolooga Granodiorite show A(Na) loss due to K-substitution.

F. Fluorine-bearing hornblende occurs in the Gibraltar Quartz Monzodiorite, monzodiorite intrusions and in the NW section of the Rush Creek Granodiorite. The fluorine content decreases from core to rim of individual crystal. Amphiboles from other plutons have less than 0.1% F are not presented.


82

Total (Al) - T(Al) = Al in octahedral site

C. Total(Al) versus T(Al)

A(N

a+K

) cat

ions

/ 23

oxyg

en

T(Al )/ 23 oxygen3 +

00 21

0.6

0.4

0.2

~3T(Al): 1A

(K+Na)

A. T(Al) versus A(Na+K)

T(A

l)/

23 o

xyge

n3

+

C(Mg+Total Fe) cations/ 23 oxygen2 3 4 5

0

1

2 Al & Ti substitution

B. C(Mg + Total Fe) versus T(Al)

T(A

l)/

23 o

xyge

n3

+

1

2

0

C(Ti) /23 oxygen0 0.40.1 0.2 0.3

5T(Al):1C(Ti)

D. T(Al) versus C(Ti)

B(N

a)/ 2

3 ox

ygen

0

0.1

0.2

0.3

A(Na)/ 23 oxygen0 0.2 0.4 0.50.30.1

B(Na)

: A(N

a)

Richte

rite su

bstitu

tion

A(Na) loss

E. B(Na) versus A(Na) F. F versus T(Si)


83

petrography shows no evidence of K-metasomatism or A(Na) loss in these magmatic

amphiboles. The amphiboles from the Gibraltar Quartz Monzodiorite and granites of

the Rush Creek Granodiorite have slight A(Na) gains.

Fluorine-bearing amphibole (>0.1 weight %) occurs in the Gibraltar Quartz

Monzodiorite (late stage amphibole), in a Late Triassic-Early Jurassic monzodiorite

intrusion into Woolooga Granodiorite, and in the NW section of Rush Creek

Granodiorite (Figure 4.8F). The F-content decreases from the core towards the rim of

crystals. The amphiboles from the Woonga Granodiorite, Woolooga Granodiorite,

Mount Mucki Diorite and from the southern section of the Rush Creek Granodiorite

contain less than 0.005 weight percent fluorine. Trace amount of chlorine (<0.2

weight %) occurs in all amphiboles of the Station Creek Igneous Complex.

Biotite

Magmatic biotite occurs in the Woonga Granodiorite, Woolooga Granodiorite

and Rush Creek Granodiorite. The Fe2+/(Fe2++Fe3+) ratios of biotite in the Woolooga

Granodiorite, Woonga Granodiorite and Rush Creek Granodiorite are 0.26-0.27, 0.17

and 0.18-0.21 respectively (Table 4.4).

Table 4.4: Semi-quantitative Fe2O3 and FeO results for biotite separates determined by titrametric method (weight percent)

Sample No. Plutonic Unit % Fe2O3* % FeO* Fe3+

(Fe3+ + Fe2+)

SC582 Woolooga Granodiorite 8.121 10.477 0.26

SC582 rpt Woolooga Granodiorite 8.444 10.187 0.27

SC820** Woolooga Granodiorite** 9.477 5.578 0.43

SC1129 Woonga Granodiorite 5.576 12.565 0.17

SC1149 Rush Creek Granodiorite 5.892 10.142 0.21

SC1185 Rush Creek Granodiorite 5.495 11.222 0.18 rpt = Repeat analysis ** Late pinnite biotite

Biotite from the SCIC has similar composition and representative biotite

chemistry from the various units is summarised in Table 4.5. The geochemistry of

magmatic biotite in the SCIC is typical of biotite from calc-alkaline magmas (Figure

4.9) (Abdel-Rahman, 1994). A minor compositional change from phlogopite towards

C


omplex

84


85

Figure 4.10: Compositional classification of biotite from the various plutons of the Station Creek Igneous Complex and associated intrusions (Deer ., 1992). The biotite from the Woolooga Granodiorite, Rush Creek Granodiorite and the Gibraltar Quartz Monzodiorite has similar mineral chemistry. Variation trend from the core to rim of individual mineral approximates the change from magmatic to late-interstitial biotite.

et al


Late biotite ininterstices or earlier minerals


Woonga Granodiorite


Black SnakePorphyry

Mount Neurum Porphyry

LEGEND

AnnitePhlogopite Fe/(Fe+Mg)

Tetra

hedr

al A

l or Z

(Al)/

22

oxyg

en

K Fe [Si Al O ](OH)2 6 6 2 2 0 4

K Mg [Si Al O ](OH)2 6 6 2 2 0 4

"Eastonite SiderophylliteK Mg Al [Si Al O ](OH)

2 4 2 4 4 2 0 4 K Fe Al [Si Al O ](OH)2 4 2 4 4 2 0 4

2

3

0 1

Core

Rim

Late & secondarybiotite

Evolving biotitetrend

Figure 4.9: Geochemical comparison of biotite from the SCIC and associated intrusions with biotite of the various granite types

The SCIC biotite is chemically similar to biotite from calc-alkaline/I-type magma. (Symbol as in Figure 4.10)

(Abdel-Rahman, 1994). geo

Peraluminous Field(collisional and S-type granite)

Calc-alkaline Field (orogenic, subductionrelated and I-type granite)

Alkaline Field (anorogenic, extensional related and A-type granite)

30

20

10

0

AlO

wei

ght p

erce

nt2

3

0 5 10 15 20 25MgO weight percent


86

Figure 4.11 (A-E): Chemical variations in

A & B: No variation relationship occurs between tetrahedral coordinated Z(Al) and whole-rock SiO and Al O .

C. Total(Ti) varies over limited changes in Z( ), implying little or no coupled substitution between these cations.

2 2 3

biotite from the Station Creek Igneous Complex and monzodiorite intrusions.

Al Fe

D. An approximately 1:1 relationship between Z(Al ) and Y(Al +Fe ) in magmatic-biotite, late-stage biotite and from core-to-rim in individual crystal, suggests siderophyllite substitution.

E. A linear 3:2 relationship between Y(Fe ) and Y(Fe ) highlights the substitution of three bivalence cations for two trivalence cations in the octahedral sites.

3 + 3 +

3 + 3 + 3 +

2 + 3 +

+

+ +Mg Mn Ti+

60 65 70 751

2

3

4Z(

Al

) /22

oxy

gen

3+

Whole rock SiO %2

A. Z(Al) versus whole-rock SiO2

Z(A

l) /

22 o

xyge

n3

+

1

2

3

4

Whole rock Al O %2 3

13 14 15 16 17

B. Z(Al) versus whole-rock Al O2 3


Late biotite in interstices or earlier minerals


Woonga Granodiorite



Neureum Mountain Porphyry

LEGEND

Total Ti /22 oxygen

Z(A

l) /

22 o

xyge

n3

+

1

2

3

4

0 0.2 0.4 0.6

C. Total(Ti) versus Z(Al Fe )3 + 3 +

+

T-si

te Z

(Al)/

22

oxyg

en

Oct.-site Y(Al + Fe )/ 22 oxygen3 + 3 +

3

4

20.5 1.0 1.5

~ 1Z(Al) : 1Y(Al+Fe )3 +

D. Z(Al ) versus Y(Al +Fe )3 + 3 + 3 +

Y(Fe +Mg+Mn) cations/ 22 oxygen2 +

*Y(F

e) /

22 o

xyge

n3

+

0

1

2

3 4 5 6 7

*=Total(Al+Fe +Ti )-Z[8-Z(Si+Al)]3 + 4 +

2Y(Fe):3Y(M

)

3+

2+

E. Y(Fe ) versus Y(Fe ) 3 + 2 +


87

“eastonite” coincides with changes from core to rim composition in individual crystal,

and from magmatic-phase to the interstitial- and secondary biotite (Figure 4.10).

There is no systematic variation relationship between Z(Al) and Fe/(Fe+Mg) in the

biotite, and between the whole rock SiO2 and Al2O3 in biotite (Figure 4.11A, B).

Within the primary biotite, the relationship between Fe3+ and SiO2 is antipathetic, and

Fe3+ is sympathetic with Al2O3. The Ti4+ in biotite has a positive correlation with SiO2

and has a negative correlation with Al2O3. The biotite stoichiometry highlights that

combined cationic charges of Si4+ and Al3+ do not fill the tetrahedral co-ordinated site,

and require minor substitution by M3+ or M4+ elements.

There is no systematic variation between the Total (Ti) and Z(Al) in biotite

(Figure 4.11C). This lack of systematic change despite a negative correlation between

Ti4+ and Al2O3 implies that the Ti4+ enters the Z-site instead of the octahedral or Y-

site. A positive relationship between Y(Fe3++Al) and Z(Al) (Figure 4.11D) proposes a

coupled substitution where ferric iron enters the Y-site to balance the Al in Z-site.

This substitution is the siderophyllitic substitution, summarised as Y(Al,Fe)3+ +

Z(Al)3+ <=> Y(Mg)2+ + Z(Si)4+ (Speer, 1984). Y(Fe3+) and Y(Fe2++Mg+Mn) are

related by a negative 2:3 ratio (Figure 4.11E). The ratio indicates that two ferric irons

enter the octahedral site to balance the ionic charges of three (Fe,Mg,Mn)2+ cations as

suggested by the equation 3Y(M)2+ <=> 2Y(R)3+ (Monier & Robert, 1986). Therefore,

as biotite evolves from early to late-crystallisation stage and from core to rim, ferric

iron substitutes for ferrous iron its octahedral sites.

Pyroxenes

Pyroxenes are minor constituents of the Mount Mucki Diorite, the Gibraltar

Quartz Monzodiorite, the Woolooga Granodiorite, the monzodiorite intrusions and the

volcanic rocks. Their chemistry is similar to pyroxenes from sub-alkaline (i.e. calc-

alkaline and tholeiite) magmas (Figure 4.12) (LeBas, 1962).

Pyroxenes of the SCIC have augite and diopsidic augite compositions (Figure

4.13), with coexisting orthopyroxene occuring only along chilled margins of the

Woolooga Granodiorite and locally in monzodiorite intrusions. The augite in the

SCIC is more calcic (Wo40-49En38-44Fs10-20) than those in volcanic units (Wo28-29En41-

47Fs25-30) (Table 4.6). However, augite from some andesitic units in the Neara

Volcanics has similar compositions to the plutonic augite. Slight iron enrichment (1-

C


omplex

88


89

Figure 4.12: Variation of SiO versus Al O in pyroxene from the and associated rocks. Pyroxene from the SCIC has similar

compositions to the pyroxene from the non-alkaline or the calc-alkaline and tholeiite magmas

2 2 3Station Creek Igneous

Complex

(alkaline and non-alkaline fields after LeBas, 1962).

LEGENDWoolooga Granodiorite (SC235, 382, 588, Mount Mucki Diorite (SC936, 1001)

Monzodioritic intrusion (SC820, 1204)

North Arm Volcanics (Andesite, SC1030)

Neara Volcanics (SC725, 886)

Highbury Volcanics (Basalt, SC1098)

Mafic enclaves in the net-vein along contacts between the Gibraltar Quartz Monzodiorite and the Mount Mucki Diorite(SC1018F)

SiO

Wei

ght %

2

Al O Weight %2 3

50

58

0 1 2 3 4 5 6

52

54

56 Non-alkaline

Alkaline

Figure 4.13: Classification of pyroxenes from the

The arrows approximate the chemical variation trends from core-to-rim of individual crystal as well as the chemical variation of pyroxenes from the associated diorite , basalt, andesite and quartz monzodiorite.

Station Creek Igneous Complex, the monzodioritic intrusions and associated volcanic rocks (after Morimoto, 1988).

DiopsideCaMgSi O

2 6

EnstatiteMg Si O

2 2 6

FerrosiliteFe Si O

2 2 6

WollastoniteCa Si O

2 2 6

Enlarged area

HedenbergiteCaFeSi O

2 6

(After Morimoto, 1988)

Clinoenstatite

Pigeonite

Augite

DiopsideCaMgSi O

2 6

EnstatiteMg Si O

2 2 6

90 80 70 60 50

10

20

30

40

50LEGEND

Woolooga Granodiorite (SC235, 382, 588, Mount Mucki Diorite (SC936, 1001)

Monzodioritic intrusion (SC820, 1204)

North Arm Volcanics (Andesite, SC1030)

Neara Volcanics (SC725, 886)

Highbury Volcanics (Basalt, SC1098)

Mafic enclaves in the net-vein along contacts between the Gibraltar Quartz Monzodiorite and the Mount Mucki Diorite (SC1018F)


90

Figure 4.14(A-D): Molar cationic variations

A. A T(Al) and T(Si) suggests coupled substitution of T(Al) for T(Si).

B. P

in pyroxenes from the Station Creek Igneous Complex and associated intrusive and volcanic rocks.

linear relationship between

lutonic and volcanic pyroxenes have different variation trends for C(Mg+Fe ) versus T(Si), highlighting different cation substitution processes. The main cationic substitution in plutonic pyroxene is the ferran aluminium augite substitution and in volcanic pyroxene is the tschermakitic substitution

C. A linear relationship between C(Mg+Fe ) and C(Fe +Al) highlights the omphacitic substitution.

D. The C(Al+Fe ) loss in the Mount Mucki Diorite and volcanic pyroxenes resulted from ferran aluminium augite substitution. The T(Al) loss in the monzodioritic intrusions resulted from tschermakite substitution.

2 +

2 + 3 +

3 +

N o rth A rm Vo lcan ics

M on zo d iorite in trus ionN e ara Vo lcan ics

H igh bu ry Vo lcan ics (ba sa lt)

M ou nt M u ck i D ioriteW o oloog a G ra no d iorite Xenoliths in the net-vein of


T(Si) cation/ 6 oxygen

T(A

l) ca

tion/

6 o

xyge

n 0.10

1.8 2.11.9 2.0

0.05

0

-1T(Al) : 1T(Si)

A. T(Al) versus T(Si)

C(M

g+Fe

) cat

ion/

6 o

xyge

n2

+

T(Si) cation/ 6 oxygen1.8 1.9 2.0 2.1

0.8

0.9

1.0

1.1

1C(Mg+

Fe) :

1T(Si)

2+

1C(Mg+Fe ) :2T(Si)2 +

Ferran aluminium augitesubstitution

Tschermakitic substitution

B. C(Mg+Fe ) versus T(Si)2 +

C(M

g+Fe

)/ 6

oxyg

en2

+

C(Fe +Al)/ 6 oxygen3 +

0.8

1.1

0.9

1.0

0 0.1 0.2

1C(Fe +Mg) :

2 +

1C(Fe +Al)3 +

C. C(Mg+Fe ) versus C(Fe +Al)2 + 3 +

C(Al+Fe ) /6 oxygen3 +

T(A

l)/ 6

oxy

gen

0

0.10

0 0.1 0.2

0.05C(Al+Fe ) loss

3 +

T(Al) loss

D. T(Al) versus C(Al+Fe )3 +


91

5% ferrosilite component) is noted between the core and rim of individual grains.

Augite shows decreasing T(Al) (Figure 4.14A) and increasing C(Mg,Fe2+)

(Figure 4.14B) with increasing T(Si). Such relationships are also reflected by the

compositional changes from core to rim of individual crystal. Plutonic and volcanic

pyroxenes have different C(Mg,Fe2+) to T(Si) ratios (Figure 4.14B), which reflect

differences in pyroxene composition as well as differences in coupled substitution

mechanisms. The main substitution in the plutonic pyroxene is the ferrian aluminium

augite substitution (Deer et al., 1992), summarised as C(Mg,Fe2+) + T(Si) <=>

C(Al,Fe3+) + T(Al). The coupled substitution of the volcanic pyroxene is dominated

by the tschermakitic substitution (Larsen, 1976), summarised as C(M2+) + 2T(Si) <=>

C(Ti4+) + 2T(Al). Ti makes up less than 2 percent of the octahedral co-ordinated site

and therefore additional substitutions by (Al,Fe)3+ and (Fe,Mg)2+ cations are necessary

to fill the C-sites.

The C(Fe+Al)3+ and C(Mg,Fe)2+ show an approximate linear relationship

(Figure 4.14C) that involve the omphacite substitution (Deer et al., 1992) or B(Ca) +

C(Mg,Fe2+) <=> B(Na) + C(Fe3+,Al). Augite from the volcanic rocks and from the

Mount Mucki Diorite has C(Al+Fe3+)-loss as a result of omphacite substitution

(Figure 4.14D) and incorporated 1-6% Na into the B-sites (or 0.6-3.2% aegirine

component in augite). The T(Al)-loss in augite from the monzodiorite intrusion is due

to minor tschermakitic substitution.

Feldspars

Plagioclase makes up 30-60 modal % of the plutonic rocks in the SCIC and 5-

30% of phenocrysts in the volcanic rocks. Its composition varies from bytownite in

gabbro (and basalt) to oligoclase in granodiorite (and andesite) (Figure 4.15). Most

plagioclase crystals are normal zoned.

Plagioclase of the various textural groups in the Woolooga Granodiorite has

similar compositions (Table 4.7) and is zoned from labradorite core to oligoclase rim.

The orthoclase component is <3 mole % in the cores and <5 mole % in the rims of

individual crystals. Late-stage plagioclase within the interstitices has An5-20

composition and less than 5% orthoclase component. In the Rush Creek Granodiorite,

plagioclase from all the textural groups has similar compositions and is zoned from

C


omplex

92


93

Figure 4.15: Variations in feldspar composition from plutons ssociated hypabyssal and volcanic rocks.

of the Station Creek Igneous Complex and a

Core composition

Intermediate between core and rimRim composition

K-feldspar including perthite and orthoclase

Legend

Monzo-diorite

A. Early Permian Highbury Volcanics andesitic basalt, B. Early Triassic Neara Volcanics, C. Late Triassic North Arm Volcanics andesite, D. Mid-Late Triassic igneous porphyry (Black Snake Porphyry and Neureum Mt Porphyry), E. Monzodiorite intrusion into Rush Creek Granodiorite and F. Xenoliths

ANORTHITE

ALBITE

Labradorite

Andesine

Bytownite

Anorthite

Albite ORTHOCLASEOrthoclase

A B C D

E

Oligoclase

F.

Volcanic units, hypabyssal, igneous porphyries and xenoliths F

C. Gibraltar Quartz Monzodiorite

ALBITE

Labradorite

Andesine

Oligoclase

Bytownite

Anorthite

Albite

ORTHOCLASE

ANORTHITE

Orthoclase

Quartzmonzo-diorite Granodiorite

D. Mount Mucki Diorite

ALBITE

ANORTHITE

ORTHOCLASE

Labradorite

Andesine

Oligoclase

Bytownite

Anorthite

Albite

ORTHOCLASEO r t h o c l a s e

E. Woonga Granodiorite

ANORTHITE

ALBITE

ORTHOCLASE

ALBITE

ANORTHITE

Labradorite

Andesine

Oligoclase

O r t h o c l a s e

Bytownite

Anorthite

Albite

Rgs1

Rgs3

Rgs1 (granophyric monzogranite and granodiorite); Rgs2 (porphyritic granular monzogranite and granodiorite); Rgs3 (hypidiomorphic granular granodiorite and monzogranite)

B. Rush Creek Granodiorite

Rgs2

A. Woolooga Granodiorite

Rgw1 Mzd (porphyritic quartz monzodiorite); Rgw1 Gd (porphyritic granodiorite); Rgw2 (granophyric granodiorite) & Rgw3 (hypidiomorphic granular granodiorite)

ORTHOCLASEALBITE

ANORTHITE

Labradorite

Andesine

Oligoclase

Orthoclase

Bytownite

Anorthite

Albite

Rgw3Rgw2 Rgw1Mzd

Rgw1 Gd


94

Figure 4.16: Variation of Na versus Ca in feldspars from the Station Creek Igneous Complex and associated rocks. Two variation trends (Main Series and Minor Series) suggest different cationic substitution .

+ 2 +

Main series (Plagioclase from the Woolooga Granodiorite, Gibraltar Quartz Monzodiorite, Woonga Granodiorite, Mount Mucki Diorite, monzodioritic intrusions, volcanics and southern Rush Creek Granodiorite)

Minor Series (Plagioclase from the NW section of the Rush Creek Granodiorite and granodiorite xeno l i ths in the Nor th Arm Volcanics)






Neureum Mt Porphyry

Xenoliths

North Arm Volcanics

Late Triassic dykes

Highbury Volcanics

SYMBOLS

Neara Volcanics

Figure 4.17: Variation of Al versus Ca in feldspars from the Station Creek Igneous Complex and associated rocks. The relationship displayed by the Main series is consistent with albitic substitution. The Minor Series has lower Al and Ca contents (and higher Si), which implies a probable disordered feldspar structure.

3 + 2 +

Ca cations/ 32 Oxygens

Al c

atio

ns/ 3

2 O

xyge

ns

Main series

Minor series






Neureum Mt Porphyry

Xenoliths

North Arm Volcanics

Late Triassic dykes

Highbury Volcanics

SYMBOLS

Neara Volcanics


95

An55 to An23. The core composition varies from An40-55 in granodiorite to An40-43 in

granite, with a corresponding orthoclase component of 1-2% and 2-3% respectively.

Plagioclase in the Mount Mucki Diorite is zoned from An85 to An50, and rimmed by

oligoclase-andesine taxial growth. Subhedral plagioclase chadacrysts in pyroxene of

the Mount Mucki Diorite have bytownite to anorthite compositions (An85-100). The

composition of plagioclase in the Gibraltar Quartz Monzodiorite varies from An55-29

in quartz monzodiorite to An35-22 in granodiorite. The plagioclase in the Woonga

Granodiorite is zoned from andesine (An40) to oligoclase (An28).

Perthitic orthoclase in the Woolooga Granodiorite has variable compositions

ranging from Or40 to Or95, and the later is associated with the exsolution. Orthoclase in

the Rush Creek Granodiorite has relatively uniform composition (Or83 to Or93) and

occurs as a perthitic interstitial mineral with plagioclase (An23). In the Mount Mucki

Diorite, orthoclase (Or55-91) crystallises interstitially between plagioclase, pyroxene

and hornblende. Orthoclase (Or55) in the Gibraltar Quartz Monzodiorite crystallises

with albite (An0-8) and quartz between plagioclase, pyroxene and hornblende crystals.

The variation of Na versus Ca in feldspars highlights two variation trends

named as the “Main Series” (An100Ab0Or0 to An1Ab98Or1) and the “Minor Series”

(An55Ab43Or2 to An9Ab89Or2) (Figure 4.16). The Na and Ca are related by a -1:1 ratio

in the Main Series and a -1:2 ratio in the Minor Series. Al and Ca are related by a 1:1

ratio (Figure 4.17), though the Minor Series has lower total Ca and Al contents than

the Main Series. The ionic variations in the Main Series reflect continuous albite

substitution summarised as Ca2+ + Al3+ <=> Na+ + Si4+ (Bowen, 1915). Plagioclase

stoichiometry of the Minor Series indicates cation deficiency in the Z-site and high Si

in the X-sites, possibly due to entry of Si or Al into the Z-site of a disordered crystal

structure (Deer et al., 1992). The plagioclase contains low CaO, Na2O, K2O and

Al2O3, and high SiO2 contents. Spatially, the Minor Series plagioclase is limited to the

NW section of Rush Creek Granodiorite and in xenoliths that have been thermal-

overprinted, recrystallised and possibly silicified.

Fe-Ti oxides

Coexisting primary magnetite and ilmenite occur in the Woolooga

Granodiorite, Rush Creek Granodiorite, Gibraltar Quartz Monzodiorite, Mount Mucki


96

Diorite, and in hypabyssal and volcanic rocks (Figure 4.18, Table 4.8). The Woonga

Granodiorite has only magnetite. The terms “magnetite” and “ilmenite” refer to the

series magnetite-ulvospinel and ilmenite-haematite respectively, in accordance to

definitions of Mathison (1975). There are two varieties of magnetite; a titaniferous

magnetite (2-14% TiO2, 0-0.3% MgO, 0.1-1.4% MnO) and the magnetite stricto

senso (<2% TiO2, <0.4% MgO and <0.4% MnO). The titaniferous magnetite occurs

as inclusions in mafic minerals and as accessory mineral within the chilled margins of

the Woolooga Granodiorite and Gibraltar Quartz Monzodiorite, and in volcanic rocks

and monzodiorite intrusions. The magnetite s.s. occurs in all the plutons of the Station

Creek Igneous Complex.

Magnetites from plutonic, hypabyssal and volcanic rocks have similiar

compositions (Figure 4.18). However, their Al-Fe3+-Ti cations highlight three

variation trends (variation trends I, II, III) due to different amount of Al in magnetite

(Figure 4.19). Variation trend I belongs to the primary titaniferous magnetite and

shows continuous change in Fe3+ and Ti contents with little change in the Al content.

The increase in Ti resulted from ulvospinel substitution. Magnetites from the Rush

Creek Granodiorite, Mount Mucki Diorite, Woonga Granodiorite and Black Snake

Porphyry form the Variation trend II. This trend shows increases in Al simultaneous

to decreases in the Fe3+ content and minor increases in the Ti cations. The change

towards Al is attributed to spinel substitution that ranged from 0.02 to 3.8%. Variation

trend III has negligible Al and reflects substitution of Fe3+ by Ti. This trend represents

the secondary brookite and some of the titaniferous magnetite from the

hydrothermally altered Gibraltar Quartz Monzodiorite, the Woolooga Granodiorite,

Neureum Mountain Porphyry, Highbury Volcanics and the Neara Volcanics. The Mn

and Mg contents in magnetite are minor, and make up less than 0.8% and 0.2% of the

cations respectively.

Ilmenite from the various rock units is compositionally similiar (Figure 4.18).

The haematite component ranges from 0.05 to 31 percent with the majority having

less than 5 molar percent. The linear relationship between Mn and Fe2+ (Figure 4.20)

indicates pyrophanite substitution (0.5 to 35 molar percent) in ilmenite.


97

Table 4.8: Representative magnetite and ilmenite analyses from plutons of the Station Creek Igneous Complexvolcanic rocks and monzodiorite intrusions

UNIT Woolooga Woolooga Woolooga Gibraltar Mt Mucki Woonga Rush Ck. Rush Ck. Monzodio. Neara North Arm HighburyGranodio Granodio Granodio Qtz Mdio Diorite Granodio Granodio Granodio intrusion Volcanics Volcanics Volcanics

Lithology Granodio Qtz Mdio Qtz Mdio Qtz Mdio Diorite Granodio Granodio Granodio Monzodio. Andesite Andesite Andesite

Magnetite analysesSample 328-1I 494-1E 1069-4E 792-2 1000-1B 1129-1MT 1149-3G 1166-4D 1204-9C 725-3D 1030-4A 1098-5BSiO2 0.26 0.40 0.42 0.43 0.25 0.48 0.38 0.42 0.09 0.28 0.34 0.17TiO2 3.75 1.71 1.96 1.59 0.04 0.01 0.21 0.17 6.36 2.71 0.29 0.75Al2O3 0.89 0.52 0.36 0.25 0.00 0.23 0.80 0.31 0.94 0.75 0.07 0.00Cr2O3 0.16 0.10 0.00 0.00 0.00 0.06 0.06 0.05 0.00 0.00 0.00 0.00Fe2O3 60.16 65.80 63.82 64.82 68.32 67.58 66.72 67.35 55.55 63.04 67.55 67.21FeO 33.54 31.18 33.16 32.14 31.39 31.16 31.66 31.59 36.72 32.99 31.76 31.68MnO 0.83 0.13 0.21 0.60 0.01 0.33 0.08 0.02 0.01 0.00 0.00 0.00MgO 0.42 0.17 0.07 0.18 0.00 0.16 0.09 0.10 0.32 0.12 0.00 0.08CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.12 0.00 0.11Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

Cation calculated on the basis of 24 O for magnetite.Si 0.078 0.12 0.129 0.13 0.076 0.15 0.116 0.13 0.028 0.09 0.104 0.051Ti 0.857 0.39 0.451 0.37 0.009 0.00 0.048 0.04 1.453 0.62 0.066 0.173Al 0.320 0.19 0.132 0.09 0.000 0.08 0.289 0.11 0.337 0.27 0.026 0.000Cr 0.039 0.02 0.000 0.00 0.000 0.01 0.015 0.01 0.000 0.00 0.000 0.000Fe3+ 13.771 15.17 14.709 14.94 15.829 15.61 15.367 15.55 12.702 14.50 15.635 15.553Fe2+ 8.532 7.99 8.494 8.23 8.082 7.99 8.102 8.11 9.330 8.43 8.169 8.148Mn 0.213 0.03 0.055 0.16 0.003 0.09 0.021 0.01 0.003 0.00 0.000 0.000Mg 0.190 0.08 0.031 0.08 0.000 0.07 0.041 0.04 0.144 0.05 0.000 0.038Ca 0.000 0.00 0.000 0.00 0.000 0.00 0.000 0.00 0.004 0.04 0.000 0.038Sum cations 24.000 24.00 24.000 24.00 24.000 24.00 24.000 24.00 24.000 24.00 24.000 24.000

Magnetite 88.62 94.80 94.19 95.22 99.88 99.97 99.37 99.51 81.38 91.95 99.16 97.83Ulvospinel 11.38 5.20 5.81 4.78 0.12 0.03 0.63 0.49 18.62 8.05 0.84 2.17

Ilmenite analysesSample 328-1H 494-1F 1069-4D 792-2C1 1000-1A - 1149-3F 1166-4C 1204-9B 725-3C 1030-4B 1098-5ASiO2 0.27 0.52 0.40 1.02 0.38 - 0.31 0.34 0.00 2.27 0.28 0.12TiO2 50.16 45.88 48.77 39.90 44.94 - 42.23 46.00 50.46 44.50 46.14 48.47Al2O3 0.00 0.00 0.16 0.00 0.00 - 0.29 0.10 0.00 0.43 0.25 0.00Cr2O3 0.01 0.00 0.00 0.03 0.00 - 0.00 0.00 0.00 0.00 0.00 0.00Fe2O3 4.49 12.27 6.68 22.62 13.90 - 19.05 11.91 4.84 10.80 11.86 8.19FeO 39.06 34.28 38.29 16.44 33.43 - 31.23 36.42 42.87 35.81 34.44 38.98MnO 5.61 6.16 5.27 19.11 7.35 - 6.75 5.12 0.93 4.93 6.70 3.66MgO 0.34 0.19 0.28 0.10 0.00 - 0.16 0.10 0.82 0.65 0.33 0.21CaO 0.06 0.61 0.17 0.66 0.00 - 0.00 0.00 0.08 0.61 0.00 0.19Total 100.00 100.00 100.00 100.00 100.00 - 100.00 100.00 100.00 100.00 100.00 100.00

Cation calculated on the basis of 6 O for ilmenite.Si 0.014 0.026 0.02 0.052 0.02 - 0.016 0.017 0 0.113 0.014 0.006Ti 1.901 1.742 1.849 1.519 1.715 - 1.612 1.753 1.908 1.671 1.753 1.841Al 0 0 0.009 0 0 - 0.017 0.006 0 0.025 0.015 0Cr 0 0 0 0.001 0 - 0 0 0 0 0 0Fe3+ 0.17 0.466 0.253 0.862 0.531 - 0.728 0.454 0.183 0.406 0.451 0.311Fe2+ 1.647 1.448 1.614 0.696 1.419 - 1.325 1.543 1.803 1.495 1.456 1.647Mn 0.24 0.264 0.225 0.82 0.316 - 0.29 0.22 0.039 0.209 0.287 0.157Mg 0.026 0.014 0.021 0.007 0 - 0.012 0.007 0.061 0.048 0.025 0.016Ca 0.003 0.033 0.009 0.036 0 - 0 0 0.004 0.032 0 0.01Sum cations 4 4 4 4 4 - 4 4 4 4 4 4

Ilmenite 0.951 0.87 0.924 0.759 0.857 - 0.806 0.876 0.954 0.835 0.877 0.919Haematite 0.02% 0.043 0.005 0.01 0.059 - 0.11 0.061 0.02 0.058 0.038 0.029

1. Fe2+ and Fe3+ recalculated from FeO* using method of Buddington & Lindsley (1964).2. Cation calculated on the basis of 24 oxygens for magnetite and 6 oxygens for ilmenite.3. Abbreviations: Granodio = granodiorite; Qtz Mdio = quartz monzodiorite; Monzodio. = monzodiorite.


98

Figure 4.19: ationic variations in magnetites from the Station Creek Igneous Complex, monzodiorite intrusions and volcanic rocks. The three variation trends (I, II and III) shows different amounts of Al-substi tution (spinel component) in magnetites. (Symbols as in Figure 4.18)

Fe -Al-Ti c3 +

Fe3 +

50xTi50xAl

III III

Figure 4.18: Composition variations of Fe-Ti oxides plotted on a FeO-TiO -Fe O ternary diagram for A. Plutonic rocks of the Station Creek Igneous Complex, and B. Volcanic and hypabyssal rocks. Fe-Ti oxide end-members are plotted as references. The trend towards TiO enrichment is influenced by hydrothermal and deuteric alterations.

2 2 3

2

Alteration

Solid solution

TiO2

(Rutile, Anatase, Brookite)

FeO Fe O2 3

(Haematite)(Magnetite)Fe O

3 4

Fe TiO2 5

Ilmenite(Pseudo- brookite)

B.

VOLCANIC & HYPABYSSALROCKS

Ulvospinel

A. PLUTONIC ROCKS

TiO2

(Rutile, Anatase, Brookite)

(Haematite)(Magnetite)

TRENDS

FeO Fe O2 3

Fe O3 4

FeTi O2 5

FeTiO3

Fe TiO2 4

(Ilmenite)

(Ulvospinel)

Pseudo-brookite

Figure 4.20: Variation of Mn versus Fecations in ilmenite from the Station Creek Igneous Complex and associated rocks. Their linear relationship highlights the Mn substitution in ilmenite. (Symbols as in Figure 4.18)

2 +

(pyrophanite)

Fe cations/ 6 oxygen2 +

0.0

0.2

0.4

0.6

0.8

0 1 2

Mn:Fe = ~1:12 +

Rutile & Brookite


99

Accessory phases (titanite, apatite and epidote)

Titanite (sphene) is a common accessory mineral in all plutons of the Station

Creek Igneous Complex, and is generally more abundant in gabbroic to monzodioritic

rocks. Its geochemical variation relates to differences in TiO2, Al2O3 and FeO (Table

4.9). Anhedral sphene associated with Fe-Ti oxides has higher TiO2, Al2O3 and FeO

contents than interstitial sphenes. The principle ionic substitutions in sphene are

C(Al,Fe3+)3+ + (F,OH)- <=> T(Ti4+) + O2- and A(Mn2+) <=> A(Ca2+) (Higgins &

Ribbe, 1976), and B(Mg2+) <=> B(Ti4+) and A(Na+K)- <=> A(Ca2+) (Deer et al.,

1992).

Apatite is another common accessory mineral in the Station Creek Igneous

Complex. Its geochemical difference relates to the FeO content (Table 4.10), which is

highest in apatite inclusions within Fe-Ti oxides (0.5-3 %) and lowest in magmatic

apatite that forms the granitoid groundmass (<0.3%). The chlorine content varies from

0.09 to 1.67%, and higher Cl content occurs within the silicic and deuteric altered

rocks. Fluorine values range from 3.0% to 4.2% but there is no systematic

geochemical variation trend. The F/Cl ratio in apatite is highly variable and shows no

systematic relationship to either pluton or mineral chemistry.

Epidote is a common accessory mineral in Station Creek Igneous Complex

and in the deuteric altered Neara Volcanics. In plutonic rocks, epidote crystalises as a

late-stage mineral exclusive to the interstices of earlier minerals. Its chemistry is

similar (Table 4.11) except for slight Fe2O3 increases from quartz monzodiorite

(12.5%) to granodiorite (14.3%). The pistacite or Ps component (Deer et al., 1992, p.

91) varied from 0.26 to 0.31.


100

Table 4.9: Apatite analyses from the various plutons of the Station Table 4.10: Epidote analyses from the various units of theCreek Igneous Complex and monzodiorite intrusions Station Creek Igneous Complex and volcanic rocks

UNIT Woolooga Woolooga Woolooga Gibraltar Mt Mucki Monzodio Bl Snake UNIT Woolooga Gibraltar Gibraltar Monzodio Xenolith North ArmGranodio Granodio Granodio Qtz Mon. Diorite intrusion Pophyry Granodio Qtz Mon. Qtz Mon intrusion in GibraltarVolcanics

Rgw1 Rgw1 Rgw3 Rgw1SAMPLE 494-1 710-1B 794-2B 816-1A 1018F-3A 1030-4A

SAMPLE 328-1E 582-2G 1069-1E SC710-3C 999-1F 816-3F 1286-4C Remarks Miarolite Alteration Alteration Miarolite Alteration AlterationHost Magnetite Matrix Magnetite Matrix Matrix Magnetite Biotite Core Core Matrix Core Core -

FeO 1.91 0.12 0.66 0.31 0.00 0.19 0.24 SiO2 38.40 39.46 39.31 39.31 38.96 39.21MnO 0.00 0.00 0.00 0.28 0.00 0.00 0.00 TiO2 0.24 0.41 0.27 0.03 0.00 0.00MgO 0.21 0.00 0.00 0.00 0.00 0.00 0.00 Al2O3 21.68 22.00 22.91 23.72 22.65 23.11CaO 51.63 54.54 55.48 53.00 55.79 54.02 55.00 Fe2O3 15.09 14.81 13.91 12.98 14.54 13.38Na2O 0.50 0.01 0.17 0.43 0.00 0.29 0.04 MnO 0.14 0.50 0.27 0.71 0.24 0.31K2O 0.01 0.03 0.00 0.00 0.25 0.00 0.00 CaO 24.41 22.80 23.18 23.17 23.58 23.94P2O5 40.87 42.83 41.50 42.10 43.84 42.19 43.17 Na2O 0.00 0.00 0.12 0.06 0.00 0.00F 3.25 3.56 0.00 2.97 - 4.21 3.24 K2O 0.00 0.01 0.03 0.02 0.00 0.00Cl 1.62 0.63 0.21 1.36 0.10 0.39 0.74 F - 0.00 - - - -TOTAL 100.00 101.72 98.02 100.45 99.97 101.29 102.43 Cl 0.04 0.00 - - 0.03 0.05

Total* 100.00 100.00 100.00 100.00 100.00 100.00O=F,Cl 1.73 1.64 0.05 1.56 0.02 1.86 1.53 O=F,CL 0.01 0.00 0.00 0.00 0.01 0.01

Cations calculated on the basis of 26 (O, OH, F, Cl) Cations calculated on the basis of 12.5 oxygenFe2+ 0.29 0.02 0.10 0.05 0.00 0.03 0.04 TSi 3.02 3.08 3.06 3.06 3.05 3.06Mn 0.00 0.00 0.00 0.04 0.00 0.00 0.00 AlIV 0.00 0.00 0.00 0.00 0.00 0.00Mg 0.06 0.00 0.00 0.00 0.00 0.00 0.00 Sum T 3.02 3.08 3.06 3.06 3.05 3.06Ca 9.97 10.18 10.44 10.06 10.18 10.19 10.18Na 0.18 0.00 0.06 0.15 0.00 0.10 0.01 AlVI 2.01 2.02 2.10 2.17 2.09 2.12K 0.00 0.01 0.00 0.00 0.05 0.00 0.00 Ti 0.01 0.02 0.02 0.00 0.00 0.00Σ subtotal 10.49 10.21 10.60 10.29 10.23 10.32 10.23 Fe3+ 0.89 0.87 0.81 0.76 0.85 0.78

Subtotal 2.91 2.92 2.93 2.93 2.94 2.90P 6.24 6.32 6.17 6.31 6.32 6.29 6.31Σ All cations 16.73 16.53 16.77 16.61 16.55 16.61 16.54 Mn 0.01 0.03 0.02 0.05 0.02 0.02

Ca 2.06 1.91 1.94 1.93 1.98 2.00CF 3.71 3.92 0.00 3.33 0.00 4.69 3.54 Na 0.00 0.00 0.02 0.01 0.00 0.00CCl 0.99 0.37 0.13 0.82 0.06 0.23 0.43 K 0.00 0.00 0.00 0.00 0.00 0.00

F/Cl 2.01 5.65 0.00 2.18 - 10.79 4.38 Sum B 2.07 1.94 1.97 1.99 1.99 2.021. All Fe represented as FeO.2. MinPet program was used to calculate cations proportions per 26 (O, OH) using method of Deer et al., 1992. CF 0.00 0.00 0.00 0.00 0.00 0.003. Abbreviations: Granodio. = granodiorite, Qtz Mon.= quartz monzodiorite, Monzodio.= monzodiorite CCl 0.01 0.00 0.00 0.00 0.01 0.01

Ps 0.31 0.30 0.28 0.26 0.29 0.271. * Geochemistry normalised to 100% anhydrous.2. Granodio = granodiorite, Qtz Mon.= quartz monzodiorite, Monzodio.= monzodiorite

Table 4.11: Representative sphene analyses from the various units of the Station Creek Igneous Complex and volcanic rocksand monzodioritic inrusions

UNIT Woolooga Woolooga Woolooga Gibraltar Gibraltar Gibraltar Woonga Woonga Mt Mucki Mt Mucki Monzodio Xenolith HighburyGranodio Granodio Granodio Qtz Mon. Qtz Mon. Qtz Mon. Granodio Granodio Diorite Diorite intrusion in Gibraltar Volcanics

Rgw1 Rgw1 Rgw3 Qtz Mon.

SAMPLE 382-2D 497-2D 1069-5F 710-1A 791-4B 794-4B 1086-1A 1129-1A 999-1SP SC999-3C 816-1C 1018D-6B 945-5BRemarks Core Exsolved Mantling Core Core Matrix Matrix Matrix Matrix - Core - -

SiO2 31.71 30.4 30.59 30.28 30 30.46 30.92 31.11 30.22 29.30 29.93 30.70 30.90TiO2 28.26 39 39.04 37.55 36.5 39.19 38.32 37.96 37.42 39.50 36.37 38.20 34.80Al2O3 5.99 0 1.97 0.17 1.77 0 1.16 1.14 0.04 1.08 0.30 1.65 2.59FeO 2.59 1.58 1.13 1.48 1.87 1.37 0.85 2.00 0.99 0.84 1.25 1.50 1.41MnO 0 0 0.07 0 0.03 0 0 0.00 0.00 0.11 0.00 0.04 0.10MgO 0.01 0 0.00 0 0.02 0 0 0.00 0.00 0.00 0.00 0.00 0.15CaO 28.63 28.13 27.14 28.21 26.8 27.76 28.53 27.78 27.77 28.50 27.34 28.50 27.70Na2O 0.13 0.36 0.05 0 0.04 0.1 0.16 0.00 0.10 0.00 0.00 0.00 0.13K2O 0 0 0.01 0 0.08 0 0 0.00 0.00 0.08 0.00 0.00 0.03Total 97.32 99.47 100 97.69 97.11 98.88 99.94 99.99 96.54 99.41 95.19 100.59 97.81

Cation calculated on the basis of 4 SiSi 4 4 4.00 4 4 4 4 4.00 4.00 4.00 4.00 4.00 4.00

Al 0.89 0 0.30 0.03 0.28 0 0.18 0.17 0.01 0.17 0.05 0.25 0.40Ti 2.68 3.86 3.84 3.73 3.66 3.87 3.73 3.67 3.73 4.06 3.66 3.74 3.39

Mg 0 0 0.00 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.03Fe2+ 0.27 0.17 0.12 0.16 0.21 0.15 0.09 0.22 0.11 0.10 0.14 0.16 0.16Mn 0 0 0.01 0 0 0 0 0.00 0.00 0.01 0.00 0.00 0.01Na 0.03 0.09 0.01 0 0.01 0.03 0.04 0.00 0.03 0.00 0.00 0.00 0.03Ca 3.87 3.97 3.80 3.99 3.83 3.91 3.95 3.83 3.94 4.17 3.91 3.98 3.84K 0 0 0.00 0 0.01 0 0 0.00 0.00 0.01 0.00 0.00 0.01

Sum Cations11.75 12.09 12.09 11.91 12.01 11.95 12.00 11.89 11.80 12.52 11.76 12.14 11.86Sum Oxygen18.86 19.91 20.07 19.66 19.80 19.81 19.80 19.64 19.52 20.66 19.44 20.01 19.43

1. Cation recalculations are based on 4 Si using method by Deer et al., 1992.2. All iron reported as FeO.3. Abbreviations: Granodio. = granodiorite, Qtz Mon.= quartz monzodiorite, Monzodio.= monzodiorite

Chapter5: Geochemistry

101

CHAPTER 5: GEOCHEMISTRY

Integrity of geochemical data and the calculation of ferrous-ferric ratios

Plutonic rock geochemistry plotted on molar Al2O3-(CaO+Na2O)-K2O

triangular plot (Nesbitt & Young, 1989) shows minimal deviation from the standard

granitoid compositions, with the exception of two slightly altered samples from the

Woonga Granodiorite (Figure 5.1). Samples from the Mount Mucki Diorite deviate

from the average gabbro composition towards higher CaO+Na2O content, which

could be attributed to the presence of cumulates. The geochemical data presented in

this thesis show minimal effects of weathering and are reliable. Representative whole-

rock geochemistry from the various units is presented as Table 5.1.

The FeO/(FeO+Fe2O3) ratio of the plutonic rock ranges from 0.4 to 0.6 and the

ratio for volcanic rock is 0.6 (Table 5.2). The normative calculation uses a

FeO/(FeO+Fe2O3) ratio of 0.6, which are the upper ratio for plutonic rocks and the

ratio for volcanic rock.

Table 5.2: Titrametric results of ferrous and ferric iron in representative whole-rock plutonic and volcanic rock samples. The ferrous and ferric contents are determined by titration (Appendix 1)

Sample No. IGNEOUS UNIT Fe2O3 Wt %

FeO Wt %

FeO * (FeO+Fe2O3)

Fe3+ #

(Fe2+ + Fe3+)

SC082 North Arm Volcanics 2.31 3.91 0.63 0.21

SC382 Woolooga Granodiorite(north) 2.14 2.34 0.53 0.29

SC826 Woolooga Granodiorite (south) 2.41 2.34 0.49 0.32

SC854 Woolooga Granodiorite (south) 1.56 2.29 0.59 0.24

SC710 Gibraltar Quartz Monzodiorite 4.62 3.40 0.42 0.38

SC999 Mount Mucki Diorite 6.13 4.63 0.43 0.37

SC1129 Woonga Granodiorite 1.85 1.73 0.48 0.32

SC1129rpt Woonga Granodiorite 1.89 1.69 0.47 0.33

SC1160 Rush Creek Granodiorite 1.62 1.79 0.53 0.29

SC1179 Rush Creek Granodiorite 1.11 1.16 0.51 0.30

* Weight percent ratio # Cation ratio rpt Repeat analysis

THE STATION CREEK IGNEOUS COMPLEX

Geochemical classification

The Station Creek Igneous Complex ranges compositionally from


102

Table 5.1: Major, trace and isotopic element data for representative samples of the Station Creek Igneous Complex and associated rocks, southeast Queensland

SAMPLE SC1166 SC1185 SC1153 SC710 SC1018 SC1037 SC472 SC582 SC854 SC1125 SC1129 SC936Rush Ck Rush Ck Rush Ck Gibraltar Gibraltar Woolooga Woolooga Woolooga Woolooga Woonga Woonga

SiO2 64.45 70.92 74.55 55.09 61.74 60.17 61.84 64.29 66.23 65.09 67.04 47.33TiO2 0.58 0.33 0.18 1.49 0.84 0.70 0.57 0.56 0.65 0.24 0.42 1.18Al2O3 14.74 14.25 13.37 17.72 16.84 15.27 14.60 15.15 15.78 15.43 16.01 15.51Fe2O3 4.92 2.83 1.61 8.40 5.08 5.50 4.98 5.15 4.07 2.52 3.74 14.00MnO 0.09 0.08 0.03 0.27 0.13 0.09 0.09 0.11 0.10 0.04 0.07 0.24MgO 2.73 1.27 0.46 3.15 1.82 2.71 3.04 2.67 1.24 1.07 1.61 6.15CaO 4.41 2.34 1.18 6.09 5.21 4.54 4.56 4.19 2.79 3.84 3.78 12.38Na2O 3.83 3.87 3.32 4.32 3.83 3.80 4.00 3.79 4.20 4.71 4.47 2.11K2O 2.77 3.94 4.41 2.20 3.64 2.75 2.98 3.26 3.99 2.78 2.60 1.01P2O5 0.15 0.10 - 0.17 0.26 0.21 0.17 0.12 0.18 0.08 0.11 0.14LOI 0.87 0.82 0.67 1.82 0.92 1.48 2.13 1.15 1.17 3.47 0.95 1.01TOTAL 99.53 100.75 99.78 100.71 100.31 97.22 98.96 100.44 100.40 99.27 100.80 101.06

Felsic index 0.60 0.77 0.87 0.52 0.59 0.59 0.60 0.63 0.75 0.66 0.65 0.20Mafic index 0.64 0.69 0.78 0.73 0.74 0.67 0.62 0.66 0.77 0.70 0.70 0.69SOI 19.16 10.66 4.69 17.43 12.67 18.36 20.27 17.96 9.19 9.66 12.96 26.43

Trace elementsBa 353 405 367 505 553 403 399 463 520 354 571 199Ce 47 48 42 60 54 50 44 43 49 20 22 11Co 14 6 3 11 13 16 16 15 38 6 8 44Cr 228 291 286 61 120 193 234 174 51 196 240 64Cs 5.74 9.33 8.39 5.90 2.23 4.26 4.18 3.86 4.50 5.60 2.95 2.37Cu 32 11 28 25 71 32 25 52 22 - 8 216Dy 3.54 2.91 2.02 5.61 4.33 3.83 3.78 3.52 3.86 - 1.78 2.33Er 2.11 1.91 1.36 3.00 2.52 2.12 2.22 2.04 2.16 - 1.05 1.24Eu 0.88 0.66 0.42 2.57 1.58 1.14 1.00 0.97 1.02 0.54 0.65 0.78Ga 17 15 14 20 18 19 17 17 18 - 16 18Gd 3.66 2.89 1.96 7.20 4.92 4.33 3.99 3.73 4.27 - 1.83 2.43Hf 4.06 3.96 3.55 2.81 4.43 5.21 4.86 4.31 4.18 2.27 2.92 1.52Ho 0.72 0.62 0.43 1.088 0.872 0.744 0.760 0.712 0.757 - 0.358 0.465La 23.14 24.39 22.68 25.45 26.24 22.53 20.07 19.71 22.40 9.65 13.61 4.90Lu 0.33 0.36 0.27 0.39 0.37 0.31 0.34 0.31 0.31 0.11 0.18 0.17Ni 23 11 8 0 6 22 22 18 18 - 11 19Nb 6.58 7.03 7.23 5.66 8.18 7.61 6.06 6.01 7.53 - 5.67 3.01Nd 20.33 18.54 14.07 35.84 26.67 23.56 20.61 19.88 23.10 - 10.16 7.74Pb 20 17 19 8 14 14 14 15 17 - 7 11Pr 5.6 5.5 4.5 8.30 6.94 6.30 5.52 5.36 6.16 - 2.87 1.65Rb 81 147 188 65 87 111 106 115 110 95 67 26Sc 11.5 5.3 2.4 16.7 10.5 12.1 13.1 11.7 11.2 6.0 6.9 35.4Sm 4.2 3.4 2.4 8.00 5.49 5.00 4.45 4.21 4.85 1.77 2.00 2.25Sn 3.07 2.52 2.61 1.49 1.59 2.76 2.01 1.80 3.10 - 1.20 1.17Sr 320 226 123 1637 846 378 349 348 513 441 592 755Ta 0.67 0.81 1.06 0.38 0.60 0.67 0.57 0.58 0.83 0.44 0.42 0.25Tb 0.57 0.46 0.32 0.97 0.72 0.64 0.62 0.57 0.65 <0.5 0.29 0.38Th 16.06 19.41 22.85 4.52 8.70 12.35 11.20 11.75 11.85 3.98 5.74 2.40Tm 0.32 0.31 0.22 0.41 0.36 0.31 0.33 0.31 0.32 - 0.16 0.18U 2.65 4.83 7.06 1.05 1.67 3.69 3.20 2.88 2.89 <2 1.31 0.74V 88 30 12 133 128 95 97 91 89 - 54 443Y 19.18 17.12 12.70 27.21 22.85 19.55 19.80 18.79 19.95 - 9.51 11.27Yb 2.12 2.20 1.61 2.52 2.39 2.00 2.20 2.01 2.05 0.82 1.08 1.12Zn 44 28 16 116 78 60 41 49 81 <50 30 89Zr 135.4 124.8 95.1 98.9 160.0 192.3 167.4 150.0 146.0 - 107.7 52.0

NormativeQuartz 18.61 26.11 34.96 5.4 12.4 14.4 14.3 16.9 18.9 18.7 20.9 -Corundum - - 0.96 - - - - - - - - -Orthoclase 16.68 23.4 26.4 12.7 21.8 17.1 18.3 19.5 23.3 17.2 15.2 6.0Albite 32.95 32.83 28.37 35.7 32.7 33.7 35.1 32.4 35.0 41.7 37.2 18.0Anorthite 15.11 9.92 6.04 22.0 18.2 17.3 13.6 14.9 12.3 13.4 15.7 30.2Nepheline - - - - - - - - - - - -Diopside 5.26 1.11 - 5.7 5.6 4.4 6.9 4.5 0.6 5.2 1.9 25.5Hypersthene 7.48 4.43 2.15 5.1 4.7 8.4 7.8 7.9 2.8 2.0 3.1 5.5Olivine - - - - - - - - - - - 5.1Magnetite 2.54 1.44 0.83 7.3 2.6 2.9 2.6 2.6 5.7 1.3 4.5 7.2Haematite - - - 3.2 - - - - 0.1 - 0.6 -Ilmenite 1.12 0.63 0.35 2.8 1.6 1.4 1.1 1.1 1.2 0.5 0.8 2.3Apatite 0.36 0.24 - 0.4 0.6 0.5 0.4 0.3 0.4 0.2 0.3 0.3Calcite - - - - - - 0.23 0.05 - - - -

Analytical methods of trace elements are given in Appendix 2A1. Normative calculation based on FeO/(FeO +Fe2O3) = 0.62. Felsic# = (Na2O+K2O)/(Na2O+K2O+CaO)3. Mafic# = (Fe2O3+FeO)/(FeO+Fe2O3+MgO)4. SOI (Solidification Index) = 100MgO/(MgO+FeO+Fe2O3+Na2O+K2O)


103

Table 5.1: Major, trace and isotopic element data (continued)

SAMPLE SC999 SC901 SC1286 SC1204 SC808 SC082 SC094 SC1134 SC1098 SC106 SC911Mt Mucki Neureum Bl Snake Intrusion Jurassic Neara Vol North Arm Highbury Volcanics Foliated Granodiorite

SiO2 52.43 63.24 63.52 53.89 61.32 52.47 58.13 48.65 48.81 65.19 66.01TiO2 1.05 0.62 0.57 0.99 0.70 0.79 0.95 1.37 1.25 0.87 0.89Al2O3 16.15 15.89 16.07 17.29 15.70 15.08 16.76 14.40 17.73 13.56 14.40Fe2O3 11.21 4.69 4.59 9.15 5.45 6.65 6.92 11.86 10.49 5.24 5.86MnO 0.17 0.08 0.09 0.18 0.13 0.10 0.16 0.20 0.17 0.09 0.11MgO 4.12 2.52 3.06 3.47 2.75 4.83 2.58 8.51 4.02 2.06 1.84CaO 8.92 3.33 3.52 8.00 4.37 5.55 5.95 11.20 7.47 2.24 2.84Na2O 3.16 4.80 4.83 3.61 3.48 3.90 3.37 2.88 3.20 3.60 3.27K2O 1.55 2.75 2.43 1.75 2.95 1.76 2.46 0.11 3.62 2.43 3.26P2O5 0.31 0.25 0.24 0.40 0.36 0.20 0.24 0.13 0.58 0.17 0.18LOI 0.90 2.49 1.32 0.13 1.50 6.23 2.95 0.95 1.28 3.18 0.88TOTAL 99.97 100.66 100.24 98.86 98.71 101.48 100.47 100.26 98.62 98.63 99.54

Felsic index 0.35 0.69 0.67 0.40 0.60 0.50 0.49 0.21 0.48 0.73 0.70Mafic index 0.73 0.65 0.60 0.70 0.66 0.60 0.73 0.58 0.70 0.72 0.76SOI 20.56 17.07 20.52 19.30 18.80 28.18 16.83 36.43 18.85 15.46 12.93

Trace elementsBa 218 464 433 476 447 438 549 28 667 633 456Ce 34 45 40 55 55 36 58 9 77 44 61Co 30 12 13 22 16 25 18 53 34 19 13Cr 65 112 162 64 148 79 225 393 21 168 227Cs 1.67 1.22 4.12 2.09 3.65 2.21 1.90 0.90 7.09 1.78 6.20Cu 51 24 12 43 - 48 - - 56 49 -Dy 3.59 3.03 2.64 4.74 - 3.46 - - 4.57 5.41 -Er 2.16 1.73 1.53 2.69 - 2.00 - - 2.45 3.15 -Eu 1.22 1.15 0.94 1.85 1.27 1.09 1.88 1.09 2.08 1.36 1.30Ga 19 21 19 22 - 17 - - 19 18 -Gd 3.83 3.66 2.94 5.77 - 3.70 - - 6.16 5.45 -Hf 2.40 4.13 3.46 3.68 5.51 3.85 4.49 2.00 4.03 7.05 7.21Ho 0.744 0.598 0.53 0.95 - 0.702 - - 0.867 1.114 -La 15.97 21.00 19.33 23.97 23.30 16.35 25.90 3.47 34.06 21.04 27.40Lu 0.33 0.26 0.23 0.38 0.28 0.28 0.38 0.39 0.32 0.43 0.56Ni 9 19 30 9 - 29 - - 11 46 -Nb 5.79 6.23 6.62 5.15 - 4.84 - - 13.44 8.55 -Nd 17.56 22.22 18.19 31.11 - 18.20 - - 38.77 22.82 -Pb 10 13 10 8 - 14 - - 17 17 -Pr 4.36 5.84 4.9 7.5 - 4.67 - - 9.92 5.79 -Rb 36 65 55 51 89 58 64 <10 89 73 120Sc 11.9 9.9 10.8 16.3 12.60 19.4 18.5 44.8 18.5 16.6 14.8Sm 4.04 4.49 3.6 6.8 5.19 4.00 6.76 2.91 7.78 5.37 6.91Sn 2.12 2.23 1.82 2.32 - 1.16 - - 2.53 1.56 -Sr 889 780 676 698 421 455 624 160 1014 214 247Ta 0.42 0.43 0.50 0.31 0.77 0.37 0.49 0.33 0.79 0.61 0.65Tb 0.57 0.51 0.43 0.81 0.83 0.56 1.02 0.77 0.82 0.86 1.20Th 4.93 6.53 5.69 6.18 12.80 6.75 7.11 <0.2 9.07 6.23 9.14Tm 0.33 0.25 0.23 0.39 - 0.29 - - 0.34 0.46 -U 1.68 2.05 1.66 1.32 2.60 1.92 <2 <2 2.42 1.38 <2V 289 82 71 187 - 150 - - 220 92 -Y 19.03 15.53 13.61 23.48 - 18.08 - - 22.11 28.86 -Yb 2.13 1.64 1.48 2.49 2.12 1.86 2.93 2.72 2.13 2.85 4.16Zn 73 59 55 91 94 58 119 115 93 67 87Zr 81.8 157.3 127.8 137.7 144.2 - - 164.2 269.3 -

NormativeQuartz 7.0 13.7 13.66 4.66 16.35 6.1 12.5 - - 28.5 24.9Corundum - - - - - - - - - 2.1 0.6Orthoclase 8.9 16.6 14.59 10.56 18.04 10.9 15.0 0.7 22.1 15.1 19.7Albite 25.8 41.5 41.44 31.14 30.4 34.7 29.4 24.7 23.9 32.0 28.2Anorthite 24.4 14.1 15.25 26.33 19.14 19.4 24.1 26.4 24.2 8.6 13.6Nepheline - - - - - - - - 2.2 - -Diopside 13.2 1.5 1.22 10.05 1.24 6.8 4.4 23.5 9.4 - -Hypersthene 3.8 8.5 9.99 9.9 9.93 10.1 8.8 10.3 - 8.4 8.0Olivine - - - - - - - 5.3 9.1 - -Magnetite 12.0 2.4 2.36 4.73 2.86 10.1 3.6 6.1 5.5 2.8 3.0Haematite 2.5 - - - - - - - - - -Ilmenite 1.9 1.2 1.1 1.92 1.37 1.6 1.9 2.6 2.5 1.7 1.7Apatite 0.7 0.6 0.58 0.97 0.89 0.5 0.6 0.3 1.4 0.4 0.4Calcite - - - - - - - - - 0.85 -

Analytical methods of trace elements are given in Appendix 2A1. Normative calculation based on FeO/(FeO +Fe2O3) = 0.62. Felsic# = (Na2O+K2O)/(Na2O+K2O+CaO)3. Mafic# = (Fe2O3+FeO)/(FeO+Fe2O3+MgO)4. SOI (Solidification Index) = 100MgO/(MgO+FeO+Fe2O3+Na2O+K2O)


104

PlagioclaseAlkali feldspar

Quartz

CaO+Na O2

K O2

Al O2 3

Average gabbro

Average granite

Plagioclase

Smectite

Kaolinite

IlliteMuscovite

K-feldspar

Weathering trends

Advanced weathering trend

Figure 5.1: The molar (Na O+CaO)-Al O -K O diagram shows little deviation from a variation trend from average gabbro to granite compositions. Weathering trends for gabbro and granite are plotted and only two samples from the Woonga Granodiorite indicated slight weathering effects (diagram and the average granite and gabbro compositions adopted from Nesbitt & Young, 1984 & 1989).

2 2 3 2

geochemistry of the Station Creek Igneous Complex plotted on a

Monzodiorite/monzogabbroQuartz diorite

Diorite/gabbro

Quartz monzodiorite

12345 Tonalite6 Granodiorite7 Monzogranite

Lithologic fields

7 6 5

4 3

2 1

Mount Mucki Diorite

Gibraltar Quartz

Wooolooga Granodiorite


Woonga Granodiorite

Figure 5.2: Geochemical classification of plutonic rocks based on mesonormative quartz, plagioclase and alkali-feldspar The Woolooga, Rush Creek and Woonga Granodiorites have uniform compositions and plot as tight clusters. The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite varies compositionally from monzogabbro to quartz monzodiorite (quartz under-saturated samples are not plotted). ( NewPet program)

(Le Maitre, 1989).

Mesonorm was calculated by the




Woonga Granodiorite

Mount Mucki Diorite

Xenolith in plutonic units

Mid-Triassic porphyry

SYMBOLS

Late Triassic-Jurassic stocks

Mafic component in the net-veinof the Mount Mucki Diorite-Gibraltar Quartz

ST

ATIO

N C

REE

K

IGN

EOU

S C

OM

PLEX


105

monzogabbro to monzogranite and includes diorite, monzodiorite, quartz

monzodiorite and granodiorite (Figure 5.2). The geochemical classification of the

SCIC using mesonormative compositions resembles the Streckeisen modal

mineralogic classification (Figure 4.3). The Woonga Granodiorite, Woolooga

Granodiorite and Rush Creek Granodiorite have relatively uniform granodiorite to

monzogranite composition, whereas compositions of the Mount Mucki Diorite and the

Gibraltar Quartz Monzodiorite vary from monzogabbro to quartz monzodiorite. The

chemistry of the mafic enclaves in the net-vein of the Mount Mucki Diorite-Gibraltar

Quartz Monzodiorite is similar to the Mount Mucki Diorite. The SCIC has high-K to

medium-K geochemistry of calc-alkalic affinity (Figure 5.3). The Mount Mucki

Diorite is a medium-K pluton with K2O content of 1.01 to 2.25%. The thermal

metamorphosed Woonga Granodiorite shows K-loss at relatively constant SiO2.

Based on Miyashiro (1974) classification, the Woolooga Granodiorite, Rush Creek

Granodiorite and Woonga Granodiorite are calc-alkalic, whereas the Mount Mucki

Diorite is tholeiitic (Figure 5.4). The Gibraltar Quartz Monzodiorite has composition

that is transitional between calc-alkalic and tholeiitic. Monzodiorite and quartz

monzodiorite intrusions into the southern Woolooga Granodiorite are tholeiitic,

whereas intrusions of granodiorite composition are calc-alkalic.

Two sub-parallel variation trends on the AFM diagram (Figure 5.5) highlight

two magma series with different FeO* and MgO ratios. The higher FeO*/MgO trend

consists of rocks from the Mount Mucki Diorite and the Gibraltar Quartz

Monzodiorite. The lower FeO*/MgO trend comprises rocks from the Woonga

Granodiorite, Woolooga Granodiorite and Rush Creek Granodiorite. The majority of

samples from the SCIC plots in the calc-alkaline field of the AFM diagram and all

show progressive decrease in FeO* with increasing alkalis contents. Only

monzogabbro and monzodiorite samples of the Mount Mucki Diorite and Gibraltar

Quartz Monzodiorite plot in the tholeiite field. Despite a tholeiitic affinity based on

Miyashiro (1974) plot, the Mount Mucki Diorite is predominantly calc-alkalic that

displays continuous decreases in FeO* with increasing alkalis.

The Station Creek Igneous Complex is metaluminous, except for the granitic

end-members of the Rush Creek Granodiorite that are marginally peraluminous and

weathered samples of Woonga Granodiorite which are peraluminous (Figure 5.6). The

Mount Mucki Diorite is the most metaluminous pluton. The metaluminous


106

Figure 5.4: Geochemical classification of plutonic rocks of the SCIC . The Mount Mucki Diorite and Gibraltar

Quartz Monzodiorite are tholeiitic and transitional tholeiitic respectively. The Woonga, Woolooga and Rush Creek Granodiorites are calc-alkalic. The mafic enclaves in the Gibraltar Quartz Monzodiorite are tholeiitic and have similar composition to the Mount Mucki Diorite.

into calc-alkaline and tholeiite associations (Miyashiro, 1974)

0 1 2 3 4 5

Figure 5.3: Subdivision of plutonic rocks of the SCIC into low-, medium- and high-K fields on the K O versus SiO diagram (Le Maitre, 1984). The Woolooga and Rush Creek Granodiorites are high-K, and the Mount Mucki Diorite and Gibraltar Quartz Monzodiorite are medium- to high-K. The Woonga Granodiorite shows K-depletion at relatively constant SiO . Medium-K and high-K-fields match the calc-alkaline composition of Rickwood (1989).

2 2

2

Rickwood, 1989

Low-K Medium-K High-KLow-K tholeiite Calc-alkaline High-K calc-alkaline

0

1

2

3

4

5


Gibraltar Quartz MonzodioriteRush Creek Granodiorite

Woonga Granodiorite

Mount Mucki Diorite

Mafic component in the net-vein of the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite


SYMBOLS

Late Triassic-Jurassic stock




Woonga Granodiorite

Mount Mucki Diorite



SYMBOLS

Late Triassic-Jurassic stock


High-K

Medium-K

Low-K

SiO (wt %)2

KO

(w

t %)

2

45 55 65 75

Calc-alkalic

Tholeiite

80

75

70

65

60

55

50

45

SiO

(w

t %)

2

FeO* / MgO


107

Figure 5.5: AFM diagram shows the chemical variation trends of intrusive rocks of the SCIC. The Woolooga, the Rush

tholeiite and

Creek and the Woonga Granodiorites plot with lower FeO*/MgO ratios in the calc-alkaline field. The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite have higher FeO*/MgO ratios and plot from the tholeiite field to the calc-alkaline field ( calc-alkaline division of Irvine & Baragar (1971).

Figure 5.6: Plot of alumina saturation versus alkalinity for the SCIC (after Maniar & Piccoli, 1989). All plutons are metaluminous, except for granite samples in the Rush Creek Granodiorite which are marginally peraluminous and altered samples of the Woonga Granodiorite which are peraluminous. Composition of the SCIC matches the I-type granite of Chappel & White (1974)'s granite classification.




Woonga Granodiorite

Mount Mucki Diorite



SYMBOLS



MgO

FeO*

Tholeiite

Calk-alkaline

Na O + K O2 2




Woonga Granodiorite

Mount Mucki Diorite



SYMBOLS



Peraluminous

Peralkaline

Metaluminous

I-Type S-Type

1 1.5

1

2

3

Altered samples

Al O /(CaO + Na O + K O)2 3 2 2

AlO

/(Na

O +

KO

)2

32

2


108

compositions of the SCIC (<1.1 A/CNK) match the composition of I-type granites

(Chappell & White, 1974). The calcic-alkali ratios or CaO/(Na2O+K2O) versus SiO2

plot highlights two variation trends (Figure 5.7). The Mount Mucki Diorite and

Gibraltar Quartz Monzodiorite form an overlapping trend, and the Rush Creek

Granodiorite and Woolooga Granodiorite form one linear trend. The calcic-alkali

ratios of the Woonga Granodiorite superimpose on the Woolooga Granodiorite-Rush

Creek granodiorite trend. Based on Peacock (1931) definition, the Mount Mucki

Diorite-Gibraltar Quartz Monzodiorite trend fits an alkalic-calcic to calcic-alkalic

group, whereas the Woolooga Granodiorite-Rush Creek Granodiorite trend is calc-

alkalic.

Major element geochemistry

The geochemistry of the SCIC varies from quartz undersaturated to quartz

saturated composition, with Mg# varying from 31 to 53 (Appendix 2). The Woonga

Granodiorite, Mount Mucki Diorite and Woolooga Granodiorite have limited SiO2

variability of 65.5-67%, 47-53% and 62-69% respectively whereas the Rush Creek

Granodiorite and Gibraltar Quartz Monzodiorite have broader SiO2 range of 65-75%

and 53-61.5% respectively. Compatible elements (TiO2, Fe2O3, MnO, CaO and MgO)

generally have antipathetic correlations with SiO2 whereas K2O has a sympathetic

correlation (Figure 5.8). Al2O3 and Na2O are sympathetic with SiO2 up to ~57% SiO2

and define poor antipathetic relationships with SiO2 above ~57% SiO2.

The Harker diagrams highlighted three general geochemical variation trends.

The Woolooga Granodiorite and Rush Creek Granodiorite have continuous and co-

linear geochemical trends for their compatible elements. Their incompatible elements

show poor correlation with SiO2 and individual pluton forms respective Na2O and

K2O variation domains. The Na2O and K2O contents in the Woolooga Granodiorite

are relatively uniform. The K2O in Rush Creek Granodiorite bifurcates into a positive

and a negative trend from ~71% SiO2. The point of bifurcation of the K2O trend

coincides with decreasing modal percentages of biotite (see Figure 4.5).

The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite have continuous

geochemical trends for their incompatible elements, Fe2O3, MgO and CaO. These

variation trends differ significantly (gradients or ratios) from that of the Woolooga

and Rush Creek Granodiorites. The concentrations of compatible elements (TiO2,


109

Figure 5.7: Calcic-alkali ratio versus silica trends for intrusive units of the Station Creek Igneous Complex. The 'Rush Creek-Woolooga Granodiorites trend' has

'Mount Mucki Diorite-Gibraltar Quartz Monzodiorite trend'. The Woolooga-Rush Creek Granodiorites group has calcic-alkalic composition, whereas the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group is alkalic-calcic to calcic-alkalic. The Woonga Granodiorite plots as a cluster with no obvious variation trend.

lower CaO/(Na O+K O) ratio than the

2 2

SiO %2

Log

CaO

/(Na

O+K

O)

22

Mount Mucki Diorite

Gibraltar QtzMonzodiorite

Woolooga-RushCreek Granodiorites

Woonga Granodiorite

Woolooga GranodioriteGibraltar Quartz Monzodiorite

Rush Creek Granodiorite Woonga GranodioriteMount Mucki Diorite


110

Figure 5.8: Harker variation diagrams for major element geochemistry of the Station Creek Igneous Complex.

14

16

18

20

Al2O

3 (w

t %)

Al O2 3

0

5

10

CaO

(wt %

)CaO

45 50 55 60 65 70 75 800

1

2

3

4

5

6

SiO2 (wt %)

K2O

(wt %

)

K O2

MgO

2

3

4

5

6

7

8

MgO

(wt

%)

.1

.2

.3

MnO

(wt

%)

MnO0.4

P O2 5

TiO2

.5

1

1.5

TiO2

(wt

%)

0

1

2

3

4

5

Na2O

(wt

%)

Na O2

0

0

Fe O2 3



Woonga Granodiorite

Mount Mucki Diorite

Xenolith


Legend

Late Triassic- Jurassic intrusive

Dioritic component in the net-vein of the Gibraltar Quartz Monzodiorite

1 Xenolith in Late Triassic volcanics2 Xenolith in the Woolooga Granodiorite

2

1

1

2

21

12

1 Xenolith in Late Triassic volcanics2 Xenolith in the Woolooga Granodiorite

1

2

12

1

2

1

2

1

2


111

Fe2O3, CaO, MnO and P2O5) in the Mount Mucki Diorite and Gibraltar Quartz

Monzodiorite are higher than the Rush Creek, Woolooga and Woonga Granodiorites.

Significant scatter occurs in the low SiO2 range and in cumulate rocks of the Mount

Mucki Diorite and the Gibraltar Quartz Monzodiorite. The Gibraltar Quartz

Monzodiorite defines scattered domains for TiO2, MnO, MgO, CaO and K2O that

deviate from the Woolooga-Rush Creek Granodiorites trend. Monzodiorite intrusions

(referred to as the Mid-Triassic porphyry) into the southern Woolooga Granodiorite

have similar compositions to the Mount Mucki Diorite.

The Woonga Granodiorite has relatively uniform compatible element

geochemistry and SiO2 content. Its TiO2, Fe2O3, MgO, MnO and CaO contents are

generally less than the Woolooga-Rush Creek Granodiorites group at equivalent SiO2.

The pluton has Al2O3 and Na2O gains and K2O depletion, and the magnitude of both

gains and depletion increases with increased intensity of thermal metamorphism. The

Al2O3 gain relates to chloritisation of biotite and tremolitic replacement of

hornblende, and the variations of Na2O and K2O are related to albitisation.

Trace element geochemistry

The Harker variation diagrams for trace elements in the SCIC highlight

geochemical characteristics as well as differences between individual pluton. The

concentrations of the incompatible large ion lithophiles (or LIL in particular Cs, Rb

and K) and high ionic charged (>+3) high field strength (HFS) elements (Th, U and

Ta) increase with increasing SiO2 (Figure 5.9). Transition elements (TE), rare earth

elements (REE) and Sr generally behave like compatible elements and decrease with

increasing SiO2.

The Harker diagrams express three overall variation trends defined by their co-

linear and/or continuous variation patterns. The three trends are similar to ones

identified by their major element chemistry, i.e. the Woolooga-Rush Creek

Granodiorites, the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite and the

Woonga Granodiorite. Most trace elements in the Woolooga Granodiorite and Rush

Creek Granodiorite form almost linear variation trends with SiO2 except for Ba and K.

The Gibraltar Quartz Monzodiorite and Mount Mucki Diorite have approximately co-

linear variation trends for most LIL, HFS and REE with the exception of Cs and Sr.


112

Figure 5.9: Harker variation diagrams for trace element geochemistry of representative samples from the Station Creek Igneous Complex and associated intrusions (to continue).

Ta1 .5

0.1

0.5

1.0

K (x1 0 p p m3

)

20

40

30

50

10

0

R b

0

2 0 0

100

B a

0

1 2 0 0

500

S r

500

0

1000

1500

SiO240 50 60 70 80

C s1 2

1

4

8

Low field strength and LIL elements

1

1 2U

5

10

High field strength, ionic charge >+3

T h

0

3 5

10

20

30

SiO240 50 60 70 80


113

Figure 5.9: (continued): Harker variation diagrams for trace element geochemistry (ppm) of representative samples from the Station Creek Igneous Complex and associated intrusions.

Rush Creek GranodioriteWoolooga GranodioriteWoonga Granodiorite


Neureum Mountain Porphyry

Porphyritic intrusion

Mount Mucki DioriteGibraltar Quartz Monzodiorite

C o

0

5 0

20

40

S c

0

4 0

30

20

10

40 50 60 70 80SiO2

T i

1 ,0 0 0

9 ,0 0 0

5,000

Transition elements (HFS)

S m

1

1 0

3

5

7

9

0

4 0L a

30

20

10

Rare earth elements (REE)

1

2

3

4

040 50 60 70 80

SiO2

3

0

E u2

1

Yb


114

The Woonga Granodiorite defines unique geochemical domains that vary in elemental

concentrations at approximately constant SiO2. It has lower abundance of trace

elements than other plutons at their equivalent SiO2 content. All elements (except Cs,

Rb, Ba and Sr) plot below the main variation trends of the Woolooga-Rush Creek

Granodiorites and the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite.

The Woolooga-Rush Creek Granodiorites and the Mount Mucki Diorite-

Gibraltar Quartz Monzodiorite groups display sub-parallel or different variation trends

for Ba, K, Zr, Hf, Sr, U, Th, Ta, Co, Sc and REE. Ba increases sympathetically with

SiO2 in the Mount Mucki Diorite and Gibraltar Quartz Monzodiorite. In the

Woolooga and Rush Creek Granodiorites, Ba increases to ~71% SiO2 and then

bifurcates into antipathetic and sympathetic trends. This Ba-inflection at 71% SiO2

matches similar patterns for the K and Or#, and coincides with decreasing biotite

modes (Figure 4.5). Zr and Hf have sympathetic relationships with SiO2 in the Mount

Mucki Diorite and Gibraltar Quartz Monzodiorite, whereas these elements are

antipathetic in the Woolooga and Rush Creek Granodiorites. The REEs in the Mount

Mucki Diorite behave like incompatible elements and their concentrations increase

with increasing SiO2. La and Yb levels in the Gibraltar Quartz Monzodiorite remain

relatively constant with SiO2 whereas the middle REE decrease with SiO2 increases.

In more silicic compositions of the Woolooga and Rush Creek Granodiorites, the REE

decrease with increasing SiO2.

The Mount Mucki Diorite (47-53% SiO2) is the most basic pluton of the SCIC

and has lower concentrations of LIL, high ionic charged HFS and light rare earth

elements (LREE). These elements have positive correlations with SiO2. Conversely,

the pluton has higher concentrations of Ti, Co, Sc (transition elements) and Sr than

other SCIC plutons and these concentrations progressive decrease with increasing

SiO2. The average Rb, Ba and Sr contents in the pluton are 30.6, 262 and 837 ppm

respectively.

Element ratio diagrams

The Mg#, Or# and An# are regarded as indices for ferromagnesian minerals,

orthoclase and plagioclase fractionation (Best & Christiansen, 2001). The magnesium

number 100(Mg/Mg+Fe) or Mg# of the Mount Mucki Diorite (40 to 47) and Gibraltar


115

B. An#

45 50 55 60 65 70 75 80SiO2 (wt %)

45 50 55 60 65 70 75 80

100x

Ca/

(Ca+

Na)

or A

n#

10

20

30

40

60

70

50

80

Mount Mucki Diorite-Gibraltar Quartz Monzo-diorite group

Woolooga-Rush CreekGranodiorites group

Woonga Granodiorite

30

40

50

60

100

x M

g/(M

g+Fe

*) o

r Mg# A. Mg#

Mount Mucki Diorite-Gibraltar Quartz Monzo-diorite group

Woolooga-Rush CreekGranodiorites group

WoongaGranodiorite

C. Or#

10

30

40

50

2010

0xK

/(K+N

a) o

r Or#

45 50 55 60 65 70 75 80SiO2 (wt %)

45 50 55 60 65 70 75 80

Mount Mucki Diorite-Gibraltar QuartzMonzodioritegroup

Woolooga-Rush CreekGranodioritesgroup

Woonga Granodiorite

Geochemical vatiation trendor grouping



Woonga Granodiorite

Mount Mucki Diorite

Legend


Figure 5.10: Cation ratios versus SiO plots of the SCIC highlight three geochemical variation trends: the Woolooga-Rush Creek Granodiorite group, the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group and the Woonga Granodiorite.

2

Figure 5.11: element ratio diagram of the SCIC highlights four variation

converge to a common point (asterisk) corresponding to ~zero Ti/K and a Si/K ratio of 50, and the composition of samples at this convergence point (asterisk) are granitic.

Ti/K versus Si/K trends of different element ratio-ratios. The Woolooga Granodiorite and the Rush Creek Granodiorite form one continuous trend. All variation trends



Woonga Granodiorite

Mount Mucki DioriteSYMBOLS


Projected intersection point of the ratio-ratios variation trends for the SCIC.

Si/K

Mount MuckiDiorite trend


116

Quartz Monzodiorite (38 to 45) are similar (Figure 5.10A). The Mg# of the Woolooga

Granodiorite (from 31 to 55), Rush Creek Granodiorite (36 to 52) and Woonga

Granodiorite (36 to 52) are more variable, and Mg# decreases with increasing SiO2.

The anorthite number 100(Ca/(Ca+Na)) or An# decreases progressively with

increasing SiO2 (Figure 5.10B). The An# of the Mount Mucki Diorite (53 to 76) and

Gibraltar Quartz Monzodiorite (15 to 51) forms one variation trend parallel to the

Woolooga-Rush Creek Granodiorites trend (An# of 22-46 and 16-39 respectively).

Orthoclase number 100(K/(K+Na)) or Or# increases with increasing SiO2 (Figure

5.10C). The Or# of the Mount Mucki Diorite remains relatively constant whereas the

Or# of the Woonga Granodiorite varies significantly between its narrow 65-67% SiO2

range. In Rush Creek Granodiorite, Or# bifurcates into two variation trends from

~71% SiO2.

Mg#, An# and Or# of the SCIC crudely define three variation trends or

domains. The domains are the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite,

the Woolooga-Rush Creek Granodiorites and the Woonga Granodiorite. These groups

mimic trends observed in the Harker diagrams for both major and trace elements.

Immobile to mobile elements ratios are commonly referred to as Pearce

element ratios (after Pearce, 1983). Rocks from the same magmatic source have

similar Pearce element ratios and should plot along linear trends of magmatic

differentiation. In granites, Ti, P and Si are considered immobile elements, whereas K,

Na and Ca are mobile elements (Rollinson, 1993). The Woolooga Granodiorite and

the Rush Creek Granodiorite have similar Ti/K and Si/K cationic ratios that plot as

one continuous trend (Figure 5.11). The Gibraltar Quartz Monzodiorite, Woonga

Granodiorite and Mount Mucki Diorite have unique Ti/K versus Si/K relationships

that plot as respective linear trends. All Ti/K versus Si/K variation trends in the SCIC

converge to a common point that corresponds to Ti/K and Si/K values of zero and 50

respectively. The rock composition at this convergence point is granitic.

Component plutons of the SCIC display different inter-elements correlation

trends (Figure 5.12), except for the Woolooga and Rush Creek Granodiorites that

have a common trend for their K/Rb versus Rb relationship. Each pluton does not

maintain relatively constant incompatible element ratios over their range of whole-

rock SiO2. Incompatible elements generally increase with SiO2, with the exceptions of

Rb in the Woonga Granodiorite and Ba in the Rush Creek Granodiorite. The


117

Figure 5.12: Variation diagrams of bivariant trace elements and incompatible element ratios. Dashed-line generalised the variation within an individual pluton, and the arrow indicates the trend of increasing SiO . The Rush Creek Granodiorite has inflection points in some trends that reflected the of elemental concentrations at 71% SiO .

2

2

bifurcation

SYMBOL AND ABBREVIATIONS

Approximate variation trend, and arrow indicates the general direction of increasing whole-rock SiO within a pluton.

2

Mafic enclaves in GQM net-veinMM Mount Mucki DioriteWOG Woonga GranodioriteGQM Gibraltar Quartz MonzodioriteWG Woolooga GranodioriteRCG Rush Creek Granodiorite

MM

RCG

WG

WOG

0 100 200Rb (ppm)

0

200

400

600

800

1000

Ba

(ppm

)

B. Ba vs Rb

MM

GQM

RCG

WOG

WG

170

20

40

60

80

100

120

140

160

K/Ba

100 300 500 700 800Ba (ppm)

C. K/Ba vs Ba

GQM

WOG

RCG-

WG

MM

RCG+

100 300 500 700 8000

1700

500

1000

1500

Ba (ppm)

Sr (

ppm

)

E. Sr vs Ba

RCG+

GQM

MM

WOG

RCG-WG

0 10 20 30 40 50 60 70Th/Tb

0

10

20

30

40

Th/T

a

D. Th/Ta vs Th/Tb

RCG

MM

GQM

WG

MM

GQ

M

WO

G

WG

RC

G

Th/T

a ra

nge


118

Woolooga Granodiorite shows limited variations in its elemental concentrations. The

Rush Creek Granodiorite has higher LIL, K/Rb, Th/Tb and Th/Ta, and lower Sr than

other plutons. The Mount Mucki Diorite has the lowest LIL and K/Rb in the SCIC.

The K/Rb vs Rb and K/Ba vs Ba curves of the Mount Mucki Diorite and Gibraltar

Quartz Monzodiorite are sub-parallel and converge towards a region of low LIL

(~150-170 ppm Ba, <30 ppm Rb, ~0 mole K). Both plutons have similar Th/Ta and

Th/Tb ratios. Incompatible-elements ratios of mafic enclaves in the net-vein of

Gibraltar Quartz Monzodiorite are similar to the Mount Mucki Diorite.

REE geochemistry

The REE abundances in the Mount Mucki Diorite increase with SiO2, whereas

REEs decrease with increasing SiO2 in the other plutons of the SCIC (Figure 5.9). A

chilled-margin sample of the Mount Mucki Diorite (sample SC936) is the most mafic

rock of the SCIC, and has the lowest light rare earth elements (LREE) concentrations

and relatively low concentrations of medium- and heavy-REEs. The Woonga

Granodiorite has the lowest medium rare earth elements (MREE) and low heavy rare

earth elements (HREE) concentrations.

Chondrite (values of Nakamura, 1974 and Haskin et al., 1968) normalised

REE patterns for representative samples of the SCIC show significant (<100)

enrichment of LREE relative to HREE (Figure 5.13). The Woolooga Granodiorite has

identical REE patterns and very similar REE concentrations and enrichment factors

for all samples. It has a small negative europium anomaly or Eu-trough that deepens

with increasing SiO2. The Gibraltar Quartz Monzodiorite and the Rush Creek

Granodiorite vary mainly in their MREE and HREE with respect to SiO2. In the Rush

Creek Granodiorite, the negative europium anomaly deepens and the MREE-HREE

abundances decrease with increasing SiO2. The REE abundances in the Mount Mucki

Diorite increase with increasing SiO2 and the LREE are more enriched relative to the

MREE and HREE at higher SiO2 contents.

Negative Eu anomalies (Eu/Eu*) characterise the chondrite normalised REE

patterns of the Woolooga Granodiorite (Eu/Eu*=0.67-0.85) and the Rush Creek

Granodiorite (Eu/Eu*=0.47-0.76) (Figure 5.14). The Eu anomaly increases

sympathetically with bulk-rock SiO2 i.e. an increase in Eu anomaly from quartz

monzodiorite to granite. Negative Eu anomalies also occur in porphyritic intrusions


119

such as the Black Snake Porphyry (Eu/Eu*=0.81) and Neureum Mount Porphyry

(Eu/Eu*=0.89).

The chondrite normalised La/Yb ratio or (La/Yb)n expresses the relative

abundance of LREE to HREE, commonly used as an index to represent the degree of

REE fractionation during magmatic evolution. The (La/Yb)n for the Mount Mucki

Diorite is 2.91-5.00, Woonga Granodiorite is 5.57-8.34, Woolooga Granodiorite is

5.83-7.50, Gibraltar Quartz Monzodiorite is 6.73-7.33 and for the Rush Creek

Granodiorite is 3.34-9.40. The (La/Yb)n ratios of the Mount Mucki Diorite, Woonga

Granodiorite and Rush Creek Granodiorite increase with whole-rock SiO2 (Figure

5.15A). The Woolooga Granodiorite and the Gibraltar Quartz Monzodiorite have

relatively uniform (La/Yb)n and show no systematic variation.

The (La/Sm)n versus Smn diagram compares the abundances of La (LREE)

relative to Sm (MREE) and the (Tb/Yb)n versus Ybn diagram compares the

abundances of Tb (MREE) relative to Yb (HREE). Ratios of LREE/MREE (La/Sm)n

and MREE/HREE (Tb/Yb)n are used to represent LREE and HREE fractionation

(Rollinson, 1993). The (La/Sm)n values for all plutons of the SCIC increase whereas

their (Tb/Yb)n ratios (except Woolooga Granodiorite) decrease with increasing SiO2

(Figures 5.15B and 5.15C).

In the Mount Mucki Diorite, the (La/Sm)n, Smn and Ybn values increase and

(Tb/Yb)n ratio decreases with increasing SiO2, which suggests enrichment of all REE

and a lesser increment of MREE relative to LREE and HREE. In the Woonga

Granodiorite, the (La/Yb)n and (La/Sm)n ratios increase over minor increases in Smn.

and Ybn, suggesting higher rate of LREE increases relative to MREE and HREE. In

the Gibraltar Quartz Monzodiorite, the constant (La/Yb)n values imply relatively

constant LREE and HREE compositions despite changes in SiO2. The increasing

(La/Sm)n and decreasing Smn and (Tb/Yb)n values imply decreasing MREE

abundances relative to LREE and HREE. In the Rush Creek Granodiorite, (La/Yb)n

and (La/Sm)n ratios and Lan abundances increase, and Ybn and Smn values decrease

with increasing SiO2. The REE ratios suggest declines in HREE and MREE values

with increasing SiO2. On the (La/Sm)n versus Smn plot (Figure 5.15B), the Rush

Creek Granodiorite has two REE-ratio trends. A minor variation trend originates from

a monzodiorite intrusion (SC1204) at the centre of the pluton, and coalesces into the

main trend that is representative of the pluton. The (La/Yb)n, (La/Sm)n and (Tb/Yb)n


120

Figure 5.13: C or representative samples from plutons of the Station Creek Igneous Complex (normalising chondrite values of Nakamura (1974) including Pr, Tb, Ho and Tm from Haskin ., (1968)). Vertical arrow on graph indicates the general trend of increasing SiO (wt %) between the samples (SiO content of individual sample is expressed as anhydrous weight percent in bracket). The 'SCIC composite plot' compares the REE patterns and the chondrite normalised enrichment factors between individual pluton. (Geochemical error for ICP-MS data (black lines) 0.005 ppm).

et al2 2

+

hondrite normalised rare earth element abundances f

Abun

danc

e/C

hond

rite SCIC COMPOSITE

Abun

danc

e/C

hond

rite

4

1 0

1 0 0WooloogaGranodiorite

General trend of increasing SiO2 wt % between samples

Samples SC472 (64.20%) SC582 (65.09%) SC854 (67.02%)

SC1037 (63.21%)

Abun

danc

e/C

hond

rite

4

1 0

1 0 0Rush CreekGranodiorite


Monzodiorite intrusion SC1204

Sample SC1204 (55.09%) SC1166 (65.65%) SC1185 (71.17%) SC1153 (75.31%)

Abun

danc

e/C

hond

rite

4

1 0

1 0 0Gibraltar QuartzMonzodiorite


Samples SC710 (56.18%) SC1018 (62.44%)

Abun

danc

e/C

hond

rite

4

1 0

1 0 0Mount Mucki Diorite


Samples SC999 (53.53%) SC936 (47.98%)

L a C e P r N d S m E u G d T b D y H o E r T m Y b L u

Abun

danc

e/C

hond

rite

4

1 0

1 0 0Woonga GranodioriteSample SC1129 (67.39%) SC1086 (67.82%) SC1125 (67.94%)

INAA data (dashed lines )Samples SC1086, SC1125 Errors 0.1 ppm+



121

Figure 5.14: The europium anomaly of the Station Creek Igneous Complex. The vertical error bar shows the uncertainty ( 0.05). (Eu anomaly calculation is based on Taylor & McLennan (1985); the normalising chondrite values of Nakamura (1974); Pr, Tb, Ho and Tm from Haskin . (1968)).

or Eu/Eu* +

et al

Cen

0.4

0.6

0.8

1.0

1.2

Euro

pium

ano

mal

y Eu

/Eu*

0 20 40 60 80 100

Eu/Eu* vs Cen

Positive anomaly

Negative anomaly

UNIT

Woonga GranodioritePorphyritic intrusion

Gibraltar Qtz Monzodiorite

Rush Creek GranodioriteWoolooga Granodiorite

Mount Mucki Diorite

Note: The anomaly is calculated by interpolating normalised values of Sm and Gd using the geometric mean equation of Taylor and McLennan (1985). In the absence of Gd data, interpolation from Tb calculates the Eu anomaly to 4% accuracy from Eu/Eu* calculated using the Taylor and McLennan equation.

Figure 5.15: Rare earth element ratio diagrams for the Station Creek Igneous Complex. The ratio expresses the concentration of LREE/HREE (chondritic values of Nakamura (1974), Haskin . (1968)). The dashed arrows represent trends of increasing whole-rock SiO within individual pluton.

et al2

chondrite normalised

Abbreviation and symbol

Trend of increasing whole-rock SiO2

Porphyritc intrusion (monzodioritie)

WOG Woonga Granodiorite

RCG Rush Creek Granodiorite

MM Mount Mucki Diorite

GQM Gibraltar Quartz Monzodiorite

WG Woolooga Granodiorite

(La/

Yb) n

2

4

6

8

10

20 40 60 80 100

WOG RCG

MM

GQM

Lan

(La/

Sm

) n

0

1

3

4

5

6

2

10 20 30 40 500 Smn

(La/Sm) vs Smn n

GQM

? RCG

MM

WOG

RCG

B.

Monzodiorite intrusioninto RCG

MM

GQMRCG

Intrusion

WG

WG


122

ratios of the Woolooga Granodiorite show no systematic variation with SiO2.

Spider diagram

Mid-ocean-ridge basalt- or MORB-normalised spider diagrams (devised by

Pearce, 1983) show similar patterns for the various plutons of the SCIC despite

differences in their enrichment-depletion factors (Figures 5.16). MORB-normalisation

facilitates comparison of the rock geochemistries to mantle-derived melt with minor

involvement of oceanic sediments. Relative to MORB, LIL and incompatible HFS

elements (Sr, K, Rb, Ba, Th, Ta, Nb, Ce, Zr and Hf) are generally enriched whereas

Ti, Y and Yb are depleted. This pattern is typical of subduction-related continental

rocks (Pearce et al., 1984), and very similar to the average upper crustal composition

(Taylor & McLennan, 1985) except for the lower Ta and Nb abundances in the SCIC

(values of Ta and Nb are close to MORB-values).

Monzogabbro and diorite samples from the Mount Mucki Diorite and

Gibraltar Quartz Monzodiorite have similar immobile-element (Ta to Yb) abundances

to the MORB values. The characteristic shape of the spider diagram pattern is

maintained while their absolute abundances increases with increasing SiO2. In the

Woolooga and Rush Creek Granodiorites, the enrichment and depletion factors of

elements are amplified with increasing SiO2, which typify fractional crystallisation

process that partitioned compatible elements into the earlier mafic minerals and

incompatibles into the melt fraction.

The SCIC is compared against ocean-ridge-granite (ORG) to highlight

possible contributions from crustal and subduction-zone components to the SCIC

(Pearce, 1983). Ocean-ridge-granite represents fractionated depleted mantle-sourced-

melt with minimal inputs from altered oceanic crust (Whalen, 1985; Pearce et al.,

1984). On the graphs, the areas above the ORG curve and below the SCIC curves

represent elemental enrichments, likely derived from crustal and/or subduction-zone

components (Wilson, 1989). The SCIC is enriched in the mobile elements (Sr, K, Rb,

Ba and Th) relative to the ORG, and such enrichments require the addition of mobile-

element rich components such as the subduction slab or the subduction-zone fluids

(e.g. Pearce, 1983; Gill, 1981). The enrichment is more pronounced in the Woolooga

and Rush Creek Granodiorites, and is least in the Mount Mucki Diorite, implying


123

Figure 5.16: Spider diagrams for selected samples from plutons of the Station Creek Igneous Complex. The MORB normalising values are from Pearce (1983) and the ocean-ridge granite (dashed-line) composition is from Pearce . (1984). Also plotted is the average upper crustal composition (data from Taylor & McLennan, 1985; bold broken line). (Errors on graphs are 0.01 ppm, 1 )

et al

+ σ

0 .1

1 . 0

1 0

1 0 0

Ab

un

da

nc

e/

MO

RB

S r K R bB aT hTaN bC eP Z rH fS mT i Y Y b

W o o n g a G ra n o d io r i teSC1129 (67.39 wt% SiO)

2

SC1153 (75.31)SC1185 (71.17)SC1166 (65.65)SC1204 (55.09)


0 . 1

1 .0

1 0

1 0 0

Ab

un

da

nc

e/

MO

RB

W o o lo o g a G ra n o d io r i teIncreasingwhole-rock SiO 2

SC854 (67.02)SC582 (65.09)SC472 (64.20)SC1037 (63.21)


0 . 1

1 . 0

1 0

1 0 0A

bu

nd

an

ce

/ M

OR

BM o u n t M u c k i D io r i te

SC999 (53.53% SiO2)SC936 (47.98% SiO2)

S r K R bB aT hTaN bC eP Z rH fS mT i Y Y b0 . 1

1 . 0

1 0

1 0 0

Ab

un

da

nc

e/

MO

RB


Explanations

Upper Crust

Ocean-ridge granite

Shaded area represents the geochemical differences between MORB and ocean-ridge granite (ORG) due largely to magmatic differentiation (fractional crystallisation and/or partial melting)

Shaded area represents the geochemical differences between ORG and the upper crustal composite due to enrichment of K, Rb, Ba, Th, Ta and Nb (possible crustal contributions).

ORG-baseline

MORB

ORG-baseline

MORB

ORG-baseline

MORB

ORG-baseline

MORB

ORG-baseline

MORB

0 . 1

1 .0

1 0

1 0 0

Ab

un

da

nc

e/

MO

RB

MORB


ORG-baseline


124

Figure 5.18: TAS classification of volcanic rocks of the northern North D'Aguilar Block. The bold line divides the alkaline and subalkaline fields (Irvine & Baragar, 1971) and the volcanic fields are adapted from Le Maitre (1984).

Rhyolite

Dacite

Basalt

Basalticandesite

Andesite

Trachydacite

Trachybasalt

Basaltic trachyandesite

Trachyandesite

Trachyte

Late TriassicNorth Arm Volcanics

Early PermianHighbury Volcanics

Dyke

Early TriassicNeara Volcanics

Altered basalunit of NearaVolcanics (ABU)

SYMBOLS

Figure 5.17: Normalised trace element abundances for representative samples of the Station Creek Igneous Complex. The samples are normalised to the most mafic sample of the SCIC (SC936) from the Mount Mucki Diorite. The horizontal line is the reference to enrichment (>1.0) or depletion (<1.0) relative to SC936. The figure in bracket refers to the SiO wt %, recalculated to 100% anhydrous total.

2(Error on the

graph is 0.01).+

SC1166 (65.65%) (Rush Creek Granodiorite)

SC1037 (63.21%)(Woolooga Granodiorite)

SC710 (56.18%)(Gibraltar Qtz Monzodiorite)

SC1129 (67.39%)(Woonga Granodiorite)

SC999 (53.53%)(Mount Mucki Diorite)

SC936 (47.98%)(Mount Mucki Diorite)

S r K R b B a T h Ta N b C e P Z r H f S m T i Y Y b

The Mount Mucki Diorite, Gibraltar Quartz Monzodiorite and Woonga Granodiorite

The Woolooga and Rush Creek Granodiorite

Abu

ndan

ce/S

C93

6

S r K R b B a T h Ta N b C e P Z r H f S m T i Y Y b0 .3

1 .0

1 0

Sub-alkaline

Alkaline

Na

O +

KO

(w

t %)

22

10

5

0

SiO (wt %)2

45 55 65 75


125

greater addition of subduction-zone or crustal components in the Woolooga and Rush

Creek Granodiorites.

The most mafic composition of the SCIC is a monzogabbro (SC936) from the

chilled margin of the Mount Mucki Diorite. SC936 is enriched in mobile elements (Sr,

K, Rb, Ba and Th) and has similar or slight depletion of immobile elements (Ta to

Yb) relative to MORB. Normalised to this composition facilitates comparison of the

more evolved members of the SCIC (Figure 5.17). Rush Creek and Woolooga

Granodiorites have similar patterns, and are enriched in most trace elements relative

to SC936, except Sr and Ti. The Woonga Granodiorite is enriched in large lithophilic

elements (except Sr), and is depleted in higher-field-strength elements (P, Sm, Ti, Y

and Yb). The Gibraltar Quartz Monzodiorite and a more silicic sample of the Mount

Mucki Diorite are enriched in all elements relative to SC936.

VOLCANIC ROCKS AND DYKES

The Late Triassic North Arm Volcanics, the Early Triassic Neara Volcanics

and the Early Permian Highbury Volcanics make up the volcanic rocks of the northern

NDB. Within the Neara Volcanics, its “altered basal unit” (or ABU) differs

compositionally and geochemically from the rest of the unit. ABU has been

demarcated in the geochemical plots to indicate its uniqueness and possible alteration

overprint on its chemistry.

Geochemical classification of volcanic and hypabyssal rocks

The Neara Volcanics

The composition of the Neara Volcanics ranges from basaltic andesite to

trachyandesite, and its “altered basal unit” (or ABU) defines a parallel trend of lesser

K2O+Na2O composition from basaltic andesite to rhyolite (Figure 5.18). The volcanic

unit is subalkaline and medium- to high-K (ABU is medium-K, Figure 5.19). Based

on Rickwood’s (1989) definition, the medium- and high-K fields are predominantly

calc-alkalic. Geochemical classification using Miyashiro’s (1974) scheme categorises

the composition of the Neara Volcanics as transitional between the tholeiite and calc-

alkalic fields, whereas the ABU is calc-alkalic (Figure 5.20). On the AFM diagram,

the Neara Volcanics plots within the calc-alkalic field (Figure 5.21) and geochemical


126

Figure 5.19: The division of subalkalic volcanic rocks of the northern North D'Aguilar Block into low-,medium- and high-K fields based on the K O vs SiO diagram (Le Maitre, 1989). Related definitions of the various K-fields by Le Maitre (1984), Rickwood (1989) and Middlemost (1975) are summarised in the table above. The basalt from Highbury Volcanics falls into the low-K field that corresponds to a low-K tholeiite

2 2

composition.

Rickwood, 1989

Middlemost, 1975

Le Maitre, 1984

Low-K Medium-K High-KBasalt to basalticandesiteLow-K tholeiite

Low-K subalkalic basalt

Basaltic andesite to andesiteCalc-alkaline

Sub-alkalic basalt

Andesite to dacite

High-K calc-alkaline

Alkalic basalt

0

1

2

3

4

5

6

Late TriassicNorth ArmVolcanics

Early PermianHighburyVolcanics

Dyke

Early TriassicNeara VolcanicsAltered basalunit of NearaVolcanics (ABU)

SYMBOLS

0 1 2 3 4 5

Figure 5.20: Geochemical classification of volcanic rocks of the northern North D'Aguilar Block . The basalt of the Highbury Volcanics is tholeiitic whereas the Neara Volcanics displays transitional tholeiitic-calc-alkalic characteristics. The altered basal unit of the Neara Volcanics is calc-alkalic.

into calc-alkaline and tholeiite associations (fields of Miyashiro, 1974)

Calc-alkaline

Tholeiite

SiO

(w

t %)

2

FeO* / MgO

80

75

70

65

55

50

45

60

KO

(w

t %)

2

High-K

Medium-K

Low-KDac

ite a

nd rh

yolit

e

And

esite

Bas

altic

and

esite

Bas

alt

SiO (Wt %)2

75655545

Late TriassicNorth ArmVolcanics

Early PermianHighburyVolcanics

Dyke

Early TriassicNeara VolcanicsAltered basalunit of NearaVolcanics (ABU)

SYMBOLS


127

Figure 5.21: AFM diagram shows the geochemical variation trends for volcanic rocks. The basalt of the Highbury Volcanics plots within the tholeiite field whereas the Neara Volcanics, the North Arm Volcanics and dykes plot within the calc-alkaline field. T

holeiite and he Highbury Volcanics has initial FeO* enrichment with increasing alkalis, which

is typical of the tholeiite trend. (T calc-alkaline division is based on Irvine & Baragar, 1971).

Tholeiite

Calk-alkaline

Na O + K O2 2 MgO

FeO*

Late Triassic North ArmVolcanics

Early Permian Highbury Volcanics

Dyke

Early Triassic Neara Volcanics

Altered basal unit of the NearaVolcanics (ABU)

SYMBOLS

Figure 5.22: Plot of alumina saturation versus alkalinity for volcanic rocks (Maniar & Piccoli, 1989). The Highbury Volcanics, the North Arm Volcanics, dykes and upper flows of the Neara Volcanics are metaluminous. The altered basal unit of the Neara Volcanics is marginally metaluminous to peraluminous. Based on classification scheme of Chappel & White (1974), the Highbury Volcanics, North Arm Volcanics, dykes and upper flows of the Neara Volcanics have compositions similar to I-type granite and the peraluminous samples from the basal unit of the Neara Volcanics are similar to S-type granite.

Peraluminous

Peralkaline

MetaluminousI-Type S-Type

1

2

3

Late TriassicNorth Arm Volcanics

Early Permian HighburyVolcanics

Dyke

Early TriassicNeara Volcanics

Altered basalunit of NearaVolcanics (ABU)

SYMBOLS

Al O /(CaO + Na O + K O)2 3 2 2

AlO

/(Na

O +

KO

)2

32

2

1.51


128

variation trend shows progressive decreases in FeO* with increasing alkali content,

which is the typical crystallisation trend of calc-alkalic rocks.

The basaltic andesite and trachyandesite of the Neara Volcanics are

metaluminous (hypersthene normative) with ASI of <1, which match the I-type

granite composition (Chappell & White, 1974). The ABU defines continuous trends

of higher Al2O3/(Na2O+K2O) contents ranging from metaluminous to peraluminous

(Figure 5.22), which suggest compositions akin to the S-type granite of Chappell &

White (1974).

The North Arm Volcanics and Late Triassic dykes

The composition of the North Arm Volcanics ranges from andesite to

trachyandesite, and Late Triassic dykes that intrude the SCIC have basaltic andesite to

rhyolite compositions. The volcanic unit and dykes are metaluminous, subalkaline and

medium- to high-K, corresponding to a calc-alkalic composition on the Rickwood

(1989) classification (Figure 5.19). Miyashiro’s (1974) classification categorises the

North Arm Volcanics and dykes as calc-alkalic (Figure 5.20), and the compositions of

both volcanic rocks and dykes plot within the calc-alkalic field on the AFM diagram

(Figure 5.21). The metaluminous (hypersthene normative) nature of the North Arm

Volcanics (ASI <1) matches the I-type granites that are derived from igneous sources

(Chappell & White, 1974).

The Highbury Volcanics

The Highbury Volcanics has low-K composition that ranges from basalt to

trachybasalt. The basalt is subalkalic whereas the trachybasalt is marginally alkalic

(Figure 5.19). Based on Rickwood’s (1989) definition, a low-K field is tholeiitic; and

Miyashiro’s (1974) geochemical classification identifies the Highbury Volcanics as

tholeiite (Figure 5.20).

The Highbury Volcanics plots in the tholeiite field of the AFM diagram and

shows an initial increase in FeO* followed by a progressive decrease with increasing

alkalis, typical of the tholeiitic trend (Figure 5.21). Basaltic rocks of the Wratten Beds

are metaluminous (diopside and hypersthene normative) and have ASI of <0.9 (Figure

5.22).


129

Geochemistry

The Neara Volcanics

The Neara Volcanics (53-66 wt% SiO2) of the northern North D’Aguilar

Block comprises of two distinct geochemical groups - ABU and the overlying

basaltic-andesite to trachyandesite. TiO2, Al2O3, Fe2O3, MgO, CaO and Sr

demonstrate compatible behaviours and have antipathetic correlation with SiO2

(Figure 5.23). K2O, Na2O and Ba define poor correlations with SiO2. The ABU has

higher TiO2, Fe2O3, MgO and CaO; and lower LIL, K2O, Na2O, Al2O3 and Sr than the

overlying basaltic-andesite to trachyandesite. On the Al2O3 versus (Al2O3+K2O+

Na2O+CaO) plot, ABU forms a higher alumina group (>0.6) which could result from

weathering (Nesbitt & Young, 1989) or additional of supracrustal components (e.g.

Arculus & Johnson, 1981; Chappell & Stephens, 1988).

Chondrite normalised REE pattern of the Neara Volcanics shows moderate

enrichment of LREE relative to HREE (Figures 5.24). The (La/Yb)n values are 4.71 to

5.87 and (La/Yb)n increases with SiO2. On the MORB-normalised spider diagram,

LIL and highly incompatible HFS elements (Th, Ta, Nb, Ce, Zr and Hf) are enriched

whereas Ti, Y and Yb are depleted. Such variation pattern is similar to subduction-

related rocks (Pearce et al., 1984; Wilson, 1989) and to the average upper crustal

composition.

The major element geochemistry of the Neara Volcanics differs from the

SCIC. The volcanic unit contains less TiO2, Fe2O3, MgO and CaO, and is enriched in

Al2O3, K2O and Ba compared to plutonic units of the SCIC at equivalent SiO2 (Figure

5.23). However, its REE pattern and enrichment factors are almost identical to the

SCIC (the Mount Mucki Diorite).

The North Arm Volcanics

The North Arm Volcanics (58-65 wt% SiO2) has similar geochemistry to the

SCIC at equivalent SiO2 contents. On the Harker diagrams, the volcanic unit

superimposes on the plutonic domains. The REE pattern and enrichment factors of the

North Arm Volcanics are similar to the SCIC (Figures 5.24). Its chondrite normalised

REE pattern shows moderate enrichment of LREE relative to HREE and the (La/Yb)n

values are 5.89 to 6.27. (La/Yb)n increases with SiO2, which suggests that REE are

fractionated into more evolved magma.


130

Figure 5.23: Harker variation diagrams for volcanic rocks of northern North D’Aguilar Block.

hemistries of the volcanic rocks are compared against plutonic rocks from the Station Creek Igneous Complex.

The variation diagrams highlight two 'geochemical suites' within the Neara Volcanics. The domain for the significantly altered, porphyritic basal unit (ABU) of the Neara Volcanics is highlighted (grey-fills). C

geochemical fields of the

Mount Mucki DioriteGibraltar Quartz MonzodioriteWoolooga GranodioriteRush Creek GranodioriteWoonga Granodiorite

North Arm Volcanics (epiclastics)

Neara Volcanics (basaltic andesite, trachy-andesite to rhyolite; flows and epiclastics) Wratten Beds (basalts)

Legend

Domain of a porphyritic, basal unit withinthe Neara Volcanics (partially propylitised)

Dyke

MgO

2

3

4

5

Na2

O (

wt %

)

Na O2

Ba

Sr

45 50 55 60 65 70 75 80SiO2 (wt %)

0.5

0.6

AlO

(AlO

+K

O+

Na

O+

Ca

O)

23

23

22

Altered basalunit of the Neara Volcanics

Fresh NearaVolcanics


131

Highbury Volcanics

Neara Volcanics

Mount Mucki Diorite (SC999)

North Arm Volcanics

Basalt

Increasing SiO2

SCIC domain

Trachybasalt

Trend towards increasing SiO2

SCIC REE domain

200

Abu

ndan

ce/C

hond

rite

10

100

4La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Figure 5.24: REE (normalised using chondrite values of Nakamura (1974) and Pr, Tb, Ho and Tm from Haskin ., (1968)). The SCIC REE domain (broken-line) and a diorite from the Mount Mucki Diorite is plotted for comparison.

et al

patterns of volcanic rocks of the northern North D'Aguilar Block

0.1

10

100

Abun

danc

e/ M

OR

B (P

earc

e, 1

983)

1.0

Ta NbCe P Zr Hf SmTi Y YbSr K Rb BaTh

North Arm Volcanics

Upper crustal averageHighbury VolcanicsNeara Volcanics

Figure 5.25: Spider diagrams of volcanic The patterns for the North Arm and Neara Volcanics, and trachybasalts of the Highbury Volcanics are similar to the upper crustal average. Compositions of basalt from the Highbury Volcanics are similar to MORB (Normalising values of Pearce, 1983).

rocks of the northern North D'Aguilar Block.


132

The MORB-normalised multi-element variation diagram of the North Arm

volcanics has similar pattern and enrichment factor to the average upper crustal

composition (Figures 5.25). The LIL and highly incompatible HFS elements (Th, Ta,

Nb, Ce, Zr and Hf) are enriched whereas Ti, Y and Yb are depleted.

The Highbury Volcanics

The Highbury Volcanics (48-51 wt% SiO2) differs geochemically from the

North Arm and Neara Volcanics by its higher TiO2, Fe2O3, CaO and MgO contents

and lower Al2O3, Na2O, K2O, Ba and Sr abundances (Figure 5.23). The volcanic unit

differs from the SCIC by its higher TiO2, MgO and Na2O, and lower Al2O3, CaO,

K2O, Ba and Sr contents.

On the chondrite normalised REE plot (Figure 5.24), basalts of the Highbury

Volcanics is slightly enriched in MREE relative to the LREE and HREE, whereas its

trachybasalt from the Highbury Volcanics has similar pattern to the Neara Volcanics.

The (La/Yb)n values for basalts are 0.55-1.12 and 9.40-10.66 for the trachybasalt.

The basalt of the Highbury Volcanics displays flat patterns on the MORB-

normalised spider diagram for its basaltic rocks (Figure 5.25). The trace element

abundances are slightly enriched or depleted (+ 0.8 to 4 times) relative to the MORB.

The trachybasalt associated with the Highbury Volcanics displays similar pattern to

the Neara Volcanics on the MORB-normalised spider diagram. The LIL and HFS

elements are enriched whereas the Ti, Y and Yb are slightly depleted with respect to

MORB.

THE FOLIATED GRANODIORITES OF THE WRATTEN IGNEOUS SUITE

The composition of the Late Carboniferous foliated or cataclastic granodiorites

of the Wratten Igneous Suite ranges from tonalite to granodiorite (Figure 5.26). The

granitoids have higher normative quartz contents than the SCIC, and are corundum

normative. The Wratten Igneous Suite is classified as high-K, calc-alkaline (Figure

5.27) and peraluminous with A/CNK of >1.0 (Figure 5.28), typical of S-type granite

(Chappell & White, 1974).

Harker variation diagrams show that the foliated granodiorites differ

geochemically from the SCIC by its higher TiO2, P2O5, Sc and Sm; and lower Al2O3,


133

Figure 5.26: QAP classification of cataclastic or foliated granodiorite of the Wratten Igneous Suite using normative mineral compositions (Le Maitre, 1989). The cataclastic granodiorite has uniform composition that differs from the Station Creek Igneous Complex.

GMWG

WOGRCG

SYMBOLS

GM

RCG

WG

WOG



Woonga Granodiorite

Mount Mucki Diorite-Gibraltar Quartz Monzodiorite

Cataclastic granodiorite

A P

Q

1 2 3

4 5 67 8

GranodioriteTonalite

Quartz diorite

Monzogranite

Quartz monzoniteQuartz monzodiorite

MonzodioriteDiorite/gabbro

12345678

Lithologic fields

Figure 5.27: The geochemical classification of foliated of the Wratten Igneous Suite in the Woolooga area. The granodiorite is medium-K and

granodioritecalc-alkaline, and

differs geochemically from the SCIC. (Diagrams from: A. Miyashiro (1974) and B. Le Maitre (1989)).

45

50

55

60

65

70

75

80

0 1 2 3 4

M

G

RCG

WGW oWOG

M

G

WGRCG

WOG

Woolooga GranodioriteGibraltar Quartz Monzodiorite

Rush Creek Granodiorite Woonga GranodioriteMount Mucki Diorite

Foliated granodiorite

M

G

RCG

WG

WOG

Tholeiite

Calc-alkaline

SiO

(w

t %)

2

FeO* / MgO

High-K

Medium-K

Low-K

SiO (wt %)2

KO

(w

t %)

2


134

Figure 5.28: Alumina saturation versus alkalinity for the foliated granodiorite of the Wratten Igneous Suite compared to domains of the SCIC. The granodiorite is peraluminous with

granite classification of Chappel & White, 1974). a transitional S- to I-

type geochemical characteristic (




Woonga Granodiorite

Mount Mucki Diorite

SYMBOLS


M

G

RCG

WG

WOG

1 2

1

2

3

M

G

W G

R C G

W O G

W O G

S-TypePeraluminousMetaluminous

Peralkaline

I-Type

(Maniar & Piccoli, 1989)

Figure 5.29: Harker variation diagrams of foliated granodiorite of the Wratten Igneous Suite. Plotted for comparison are the domains of the SCIC plutons. Symbols and abbreviations used as in Figure 5.28.

M

G

W G

R C GW O G

S iO 25 0 6 0 7 0 8 0

P O2 5

(wt %)

MG

W G

R C G

W O G

Ta (ppm)1.5

0 .1

0 .5

1.0

Sc (ppm)

0

40

30

20

10

R C GW O G

W G

M

G

S iO 24 0 5 0 6 0 7 0 8 0

Sm (ppm)

1

10

3

5

7

9

M

G

W G

R C G

W O G

Rb (ppm)

0

200

100

M

G

W G

R C G

W O G

Trace elements (ppm)

TiO2 (Wt %)

0

.5

1

1.5

M G

W G

R C GW O G

Al O2 3

(wt %)

14

16

18

20

M

G

W O G

R C G

W G

CaO (wt %)

5

10 M

G

W G

R C G

W O G

0

K O2

(wt %)

4 0 5 0 6 0 7 0 8 0S iO 2

Sr (ppm)

500

0

1000

1500

AlO

/(Na

O +

KO

)2

32

2

Al O /(CaO + Na O + K O)2 3 2 2


135

Granulite

SCIC REE domain


Average upper crustNorth America Shale composite

Abu

ndan

ce/C

hond

rite

10

100

4La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Figure 5.30: REE (normalised using chondrite values of Nakamura (1974) and Pr, Tb, Ho and Tm from Haskin ., (1968)). Plotted for comparison are the SCIC domain, the North American Shale Composite (Gromet , 1984), the upper crustal average (Taylor & McLennan, 1985) and a granulite composition (Weaver ., 1981).

et alet al.

et al

pattern of foliated granodiorite of the Wratten Igneous Suite

U

La

Nd Eu

Tb Lu Ni

Abu

ndan

ce/ N

ASC

(Gro

met

.,

1984

)et

al

Figure 5.31: Spider diagram of foliated granodiorite of

pper crust and a diorite sample from the Mount Mucki Diorite are plotted as comparisons.

the Wratten Igneous Suite, northern North D'Aguilar Block (normalised to NASC or North America Shale Composite of Gromet ., 1984). Compositions of the average u

et al


136

CaO, K2O, Rb, Ta and Sr contents (Figure 5.29). The K/Rb ratio is higher whereas the

K/Ba ratio is lower than the SCIC.

The chondrite normalised REE pattern shows moderate enrichment of LREE

relative to HREE (Figure 5.30) with a (La/Yb)n value of 4.93. It has a small negative

europium anomaly and a flat medium- to heavy-REE pattern. Compared to the SCIC,

the average upper crustal and the average granulite compositions, the foliated

granodiorite has higher MREE and HREE abundances. Its REE pattern and

enrichments are very similar to the North America Shale Composite or NASC

(Gromet et al., 1984).

Relative to the NASC, the foliated granodiorite is slightly depleted in LIL

and has very similar HFS elements, MREE and HREE abundances (Figure 5.31). It

has higher trace element abundances than the average upper crustal composition of

Taylor & McLennan (1985) and a diorite sample from the Mount Mucki Diorite.

ISOTOPE CHEMISTRY

Radiogenic isotope (Sm/Nd and Rb/Sr) and stable isotope (δO and δD)

chemistries of rock and mineral samples from the SCIC are tabulated in Table 5.3.

The Rb/Sr, Sm/Nd and 18O/16O isotopic compositions are for whole rock samples, and

the hydrogen-deuterium isotopes are for biotite and hornblende separates.

Radiogenic isotopes

Rb/Sr radiometrics

The 87Rb/86Sr and 87Sr/86Sr data of the SCIC defines a good-fitting

(correlation coefficient of 0.99950) whole-rock isochron of 246 + 7 Ma and an overall

initial 87Sr/86Sr isotopic ratio of 0.70326 + 0.00018 (Figure 5.32), based on the

assumption that the various plutons belong to a cogenetic suite. The range of initial 87Sr/86Sr ratios (87Sr/86Srinitial) for the igneous complex is 0.70312 to 0.70391 +

0.000006. The 87Sr/86Srinitial increases from the Mount Mucki Diorite (0.70312),

Woonga Granodiorite (0.70318), Gibraltar Quartz Monzodiorite (0.70317-0.70325),

Woolooga Granodiorite (0.70353-0.70391), to the Rush Creek Granodiorite (0.70366-

0.70387).

C

hapter5: Geochem

istry

137


138

Figure 5.32: Rb-Sr data of whole-rock samples from the SCIC, foliated granodiorite, Black Snake Porphyry and Neara Volcanics. A regression line for the SCIC (i.e. Rb-Sr whole-rock isochron) yields a isotopic magmatic age of 246 7 Ma and an initial Sr/ Sr ratio of 0.70326 for the igneous suite.

+8 7 8 6

0.7000

0.7050

0.7100

0.7150

0.7200

87

86

Sr/

Sr

0 1 2 3 4 58 7 8 6

Rb/ Sr

Plutonic-rock isochron age: 246 7 Ma (2 )Initial ratio: 0.70326 0.00018

++

σ(2 )

Correlation coefficient: 0.99950σ

Neara Volcanics

Mount Mucki Diorite

Gibraltar Qtz MonzodioriteRush Creek GranodioriteWoolooga Granodiorite


SCIC

Other units

Woonga Granodiorite

Symbols


Figure 5.33: Nd/ Nd versus Sm/ Nd data for whole-rock samples from the SCIC, the Black Snake Porphyry, the Neara Volcanics and the foliated granodiorite.

1 4 3 1 4 4 1 4 7 1 4 4

The poor regression line for the SCIC ( Nd/ Nd - Sm/ Nd isochron) calculated an age of 543 11 Ma and an initial Nd/ Nd ratio of 0.512317.

1 4 3 1 4 4 1 4 7 1 4 4

1 4 3 1 4 4

+

0 0.05 0.10 0.151 4 7 1 4 4

Sm/ N

14

31

44

Nd/

Nd

Isochron age: 543 11 MaInitial ratio: 0.512317 0.0001Correlation coefficient: 0.79589

++

Neara Volcanics

Mount Mucki Diorite

Gibraltar Qtz MonzodioriteRush Creek GranodioriteWoolooga Granodiorite


SCIC

Other units

Woonga Granodiorite

Symbols



139

The Rb/Sr data of the Triassic Neara Volcanics and foliated granodiorite do

not plot on the SCIC isochron. The Neara Volcanics has lower 87Sr/86Srinitial (0.70152

+ 0.00005) than the SCIC whereas the foliated granodiorite has a higher ratio

(0.70534 + 0.00004). A satelite porphyritic intrusion to the SCIC- the Black Snake

Porphyry (0.70341 + 0.000006) has similar initial Sr ratio to the SCIC and plots on

the SCIC isochron.

Sm/Nd radiometrics

The Sm/Nd radiometrics of the SCIC define a poor isochron (correlation

coefficient= 0.79589) of 534 + 11 Ma and an initial 143Nd/144Nd ratio of 0.512317 +

0.0001 (Figure 5.33). The 143Nd/144Nd values of the SCIC are relatively consistent

(0.51270-0.51285), but vary in their 147Sm/144Nd ratios (0.10295-0.14082). The

calculated initial 143Nd/144Nd ratios (143Nd/144Ndinitial) for individual plutons of the

SCIC range from 0.51252 to 0.51266 + 0.00001.

The Sm/Nd data of the Black Snake Porphyry and the Neara Volcanics plot

within the error range of the SCIC isochron. The calculated 143Nd/144Ndinitial of the

Black Snake Porphyry (0.51250 + 0.000007) and the Neara Volcanics (0.51253 +

0.000009) are similar to the SCIC. A foliated granodiorite sample plots outside the

SCIC isochron and has lower 143Nd/144Ndinitial of 0.51230 + 0.000008.

The depleted mantle model ages (TDM) for the SCIC range from 615 to 768

Ma (Table 5.3), and its mean is 695 + 55 Ma (1σ). For uncontaminated magma, model

ages estimate the time when the magma or its source separated from the mantle. The

model ages of the Black Snake Porphyry (TDM =737 Ma) and the Neara Volcanics

(TDM =776 Ma) are similar to the SCIC, whereas the model age of the foliated

granodiorite (TDM =1,222 Ma) is significant older.

The Sm/Nd and Rb/Sr systematics

Initial 143Nd/144Nd and 87Sr/86Sr ratios recalculated to the isochron age of the

SCIC (246 Ma or T246) facilitate better isotopic comparisons at the time of formation.

The initial Nd ratios of the SCIC, the Black Snake Porphyry and the Neara Volcanics

are elevated with respect to CHUR246 (chondrite uniform reservoir at 246 Ma;


140

recalculated from Goldstein et al., 1984) and are positive εNd246. Their initial 87Sr/86Sr

ratios of the SCIC are less than T246 (bulk earth values at 246 Ma) and are negative

εSr246. The foliated granodiorite has negative εNd246 and positive εSr246 (i.e. lower

initial Sm/Nd than CHUR246 and higher initial Rb/Sr than T246).

The Nd and Sr initial ratios for plutons of the SCIC defined a curvilinear

domain (Figure 5.34) between fields of depleted mantle (DM246) and the upper crustal

isotopic domain of DePaolo & Wasserburg (1979). The more silicic samples in

Woolooga Granodiorite, Rush Creek Granodiorite and the Gibraltar Quartz

Monzodiorite have less radiogenic Sr and more radiogenic Nd ratios. The Black

Snake Porphyry has similar initial ratio to the SCIC and the foliated granodiorite plots

within the upper crustal isotopic domain. The Neara Volcanics has Nd and Sr initial

ratios that plot outside the mantle-array domain and proximal to the HIMU mantle

isotopic reservoirs of Zindler & Hart (1986).

STABLE ISOTOPES

Background

The oxygen (18O/16O) and deuterium-hydrogen (D/H) isotopic ratios

characterise rock types, source regions and formation waters (O’Niel et al., 1977;

Kyser, 1986; Woodland et al., 1993). Igneous rocks inherit the 18O/16O and D/H ratios

from their source region, but the ratios can subject to modifications by atmospheric

and hydrospheric processes (Taylor, 1978a). The isotope compositions are expressed

as ratios (δ notations) to standard mean ocean water (SMOW) 18O/16O and D/H

standards according to the following equations:

δ18O = 1000 x (18O/16Osample - 18O/16Ostandard) per mille (‰), and 18O/16Ostandard δD = 1000 x (D/Hsample - D/Hstandard) per mille (‰). D/Hstandard

Standard mean ocean water (SMOW) has δ18O and δD of zero.

Oxygen Isotopes

The Woonga Granodiorite, Rush Creek Granodiorite and Mount Mucki


141

Diorite have similar and overlapping δ18O (from +7.3 to +8.7‰) that are greater than

the mantle values (+5.5 to +6‰; James, 1981) (Figure 5.35). The δ18O values of the

Rush Creek Granodiorite increase with corresponding increases in whole-rock SiO2.

The δ18O values of the Woolooga Granodiorite (+2.5 to +4.3‰) and the Gibraltar

Quartz Monzodiorite (+0.4‰) are between the mantle and SMOW range. The low

δ18O value of the Gibraltar Quartz Monzodiorite is associated with subsolidus

alteration.

Selected country rocks to the SCIC have relatively low δ18O values below the

range for mantle. The δ18O of the Neara Volcanics is -0.8 to +0.2‰, trachybasalt of

the Highbury Volcanics is +4.6‰ and the Mount Mia Serpentinite is +5.4‰. Previous

work by Golding et al. (1987) reported δ18O values of +6.3 to 12.6‰ in greenstone

from the Kilkivan district. The δ18O of the Palaeozoic country rocks are within the

range for metamorphic waters.

Ore deposits in the Kilkivan region have similar oxygen isotopic ratios to their

host-formations. The δ18O of quartz separates from the Mount Victor vein (δ18O=

10.3‰) and the Shamrock ore deposit (δ18O= 12.9‰) lies within the isotopic range

for their greenstone and serpentine host (5.4-12.9‰). Quartz veins within the

Greenrock mine intruded the silicified and pyritised Neara Volcanics. The δ18O value

of quartz from the ore zone (δ18O= +2.8‰) lies between ratios for the Neara

Volcanics (-0.8 to +0.2‰) and Woolooga Granodiorite (+2.5 to +4.3‰). The Yorkeys

stibnite-calcite-quartz vein has slightly lower δ18O value (δ18O= +4.4‰) than the host

diorite rock (δ18O= +5.5‰). Quartz-cinnabar veins (from Kilkivan Mine) in epiclastic

volcanics to the west of Kilkivan have high δ18O values (+20.3‰) and there is no

isotopic information on the host rocks.

The overall δ18O range of the SCIC (+0.4 to +8.7 ‰) falls within the δ18O

range for I-type (mantle-derived or predominantly igneous source) granite (δ18O <9.0)

(Chappell & White, 1992). The Woonga Granodiorite, Rush Creek Granodiorite and

Mount Mucki Diorite have similar δ18O values to the orogenic Cordilleran gabbro to

granite range (+6 to +9‰) (Taylor, 1979).


142

Hydrogen-oxygen isotopic systems

The δD (biotite and hornblende) and δ18O (whole-rock) of the SCIC and

selected porphyritic bodies plot outside the fields for primary magmatic water and

igneous biotites and hornblende (Figure 5.36). The stable isotopes data are skewed

towards lower δD compared to the primary magmatic values. Ohmoto (1986) and

Taylor (1979) justify the δD isotopic departures from the primary magmatic-water to

post-crystallisation isotopic exchange between rock and heated meteoric water, and to

the possibility that the low δD are inherent characteristics of the magma themselves.

The data for the Woolooga Granodiorite and Gibraltar Quartz Monzodiorite plot close

to the mixing line between meteoric and hydrothermal waters, which are typical of the

results from hydrothermal alteration (Criss & Taylor, 1986).

Ore bodies (e.g. the Shamrock and Yorkeys deposits) around the SCIC have

different δD and δ18O values to the igneous complex, but have similar isotopic

signatures of the host formation. A quartz separate from the Shamrock mine plots

within the isotopic fields for metasediments, which is similar to the δ18O of the host

greenstone. Quartz from the Yorkeys mine plots within the field for igneous biotite

and hornblende, similar to the values expected for the host Yorkeys Diorite (δ18O=

+5.5 o/oo).


143

Figure 5.34: Initial Nd/ Nd versus Sr/ Sr ratios recalculated to 246 Ma (. The domain for depleted

mantle at 246 Ma was calculated from present day Sm/Nd and Rb/Sr data ( Nd/ Nd = 0.51317-0.51330,

and 0.51315 and 0.222 ( .

values are from Goldstein . (1984) and Peucat . ( 1988).

1 4 3 1 4 4 8 7 8 6

1 4 3 1 4 4o o

o

et al et al

Rb-Sr isochron age for the SCIC) T246 is the bulk earth Sr-Nd ratios at 246 Ma.

Sm/ Nd = 0.233-0.251, Rb/ Sr = 0.024-0.0007, Sr/ Sr = 0.70265-0.70216 (Allegre ., 1983); Nd/ Nd = Sm/ Nd = Peucat ., 1988) BSE is the present day bulk silicate earth

isotopic reservoir (Zindler and Hart, 1986) and its isotopic Taylor & McLennan (1985),

1 4 7 1 4 4 8 7 8 6

8 7 8 6 1 4 3 1 4 4

1 4 7 1 4 4

o o

o o

o

et alet al

εNd(246)

0.702 0.703 0.704 0.705 0.706 0.707

0

+ N

dε

(246

)

0

- Srε (246) + Srε (246)0

Common domain of initial ratios for the SCIC plutons

Depleted Mantle at 246 Ma

Present-daybulk silicateearth

T246

BSE

_

0.51232

0.70

420

DM

Upper crust

Figure 5.35: The O isotopic values of the Station Creek Igneous Complex, associated volcanic and country rocks and mineralisation. Horizontal bars show the

antle values (Ohmoto, 1986); I- and S-type granite values (Chappell & White, 1992); (1) greenstones of northern NEO (Goldings ., 1987); (2) orogenic gabbro to granite (Taylor, 1979); (3) MORB (Javoy, 1977); (4) shale.

δ1 8

et al

δ1 8

O ranges. Plotted for comparisons are m

Comparison

WORKINGS:

ST

ATIO

N C

RE

EKIG

NEO

US

CO

MP

LEX

Mount Mucki Diorite

MA

NTL

E R

AN

GE


144

Figure 5.36: Plot of D versus O for plutons of the SCIC and proximal intrusions (the Black Snake Porphyry and Yorkeys Diorite). The

adjacent to the SCIC. Fields of magmatic, sedimentary and metamorphic waters are from Taylor (1978b) and

δ δ1 8

δδ

δ δ

1 8

1 8

O compositions are whole rock values and D compositions are water of crystallisation from biotite (black) and hornblende (grey). Also plotted are the D and O compositions of quartz veins from mineralised zones

Kerrich (1989); meteoric-hydrothermal and meteoric-epithermal trends from Criss & Taylor (1986).

LEGEND



Woonga Granodiorite

Mount Mucki Diorite

Yorkeys Diorite


MINERALISED ZONE

Yorkeys low quartz

Shamrock low quartz

δ1 8

O

-180

-160

-140

-120

-100

-80

-60

-40

-20

020

Metamorphic waters

Meteor

ic W

ater L

ine

OceanWaters

Primary magmaticwaters

δ DSedimentary waters

Meteoric-hydrothermal alteration

Meteoric-epithermalalteration

SMOW

Fields of igneous biotite and hornblende

Chapter 6: Discussion

145

CHAPTER 6: DISCUSSION

This chapter discusses the petrogenesis of the SCIC, which includes the

examination of tectonic environments, intrusive timing, crystallisation and

emplacement conditions, magmatic differentiation and geochemical modelling. The

youngest, high-level magmatic processes (intraplutonic) and emplacement conditions

are examined first, and these established assumptions are then applied to older

processes (interplutonic variation), in order to determine the parental magma and

source region.

A geochemical comparison with the contemporaneous Neara and North Arm

Volcanics attempts to establish the origin of the volcanic series, either as co-magmatic

suites to the SCIC or derived from a different source region.

THE PETROGENESIS OF THE SCIC

Tectonic environments

Geochemical signatures

The geochemical signatures of the SCIC are typical of arc-type magmas. On

the MORB-normalized spider diagram, the SCIC patterns have characteristic Ba, Nb,

Ta and Ti troughs coupled with Rb and Th peaks (Figure 5.16). The Nb, Ta and Ti

depletions are typical of island-arc basalts and subduction-related rocks (McCulloch &

Gamble, 1991; Pearce, 1983; Wilson, 1989). The Nb and Ta troughs are due to their

immobility in the presence of fluids within a subduction zone, and possibly as

inherently low concentration melts from the partially depleted mantle wedge

(McCulloch & Gamble, 1991).

The Mount Mucki Diorite-Gibraltar Quartz Monzodiorite (MMD-GQM)

group has similar immobile-element (Ta to Yb) abundances to MORB, but has

elevated mobile element contents (Figure 5.16). The transitional tholeiitic composition

suggests that the magma may be generated either from partial melting a depleted

asthenospheric mantle with minor involvements of subduction slab-derived material

(Perfit et al., 1980a; Arculus & Johnson, 1981; Gill, 1981), or from high degrees of

partial melting mafic crustal source (e.g. Rapp et al. 1991; Holloway & Burnham

1972).


146

The geochemistry of the Woolooga-Rush Creek Granodiorites (W-RC) group

is calc-alkalic and its composition matches the average upper crustal composition

(except for lower Nb and Ta abundances). The possible source environments for the

monzodiorite to monzogranite compositions are from fractionating an enriched mantle-

sourced magma, partial melts from a pre-existing diorite, or low degrees of partial

melting from a basaltic infracrustal source (Bagby et. al., 1981).

Tectonic classification

The trace element geochemistry of the SCIC plots within the volcanic-arc

granite field using the Rb versus (Nb+Y) discrimination diagram (Figure 6.1A; Pearce

et. al., 1984). The volcanic-arc granite classification supports both geochemical

(medium- to high-K, calc-alkalic) and petrological evidences (e.g. geothermometry,

geobarometry discussed in the subsequent section) that the SCIC was emplaced within

a subduction-related continental arc setting. Its chemistry is similar to granitoids

derived from partial melting of mantle or crustal underplated source e.g. the I- and M-

type granite of the Coastal Batholith (Atherton et al., 1979; Pitcher et al., 1985) and

Andean Southern Volcanic Zone (McCourt, 1981; Thorpe et al., 1984), and granitoids

from the NEO (Bryant et al., 1997; Blevin & Chappell, 1996; Kwiecien, 1997).

On the R1-R2 diagram (Figure 6.1B), the SCIC data plot primarily within the

‘pre-plate collision and post-collision uplift’ fields (Batchelor & Bowden, 1985),

hinting a close association with subduction related magmatism. The SCIC overlaps the

domains of Andean cordilleran and NEO continental arc granites. The Mount Mucki

Diorite overlaps the domains of I- and M-types magmas of the Southern Volcanic

Zone that is derived from partial melting of upper-mantle source (Hickey et al. 1986).

On the Pearce & Cann (1973) basalt discrimination diagram (Figure 6.1C),

the Woolooga and Station Creek Granodiorites plot within the calc-alkaline field

overlapping the domains of the Coastal Batholith and NEO continental arc granites.

The Mount Mucki Diorite plots within the low-K tholeiite field, whereas the Gibraltar

Quartz Monzodiorite and Woonga Granodiorite plot along the boundary between the

low-K tholeiite and calc-alkaline basalt fields. On the Meschede (1986) Nb-Zr-Y

basalt discrimination diagram designed to differentiate between mid-ocean ridge

basalts (MORB) and continental tholeiites, the SCIC plots primarily within the

volcanic arc basalt field with continental affinity.


147

W PA

W P B

P -M O R B

VA B + N -M O R BW P T

VA B

D. Meschede (1986) discrimination diagram for mid -ocean ridges basalt (MORB) and

continental basalts

WPA = Within plate alkali basalt WPB = Within plate alkali basalt + tholeiite WPT = Within plate tholeiite

P-MORB = Plume type MORB N-MORB = Normal type MORB

VAB = Volcanic arc basalt

Mount Mucki Diorite Gibraltar Quartz Monzodiorite Woonga Granodiorite Woolooga Granodiorite Rush Creek Granodiorite

Monsidale Granodiorite I-type, n= 16 (Kiewcien, 1997)

Clarence River Supersuite I-type, n=27 (Bryant ., 1997)

Stanthorpe Granite types I-A type, n=4 (Blevin & Chappell, 1996)

Coastal Batholith (Peru), I-M type, n=18 (Pitcher l., 1985; Atherton ., 1979)

Andean Southern Volcanic Zone, I-M type, n=6, (Thorpe ., 1984; Hickey ., 1986)

et al

et a et al

et al et al

1

2

5

34

67

B. R1 versus R2

Figure 6.1: Granite and tectonic discrimination diagrams for the Station Creek Igneous Complex. A) Rb versus Y + Nb (Pearce ., 1984), B) R1 versus R2 (Batchelor & Bowden, 1985), C) The Zr-Ti-Sr basalt discrimination, and D) the Meschede (1986) Zr-Nb-Y basalt discrimination diagrams. The compositions of the SCIC are compared against continental arc magmas of I-, M- and A-type granites. The SCIC plots primarily within the ‘Volcanic Arc Granite’ and ‘calc-alkaline basalt’ fields, overlapping domains of the I- and M-type granites. On the R1-R2 diagram (B), the SCIC data plot primarily within the ‘pre-plate collision and post-collision uplift’ fields, hinting a close association with subduction related magmatism.

et alPearce & Cann (1973)

A. Rb versus Y+Nb

Syn-collisionGranite Within Plate

Granite

Oceanic Ridge GraniteVolcanic Arc Granite

Pearce ., 1984et al

O c e a n f lo o rb a s a l t L o w -K

th o le i iteC a lc -a lk a lin eb a s a l t

C. Pearce &Cann (1973) basalt discrimination diagram

R2

= 6C

a +

2Mg

+ A

l

2500

2000

1500

1000

500

0R1 = 4Si - 11(Na + K) - 2(Fe + Ti)

0 500 1000 1500 2000 2500 3000


148

The intrusive timing between plutons of the SCIC

The SCIC was emplaced as five discrete plutons (227-237 Ma, Figure 6.2)

during a period of active calc-alkalic magmatism, corresponding to the changeover

from contractional to extensional tectonics (Gust et al., 1996). The geologic

relationships of composite plutons are supported by radiometric ages despite

differences in dating methods and closure temperatures (295oC to 410 + 50oC for

biotite and 530 + 30oC for hornblende; Blanckenburg et al., 1989). The Woonga

Granodiorite (237 Ma) is the oldest intrusion, and its contact with younger plutons is

either not exposed or masked by deep weathering. The largest pluton of the SCIC - the

Woolooga Granodiorite (234 Ma), intruded after the Woonga Granodiorite. The

Woolooga Granodiorite is faulted by NW-NNW sinistral faults prior to the intrusion of

Rush Creek Granodiorite (231-232 Ma). The Rush Creek Granodiorite intruded the

Woolooga Granodiorite, and stitched a NW-trending fault in the Black Snake area. The

contact between the Rush Creek and Woolooga Granodiorite is poorly exposed and

intensively argillised but is clearly demarcated by airborne magnetic survey. The

Mount Mucki Diorite (227 Ma) and Gibraltar Quartz Monzodiorite are

contemporaneous plutons with a net-vein contact between the two units. These Late

Triassic plutons encircle the Woonga Granodiorite and intrude the Woolooga

Granodiorite, causing pervasive argillisation, chloritisation and silicification along

intrusive contacts. The Woonga Granodiorite is pervasively argillised and partially

recrystallised, which is interpreted as results of the thermal overprint.

The SCIC is faulted by sub-parallel ENE sinistral faults after 227 Ma and

intruded by andesitic dykes and monzodiorite stocks. A Jurassic quartz monzodiorite

(193 Ma) intruded the Woolooga Granodiorite and Gibraltar Quartz Monzodiorite in

the Gibraltar Rock area, creating a 5 km wide alteration halo around the Jurassic

intrusion.

Crystallisation and emplacement constraints

Depth of emplacement and geobarometry

Determination of the depth of emplacement depends upon the interpretation

of the local burial metamorphism, igneous textures and geobarometry of different

mineral phases. The SCIC intrudes the Neara Volcanics and the Highbury Volcanics,


149

Figure 6.2: The geologic reconstruction of intrusive history of the Station Creek Igneous Complex. Faults were by the ages of host unit and stitching ages of pluton. A) The Woonga Granodiorite intruded the Gympie Group units and Neara Volcanics at 237 Ma. B) The Woolooga Granodiorite intruded at 234 Ma. C) By 231 Ma, earlier intrusions were faulted by NW-NNW sinistral faults, followed by the intrusion of the Rush Creek Granodiorite and Black Snake Porphyry. D) The

constrained

Mount Mucki Diorite and Gibraltar Quartz Monzodiorite intruded at 227 Ma (net-veining along their contact). NW trending andesite and rhyolite dykes and the Boogooramunya Granite (214-226 Ma) were emplaced. E) The Station Creek Igneous Complex was faulted by sub-parallel ENE sinistral faults after 227 Ma and intruded by monzodiorite stocks. A Jurassic intrusion (193 Ma) in the Gibraltar Rock region caused intense alteration and disseminated pyritisation ( chalcopyrite). Faults after 193 Ma are along N-S to NNW directions, and reactivated NW-NNW faults with sinistral movements.

+

26 15’So

26 00’So

152

30’E

o

152

15’E

o

152

15’E

o

5 k m

237 M a

WoongaGranodiorite

Rga

A

152

15’E

o

5 k m

R b

234 M a


North

South

Rgw

Rgw

Rga

B

26 15’So

26 00’So

152

15’E

o

5 k m

R g

231 M a


BlackSnakePorphyry

NeureumMountPorphyry

Rgs

Rgw

Rgw

Rga

C

26 15’So

2 6 0 0 ’ So 2 6 0 0 ’ S

o

152

30’E

o152

15’E

o1

52

15

’Eo

5 k m

R b

R g

227 M a

MountMuckiDiorite


Rga

Rgw

Rgw

Rgs

Rgmm

Rggg

Net-veined complex

D

B o o g o o r a m u n y a G r a n ite

26 15’So

152

15’E

o

Jurassic stocks

Radiometric ages+

+

+

1. Woonga Granodiorite (237 0.4 Ma Ar/Ar biotite, this research)2. Woolooga Granodiorite (234 0.4 Ma, Ar/Ar biotite, this research) 3. Black Snake Porphyry (233 Ma K/Ar biotite, Herbert, 1983)4. Rush Creek Granodiorite (232 0.3Ma, Ar/Ar biotite, this research; 231+7Ma K/Ar biotite, Brooks ., 1974)et al5. Mt Mucki Diorite (210 21 Ma K/Ar hornblende, this research; 227 Ma K/Ar biotite, Webb and McDougall, 1967)6. Boogooramunya Granite (214-226 Ma, Kr/Ar biotite, Cranfield & Murray, 1989a & b)7. Jurassic intrusive of Gibraltar Rock area (193 5 Ma K/Ar hornblende, this research)

+

+

Jura

ssic

Mid

-Lat

e T

riass

ic

Porphyritic intrusives

Porphyritic granodiorite and quartz monzodiorite

Hornblende-plagioclase quartz monzodiorite, granodiorite and monzonite

LEGEND

Dev

-C

arb

Perm

?Ea

rly

Tria

s.

Pre-intrusive basement (interpreted based on the present-day outcrops and/or distribution)

Basement rocks

Gympie Group: T hyolite, andesite, basalt and volcanogenic sediment

uffaceous r

Neara Volcanics

Intensely altered zone (The Gibraltar Rock area)

Pluton and unit boundary

FaultInferred fault

Mid

dle

Tria

ssic

Gibraltar Quartz Monzodiorite: Monzodiorite to granodiorite

Woolooga Granodiorite: Quartz monzodiorite to granodiorite

Rush Creek Granodiorite: Granodiorite

Station Creek Igneous ComplexNet-veined complex

Mount Mucki Diorite: Diorite and leucodioriteR gm m

R gg g

R g s

R g w

Woonga Granodiorite: Granodiorite to tonaliteR g a

Lat

e Tr

iass

ic


150

and these host rocks attain to a lower greenschist facies with incipient crystallisation of

pyrophyllite. Pyrophyllite crystallises between 325 and 375oC (Winkler, 1976). The

low P-T metamorphic grade is consistent with post-Middle Permian rocks elsewhere in

the New England Orogen (e.g. Offler & Hand, 1988; Liu et al., 1993; Roberts et al.,

1993; Sliwa et al., 1993b). The 6000 metres maximum thickness of the Neara

Volcanics (including fluvial sediments) (Campbell et al., 1999) constrains the SCIC

emplacement depth to ~6 km or ~1.5 kbar (using 250 bars/km load pressure; Winkler,

1976). The presence of miarolitic cavities in the Woolooga and Rush Creek

Granodiorite suggests a shallow emplacement depth and low confining pressures (<

1.5 kbar; Bodnar et al., 1985). Using the lower greenschist facies as the upper limit to

burial metamorphism and the presence of miarolite as a pressure constraint, the

maximum P-T conditions at the time of intrusion are <375oC and <1.5 kbars (Figure

6.3).

Numerous aluminium-in-hornblende geobarometers have been developed for

plutonic rocks (Hammarstrom & Zen, 1986; Johnson & Rutherford, 1989; Schmidt,

1992; Anderson & Smith, 1995). These geobarometers when applied to the SCIC

plutons resulted in slightly different crystallisation pressures (Table 6.1). The

aluminium-in-hornblende geobarometer of Hammarstrom & Zen (1986) is the

preferred barometer because its empirical equation was developed for an amphibole-

biotite-plagioclase-quartz-orthoclase-sphene-magnetite mineral assemblage, similar to

the SCIC composition.

The Hammarstrom & Zen geobarometry produces pressure estimates that

range from 0.6 to 4.5 kbars (Table 6.2, Figure 6.4). Cores of hornblende in the Mount

Mucki Diorite give higher pressures (1.2 to 4.5 kbars, equivalent to depth of 5 to 17

km) than rims (0.6-1.0 kbars or 2-4 km depths). The different pressures calculated

from hornblende cores are interpreted as the consequence of continuous crystallisation

during the magmatic ascent. The Hammarstrom & Zen geobarometry applied to the

Woolooga Granodiorite yields crystallisation pressures of 0.2 to 3.3 kbars. Hornblende

cores yield pressures of 1.6-3.3 kbars (6-13 km depth) and rims give pressures of 0.2 to

1.3 kbars (0.8 to 5 km depth), again indicating the path of crystallisation.


151

Figure 6.4: The pressures of crystallisation calculated using the aluminium-in-hornblende barometry of Hammarstrom & Zen (1986). No barometer is available for the Gibraltar Quartz Monzodiorite and Woonga Granodiorite, and their

were based on mapping. intrusive

relationships

?

Geobarometry calculated for the rim composition

Geobarometry calculated for the core composition

Lithospheric pressure at the t ime of intrusion ( f rom bur ia l metamorphism)in fer red

Net-vein complex evident of magma mingling

LEGEND

Boundary uncertain

Gibraltar QtzMonzodiorite

(3)

? ?

Pre

ssur

e (K

bar)

Mt. Mucki Diorite

(2)


(4)


(5)

0

1

2

3

4

5

20

?? ?

WoongaGranodiorite

(1)

12

3

4

5

10 Source region for theNeara Volcanics(ABU)

Source region forthe monzodioriteintrusions

Figure 6.3: diagram shows the reaction

curves of kaolinite to pyrophyllite, biotite-in and staurolite-in for pelitic rock. The of magmatic fluids (dashed-grey lines; water, and water +10% NaCl)

show the 'liquid' versus 'liquid+vapour (second boiling)' fields, and the later is associated with miarolitic cavities. (Reaction curves from

ritical curves from Bodnar ., 1985).

critical curves

et al

The interpreted P-T environment for the emplacement of the Station Creek Igneous Complex (shaded area <1.5 Kbar and <375 C). The

Winkler, 1976; facies boundaries from Yardley, 1989; c

o

100 200 300 400 500 600 700 800Temperature ( C)

o

0

0.5

1.0

1.5Pr

essu

re (k

bar)

Kao

+ Q

tzpy

roph

yllit

e

Bio t

ite- in

Stau

rolit

e-in

0

2

4

6Approxim

ate depth (km)

H O critica

l curve

2

10% N

aCl c

ritica

l curv

e

Zeolitefacies

Prehnite-pumpyellitefacies

Liquid and vapour(formation of miarolitic cavities)

Burial pressure inferred from the Neara Volcanics


152

Table 6.1: A comparison of the calculated pressure of crystallisation using the various Al-in-hornblende geobarometers for igneous rocks

SAMPLE Al3+ Hornblende geobarometric pressure (kbar)

NUMBER (per 23 O) Hammarstrom & Zen, 1986

Johnson & Rutherford, 1989

Schmidt, 1992 Anderson & Smith, 1995*

999-1A Core 1.161 1.92 1.45 2.52 2.71

1000-3A Rim 1.664 4.45 3.58 4.91 5.32

215D-1B Rim 1.039 1.31 0.93 1.94 1.96

1166-2A Core 0.883 0.52 0.27 1.19 1.23

788-7A Core 3.843 15.41 12.80 15.28 14.02 * Temperatures by geothermometry of Spencer & Lindsley (1981) & new constants of Anderson & Lindsley, 1985, 1988). Table 6.2: Representative pressure of crystallisation (kbar) calculated using the

aluminium-in-hornblende barometer of Hammarstrom & Zen (1986)

PLUTON SAMPLE EMP DATA Al3+ Pressure REFERENCE (per 23 O) (kbar)

Mt Mucki SC936 936-4A Core 1.676 4.51 Diorite 936-4B Rim 0.984 1.03

SC999 999-1A Core 1.161 1.92 999-1B Rim 1.668 4.47 SC1000 1000-3C Rim 0.898 0.60 1000-3D Core 1.017 1.19 1000-3E Core 1.465 3.45 1000-3A Rim 1.664 4.45 1000-3B Rim 1.656 4.41 1000-4C Core 1.624 4.25

Woolooga SC215D 215D-1A Core 1.087 1.55 Granodiorite 215D-1B Rim 1.039 1.31

215D-6A Core 1.191 2.07 215D-6B Rim 0.960 0.91 215D-6C Core 1.428 3.3 SC588 588-4A Mean 0.7806 0.01 588-5B Rim 0.8271 0.24 SC820 820-6C Rim 0.835 0.28

Rush Creek SC1166 1166-2A Core 0.883 0.52 Granodiorite

Neara SC788 788-7A Core 3.843 15.41 Volcanics 788-7C Rim 3.861 15.50

SC886 886-3A Core 4.238 17.40 886-4A Core 1.145 1.84


153

Table 6.3: Comparison of the temperature of crystallisation calculated using the geothermometers of Blundy & Holland (1990) and Spencer & Lindsley (1981). The temperature in the bracket represents the arithmetic mean.

Pluton Sample Hornblende-plagioclase Blundy & Holland,

Magnetite-ilmenite Spencer &

(1990)1 (oC) Lindsley (1981)2 (oC) Mount Mucki D SC1000 (Cumulates) 699-981 (855) 582-612 (601)

SC1001 (Chilled zone) 520-637 (578) 570 Gibraltar QM SC710 (Chilled zone) 553 553-555 (554)

SC792 (Metamorphosed) 487-561 (524) 714-742 (728) Woolooga Gd SC497 590-593 (592) 617

SC588 667-697(686) 671 SC1101 (Chilled zone) 698 717-758 (737)

Rush Creek Gd SC1166 585-722 (675) NA Stock SC901 746-760 (754) 715 1 Hornblende and plagioclase mineral pairs were used for the geothermometry; barometer of Hammarstrom & Zen (1986) was used to calculate the

pressure of crystallisation required in the Blundy & Holland (1990) thermometer. 2 Coexisting ilmenite and magnetite mineral pairs were used for the geothermometer. Table 6.4: Representative results of magnetite-ilmenite geothermometry and oxygen fugacity

using the thermometer of Spencer & Lindsley (1981) and the new constants of Anderson & Lindsley. (1985).

PLUTON Magnetite Ilmenite Host/ X(ulvosp.) X(ilmenite) Temp. Log fO2 fO2-QFM sample sample association (oC)

Mt Mucki 936-2B 936-2A Matrix 0.003 0.932 506 -19.369 3.73 Diorite 936-2C 936-2A Matrix 0.024 0.932 596 -17.863 1.97

1000-1B 1000-1A Matrix-sphene 0.01 0.855 612 -15.005 4.32 1000-1C 1000-1E Matrix 0.014 0.921 582 -17.523 2.76 Gibraltar 710-3B 710-2B Matrix-sphene 0.016 0.947 555 -19.591 1.65 Qtz. Mon. 710-4A 710-4C Matrix-sphene 0.099 0.976 553 -23.206 -1.89

792-2 792-2C1 Matrix 0.059 0.769 742 -12.598 3.2 794-1E 794-1E Matrix-sphene 0.059 0.85 712 -13.768 2.75

Woolooga 328-1L 328-1K Biotite 0.081 0.953 617 -19.041 0.13 Granodio 328-1I 328-1H Hornb.-sphene 0.112 0.953 630 -18.847 -0.09

382-2A 328-1K Matrix-sphene 0.02 0.953 553 -20.15 1.16 494-1E 494-1F Hornblende 0.061 0.875 700 -14.379 2.46 582-2E 582-2D Matrix 0.041 0.896 660 -15.418 2.48 588-5H 588-5D Hornblende 0.179 0.666 857 -10.93 2.41 588-6D 588-1D Matrix 0.101 0.929 671 -16.616 0.97 1069-4E 1069-4D Matrix 0.068 0.93 650 -16.97 1.22 1069-5E 1069-4D Matrix-sphene 0.084 0.93 661 -16.806 1.07 1101-2C 1101-3D Matrix 0.12 0.852 758 -13.275 2.14 1101-3D2 1101-3D Matrix 0.065 0.852 717 -13.734 2.65

Rush 1144-4A 1144-3E Matrix 0.017 0.912 600 -16.816 2.87 Creek 1149-3G 1149-3F Biotite 0.019 0.8 667 -13.621 4.1 Granodio. 1166-4D 1166-4C Hornblende 0.019 0.875 636 -15.165 3.44

1204-5B 1204-5A Matrix 0.156 0.949 655 -18.107 -0.06 1204-9C 1204-9B Matrix 0.177 0.949 661 -18.023 -0.14

Neara 725-3D 725-3C Matrix 0.084 0.888 709 -14.589 2.02 Volcanics 725-6A 725-3C Matrix 0.103 0.888 722 -14.425 1.85

N. Arm 1030-4A 1030-4B Matrix 0.02 0.876 636 -15.175 3.42 Volcanics 1030-4C 1030-4B Matrix 0.086 0.876 722 -14.14 2.13 1. Mineral stoichiometry based on the assumptions: 6 oxygens and 4 cations for ilmenite; 32 oxygens and 24 cations for magnetite. 2. Geothermometry of Spencer & Lindsley (1981) using the new constants of Anderson & Lindsley. (1985). Calculation by GPP program. 3. Matrix refers to the finer grained, intercumulate or intercrystals minerals formed late in the crystallisation sequence. 4. Abbreviations: Hornb. = hornblende, apa. = apatite


154

Geothermometry and temperature of crystallisation

Hornblende-plagioclase and magnetite-ilmenite geothermometry and oxygen

fugacities

Geothermometers for the SCIC are limited to the magnetite-ilmenite (Spencer

& Lindsley, 1981) and the hornblende-plagioclase geothermometers (Blundy &

Holland, 1990). The magnetite-ilmenite geothermometer based on the ulvospinel and

ilmenite contents in a co-existing magnetite and ilmenite pair, is sensitive to

temperature and oxygen fugacity (fO2). The hornblende-plagioclase geothermometer is

pressure dependent (the Hammarstrom & Zen geobarometer is used to constraint the

pressure). Calculated temperatures using the two geothermometers are relatively

similar temperatures (Table 6.3, + 40oC) (except for the Mount Mucki Diorite).

The crystallisation temperatures for the Mount Mucki Diorite, Gibraltar

Quartz Monzodiorite and Woolooga Granodiorite are 981-700oC (hornblende-

plagioclase geothermometer), 742-712oC and 758-~670oC (ilmenite-magnetite

geothermometer) respectively (Table 6.3 & 6.4). Coexisting ilmenite-magnetite pairs

enclosed within hornblende of the Woolooga Granodiorite yield temperatures of 857-

700oC, which suggested higher magmatic temperatures before hornblende

crystallisation. The Rush Creek Granodiorite has 600-667oC crystallisation

temperatures (ilmenite-magnetite geothermometer). The temperature-estimates

correlate strongly with bulk composition, where higher temperatures are associated

with monzogabbro to quartz monzodiorite and lower temperatures occur in

granodiorite to monzogranites. The 500-670oC temperature of the interstitial

mineralogy (quartz-orthoclase-plagioclase + biotite, hornblende) calculated using the

Spencer & Lindsley geothermometer, has re-equilibrated to submagmatic conditions

(Tuttle & Bowen, 1958; Ebadi & Johannes, 1991). The subsolidus temperature is

supported by orthoclase exsolution, which occurs between 660 and 500oC (Tuttle &

Bowen, 1958). Re-equilibration temperatures may reach as low as 550-400oC at high

water contents (Buddington & Lindsley, 1964).

All plutons of the SCIC have undergone varying degrees of deuteric alteration

during the late stages of crystallisation and in the subsolidus stage. A temperature

versus fO2 plot for the SCIC shows that the magma crystallised from magmatic

conditions to the subsolidus at fO2 equivalent to the QFM (quartz-fayalite-magnetite)

to HM (haematite-magnetite) oxygen buffers (Figure 6.5). Such redox state reflects


155

Figure 6.6: The variation of P O versus SiO the Station Creek Igneous Complex. The variation trends of the Rush Creek Granodiorite, Woolooga Granodiorite, the Woonga Granodiorite overlap the domain of the Andean Coastal Batholith. The

overlaps the mantle-derived Monsidale Granodiorite, whereas the Gibraltar Quartz Monzodiorite plots

The field for Andean Coastal Batholith is adapted from Bea . (1992); data for Monsidale and Mungore from Kwiecien (1996) and Stephens (1991) respectively. (I

2 5 2

et al

contents in

Mount Muck Diorite P O saturation P O below the

850 C isotherm.

sotherms of Harrison & Watson, 1984)

2 5

2 5 o

PO

(wei

ght %

)2

5

0

0.2

0.4

0.6

45 50 55 60 65 70 75 80SiO (weight %)

2




Woonga Granodiorite

Mount Mucki Diorite

Porphyritic stocks

Monsidale (south)

Mungore granites

Andean Coastal Batholith

SYMBOLS

Station Creek Igneous Complex

Figure 6.5: Plot of Log O versus temperature for co-existing magnetite-ilmenite pairs from the Station Creek Igneous Complex and monzodiorite intrusions. The majority of the samples plots between the QFM and haematite-magnetite buffer curves.

f2

Log

O (b

ars)

f2

-10

-12

-14

-16

-18

-20

-22

-24

Temperature ( C)o

500 600 700 800 900

Cu O-Cu2

Fe O -Fe O

2

3

3

4

NiO-Ni

QFMFe O -Fe

3

4

GQMWGRCG

MM

Rush CreekGranodiorite (RCG)

Woolooga Granodiorite (WG)

Gibraltar Quartz Monzodiorite (GQM)

Mount Mucki Diorite (MM)

Legend

Monzodiorite intrusion

Arrow represents the O vs temperaturetrend towards increasing SiO

f2

2

Subsolidus Magmatic


156

more oxidising conditions (Powell, 1978), which is typical of high-level magma

chambers (<20-30 km) (Gill, 1981; Haggerty & Tompkins, 1983). The fO2-QFM

values of the Woolooga Granodiorite (0 to 2.7) overlap that of the Gibraltar Quartz

Monzodiorite (-2 to 2.8), whereas the Rush Creek Granodiorite and the Mount Mucki

Diorite have fO2-QFM values of 3-4 and 2-4 respectively (Table 6.4). The presence of

secondary biotite and epidote supports a relatively oxidising environment, as these

minerals formed within the NNO and HM buffers (Wones, 1966). The decreasing

Fe/(Fe+Mg) cationic ratio from magmatic to secondary biotite reflects an increasing

oxidation condition (Czamanske & Wones, 1973). Secondary epidote (Ps26-31)

crystallises in the interstices of the SCIC. Epidote forms under oxidising condition

close to the HM fO2 buffer (Eugster & Wones, 1962; Czamanske & Wones, 1973;

Liou, 1973; Wones, 1981), and is unstable at fO2 below the QFM (Liou, 1973).

Pyrophanite and brookite substitutions in ilmenite of the Gibraltar Quartz

Monzodiorite suggest hydrothermal alteration (Deer et al., 1992) under oxidising

conditions (Czamanske & Mihalik, 1972; Frost & Lindsley, 1991).

Geothermometry based on P2O5 solubility

Apatite solubility in hydrous Ca-bearing granite depends strongly on

temperature and SiO2 contents (Watson, 1979), and Al2O3 (Bea et al., 1992). The

solubility relationship is expressed mathematically as a crude geothermometer over the

850 to 1500oC temperature range (Harrison & Watson (1984), subsequently refined by

Bea et al. (1992) to accommodate the higher apatite solubility in peraluminous

granites).

The Woolooga Granodiorite, Rush Creek Granodiorite, Mount Mucki Diorite

and Woonga Granodiorite have P2O5 contents that correspond to temperatures between

~850oC and 900oC (Figure 6.6). Such crystallisation temperatures are identical to the

high-level, continental-arc granitoids e.g. the Coastal Batholith (850-900oC, Bea et al.,

1992), which is derived from fractionation of mantle-derived magma. The Gibraltar

Quartz Monzodiorite has low P2O5 content that plots outside the range suitable for the

Harrison & Watson geothermometer.

Water content

The water content of the SCIC magmas is estimated from interpretations of its


157

crystallising mineralogy and crystallisation pressure-temperature (P-T). The pressures

and temperatures (calculated from igneous geothermometers and geobarometers)

superimposed on the haplogranite system (Holtz et al., 1992a & 1995, Ebadi &

Johannes, 1991; Whitney, 1988) and andesite-H2O system (Eggler, 1972a,b; Eggler &

Burnham, 1973) allow crude estimation of water activities and specific water contents

(Figure 6.7A-C). Such estimates are only applicable to magmatic conditions (>670oC).

Experimental results of Holtz et al. (1992b, 1993) show that the addition of Al2O3 and

P2O5 has minimal effect on water solubility at low pressures (<2 kbar), whereas the

addition of Fe and Mg induces crystallisation of ferromagnesian minerals (Naney &

Swanson, 1980). The crystallisation of different ferromagnesian minerals reflects

changes in the physiochemical condition of the magma. Pyroxene forms at high

temperatures of >780 to 850oC (Rutherford et al., 1985; Clemens & Walls, 1988;

Puziewics & Johannes, 1988; Rushmer, 1991) and under low water activity (Clemens

& Walls, 1988). Amphibole crystallises under magmatic conditions with 2.2-4 wt %

H2O (Eggler, 1972b; Naney, 1983) and biotite crystallises with 2-4 wt % H2O

(Clemens & Wall, 1981; Whitney, 1988; Scaillet et al., 1995).

Liquidus pyroxene is present in all plutons of the SCIC. The pyroxene is

mantled by magmatic hornblende, and biotite is a late mafic mineral that crystallises

around both hornblende and pyroxene. The mineralogical change from pyroxene to

biotite demonstrates increase water activities in magma (Tuttle & Bowen, 1958) from

a water under-saturated condition (early-stage of crystallisation) to 2-4 wt % H2O

(late-stage crystallisation) (Whitney, 1988). The stabilisation of early-formed

tschermakitic hornblende at 4.5 kbar and 981oC in the Mount Mucki Diorite suggests

that the magma attain the water activity for amphibole crystallisation early in its

magmatic history. Amphibole crystallises continuously from high a P-T field to the

subsolidus, suggesting relatively high water content during crystallisation (Figure 6.7).

The Woolooga Granodiorite and Rush Creek Granodiorite crystallise hornblende close

to the P-T fields of water-saturated solidi of both the haplogranite and the andesite

systems (Figure 6.7). These plutons are interpreted as drier magmas than the Mount

Mucki Diorite, reaching the water activities for hornblende crystallisation late in their

magmatic histories. Their relatively lower water content (>2-4 wt %) and high water


158

Figure 6.7A. Solidus curves at different water activities

Temperature ( C)o

Pres

sure

(kba

r)

500 600 700 800 900 10000

1

2

3

4

5

6

Dry

sol

idus

Wat

er s

atur

ated

sol

idus

aH2O0.10.20.30.40.50.60.70.81.0

QKfAn

Q + 2Af + HO

2

Q + Af + HO

2

L

60

An100

RE-EQUILIBRATED

Figure 6.7B. Liquidus curves for minimum melt compositions at specific water contents

500 600 700 800 900 1000Temperature ( C)

o

0

1

2

3

4

5

6

Pres

sure

(kba

r)

2 wt % HO2

4

6

8

10

1 wt %HO

2

2345678910

Dry

sol

idus

Wat

er s

atur

ated

sol

idus

RE-EQUILIBRATED


159

Pre

ssur

e (k

bar)

500 600 700 800 900 1000

Figure 6.7: Crystallization pressures and temperatures of plutons of the Station Creek Igneous Complex. The P-T data are plotted against: ( ) Solidus curves of the system Qz-Ab-Or-H O-CO for given water activities (

( ) L

A

B

2 2Ebadi and Johannes,

1991; Johannes and Holtz, 1996). The bold lines correspond to solidus of haplogranite and haplogranodiorite (An , An ) of the system Q-Ab-Or-An-H O. iquidus curves of the system Q-Ab-Or for minimum liquid/melt compositions and specific water contents. Horizontal dotted lines are water solubility curves (Holtz .,1992a, 1995). ( ) Solidus for andesite-H O system. Also plotted are the amphibole-out reaction curves at various X ,and amphibole+quartz dehydration curves; dash-lines are metastable (Eggler, 1972a).

6 0 1 0 0

2

2

H 2 O

et al Cf l

Temperature ( C)o

Bold crosses and grey-inf il led symbols: Temperatures calculated using ilmenite-magnetite geothermometers of Spencer and Lindsley (1981).

Open symbols and small crosses: Temperatures calculated using plagioclase-hornblende pair (Blundy and Holland, 1990)

LEGEND

Rush Greek Granodiorite



Woonga granodiorite

Mount Mucki Diorite

Porphyritic intrusives

Figure 6.7C: Solidus for the andesite-H O system (Eggler, 1972)2


160

activity (0.4 to 1) at low pressures are consistent with the high-level emplacement of

relatively dry granitic magma, capable of migrating to higher-level before

solidification (Wyllie, 1983; Whitney, 1988; Clemens & Droop, 1998). Increase in

water content during crystallisation in the SCIC is also supported by plagioclase

zonation towards albitic rim. Albite has a high capacity to incorporate water by the

following reactions: NaAlSi3O8 + H2O => HAlSi3O7(OH).NaO (Burnham, 1975) and

NaAlSi3O8 + H2O => AALSi3O8 + Na(OH) (Kohn et al., 1989). The crystallisation of

graphic and myrmekitic quartz, orthoclase and albite in interstices suggest a near-

eutectic point crystallisation (Tuttle & Bowen, 1958) and the presence of an aqueous

phase (Fenn, 1986). Reactions between the late fluid with Fe-oxides and hornblende

crystallise secondary biotite in the interstices (Hibbard, 1995).

A late separation of hydrous phase is evident in the Woolooga and Rush

Creek Granodiorites. The presence of fine- to microcrystalline-perthite and miarolitic

cavities suggests rapid crystallisation related to vapour loss (Sawka et al. 1990; Shelly,

1992). Vesiculation of magma and rapid decompression relative to the confining

lithostatic pressure from the loss of vapour through fractures is typical of shallow

intrusions (Figure 6.3) (Bodnar et al., 1985; Whitney & Stormer, 1986).

Stable-isotopic evidences suggest a subsolidus meteoric-magmatic water

interaction (Figure 5.36) that modifies the δ18O (e.g. δ18O of 2.5-4.3 in the Woolooga

Granodiorite, and 0.4 in the Gibraltar Quartz Monzodiorite). Chloritisation,

uralitisation, argillisation and feldsphatisation are common in all plutons of the SCIC.

Amphibole and biotite alter to chlorite at ~340oC (Eggleton & Banfield, 1985).

Deuteric alteration and coarse perthite crystallisation from fluid-induced K and Na

exchange occurs at temperatures below 400oC (Parsons & Brown, 1984). The

feldsphatisation (i.e. alkali enrichment) indicates submagmatic potassic metasomatism

(Sidle & Barton, 1992) and the accompanied Mn-enrichment in ilmenite suggests an

oxidation environment (Czamanske & Mihalik, 1972).

Geochemical diversity and variation within the SCIC

The SCIC comprises of three geochemical groups: the Woolooga-Rush Creek

Granodiorite group (W-RC), the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite

group (MMD-GQM) and the Woonga Granodiorite group. The Woonga Granodiorite


161

has been established as a partially recrystallised and albitised pluton, locally thermal

overprinted by the Mount Mucki Diorite. Its geochemistry reflects some post-

magmatic modification with losses of incompatible and mobile elements, and gains in

Al2O3 and Na2O. Therefore, the Woonga Granodiorite cannot be regarded as a

“primary” geochemical group for petrogenetic modelling.

Within the W-RC and MMD-GQM groups, the possible processes causing

geochemical variation are fractional crystallisation, partial melting, magma mixing,

restite unmixing and contamination (e.g. Pitcher, 1993). There is no petrographic or

geochemical evidence for either restite unmixing or magma mixing within the SCIC.

All mafic xenoliths are identified as chilled cognate-magma of the host rocks, lacking

the petrographic criteria for restite (e.g. ‘old zircon’, plagioclase with uniform core

compositions, Chappell et al, 1987). There is also no evidence of magma mixing (e.g.

the abrupt composition changes in zoned plagioclase, resorbed crystals and skeletal

growth in ferromagnesians; Helz, 1987; Nixon & Pearce, 1987; Huppert & Sparks,

1988; Haslor, 1989).

Gradational compositional changes within the SCIC plutons are typical of in

situ differentiation by fractional crystallisation process. All mineral phases within the

igneous complex are zoned towards lower temperature rims e.g. labradorite is zoned

towards oligoclase, and augite is sequentially mantled by hornblende and biotite. The

mineralogic change reflects progressive increase in silica, potassium, oxygen activity

(Eugester & Wones, 1962) and water, during the course of crystallisation of magma,

which is consistent with consequences of fractional crystallisation (O’Hara, 1965;

Tuttle & Bowen, 1958).

The geochemical variation within individual pluton or geochemical group

displays coherent trend (Figure 6.8), which can be interpreted in terms of fractional

crystallisation process. The curvilinear inter-element trends (Figure 5.12); variation

trends for Mg#, An# and Or# (Figure 5.10); and REE patterns (Figure 5.13);

demonstrate strong mineralogic controls on the magma chemistry. Mineral-vector

diagrams based on Rayleigh fractionation of olivine (Fo85), clinopyroxene (Wo45En40),

hornblende (Ca2(Mg4Al)(Si7Al)O22(OH)2), plagioclase (An85) and K-feldspar (Ab5),

show that no single mineral is accountable for the gross geochemical change (Figure

6.8). The variation trend for the Mount Mucki Diorite involves the possible

fractionation of olivine, hornblende, pyroxene and anorthite. The geochemical


162

OlCpx

Plag-KspHb

MM-GQM

WOG

RCG-WG

Geochemical variation trends explained by fractionation of major mineral phases.

Woolooga-Rush Creek Granodiorite trend

Hb - Plag Cpx+

Mount Mucki Diorite-GibraltarQuartz Monzodiorite trend

Ol?-Hb-Cpx

Cpx-Hb

Woolooga-Rush Creek Granodiorite trend Mount Mucki Diorite-Gibraltar

Quartz Monzodiorite trend

Ol

PlagCpx

Hb

Ksp

Plag-Ksp accumulation Plag-Ksp

accumulation

Mount Mucki Diorite-GibraltarQuartz Monzodiorite trend

Woolooga-Rush Creek Granodiorite trend

MM-GQM

RCG-WG

WOG

MM-GQM

RCG-WG

RCG-WG

MM-GQM

MM-GQM

WOG

Cpx dominated

Hb-Cpx

Hb - Plag Cpx+

MM-GQMRCG-WG

Geochemical variation trends

Ol Cpx

Plag

Hb

Ksp

Plag

Hb

RCG-WG

Al O -MgO2 3

FeO-MgO

CaO-MgO

0 1 2 3 4 5 6 7MgO wt %

0

5

10

15

CaO

wt %

12

14

16

18

20A

lO w

t %2

3

0

4

16

12

8

FeO

wt %

Figure 6.8:

arrows) represent the geochemical shifts resulted from Rayleigh fractionation of olivine (Fo ), clinopyroxene (Wo En ), hornblende [Ca (Mg Al)(Si Al)O (OH) ], plagioclase (An ) and K-feldspar (Ab ) respectively. The bold arrows represent the generalised variation trends for individual pluton or geochemical group. Geochemical variation of the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group (MM-GQM) resulted mainly from fractionation of hornblende and clinopyroxene olivine?. The geochemical variation of the Woolooga-Rush Creek Granodiorite group resulted from fractionating hornblende, clinopyroxene and plagioclase. Variations within the Woonga Granodiorite is attributed to hornblende fractionation.

8 5 4 5 4 0

2 4 7 2 2 2 8 5 5

+

Inter-element plots comparing the geochemical variations within the Station Creek Igneous Complex to the major fractionating phases (mineral-vector diagram). The mineral vectors ( 10%

Mt Mucki Diorite




Woonga Granodiorite

Ol Olivine

Cpx Clinopyroxene

Plag Plagioclase

Hb HornblendeKsp K-feldspar

MM

GQM

WG

RCG

WOG


163

variation in the Gibraltar Quartz Monzodiorite suggests fractionation of pyroxene,

hornblende and plagioclase. The variation in the Woonga Granodiorite reflects strong

control by hornblende. In the Woolooga-Rush Creek Granodiorite group (RCG-WG),

the geochemical variation is interpreted as results of hornblende, pyroxene and

plagioclase dominated fractionation.

The Woolooga-Rush Greek Granodiorite group (W-RC Group)

The Woolooga-Rush Greek Granodiorite group (W-RC Group) is high-

potassium, calc-alkaline and metaluminous. The gradual compositional change from

quartz monzodiorite to granite is attributed to pyroxene-hornblende-plagioclase

crystallisation (Figure 6.8). The Woolooga Granodiorite has relatively uniform REE

abundances, Pearce element ratio and incompatible element ratios. The uniform

geochemistry suggests limited closed-system magmatic differentiation.

The Rush Creek Granodiorite has higher Th/Ta fractionation indices (Allegre

& Minster, 1978; Bacon, 1992) that reflect a more evolved pluton than the Woolooga

Granodiorite does. Its chondrite-normalised La/Sm and Tb/Yb ratios highlight two

variation trends from granodiorite to monzogranite and from a monzodiorite intrusion

(SC1204) to granodiorite (Figure 5.15). The latter trend hints of magma mixing with

the monzodioritic intrusive, but mapping and petrography discounts a major mixing

event, except the possibility of localised mixing/assimilation at contact. Variation from

granodiorite to monzogranite in the Rush Creek Granodiorite accompanies LREE

increases, increasing Eu anomaly and decreases in both the MREE and HREE. The

greater reduction of MREE (Tb to Er) compared to the HREE (Tm to Lu) is largely

controlled by hornblende fractionation, and the HREE decreases may be caused by

additional clinopyroxene fractionation (Bea, 1996). On the MORB-normalised spider

diagram (Figure 5.16), the enrichment and depletion factors of elements are amplified

with increasing SiO2, which typify fractional crystallisation process that partitioned

compatible elements into the earlier mafic minerals and incompatibles into the melt

fraction. The compatible behaviours of K2O, Na2O, Al2O3, Ba, Sr, Eu, An# and Or#

imply feldspar fractionation (Rollinson, 1993). Fractionation of plagioclase causes

falls in CaO, Na2O, Al2O3, An#, Sr, and increases Eu anomaly, and the removal of K-

feldspar reduces K2O, Na2O, Al2O3, Or#, Sr, Eu and Ba (Hanson, 1978; Bacon, 1992;

Bea, 1996). The inflection of the Ba and K2O trends at 71% SiO2 that coincided with


164

the biotite modal maxima, likely resulted from biotite precipitation in addition to K-

feldspar.

On Harker diagrams, projections of the MgO, CaO, FeO and TiO2 trends

converge at 75-77% SiO2, which approximates the haplogranite composition at

eutectic point. The crystallisation temperatures of granites in the Rush Creek

Granodiorite are 645-720 oC and the presence of perthite (<660 oC; Tuttle & Bowen,

1958) supports near eutectic crystallisation. Melting experiments of Stern & Wyllie

(1973) concluded that the partial melting basaltic rocks (oceanic crust) in a subduction

setting could not generate and segregate primary granite. The monzogranite of the

Rush Creek Granodiorite, therefore, represents the end-stage of fractional

crystallisation.

The Mount Mucki Diorite-Gibraltar Quartz Monzodiorite Group (MMD-GQM Group)

The ‘Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group’ (MMD-

GQM Group) consists of the medium-potassium and tholeiitic Mount Mucki Diorite,

and the high-potassium, transitional calc-alkalic to tholeiitic Gibraltar Quartz

Monzodiorite. The gradual compositional change from monzogabbro to quartz

monzodiorite in the Mount Mucki Diorite is interpreted as result of olivine(?),

orthopyroxene, clinopyroxene, anorthite, and minor hornblende fractionation (Figure

6.8). The Mount Mucki Diorite has low LIL and incompatible elements and has high

HFS, MgO and CaO. The compatible behaviours of Mg#, Fe2O3, MgO, TiO2 and CaO

coincide with decreasing modal percentages of pyroxene, and minor reduction in

hornblende. Modal increase in the plagioclase content is accompanied by similar

increases in the Al2O3, Na2O and K2O contents. Or# remains relatively constant

implying that orthoclase fractionation is minimal in the K-poor rock. The chondrite-

normalised REE pattern is LREE enriched, lacks Eu anomaly and has relatively flat

MREE to HREE. REE behave as incompatibles as expected of basaltic to basaltic

andesite liquids where all REE are incompatible in olivine, orthopyroxene and

clinopyroxene (Rollinson, 1993, p. 139). A lesser increment of MREE relative to

LREE and HREE with increasing SiO2 indicates the stabilisation of hornblende during

crystallisation, which implies conditions of high f(H2O). Sphene is a common

accessory mineral that potentially controls the REE and HFS element distribution

(Bea, 1996). On the MORB-normalised spider diagram, the Mount Mucki Diorite


165

pattern is maintained while the absolute elemental abundances increase with increasing

SiO2, and such increment is attributed to crystal fractionation involving olivine,

clinopyroxene, plagioclase and magnetite (Wilson, 1989, p.210).

The Gibraltar Quartz Monzodiorite has higher LIL, Ba, Sr, REE and SiO2,

which represent a more differentiated pluton than the Mount Mucki Diorite. The

compatible behaviours of Mg#, An#, Fe2O3, MgO, TiO2 and CaO coincide with

decreasing modal percentages of clinopyroxene, hornblende and Fe-Ti oxides.

Increases in Al2O3, Na2O, K2O and Or# coincide with the increases in K-feldspar

contents, and an inflection in the plagioclase modal trend at ~55 wt % SiO2 coincides

with similar inflections for Al2O3, Na2O and CaO. The chondrite-normalised La/Sm

ratio increases while Tb/Yb ratio decreases from monzodiorite to quartz monzodiorite

due to lesser MREE increments relative to LREE and HREE. The lesser MREE

increase can be attributed to the separation of pyroxene and hornblende, and possibly

sphene (Bea, 1996; Rollinson, 1993). The Gibraltar Quartz Monzodiorite composed

predominantly of plagioclase, orthoclase and quartz (totaling 70-90%), which can

account for its high Ba and Sr and lower HFS elements. The MORB-normalised spider

diagram pattern remains almost the same while the absolute elemental abundances

increase with increasing SiO2, suggesting crystal fractionation involving olivine(?),

clinopyroxene, plagioclase and magnetite (Wilson, 1989, p.210).

The Woonga Granodiorite Group

The altered Woonga Granodiorite has lower REE, HFS and transitional group

elements than the other SCIC geochemical groups at equivalent SiO2. Its chondrite-

normalised REE patterns are LREE enriched, lack Eu anomalies and the MREE are

suppressed relative to HREE. The MREE suppression suggests fractionation of

hornblende under conditions of high f(H2O).

Petrogenetic modelling

Geochemical and isotopic studies indicated that the SCIC magmatism is arc-

related and the petrogenesis of subduction-related magma is extremely complicated

(Arculus & Johnson, 1981; Arculus, 1987, 1994; DePaolo et al., 1992; Pearce &


166

Parkison, 1993; Perfit et al., 1980a). Evaluating the origin of the SCIC is an indirect

process. The SCIC plutons have undergone some post-solidus alteration, possible

modification during the upward-migration through crust, as well as high-level

crystallisation that alter the evidence of the magma origin. Modelling is restricted by

the lack of geologic and petrologic evidences to constrain source components and

fractionating phases. Petrogenetic models for the SCIC attempt to explain the origin of

the two distinct geochemical groups, the depleted mantle-like isotopic compositions,

arc-type magmas and association with ancient arc settings. A three-stage reciprocal

modelling procedure is used to determine the composition of the parental magma - the

intraplutonic model, interplutonic model, and partial-melting/fractionation model from

arc-related sources. The youngest intraplutonic model establishes possible magmatic

process(es) (i.e. high-level, close-system fractional crystallisation and assimilation-

fractional crystallisation or AFC) that links the various compositions within a pluton to

the most mafic sample. The derived conclusions from intraplutonic models are then

applied to interplutonic models to determine possible co-genetic link between plutons

(e.g. fractionation and magma mixing), and to identify the least evolved composition

within each geochemical group. It is essential to establish if any of the rock sampled

represents “parental magma(s)” from which the respective group evolve. The

established “parental magma” is compared against modelled-magma produced by

fractional crystallisation, or by partial melting process from arc-related sources. The

geochemical difference between the “parental magma” and the standard source is

attributed to the additional component e.g. crustal contaminants. Mathematical models

calculated using the IGPET program (Appendix 5) test fractional crystallisation, AFC,

mixing and partial melting processes using their different crystal-fluid and crystal-melt

partitioning (Arth, 1976; Allegre et al., 1977; Allegre & Minster, 1978; Hanson 1978;

Perfit et al., 1980a; Pearce & Parkinson, 1993; Bea, 1996). The IGPET program

models both major and trace element geochemistries constrained by the mineral phases

present (core composition of crystals). The partition coefficients or KDs used in the

trace element modelling were selected based on the bulk compositions of the magmatic

systems (KDs for basalt, andesite, dacite and rhyolite; Appendix 5). All petrogenetic

models were based on the high precision geochemical data assayed using the ICP-MS

method, whereas INNA, ICP and XRF acquired geochemistries were used for

qualitative and graphing purposes.


167

Definition of components

The least-evolved magma of the MMD-GQM group and the SCIC

The Mount Mucki Diorite is the most mafic pluton of the SCIC, and a chilled

monzogabbro sample (SC936, SiO2 = 48.0 wt %) at its contact zone has composition

closest to the depleted mantle or N-MORB composition (Sun & McDonough, 1989).

Despite having primitive MORB-like isotopic signatures (87Sr/86Srinitial= 0.70312, εNd

= +4.2), major and trace element and REE chemistries indicate cumulate separation,

fractionation and involvement of subducted-zone and/or supracrustal components

(LaN= 2, YbN= 0.4; MORB-normalised). The medium-potassium, tholeiitic

geochemistry is similar to the high-Al basic magmas from the Alaskan plutons (Perfit

et al., 1980a). SC936 is the least evolved magma in the Mount Mucki Diorite-Gibraltar

Quartz Monzodiorite group as well as in the SCIC, and has been regarded as the

“parental magma” in petrogenetic models.

The least-evolved magma of the Woolooga-Rush Creek group

The most mafic sample of the Woolooga-Rush Creek Granodiorite group is a

quartz monzodiorite (SC1069, SiO2= 60.5 wt %). Major- and trace element chemistries

indicate a relatively evolved magma from the primary magma composition (LaN= 8.2,

YbN= 0.7; MORB-normalised). The high-Al, high-potassium and calc-alkaline

chemistry is similar to continental-arc andesite.

Possible contaminant: supracrustal melts (the foliated granodiorite of the Wratten

Igneous Suite)

The foliated granodiorite of the Wratten Igneous Suite (SC106) is a

significant component in petrogenetic modelling because it represents a composite

partial-melt of supracrustal source(s). The granodiorite is identified as an of S-type

granite derived from partial melting of juvenile supracrustal rocks (Tang & Gust,

2000). Granodiorite melt is generated at temperatures above 900oC (Whitney, 1989),

and such anatectic temperature can melt a variety of crustal rocks to form a composite

rock (e.g. Rushmer, 1991; Beard & Lofgren, 1991; Rapp et al., 1991; Wolf & Wyllie,

1994; Patino Douce & Beard, 1995).

The foliated granodiorite geochemistry is low in K2O, CaO, Al2O3, LIL (K,

Na, Cs, Rb), Th, Ta, U and K/Na ratio, and high in Fe2O3, TiO2 and MnO contents,


168

postulates a low LIL source with little pelite component. It contains less LIL and

Al2O3 than the shale-composite of Gromet et al. (1984) and has higher trace element

abundances than the average upper crustal composition of Taylor & McLennan (1985).

The low initial 87Sr/86Sr (0.70534) compared to values of >0.707 for the typical S-type

granites of the Lachlan Fold Belt (White and Chappell, 1988) deem pelitic

accretionary complex sediment as unlikely protolith for this S-type granite. Chappell

(1978) and Hensel et al. (1985) interpreted similar characteristic granitoids (with initial 87Sr/86Sr ratios between primitive mantle and metasediment) as partial melt of igneous-

characteristic sources e.g. volcanoclastic rocks. The foliated granodiorite has similar

isotopic signatures to the southeast Queensland Palaeozoic metasediments (e.g.

Neranleigh Fernvale beds; Stephens, 1991). The Neranleigh-Fernvale beds are

composed of greywacke, spilitic volcanics with minor shale and chert (Murphy et al.,

1987) that form part of the NNEO accretionary wedge. Partial melts of such juvenile

crustal material would retain low 87Sr/86Sr, LIL, K/Na, Th, U and low Rb/Sr as in the

foliated granodiorite.

Possible sources

Potential source-regions for I-type magma in a continental-margin subduction

setting are from partial melting of upper mantle overlying the subduction lithosphere

(mantle wedge), hydrated basaltic oceanic crust in the subduction plate and from the

lower continental crust above the subducting plate (Wyllie, 1984; Gromet & Silver,

1987; Chappell & Stephens, 1988; Bryant et al., 1997). The likely sources are N-

MORB, enriched-MORB, oceanic crust, lower crust and the primitive mantle that

produce compositions ranging from oceanic-island basalt to island-arc tholeiite and

andesite (compositions tabulated in Appendix 5, p. 67).

Intraplutonic models: Close-system fractional crystallisation (FC) modelling

Least-squares mass-balance calculations (Bryan et al., 1969) establish close-

system fractional crystallisation (Rayleigh fractionation) as the major cause of

geochemical variation within a pluton (Figure 6.9; calculations in Appendix 5). The

close-system fractional crystallisation models link the various compositions within a

pluton to the most mafic sample. Multiple models using various combinations of

parent-daughter pairs calculated similar major element concentrations for the predicted


169

Figure 6.9: Major elements least square modelling within and between plutons of the SCIC (arrow indicates a parent -to-daughter fractionation trend). Samples withi n plutons are arranged vertically with increasing SiO2 content from top to bottom. Accompanying each model is the sum of least squares (R2), the remaining liquid fraction (F), and crystallising phases between the parent to daughter compositions. A good mod el (R 2 < 0.2) is represented by a solid arrow, whereas a poor model (R 2>0.2) is shown as a dashed -arrow. The “geologically infeasible” means that the daughter product cannot be a direct fractionate of the parent. However, the modelling does not discount th e possibility that the daughter product could fractionate from similar composition(s) within the pluton that is not exposed or sampled. (Models calculated by IGPET, 1996).

SC936 (47.98)

SC1129 (67.39)

SC999 (53.53)

SC1204 (55.09) SC710

(56.18)

SC1069 (60.50)

SC1018 (62.44) SC472

(64.20)

SC854 (67.02)

SC1166 (65.65)

SC1185 (71.17)

SC1153 (75.31)

MODEL 13 R2 = 1.032 F = 0.578 - 9.3% opx,

14.7% cpx, 9.6% mgt, 1.9% il, 64.5% plag

MODEL 10 R2 = 0.069 F = 0.691 - 33.3% hb, 1.4 %

bio, 4.8% mgt, 60.5% plag

MODEL 11 R2 = 0.125 F = 0.821 - 15.8% hb, 11.1%

bio, 4.4% mgt, 68.7% plag

MODEL 1 R2 = 0.036 F = 0.496 - 10.5% cpx,

43.0% hb, 9.7% mgt, 35.5% plag, 1.3% sph.

MODEL 2 R2 = 0.164 F = 0.766 - 52.1% cpx,

15.1% mgt, 32.8% plag MODEL 6

R2 = 0.479 F = 0.686 - 9.2% hb, 18.3%

mgt, 6.0% il, 66.5% plag

MODEL 3 R2 = 0.185 F = 0.758 - 9.3% cpx, 19.6% mgt,

5.9% ilm, 65.3% plag

MODEL 8 R2 = 0.076 F = 0.765 - 54.4% hb,

0.2% mgt, 45.5% plag

MODEL 5 R2 = 0.154 F = 0.686 - 14.0% hb, 4.1%

mgt, 3.3% ilm, 44.2% plag, 34.5% K-feld

Mt. Mucki Diorite




Woonga Granodiorite

LEAST-SQUARES MAJOR ELEMENT MODELS

Increase SiO2 (Wt %)

Units

MODEL 4 R2 = 0.190 F = 0.700 - 29.8% hb,

9.2% mgt, 2.1% ilm, 58.9% plag

MODEL 9 R2 = 0.153 F = 0.904 - 8.8% hb,

31.0% bio, 1.3% mgt, 58.9% plag

MODEL 7 R2 = 0.198 F = 0.722 - 18.5% hb, 7.9%

mgt, 73.6% plag

SC681 (58.49)

SC112 (65.39)

R2 = 0.123 F = 0.500 - % Hb, mgt,

ilm, plag

EXPLANATION

Sample number

SiO2 wt % (anhydrous)

Sum of least squares

% of fractionating phases

Poor fractional crystallisation model

Geologically infeasible

Liquid fraction (F)

FC 1

FC 2

FC 3

FC 4

FC 5

FC 6

FC 7

FC 8

FC 9

FC 10

FC 11

FC 13

Woolooga-Rush Creek GranodioriteGroup

Mount Mucki Diorite-Gibraltar Quartz Monzodiorite Group


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and observed parent compositions (sum of least squares R2 < 0.20). Trace element

calculations are then applied based on the major element solutions, using the Rayleigh

fractionation equation of Allegre & Minster (1978). Most intraplutonic models have

similar calculated (Co’) and observed (Co) trace-element abundance in the parent

composition (i.e. [Co’-Co]/Co <<0.5 for a good model).

The geochemical variation from monzogabbro to quartz monzodiorite in the

Mount Mucki Diorite can be accounted for by fractionating 5.3 wt% augite, 21.6 wt%

hornblende, 4.9wt% magnetite and 17.8wt% plagioclase (Table 6.5). The quartz

monzodiorite daughter composition represents the 49.6% liquid fraction of the

fractionating magma. Trace elements conform well to the FC modelling except for the

depletion of REE, which is attributed to their incompatible behaviors in mafic minerals

(Arth, 1976). The monzogabbroic and dioritic end-members of the Mount Mucki

Diorite are partly cumulates, and the pyroxenes- and hornblende-rich composition

generally contains low REE (Rollinson, 1993). The REE depletion can also be

attributed to sphene and apatite separation (Bea, 1996), as the early phases are

commonly observed as inclusions within pyroxene, hornblende and labradorite.

The geochemical variation in the Gibraltar Quartz Monzodiorite is

successfully modelled by crystallization of 2.2 wt% augite, 6.8 wt% hornblende, 6.7

wt% magnetite, 1.9 wt% ilmenite and 28.8 wt% plagioclase. The quartz monzodiorite

daughter composition represents the 53.1% liquid fraction after subtraction of the

fractionating phases from a monzodiorite parent. Trace elements models calculated

similar predicted and observed parent compositions ([Co’-Co]/Co <0.3) with the

exception of Sc (likely removed by fractionation of magnetite and ilmenite).

In the Woolooga Granodiorite, the compositional variation from quartz

monzodiorite to granite is attributed to fractional crystallisation of 14.2 wt%

hornblende, 2.1 wt% magnetite and 27.6 wt% plagioclase. The granodiorite daughter

represents the 55% liquid fraction of the quartz monzodiorite parent. The variation

from granodiorite to monzogranite (57 % liquid fraction) in the more silicic Rush

Creek Granodiorite can be attributed to crystallisation of 12.2 wt% hornblende, 1.8

wt% biotite, 2.1 wt% magnetite and 27 wt% plagioclase. Trace element models agree

well to all least-square models (FC models 7, 8, 10, 11, Appendix 5), and the values of

[Co’-Co]/Co for most elements is below 0.5.


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Interplutonic models

Fractional crystallisation (FC) modelling

Geochemical variations between plutons of a geochemical group are related

by fractional crystallisation (Figure 6.9; calculations in Appendix 5). Good

fractionation models using both major and trace elements link the Woolooga to Rush

Creek Granodiorites (FC Model 9), and the Mount Mucki Diorite to Gibraltar Quartz

Monzodiorite (FC Model 2). Fractionation model between the Woolooga and Rush

Creek Granodiorites (R2 of 0.153 and [Co’-Co]/Co <0.31) suggest that the two plutons

belong to a fractionating suite, and the Rush Creek Granodiorite represents the

fractionated felsic end-member. The removal of 13.6 wt% hornblende, 3.3 wt% biotite,

3.5 wt% magnetite and 41.5 wt% plagioclase will result in the compositional change

from quartz monzodiorite of the Woolooga Granodiorite to granites of the Rush Creek

Granodiorite (Table 6.5). The granite represents the remaining 37% liquid fraction of

the parental quartz monzodiorite composition, and its mineralogy is close to the

cotectic system as discussed earlier.

Table 6.5: Summary of fractional crystallisation models within plutons and between plutons in a geochemical group of the SCIC. The ‘parent’ refers to the most mafic/primitive sample within a pluton or group and the ‘daughter’ (Daugh.) is the composition of remaining liquid fraction (F) after subtraction the crystallising minerals.

INTRAPLUTONIC FRACTIONAL CRYSTALLISATION MODELS

MODEL Parent (SiO2 %)

Cpx Horn Bio Mt Ilm Sph Plag Liquid (F) Daugh. (SiO2 %)

Mount Mucki Diorite

SC936 (47.98)

5.3 21.6 - 4.9 - 0.6 17.8 49.6 SC999 (53.53)


SC710 (56.18)

2.2 6.8 - 6.7 1.9 - 28.8 53.1 SC1018 (62.44)


SC1069 (60.50)

- 14.2 - 2.1 - - 27.6 55.1 SC854 (67.02)


SC1166 (65.65)

- 12.2 1.8 2.1 - - 27.0 56.7 SC1153 (75.31)

INTERPLUTONIC MODELS BETWEEN PLUTONS OF A GEOCHEMICAL GROUP

MM-GQM group

SC936 (47.98)

12.3 24.2 - 9.1 0.7 0.6 32.6 20.2 SC1018 (62.44)

WG-RCG group

SC1069 (60.50)

- 13.6 3.3 3.5 0 0 41.5 37.0 SC1153 (75.31)

Cpx= Augite, Horn= Hornblende, Bio= Biotite; Mt= Magnetite; Ilm= Ilmenite, Sph= Sphene, Plag= Plagioclase, G= Granodiorite, Dio.= Diorite, QM= Quartz monzodiorite, MM= Mount Mucki Diorite, GQM= Gibraltar Quartz Monzodiorite, WG= Woolooga Granodiorite, RCG= Rush Creek Granodiorite.


172

The compositional change from monzogabbro of the Mount Mucki Diorite to

quartz monzodiorite of the Gibraltar Quartz Monzodiorite is modelled by fractional

crystallisation process (R2=0.164 and [Co’-Co]/Co of 0.2 to -0.9). The separation of

12.3 wt% augite, 24.2 wt% hornblende, 9.1 wt% magnetite, 0.7 wt% ilmenite, 0.6 wt%

sphene and 32.6 wt% plagioclase from the monzogabbro parent will resulted in a

quartz monzodiorite daughter (equals to 20.2% liquid fraction). The FC model

calculates elevated Ba, Sr and Eu ([Co’-Co]/Co of -0.6 to -0.9) in the quartz

monzodiorite daughter, which is consistent with high-observed feldspar content. About

half of the removed phases are ferromagnesian minerals that effectively resulted in a

leucocratic daughter dominated by feldspars. Goode (1977) proposed that the less dense

feldspar crystals could be concentrated at the top of a magma chamber by as flotation

cumulates.

FC modelling between the Mount Mucki Diorite-Gibraltar Quartz

Monzodiorite group and Woolooga-Rush Creek Granodiorite group is unsuccessful.

The geochemical model (FC Model 6) has poor major and trace elements match (R2 =

0.479 and [Co’-Co]/Co of +0.4 to -3.3) that suggests that the two groups cannot be

related by fractional crystallization processes, and respective group evolves from

different parental compositions. A FC model between the Gibraltar Quartz

Monzodiorite and Woonga Granodiorite (FC Model 5) has good major elements mass-

balance (R2=0.154) but is poorly supported by trace element calculations ([Co’-Co]/Co

of +0.6 to -0.7). Mapping and radiometric dating show that the older Woonga

Granodiorite (237 Ma) cannot be fractionated directly from the younger Gibraltar

Quartz Monzodiorite (227 Ma). However, the model does not discount the possibility

that the Woonga Granodiorite could fractionate from similar quartz monzodiorite

parent composition within the pluton that is not exposed or sampled.

Magma-mixing models

Magma-mixing models using mathematical equations of Allegre & Minster

(1978) show that the component plutons of the SCIC cannot be generated from mixing

“parental magma” (SC936) with supracrustal melts (SC106). The ‘simple-mixing

model’ combines different proportions of parental magma (SC936) with supracrustal

melts (SC106), yields poor modelling results (R2 of 1.4 to 6.6; Mixing model 1-6,

Appendix 5, p. 49). A more realistic model that integrates magma-mixing and


173

fractional crystallisation also failed to create the compositional heterogeneity within

the SCIC.

Mixing monzogabbro (SC936) and felsic magma (SC1129) cannot generate

large volumes of intermediate magma in the SCIC (R2 of 2.4 to 5.2; Mixing model 7-

12, Appendix 5). However, localised hybridisation does occur at intrusive contact

between a monzodiorite intrusion and the Rush Creek Granodiorite (R2 = 0.34, [CL’-

CL/CL] = 0.3 to -0.11, Mixing model 13, Appendix 5). Such localised hybridisation

will not affect the overall petrogenesis of a pluton, as the more mafic magma normally

quenches at its contact with felsic rocks (Kay et al., 1992, Wilcox, 1999).

Assimilation-crystal fractionation (AFC) models

Geochemical and isotopic evidences indicate that the SCIC magma contains a

crustal or enriched mantle component. The preceding models have shown that direct

mixing of a supracrustal component with the parental magma cannot generate the

range of intermediate composition in the SCIC. However, AFC models (Allegre &

Minster, 1978) show that the ‘least-evolved-sample’ in the Gibraltar Quartz

Monzodiorite and Woolooga Granodiorite may be generated by assimilating minor

amounts of supracrustal (e.g. SC106) contaminants (R=0.1 to 0.2) into the parental

magma (SC936) (AFC Model 1 & 2, Appendix 5; R2= 0.274 and 0.286 respectively).

The daughter compositions (CL) lie between the ‘calculated parental composition’

(Co’) and the supracrustal assimilant (Ca), which support the possible involvement of

the AFC process. The ‘observed parental magma’ composition (Co) are slightly

enriched in Ba, Sr, Zr, TiO2, Na2O and K2O, and depleted in REE compared to the

‘calculated parental composition’ (Co’). Arculus & Johnson (1981) regard enrichment

of Sr and Ba relative to LREE as evidence for the involvement of either subducted,

upper-crust-derived sediments; altered oceanic crust; or seawater in the upper-mantle

source regions. The higher concentrations of Na2O, K2O and high field strength

elements e.g. TiO2 and Zr in the Co support the involvement of crustal component(s)

in the source region (Allegre et al., 1977; Hanson 1978).

The ‘least-evolved-sample’ of the Rush Creek Granodiorite (SC1166) is not a

direct product of assimilation and crystal fractionation from the Mount Mucki Diorite

(AFC Model 3, Appendix 5). AFC model shows that assimilating minor crustal


174

component (R= 0.1) and fractional crystallisation from a Mount Mucki Diorite parent

does not produce the granodiorite daughter-composition (R2 = 1.791). The Rush Creek

Granodiorite is a fractionated member of the Woolooga-Rush Creek Granodiorite

group that differs geochemically from the MMD-GQM group.

The geochemical variations within the Woolooga and Rush Creek

Granodiorites (discussed in previous models) resulted primarily from fractional

crystallisation, with little contribution from crustal contamination. The possibility of

assimilating minor amount of crustal components (R~ 0.1) is not supported by the

AFC models (AFC Model 4 and 5). The addition of supracrustal melt (SC106) elevates

the Ba, La, Nb and Zr, and reduces the HFS-element contents in the calculated

daughter composition (CL’). Comparing the AFC models with similar FC models (FC

Model 7 and 10), the calculated results (CL’) of the AFC models deviate more from the

observed compositions (CL), hence rendering the AFC model as inappropriate.

Magma source characterisation

Qualitative partial-melting modelling of a mantle source to produce the most

‘primitive’ magma in the SCIC is inappropriate due to the lack of input constraints on

the Mesozoic mantle/slab/sediment components, and the most basic sample (SC936)

does not represent a primitive magma. Therefore, magma source characterisation is

semi-qualitative base strongly on trace element and isotopic constraints.

Geochemical constraints

The geochemistry of the MMD-GQM group is typical of the continental

volcanic arc-type magmas. The isotopic ratios and immobile element abundances of

the MMD-GQM are similar to MORB (Figure 5.16), suggesting the likelihood of an

upper mantle source. Enrichment of mobile elements (Sr, K, Rb, Ba and Th) relative to

MORB and to ORG compositions implies the addition of subduction-zone

fluids/partial melts (Pitcher, 1979; Gill, 1981; Pearce, 1983). Both the Mount Mucki

Diorite and Gibraltar Quartz Monzodiorite have LREE enrichments and relatively flat

MREE and HREE patterns without a Eu anomaly. The REE pattern with moderate

(La/Yb)n enrichment (2.9-5.0 and 6.7-7.3 respectively) implies partial melting of a

garnet-free depleted mantle source, followed by fractional crystallisation of pyroxenes,

hornblende, +olivine and magnetite (as discussed earlier).


175

The geochemistry of the W-RC group matches the average upper crustal

composition (except for lower Nb and Ta abundances). The chondrite-normalised REE

pattern is LREE enriched ((La/Yb)n of 3.3-7.9) and contains a flat MREE-HREE

plateau with a prominent negative Eu anomaly. The flat MREE and HREE pattern

suggests partial melting from a garnet-free mafic source (Bagby et. al., 1981). The

presence of Eu anomaly is interpreted as the result of some plagioclase retention in the

source region during melt generation. Fractional crystallisation of plagioclase,

pyroxene and hornblende, and assimilation of subduction zone components modified

the magma chemistries. The separation of plagioclase during crystal fractionation

enhances the Eu anomaly, and the crystallisation of clinopyroxene produces a flat

MREE-HREE plateau.

Isotopic constraints

The isotopic chemistry of the SCIC identifies a depleted mantle source mixed

with components of either the subduction zone materials, juvenile supracrust or/and

the enriched mantle. The initial 87Sr/86Sr246 and 143Nd/144Nd246 ratios for the SCIC range

from 0.70312 to 0.70391 and from 0.51252 to 0.51266 respectively. The Sr and Nd

isotopes suggest that the parents to these rocks had a long-term depleted radiogenic

source compared to primitive mantle or chondrites. The calculated initial 87Sr/86Sr

ratios of the Mount Mucki Diorite, Gibraltar Quartz Monzodiorite and Woonga

Granodiorite are similar to many island-arc magmas (e.g. Marianas, Aleutian arcs,

Cascade; Figure 6.10). The magmas from the Marianas and Aleutian island-arcs were

generated from depleted asthenospheric mantle source similar to the MORB, with

minor involvement of oceanic sediments in their petrogenesis (Hawkesworth, 1979;

Woodhead & Fraser, 1985; Arculus & Powell, 1986; White & Dupre, 1986). The 87Sr/86Sr ratios of the Woolooga and Rush Creek Granodiorites are similar to ratios for

the Mexico, Ecuador, Cascade and South Sandwich Islands arcs and the more

radiogenic magmas from the Marianas and Aleutians. The higher 87Sr/86Sr ratios in

these volcanic arcs were attributed to crustal contamination or the addition of

components derived from the subduction slab (Hawkesworth et al., 1979). The 143Nd/144Nd and 87Sr/86Sr data of the SCIC plot between the depleted mantle (DM) and

the ‘upper crustal field’ of DePaolo & Wasserburg (1979) (Figure 6.11). The isotopic

array of the SCIC is characteristic of mixing two isotopically distinct sources and/or


176

Marianas

South Sandwich Islands

Aleutians

Dominica-St Kitts

Grenada

Sunda arc

Cascade

Mexico (NVZ)

Ecuador (NVZ)

Peru and northern Chile (CVZ)

Mount Mucki Diorite


Woonga Granodiorite



Foliated granodiorite(Wratten Igneous Suite)

Figure 6.10: The Sr/ Sr initial ratios of the Station Creek Igneous Complex (SCIC) compared to volcanic arc magmas derived from a variety of tectonic environments. The isotopic ratios of the Mount Mucki Diorite, Gibraltar Quartz Monzodiorite and Woonga Granodiorite match ratios of primitive magmas generated from simple oceanic island-arc systems such as the Marianas and Aleutian arcs. Magmas from both were generated from depleted asthenospheric mantle with minimal crustal contaminations. The ratios of the Woolooga Granodiorite and Rush Creek Granodiorite are similar to ratios of the Mexico, Ecuador, South Sandwich Islands arcs and the more isotopically evolved magmas from the Marianas and Aleutians. Magmas from these environments involve either crustal contamination or the addition of components derived from the subduction slab (Isotopic data and interpretations for the various arc magmas from Hawkesworth, 1979).

8 7 8 6

island-arcs Sr/ Sr

Cascade and

8 7 8 6

0.702 0.703 0.704 0.705 0.706 0.707 0.7088 7 8 6

Sr/ Sr ratio

MAGMA SOURCES T

HE

SCIC


177

Figure 6.11: The

The Woolooga and Rush Creek Granodiorites overlap the isotopic domains of the Mungore Granite and the Clarence River Supersuite.

1 4 3 1 4 4 8 7 8 6

Nd/ Nd versus Sr/ Sr data of the Station Creek Igneous Complex (SCIC) against potential crustal contaminants of the NEO. The composition of the SCIC plots between the depleted mantle (DM) and the 'upper crustal field', and differs from a primary mantle-derived magma (the Goomboorian Intrusive Complex, 234 Ma).

The deviation from a depleted mantle composition may involve contributions from enriched mantle or crustal components. Crustal involvement e.g. m CR (best fit point from Langmuir . (1978) two components mixing curve) can cause the . CR is isotopically similar to the Late Carboniferous foliated granodiorite (Wratten Igneous Suite) and the Neranleigh Fernvale Beds. An accompanying bar-graph (to the right of the Nd-Sr graph) compares the (Sr/Nd) /(Sr/Nd) ratios of potential assimilants to the depleted mantle, and the SCIC data plots between the (Sr/Nd) /(Sr/Nd) ratios of 1.5 to 4; similar to ratios for the greywacke and phyllite (Hensel ., 1985).

[Data for the Mungore Granite, Neranleigh Fernvale Beds, Rocksberg Greenstone and isotopic fields for the New England tonalites and metasediments, SE Queensland Palaeozoic metasediment and Neara Volcanics from Stephens (1991), Goomboorian Igneous Complex from Hansen (1997); Clarence River Supersuite from Bryant . (1997); 'upper crustal field' from DePaolo & Wasserburg (1979)].

i n i t i a l i n i t i a l

M O R B R O C K

M O R B C R

et al

et al

et al

plotted

The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite plot along the 'mantle array', whereas the Woolooga and Rush Creek Granodiorites deviate from the mantle array towards higher Sr/ Sr and lower Nd/ Nd.

ixing range of the SCIC compositions

8 7 8 6 1 4 3 1 4 4

Wea

ver

. 198

1et

al

Gro

met

.,

1984

et a

l

Tayl

or a

nd M

cLen

nan,

198

5

NA

SC s

hale

NE

O s

hale

and

phy

llite

Oce

anic

cru

st a

vera

geA

mph

ibol

ite0.

51

1.5

22.

53

3.5

(Sr/N

d)/(S

r/Nd)

ratio

MO

RB

RO

CK

Upp

er c

rust

ave

rage

NE

O g

reyw

acke

Nea

ra V

olca

nics

Hen

sel

., 19

85et

al

Hen

sel

., 19

85et

al

Tayl

or a

nd M

cLen

nan,

198

5Th

is s

tudy

DEPLETED MANTLEI s o t o p i c f i e l d o f t h e S C I C

U p p e r c r u s t a l r o c k s

C R

N F V

N E O G r e y w a c k e

N E O S h a le

(Sr/Nd)(Sr/Nd)

M O R B

C R

= 1.5 (R1.5)Mixing curve for

(Sr/Nd)(Sr/Nd)

M O R B

C R

= 4 (R4)Mixing curve for

10%

40%

NearaVolcanics

Station Creek Igneous Complex

C S S

MungoreGranite

Goomboorian Intrusive Complex

E.g. of primary magma of the northern New England Orogen Arbitrary Depleted Mantle (DM) end-

member (initial Nd ratio= 0.512766, initial Sr ratio =0.702648; Sr=136 ppm, Nd=8 ppm

Arbitrary supra-crustal end-member (initial Nd ratio= 0.51225, initial Sr ratio =0.7060; variable Sr and Nd values to suit model: R1.5- Nd= 26 ppm, Sr = 295 ppmR4- Nd= 27 ppm, Sr= 115 ppm

Mixing Components

Foliated granodiorite (U. Carb.)Rocksberg Greenstone (metabasalt)

NFV Neranleigh Fernvale Beds (greywacke)

Possible crustal sources

NEO greywacke (Hensel .,1984)et al

NEO shale (Hensel ., 1984)et al

Comparison with other I-type continental arc magmas

Isotopic field for the Clarence River SupersuiteCSSMungore Granite

New England tonalites &metasediments

SE QueenslandPalaeozoic metasedimentse.g. NFV

MANTLE ARRAY

UPPER CRUSTAL FIELD


178

assimilating upper-crustal rocks by depleted mantle derived magma (e.g. Barbarin,

1990; DePaolo et al., 1992). Depleted mantle (DM) is the common source for mid-

ocean ridge basalt (MORB) that forms oceanic crust (Jackson, 1998). Based on

Langmuir et al. (1978) two-components mixing model, the projected “upper crustal”

component (CR) has an initial 143Nd/144Nd ratio of 0.51225 + 0.0002 and an initial 87Sr/86Sr ratio of 0.70600 + 0.0005. The model uses (Sr/Nd)MORB/(Sr/Nd)CR ratios of

1.5 to 4 to encompass all the SCIC isotopic data. Such Sr/Nd ratios are similar to the

ratios for greywacke and phyllite of the SNEO (Hensel et al., 1985), hinting

geochemical similarities between CR and greywacke/phyllite. The CR component has

similar isotopic signatures to the southeast Queensland Palaeozoic metasediments (e.g.

the Neranleigh Fernvale beds; Stephens, 1991), and to the foliated granodiorite of the

Wratten Igneous Suite. The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite

plot along the ‘mantle array’, whereas the Woolooga and Rush Creek Granodiorites

deviate from the ‘mantle array’ towards higher 87Sr/86Sr and lower 143Nd/144Nd.

The deviation from DM along the mantle array normally involves the addition

of enriched mantle and/or fluid/partial melt derived from the subducted oceanic crust

(e.g. Hawkesworth et al., 1979; Perfit et al., 1980b; Arculus & Johnson, 1981; Arculus

& Powell, 1986). The Mount Mucki Diorite plots within the isotopic domains of

simple island-arc systems (Marianas, New Britain and Aleutians) and within the field

of oceanic island basalts (Figure 6.12). The island-arc basalts are generated from

depleted asthenospheric mantle source (Arculus & Powell, 1986) whereas the oceanic

island basalts are generated from relatively primordial mantle (Allegre et al., 1986;

Zindler & Hart, 1986). Therefore, isotopic evidences in conjunction with geochemistry

suggest that the Mount Mucki Diorite is derived from partial melting a depleted mantle

source that has been modified by influx of fluids derived from the subducted oceanic

crust within a continental volcanic arc setting.

The Gibraltar Quartz Monzodiorite plots within the isotopic fields of the

oceanic island-arcs and Azores, proximal to the HIMU field (Zindler & Hart, 1986)

(Figure 6.12). The initial 87Sr/86Sr ratios of the Gibraltar Quartz Monzodiorite are

slightly elevated relative to the Mount Mucki Diorite. Hawkesworth et al. (1979)

indicated that the magmas of the Azores involved recycle subducted oceanic sediments

in the source regions. The interpreted source region for the Gibraltar Quartz

Monzodiorite is similar to that of the Mount Mucki Diorite, with minor involvement of


179

Figure 6.12: The 143Nd/144Nd versus 87Sr/86Sr ratios of the Station Creek Igneous Complex compared to isotopic fields of island-arc and oceanic island basalts, and continentalised arc systems. A) The Mount Mucki Diorite plots within the isotopic domains of both

oceanic island basalts (Hawaii, Iceland and Azores) and simple island-arc systems (Marianas, New Britain and Aleutians), and near the PREMA field. The Gibraltar Quartz Monzodiorite plots along the 'mantle array' proximal to the HIMU field, and plots within the isotopic fields of the Azores. The Woolooga and Rush Creek Granodiorites plot within the isotopic domain of the Azores and Lesser Antilles, and have higher 87Sr/86Sr and lower 143Nd/144Nd values than the MMD-GQM group. The Neara Volcanics domain overlaps the HIMU field, and differs from the SCIC isotopic domain.

B) The Mount Mucki Diorite and Gibraltar Quartz Monzodiorite plot outside the isotopic domains of continentalised arc systems. The Woolooga and Rush Creek Granodiorites plot within the domains of the Southern Andean Volcanic Zone (SVZ) that includes the volcanic field of Patagonia.

[Isotopic fields for Azores, Hawaii, Neara Volcanics and depleted mantle are adopted from Stephens (1991); S. Sandwich island, Ecuador, Iceland and Patagonia are from Hawkesworth (1979); OIB field, Aleutians, New Britain, Marianas, and Lesser Antilles fields are from Arculus & Powell (1986); Andean volcanic rocks from the central (CVZ) and southern (SVZ) volcanic zones, and Colombian volcanics are from Hawkesworths et al. (1982), James (1982), Thorpe et al. (1984) & Hickey et al. (1986); ocean island-arc field from Wilson (1989); HIMU or mantle with high U/Pb ratio and PREMA or frequently observed PREvalent MAntle composition are from Zindler & Hart (1986)].


180

A. ISLAND-ARC AND OCEANIC ISLAND SYSTEMS

B. CONTINENTALISED ARC SYSTEMS

Lesser Antilles

Marianas, New Britain, Aleutians

0.70

4200

OCEANIC ISLAND ARCS

DEPLETEDMANTLE

OCEANICISLAND BASALTS


Mount Mucki Diorite



Station Creek Igneous

SUPRA CRUST

Ecuador (NVZ)

Colombia (NVZ)

SVZ (Southern Andean Volcanic Zone)

CVZ (Central Andean Volcanic Zone)

0.70

4200

DEPLETEDMANTLE

SUPRA CRUST

Mount Mucki Diorite



Station Creek Igneous


181

fluids and partial melts from the subducted oceanic crust and associated sediments.

The 143Nd/144Nd and 87Sr/86Sr data of the Woolooga and Rush Creek

Granodiorites plot within the isotopic domains of the Azores, Lesser Antilles, Southern

Andean Volcanic Zone (SVZ) and Patagonian volcanic arc (Figure 6.12); and the

Mungore Granite and Clarence River Supersuite (Figure 6.11). All these isotopic

domains involved crustal components in their petrogenesis (Hawkesworth, 1979;

Hawkesworth et al., 1979; Arculus & Powell, 1986; Stephens, 1991; Bryant et al.,

1997). The Azores and Lesser Antilles arc systems have subducted oceanic sediments

and crustal contamination, whereas the Andean continental-arc systems involved

continental crust (Hawkesworth et al, 1979). The Mungore Granite is derived from

fractional crystallisation of a basaltic magma contaminated with ~20% andesitic

component (Stephens, 1991). The Clarence River Supersuite originated from either

mantle-derived magma or isotopically primitive crust, contaminated by upper-crustal

material (Bryant et al., 1997). The interpreted source for the Woolooga and Rush

Creek Granodiorites is from partial melting depleted mantle or ‘juvenile depleted

mantle derived rocks’, with modification from a crustal component, which is typical

for continental-arc system.

The Neara Volcanics plots within the HIMU field (‘high mu factor’ linked to

high Pb field; Zindler & Hart, 1986), which suggests that it has a different source

region to the SCIC (dominantly oceanic island-arc and OIB signatures, Figure 6.12).

Pb is highly depleted in the upper mantle but is concentrated in continentally derived

oceanic sediments and oceanic crusts that have been altered by seawater interaction

(Zindler & Hart, 1986). The interpreted origin for the Neara Volcanics is from the

partial melting of isotopically primitive source involving terrigenous sediments on

seawater altered oceanic crusts.

Major and trace element petrogenetic models (discussed earlier) do not

support a direct high-level mixing process between supracrustal (CR) and mantle-

derived melt (DM). Subduction-slab derived fluids isotopically contaminate the

mantle-melt component in the SCIC, which is typical of subduction-zone-mantle

(SZM) (Hawkesworth, 1979). The SZM-derived magma component is represented by

monzogabbro of the Mount Mucki Diorite (MMD). The variations within the SCIC can

be explained by mixing SZM-derived magma (MMD) with upper crustal rocks (CR).

Langmuir et al. (1978) mixing models calculated 4-5 wt%, 10-13 wt% and 11-14 wt%


182

upper-crustal component (CR) in the Gibraltar Quartz Monzodiorite, Rush Creek

Granodiorite and Woolooga Granodiorite respectively (Figure 6.13; Table 6.6). The

Gibraltar Quartz Monzodiorite data plots between mixing lines with

(Sr/Nd)MORB/(Sr/Nd)CR ratios of 3 to 4, similar to ratios for marine shale (Gromet et

al., 1984; Hensel et al., 1985). The Woolooga and Rush Creek Granodiorites plot

between mixing lines with (Sr/Nd)MORB/(Sr/Nd)CR ratios of 1 to 2, similar to ratios for

greywacke, and the upper crustal and oceanic crustal averages (Hensel et al., 1985;

Taylor & McLennan, 1985). The W-RC group and Gibraltar Quartz Monzodiorite

have higher 87Sr/86Sr and lower 143Nd/144Nd ratios than the MMD, which are

diagnostic of crustal contamination and involvement of seawater in their petrogenesis

(James, 1981). The mixing of mantle with seawater can occur directly by seawater

alteration or indirectly through water released from subducting oceanic plate

(Hawkesworth, 1979).

Table 6.6: Calculated percentages of crustal component (CR) for the various plutons of

the SCIC based on two-component isotopic mixing model (Langmuir et al., 1978). Tabulated below is potential assimilants- the Neara Volcanics and the foliated granodiorite.

Pluton / Unit Sample (SiO2 %) Age Ma 87Sr/86Sr 143Nd/144Nd % CR Mount Mucki Diorite SC999 (53.53%) 227 0.70312 0.51266 0 Gibraltar Qtz Monzodiorite SC710 (56.18%) 227 0.70325 0.51259 5 Gibraltar Qtz Monzodiorite SC1018 (62.44%) 227 0.70317 0.51260 4 Rush Creek Granodiorite SC1185 (71.17%) 231 0.70387 0.51253 13 Rush Creek Granodiorite SC1153 (75.31%) 231 0.70366 0.51255 10 Woolooga Granodiorite SC1037 (63.21%) 234 0.70391 0.51252 14 Woolooga Granodiorite SC472 (64.20%) 234 0.70353 0.51254 11 Woonga Granodiorite SC1129 (67.39%) 237 0.70318 N.A. ~ 2 + 1*

Foliated Granodiorite SC106 (68.68%) 306 0.70534 0.51230 100 Neara Volcanics SC082 (57.87%) 241 0.70152 0.51253 - Estimated using the 87Sr/86Sr value at (Sr/Nd)MORB/(Sr/Nd)CR of 1.5-4

The 87Sr/86Sr ratios of the Woolooga Granodiorite, Rush Creek Granodiorite

and Gibraltar Quartz Monzodiorite decrease while their 143Nd/144Nd246 ratios increase

with increasing whole-rock SiO2 (Figure 6.13). Petrogenetic modelling indicates that

these plutons evolve by fractional crystallisation, and the more felsic compositions

represent either more evolved magmas or longer residence time in the magma

chamber. The isotopic shift towards the Neara Volcanics domain (coincides with


183

Figure 6.13: Two-component isotopic mixing model between ‘subduction zone mantle’ derived melt (MMD) and the extrapolated upper crust component (CR; initial

Nd/ Nd ratio= 0.51225, initial Sr/ Sr ratio= 0.70600). The solid-lines are mixing curves (Sr/Nd) /(Sr/Nd) ratios of 1 and 3, and the dashed-lines indicate the percentages of crustal component mixed with MMD. Modelling calculated

Gibraltar Quartz Monzodiorite, and 11 to 14 wt% crustal component in the Woolooga and Rush Creek Granodiorites.

The initial Sr/ Sr ratios of the Woolooga Granodiorite, Rush Creek Granodiorite and Gibraltar Quartz Monzodiorite decrease towards the isotopic domain of the Neara Volcanics with increasing whole-rock SiO , which is interpreted as effects of isotopic homogenisation. Also plotted are the general trends for isotopic shift due to sea-water interaction and crustal contamination. (Mixing curves are calculated by Langmuir ., 1978 equation; isotopic field for the Neara Volcanics is adapted from Stephens, 1991).

1 4 3 1 4 4 8 7 8 6

8 7 8 6

M O R B R O C K

2

et al

calculated using Langmuir . (1978) equation based on

4 to 5 wt% crustal component in the

et al

0.704000.703500.70300

0.51270

0.51260

0.51250

Initi

al

Nd/

Nd

(246

Ma)

14

31

44

Initial Sr/ Sr (at 246 Ma)8 7 8 6

Mount Mucki Diorite

Gibraltar Quartz monzodiorite



Neara Volcanics

Trend of increasing SiO contents between samples within a pluton

2

(Sr/Nd) /(Sr/Nd) or Rmixing line between MMDand a supracrustal component (CR).

M M D C R= 3;

R= 1R= 3

NearaVolcanics

20%

15%Supracrustal

component

5%

10%

MMD

Isotopic variation due tosupracrustal contamination by an andesitic component e.g. the Neara Volcanics

Isotopic shift towardshigher Sr/ Sr due tosea-water alterationor water released from subducting slab (Hawkesworth, 1978).

8 7 8 6

Isotopic change due to the addition of crustal component

CR


184

HIMU with lower 87Sr/86Sr and higher 143Nd/144Nd246 ratios) may be interpreted as

evidence for isotopic assimilation or homogenization with the Lower Triassic Neara

Volcanics. Stephens (1991) noted similar isotopic homogenization between the

mantle-derived magma and the Neara Volcanics in the Late Triassic Mungore Granite.

Parental magma

The juvenile 87Sr/86Sr and 144Nd/143Nd ratios of the SCIC verify a depleted

mantle source, and preclude recycling of older crustal material. The origins of the

magma must therefore be sought in the mantle where the parental magmas were

directly generated (single-stage petrogenetic process) or indirectly generated (multi-

stage petrogenetic process). Potential sources for I-type magma in a subduction setting

are from partial melting of subduction-zone-mantle (SZM) overlying the subduction

lithosphere (mantle wedge), from the hydrated basaltic oceanic crust in the subduction

plate, and from the lower continental crust above the subducting plate (Gromet &

Silver, 1987; Chappell & Stephens, 1988; Wyllie, 1984). Direct partial melting of

mantle and oceanic crust contributes minor volume of M-type magmas to a

continental-arc, as the denser magma will not rise above the crust. Instead, the

basalt/gabbro crystallises at higher solidus at the base of continental crust. Most I-type

granitoids at upper crustal level derived from a two-stage partial melting and

fractionation event (e.g. Bryant et al., 1997; Eggins & Hensen, 1987; Stephens, 1991).

Subsequent melting of the earlier mantle-derived basaltic rocks underplated onto the

lower continental crust, formed a relatively dry magma that could migrate into the

upper crust (Johannes & Holtz, 1996). The source composition itself can be a function

of mixing processes in the source region, and understanding the mantle dynamics

through isotopic studies of mantle-derived basalts is important. I-type granite can also

be generated from mixing between mantle-derived M-type and partial-melts of

metasediment or S-type granites (Barbarin (1990).

The low pressures (<4.5 kbars) calculated by hornblende geobarometry for

the SCIC are related to emplacement, and provide no information on the depth of

partial melting. The anorthite, pyroxenes and magnetite liquidus mineralogy indicates

a relatively low-pressure condition (<8 kbars) (Green & Ringwood, 1964, 1967,

Clemens & Walls, 1981, 1988). There is no geochemical or petrologic indication that

garnet was either a residual or a fractionating mineral in the SCIC. Dehydration partial


185

melting experiments below 8 kbar pressures do not yield garnet as a stable phase (e.g.

Rapp & Watson, 1995; Rapp et al., 1991; Rushmer, 1991). Crystallisation experiments

on andesite showed that garnets crystallize at 9 to 36 kbars pressures, and between 800

to 1400oC (Gill, 1981). In the absence of garnet as either a liquidus or residual phase,

the source for the SCIC is constrained to <8 kbar.

Partial melting versus fractional crystallisation models

Geochemical modelling argues against direct partial melting of upper mantle or

a mafic crustal source to account for the magmatic diversity in the SCIC. Partial

melting models for the SCIC have numerous unknowns: the source or parental

composition, the equilibrium mineral phases and the degree of partial melting. The

possible source compositions within a subduction setting (i.e. mantle, normal-MORB,

enriched-MORB, lower crust, island-arc calc-alkalic basalt, and island-arc tholeiitic

basalt) are tested using the Allegre & Minster (1978) batch partial melting equation

(calculations in Appendix 5). The melting models are based on the metabasalt and

amphibolite equilibrium residual assemblages of Helz (1973), Gromet & Silver (1987),

Rapp et al., (1991) and Rapp & Watson (1995).

Models using a combination of trace elements (Co-Ba, Rb-K and Sr-Ba) show

that the parental magmas of the MMD-GQM and W-RG groups are fundamentally

different. The parental magma of the MMD-GQM group is generated primarily from

the subduction-zone mantle, followed by fractionation crystallisation of hornblende,

pyroxenes and possibly olivine (Figure 6.14, calculations in Appendix 5). Partial

melting alone does not generate the MMD-GQM, but a combination of partial melting

followed by fractional crystallisation produces the range of compositions within the

group (Figure 6.14A,B). The geochemical variation within the Mount Mucki Diorite

reflects fractionation of hornblende, pyroxenes and possibly olivine, whereas the

variation in the Gibraltar Quartz Monzodiorite reflects a clinopyroxene and plagioclase

dominated fractionation. However, the K/Rb-Rb relationship of the Mount Mucki

Diorite is similar to melts derived from a calc-alkalic, island-arc source (Figure

6.14C), which suggest possible enrichment of both elements in the Mount Mucki

Diorite.

The parental magma of the W-RG group is compositionally similar to the


186

Figure 6.14: The compatible-element versus incompatible-element diagrams comparing fractional crystallisation and partial melting models for the Station Creek Igneous Complex. The grey arrows are mineral vectors from Rayleigh fractionation (Allegre & Minster, 1978) of olivine, orthopyroxene, clinopyroxene, hornblende and plagioclase. The black arrows represent batch partial melting (Allegre & Minster, 1978) trends calculated from standard source-compositions (Appendix 5, p. 67) based on metabasaltic equilibrium mineralogy at <8 kbars and water-undersaturated conditions (Helz, 1973). The bold-dashed arrows represent the overall geochemical variation trends of individual pluton in the direction of increasing SiO2, and blue arrows represent the path of representative fractional crystallisation models calculated using IGPET program. Calculations for the various models are presented in Appendix 5 (p. 60-66).

(A) Co versus Ba: The batch partial melting models from mantle, N-MORB, E-MORB, lower-crust or island-arc basalts produce significantly different variation trends to the SCIC; inferring that the SCIC cannot be generated directly by partial melting such sources. Rayleigh fractionation of ferromagnesians (hornblende, olivine and pyroxenes) from a mantle-like melt composition can generate the Mount Mucki Diorite composition (mineral vector diagram in the inserted graph to the left). The Woolooga-Rush Creek Granodiorites Group may evolve from the Mount Mucki Diorite by hornblende, olivine and pyroxenes fractionation.

The geochemical variation within the Mount Mucki Diorite reflects fractionation of hornblende, pyroxenes and possibly olivine, whereas the variation in the Gibraltar Quartz Monzodiorite reflects a clinopyroxene-dominated fractionation. In the Woolooga Granodiorite, the geochemical variation is interpreted as results of clinopyroxene-dominated fractionation, and the variation trend in the Rush Creek Granodiorite reflects a hornblende-dominated fractionation. The Ba variation at almost constant Co (and SiO2) in the Woonga Granodiorite is due to Ba gain/loss as the result of subsequent alteration.

(B) Sr/Ba versus Ba: The compositional variations of the SCIC cannot be modeled by batch partial melting of mantle, N-MORB, E-MORB, lower-crust or island-arc basalt compositions. The Mount Mucki Diorite, however, can be generated by fractional crystallisation of hornblende, olivine and pyroxenes from a mantle-like melt composition. The Woolooga-Rush Creek Granodiorites Group could evolve from the Mount Mucki Diorite by hornblende, olivine and pyroxenes fractionation.

(C) K/Rb versus Rb: The SCIC compositions cannot be modeled by batch partial melting of mantle, N-MORB, E-MORB, lower-crust or island-arc basalt compositions. 30% partial melting of the calc-alkalic island-arc basalt will yield similar K and Rb compositions to the Mount Mucki Diorite. The IAB (calc-alkalic) represents modified arc basalt with additional subduction-zone component. Intraplutonic variations of the Mount Mucki Diorite and the Gibraltar Quartz Monzodiorite are interpreted as results of olivine and pyroxenes dominated fractionation. The variations trends of the Woolooga, Rush Creek and Woonga Granodiorites support fractional crystallisation of clinopyroxene, hornblende and plagioclase.


187

0 100 200 300 400 500 600 700Ba (ppm)

0

10

20

30

40

50

Co

(ppm

)

Hornblende

Olivine

Ortho-pyroxene

Clino-pyroxene

Plagioclase

20

20

20

20

20

MANTLE

RCG

WOGGQMWG

MM

In the inserted figure, the arrows represent 30 modal % of fractional crystallisation of respective minerals from a mantle-derived melt (composition of mantle Co= 110 ppm, Sun, 1982).

The Mount Mucki Diorite occurs along the fractionation path from the mantle-derived source.

Mineral vector diagram: The arrow represents the geochemical variation trend from fractional crystallisation of an individual mineral phase. Numbers on the arrow are the % of fractional crystallisation.

Variation trend between “the most mafic sample” within each geochemical group

Intraplutonic variation trend (arrow indicates the di rect ion of increasing SiO content)

2

GEOCHEMICAL TRENDSBatch partial melting trends calcula ted f rom standard sources. Number refers to the % melt fraction.

30

MM Mount Mucki Diorite




Woonga Granodiorite

GQM

WO

RC

WOG

Normal MORB

Enriched MORB

Mantle

Lower crust

IAB (calc-alkaline)

IAB (tholeiite)

SYMBOLS

MM

WG

Clino-pyroxene

Ortho-pyroxene

Olivine

Hornblende30

30

30

Mantle

0 400Ba (ppm)

120

020

4080

100

Co

(ppm

)

10% Partial melts 60

30

10

5030

60

3010

20

10

50

30

FC 1

FC 10

FC 11

FC 7

A. Co versus Ba

R e p r e s e n t a t i v e f r a c t i o n a l crystallisation model (FC 1). The reference in bracket corresponds to the calculations in Appendix 5. The arrow indicates the parent-to-daughter trend.


188

FC3 & 4

FC 5FC 7

FC 9

FC 1

FC 1 FC 3&4

C. K/Rb versus Rb

0 50 100 150 200

Rb (ppm)

100

500

300

700

200

400

600

K/Rb

Ba (ppm)


Woolooga-Rush CreekGranodiorites


GQM

WG

WOG

MM

30

30

50

30

50

10

30

50

10

30

50

10

30

50

10

10

10

B. Sr/Ba versus Ba

30

20

10

5

30

30

3030

30

50% Olivine, orthopyroxene

50% Clinopyroxene

50% Plagioclase

30% Hornblende

5% K-feldspar

Mineral vector diagram relating to the removal of different mineral phases by fractional crystallisation (numbers are the modal percentage).

Mineral vector diagram for 30 modal % of crystal fractionation. The different arrows relate to the geochemical trends from the removal of individual mineral phases. Numbers on the arrow are the % of FC.


189

island-arc calc-alkalic basalt (Figure 6.14A), which is generated from depleted mantle

modified by the addition of subduction-zone components (Bailey, 1981). Multistage

melting of pre-existing mantle-derived melts in the lower crustal, followed by low-

pressure crystal fractionation (plagioclase, hornblende, + pyroxenes) can generate the

intermediate W-RG compositions. In the Woolooga Granodiorite, the geochemical

variation is interpreted as results of clinopyroxene + plagioclase dominated

fractionation, and the variation trend in the Rush Creek Granodiorite reflects

hornblende + plagioclase fractionation.

The parental magma of the Woonga Granodiorite is similar to the island-arc

calc-alkalic basalt (Figure 6.14B,C). The geochemical variation of the Woonga

Granodiorite is interpreted as the results of hornblende-dominated fractionation.

However, the Ba variation at constant Co (and SiO2) suggests Ba-gain/loss as the result

of subsequent alteration.

Interpreted source regions

The magma source for the MMD-GQM is from the partial melting of the

SZM mixed with an appropriate slab-derived component. The MMD-GQM group is

transitional tholeiitic to calc-alkalic with mantle-derived characteristics such as

enhanced levels of high-field strengths elements (Ti, Co, Sc) and lower LIL. Isotopic

and trace element evidences suggest that the MMD-GQM derives from partial melting

a depleted mantle source that has been enriched with the influx of fluids derived from

the subducted oceanic crust. The Gibraltar Quartz Monzodiorite has higher

concentrations of mobile and immobile elements, higher 87Sr/86Sr and lower 143Nd/144Nd ratios, which reflects a SZM melt modified by ~5 wt% crustal (CR) and

recycled subducted oceanic lithospheric components. Diapiric upwelling of the

asthenospheric mantle melt (i.e. the Mount Mucki Diorite) causes the partial melting of

lithospheric mantle and incorporates juvenile crustal components.

The W-RC is derived from the partial melting of lithospheric mantle and basalt

underplated onto the lower continental crust (<8 kbar) above the subducting plate (e.g.

Gromet & Silver, 1987; Chappell & Stephens, 1988; Wyllie, 1984; Clemens & Droop,

1998). The W-RC is isotopically evolved relative to MORB, high-K, high alumina,

calc-alkalic, and enriched in K2O, Rb, Cs, Ba, Zr, U and Th. The geochemistry is

typical of subduction zone enrichment of lithospheric mantle, coupled with crustal


190

assimilation and fractional crystallisation (AFC) in zones of thickened crust (e.g.

Brown et al., 1984). Its felsic composition and more radiogenic chemistry suggest

significant crustal contamination (10-14 wt% CR) and seawater interaction.

The W-RC geochemistry is similar to the Cordilleran granitoids derived

from partial melting of young basaltic crust (e.g. Peruvian Coastal batholith) and

mantle-sourced gabbroic underplate (e.g. Peninsular Ranges batholiths), with

modifications from subduction zone components (Brown et al., 1984; Pitcher et al,

1985; Gromet & Silver, 1987; Silver & Chappell, 1988; Atherton, 1993; Allen et al.,

1995). Anatexis of basalt/gabbro occurs between 1090oC (water-saturated at 5 kbar) to

1250oC (anhydrous) (Yoder, 1979). A dioritic or gabbroic melt cannot be generated by

anatexis of the lower-crustal underplate under normal geothermal gradient or regional

metamorphism. The melting temperatures correspond to depths of 36-42 km at the

normal continental geothermal gradient (30oC/km), which approximates to the upper

mantle. Partial melting a basaltic underplate in the lower-crust requires temperature

higher than the normal geothermal gradient- a “thermal perturbation or thermal

anomaly” (Clemens & Droop, 1998). The addition heat is brought in by mafic

intrusions from the mantle. In the NNEO, the presence coeval mantle-derived gabbro

and diorite around the SCIC during the early to middle Triassic period (e.g. the

Monsildale Granodiorite and Goomboorian Intrusive Complex) supports the thermal

perturbation hypothesis for the generation of the W-RC group.

A GEOCHEMICAL COMPARISON BETWEEN THE SCIC AND THE NEARA

AND NORTH ARM VOLCANICS

The volcanic rocks in the southern NNEO consist of a calc-alkaline and a

tholeiite series. The calc-alkalic series comprises of the Early Triassic Neara Volcanics

(240-242 Ma) and the Late Triassic North Arm Volcanics (232 Ma), and the tholeiite

series consists of the Early Permian Highbury Volcanics (not discussed here). The

spatial association of the Triassic volcanics and the SCIC plutonic rocks suggests that

the two rock-types may be genetically related (e.g. Ringwood, 1974; Brown et al.,

1984). Orogenic andesite and related volcanic rocks formed in a subduction related

zones. Cessation of volcanism followed by uplift and erosion exposed the associated

plutonic rocks, which are assumed to underlie the volcanic edifices.


191

The Neara and the North Arm Volcanics are indistinguishable geologically,

but differ slightly in their geophysical characteristics and geochemistry. Geochemical

variations within the Neara and North Arm Volcanics are interpreted in terms of

Rayleigh fractional crystallisation process. The variation trends for the Neara

Volcanics involve fractional crystallisation of hornblende, pyroxene and anorthite

(Figure 6.15). The variation within the North Arm Volcanics is typical of hornblende-

dominated fractionation. On the Sr/Ba versus Ba plot (Figure 6.16), the inter-element

trends of the volcanic units are consistent with the fractionation process and disagree

with the partial melting process. Partial melting models (Allegre & Minster, 1978)

demonstrate that the Neara and North Arm Volcanics cannot be generated from batch

partial melting of mantle, N-MORB, E-MORB and island-arc basalt compositions

(Appendix 5). The variation trend for the Neara Volcanics conforms to fractionation of

hornblende, pyroxene and plagioclase from a basaltic composition, whereas the trend

for the North Arm Volcanics supports a hornblende-clinopyroxene dominated

fractionation from a more evolved island-arc basalt composition.

The Neara Volcanics differs geochemically, petrographically and isotopically

from the SCIC. Compared to the SCIC, the Neara Volcanics contains less TiO2, Fe2O3,

MgO and CaO, and is enriched in Al2O3, K2O and Ba at equivalent SiO2. The

Hammarstrom & Zen (1986) geobarometry calculates higher crystallisation pressures

for hornblende phenocrysts in the Neara Volcanics (>10 kbars) than pressures

calculated for the SCIC (<5 kbars) (Table 6.2). The initial 87Sr/86Sr and 143Nd/144Nd

ratios of the Neara Volcanics (0.70152-0.70330 and 0.51253-0.51259 respectively) are

lower than the isotopic values of the SCIC, suggesting lower Rb/Sr and Sm/Nd in its

source. The Sr and Nd initial isotopic ratios plot within the HIMU field (Zindler &

Hart, 1986). HIMU is characterised by low 87Sr/86Sr, intermediate 143Nd/144Nd, and

high 206Pb/204Pb and 208Pb/204Pb, which suggests a source enriched in U and Th relative

to Pb. The proposed source region for HIMU is from contaminated upper mantle by

components derived from subducting oceanic plate, and Pb-Rb removal by

metasomatic fluids (Zindler & Hart, 1986; Rollinson, 1993). The model age of the

Neara Volcanics (TDM =776 Ma) is older than the SZM-derived magma (~622 Ma),

therefore, supporting evidence for crustal contamination in the source region.

Differences in isotopic chemistry, crystallisation conditions and older radiometric ages

suggest that the Early Triassic Neara Volcanics and the SCIC are not co-magmatic, but

are derived from a similar subduction setting.


192

12

14

16

18

20A

lO w

t %

23

0

4

12

8

FeO

wt %

0 1 2 3 4 5 6 7M gO wt %

0

5

10

15

Ca

O w

t %

Figure 6.15: Major elements plotted against MgO for the Neara and North Arm Volcanics. Arrows represent Rayleigh fractionation trends for 10% of olivine (Fo ), clinopyroxene (Wo En ), plagioclase (An ) and K-feldspar (An ).

8 5 4 5 4 0

8 5 5

Neara Volcanics

Figure 6.16: Sr/Ba versus Ba plot comparing geochemical variations within the Neara and North Arm Volcanics (bold arrows) to partial melting (black arrows) and crystal fractionation (grey arrows) trends. Variation in the Neara Volcanics resulted from hornblende, pyroxenes and plagioclase fractionation, whereas the variation in the North Arm Volcanics involved predominantly hornblende fractionation. Geochemical fields for the SCIC are plotted for comparison.

Mountt Mucki Diorite




Woonga Granodiorite

Ol Olivine

Cpx Clinopyroxene

Plag Plagioclase

Hb Hornblende

Ksp K-feldspar

MM

GQMWGRCG

WOG

Neara

Cpx

Plag

Hb

Ksp

Cpx

Plag-KspHb

PlagCpx

Hb

Ksp

North Arm

Hb

Plag

Neara

North Arm

North Arm

NearaHb-Plag

HbHb-Plag Cpx+

Hb

North Arm Volcanics

Interpreted fractionation trend within a geochemical group, fractionating phases indicated ( bold). Hb

Mineral vector from 10% Rayleigh fractionation.

Ba

20

10

5

30

30

3030

30

Mineral vector diagram for 30 modal % of crystal fractionation. The different arrows relate to the geochemical trends from the removal of individual mineral phases. Numbers on the arrow are the % of FC.

Mount MuckiDiorite




MANTLE

E-MORB

IAB(tholeiite)

IAB(calc-alkaline)

Partial melting trends from standard source compositions. The numbers refers to the degree of melting (wt%).


193

The North Arm Volcanics has similar geochemistry and age to the W-RC

group of the SCIC. The volcanic unit superimposes on the SCIC geochemical domains

on Harker diagrams, and has similar REE pattern and REE enrichment factors. The

likely parental magma of the North Arm Volcanics is the evolved island-arc magma,

similar to the W-RC group, and the volcanic unit may be co-magmatic to the

Woolooga and the Rush Creek Granodiorites.

PETROGENETIC SUMMARY

The SCIC is hosted in the NNEO Devonian-Carboniferous accretionary

complex suggesting that these supracrustal rocks are unlikely sources to the SCIC. Sr

and Nd isotopic ratios and an I-type granite composition ranging from monzogabbro

through monzogranite support a mantle-derived magma source. The monzogabbro-

monzogranite has primitive initial 87Sr/86Sr ratios of 0.70312 to 0.70391, and εNd of

4.19 to 1.28 that suggests close genetic linkage to mantle. A calc-alkalic composition,

negative Nb, Ta and Ti anomalies, and ‘volcanic arc granite’ classification, are

consistent with emplacement within a continental margin environment influenced by

subduction.

Chemical and isotopic data for the most primitive magma of the SCIC suggest

that magma genesis is initiated as slab-derived fluids enriched in incompatible

elements invaded the mantle wedge. Partial melting of this mantle source region

produces the primitive mafic magmas, which are parental to the range of rock types

observed in the SCIC. The parental magma (MMD) with low 87Sr/86Sr plots within

both MORB and OIB isotopic fields implying ‘enriched’ mantle source that is typical

of the subduction zone mantle (SZM) (e.g. Perfit et al., 1980b; Arculus & Johnson,

1981; Pearce, 1983; Arculus & Powell, 1986). Mixing of mantle component with slab-

derived component has displaced the bulk magma source along the mantle array

(DePaolo & Wasserburg, 1979).

The SCIC has two distinct geochemical groups: the Mount Mucki Diorite-

Gibraltar Quartz Monzodiorite (MMD-GQM) and the Wooolooga-Rush Creek

Granodiorite (W-RC) separated by a small compositional gap. (A third group- the

Woonga Granodiorite is altered and its geochemistry is unsuitable for petrogenetic

modelling). The earlier W-RC group (Middle Triassic) is calc-alkalic whereas the later


194

Late Triassic MMD-GQM group is tholeiitic to calc-alkalic. There is a strong positive

correlation between 87Rb/86Sr and initial Sr for the two geochemical groups, inferring

strong petrogenetic relationship between the groups. The initial Sr isotopic values are

relatively uniform, defining a total rock isochron of 246 + 7 Ma. The εNd and TDM are

more variable (1.28 to 4.19 and 615-768 Ma, respectively; Table 5.3) that suggest

either more heterogeneous source or a complex magmatic history. The MMD-GQM

group has REE pattern consistent with olivine, pyroxenes, hornblende and magnetite

fractionation from a basaltic parent. In contrast, the W-RC group has higher K and

SiO2, calc-alkalic and has REE pattern that is consistent with hornblende and pyroxene

fractionation. However, different fractionating mineralogy alone cannot explain the

observed geochemical and isotopic differences between the two groups, and argues

against the groups being end-members of a fractionation series. The change in

composition reflects a fundamental change in the mantle conditions, and the tectonics

of the time. Different source compositions in combination with different fractionating

mineralogy and different amounts of subduction/crustal components caused the

geochemical differences between the MMD-GQM and W-RC groups (Figure 6.17).

The MMD-GQM group (227 Ma)

The source of MMD-GQM group consists of two main components - the

mantle overlying a subduction slab of oceanic lithosphere, and a subduction slab

component (either hydrous fluid or a partial melt derived from the subducted oceanic

crust). The source region shows both MORB- and OIB-source characteristics,

implying melt components from both the asthenospheric mantle and the overlying

lithospheric mantle. Diapiric upwelling of the deeper-seated asthenospheric mantle

could have caused the partial melting of depleted lithospheric mantle (MORB-source).

TDM model ages of ~622-700 Ma estimates either the time when the depleted

lithospheric mantle magma separated from the mantle to formed part of the continental

keel, or mixing of older lithospheric mantle with younger asthenospheric mantle. In the

past 1,000 million years, Australia was part of two supercontinents- Palaeozoic

Gondwanaland and Neoproterozoic Rodinia (Li & Powell, 2001). A major episode of

rifting during the break up of Rodinia at ~780 Ma (Li & Powell, 2001) was

accompanied by mantle plume underplating the Australian lithosphere (Park et al.,

1995; Li et al., 1999). Younger Neoproterozoic model ages for the SCIC are


195

interpreted as evidence for mixing older lithospheric mantle melts with approximately

15 to 30% younger asthenospheric melt generated during subduction.

The conditions of magma production interpreted from geobarometry,

thermometry and whole rock geochemistry, suggest a high melting temperature above

980oC at relatively shallow depth (<8 kbars). The enrichment of incompatible elements

(K, Rb, Sr, Ba and Th) requires the involvement of components derived from the

subducted oceanic crust (hydrous fluids or a partial melt) (Perfit et al., 1980, Arculus

& Johnson, 1981; Arculus & Powell, 1986).

The variation within the MMD-GQM geochemical group is produced by

fractionating hydrous tholeiitic magma (~0-4 wt% H2O) generated from the partial

melting of upper mantle sources, with minor addition of juvenile crust component. The

Gibraltar Quartz Monzodiorite has higher concentrations of mobile and immobile

elements, higher 87Sr/86Sr and lower 143Nd/144Nd ratios, which reflect a modified SZM

melt by crustal (CR) and recycled subducted oceanic lithospheric components.

Langmuir et al. (1978) two-component modelling calculates ~5 wt% crustal

component in the Gibraltar Quartz Monzodiorite. Hence, both geochemical and

isotopic evidences indicate that the Gibraltar Quartz Monzodiorite deviates from the

SZM melt (MMD) because of crystal fractionation (clinopyroxene-plagioclase

dominated) and the involvement of subduction-zone sediments.

W-RG group (231-234 Ma)

The W-RC group is a more isotopically evolved, high-K, high-alumina, calc-

alkalic group, enriched in LREE, K, Rb, Cs, Ba, Sr, Zr, U and Th. The geochemistry is

typical of subduction zone enrichment of lithospheric mantle, coupled with crustal

assimilation and fractional crystallisation in zones of thickened crust (e.g. Brown et al.,

1984). The W-RC group has typical continental arc characteristics, implying at least

two components in its petrogenesis- an isotopically primitive component represented

by mantle-derived magmas or juvenile crust, and an isotopically evolved upper-crustal

melt (e.g. the Nerangleigh Fernvale beds). Calculated model ages (TDM= 733-768 Ma)

are older than the MMD-GQM group (derived from the same lithospheric mantle

source), which affirm contaminations from older upper crustal component. For

example, mixing 15 wt% of supracrustal melt (i.e. foliated granodiorite, TDM=1222


196

Ma) with the mantle-derived melt (MMD), yielded a similar model age (712 Ma) to

the W-RG group.

Enrichments in LREE, a relatively flat MREE to HREE pattern, and a

moderate negative Eu anomaly of the W-RC group involved partial melts from a mafic

source, where the resulting magma was in equilibrium with a gabbroic residue. A

mafic source region containing plagioclase constrains the source region to less than 30

km, as plagioclase does not readily crystallise from basic melts at greater depths

(Powell, 1978). Geochemistry, geobarometry and thermometry suggest a high melting

temperature above 870oC under relatively anhydrous conditions at shallow depth (<8

kbars). Low pressures calculated from hornblende geobarometry (0.3-3.3 kbars)

support evidences of a high-level crustal magma reservoir. Metasomatic interaction of

magma with crustal and high-temperature hydrothermal fluids is evident from low

oxygen isotopic values (δO = 2.5-8.5 o/oo) and the crystallisation of subsolidus biotite,

amphiboles and chlorite. The probable source for the W-RC group is from the partial

melting of SZM wedge, with additional components from meta-igneous sources (e.g.

basaltic underplate within lithospheric mantle) and the upper crust. The thermal effects

of SZM-derived basaltic magma partial melted the lithospheric mantle and crustal

underplate, producing an intermediate magma composition. Least squares and trace

elements fractionation calculations suggest that the geochemical variation within the

W-RC group is initially controlled by the removal of pyroxene, calcic plagioclase,

hornblende and magnetite; and later the removal of K-feldspars, hornblende and

ilmenite towards granitic compositions. The ‘parental magma’ (SC1069) composition

is similar to the island arc calc-alkaline basalt, contains contributions from oceanic

crust and supracrustal melts (SC106).

Comparing the SCIC with the Lower Triassic Neara Volcanics

The Neara Volcanics is calc-alkalic and has negative Nb, Ta and Ti anomalies

on MORB-normalised spidergram, typical of volcanic arc magma. The volcanic unit

plots within the HIMU isotopic reservoir (Zindler & Hart, 1986), which implies a

lithospheric mantle source with additional components derived from subducting

oceanic plate and metasomatic fluids. Hornblende geobarometry calculates >10 kbars

amphibole stabilisation pressures, inferring relatively hydrous magma conditions. The


197

model age of the Neara Volcanics (TDM =776 Ma) is older than the SZM-derived

magma (~602 Ma), supporting evidence for crustal contamination in the source region.

Geochemical variation within the Neara Volcanics resulted from shallow-level

fractionation of hornblende, pyroxene and plagioclase from a hydrous basaltic

composition. The differences in isotopic chemistry, crystallisation conditions and older

radiometric ages suggest that the Neara Volcanics and SCIC are not co-magmatic, but

are derived from a similar subduction setting.


198

Fractionalcrystallisation

Granodiorite

1st Stage

2nd stage

Quartzmonzodiorite Monzogabbro

Granite Quartzmonzodiorite

Woonga Granodiorite 237 Ma

Woolooga-Rush CreekGranodiorite 231-234 Ma

Mount Mucki Diorite- Gibraltar Quartz Monzodiorite 227 Ma

GROUP Age Ma

MANTLE-DERIVED BASALTIC UNDERPLATE

? Dioritic

Partial melting

Direct subduction-zone mantle contribution

PyroxenesOlivine?PlagioclaseMagnetite

AugiteHornblendePlagioclaseMagnetite

???AugiteHornblendePlagioclase

? Direct subduction-zone mantle contribution


Figure 6.17: A petrogenetic summary of the Station Creek Igneous Complex.

Chapter 7: Geological Synthesis and Conclusions

199

CHAPTER 7: GEOLOGICAL SYNTHESIS AND CONCLUSIONS

Magmatism: implications for growth and evolution of the eastern Australian

continental margin

Eastern Australia evolved from an island-arc or back-arc system to an Andean-

style convergent margin (Bruce et al., 1998). Modern plate-tectonic theory suggests that

magmatism at convergent plate boundaries played a dominant role in the growth of

continents. Westward subduction of oceanic crust beneath the eastern margin of the

Australian plate initiated partial melting, giving rise to magmatism in the NEO (e.g.

Murray et al., 1987; Flood & Aitchison, 1993; Aitchison & Flood, 1995; Aitchison et al.,

1999). The differentiation of predominantly mantle-derived magmas led to the production

of intermediate rocks that made up the continental crust.

Magmatism in southeast Queensland of the NNEO was episodic and showed

temporal geochemical changes (Figure 7.1; data in Appendix 7). The geochemical

variation appraised using the combination of K2O, MgO and aluminousity, reflected

different tectonics and source regions (Gust et al., 1993, 1996). Plutonic rocks between

320 and 300 Ma included both I-type and S-type calc-alkalic granitoids associated with

the Devonian to Mid Carboniferous convergent margin (Tang & Gust, 2002). The I-type

granitoids were primarily hypersthene bearing diorites, low-K and metaluminous; typical

of mantle derived magma. The S-type granites were derived from juvenile crustal sources

at depth >26 km, and were emplaced along extensional faults (Holcombe et al., 1993).

Magmatism recommenced at 280 Ma following approximately 20 Ma lapse. The I-type

rocks between 280 and 260 Ma were predominantly tholeiitic and bimodal in character.

Widespread calc-alkalic magmatism recurred at 260 Ma, peaking between 240 and 230

Ma. The 260-245 Ma magmatism was low- to medium-K and metaluminous, reflecting

strong mantle affinity. Magmatism between 245 and 230 Ma was compositionally diverse

(high to low K2O and MgO, metaluminous to peraluminous) ranging from gabbro/diorite to

granite, and the dominant composition being granodiorite. Available strontium isotopic

data showed that these granitoids have mantle-derived sources with crustal components.

Bimodal magmatism dominated during the period 230-220 Ma, followed by anorogenic


200

010

20

30

Fre

qu

en

cyA. Temporal distribution of magmatism in southeast Queensland from 120 to 320 Ma.

120 150 200 250 300 Ma

B. Variations of K O (wt %) contents of representative magma from 120 to 320 Ma.2

KO

con

tent

(Wt %

)2

120 150 200 250 300 Ma

Age

Age

297-320 Ma

I- and S-type calc-alkalic granites.

ubduction of

Magmatism associated with

crustal thickening and

active s

280-297 Ma

No magmaticactivity.

End of the Devonian to mid Carboniferous subduction?

Tectonic quiescence.

260-280 Ma

Bimodal, I-type magmatism.

Back-arc extension related to a westward-

dipping subduction - the

Gympie Arc?

245-260 Ma

Low- to medium-K, I-type, calc-alkalic

magmatism.

Subduction related magmatism, derived

primarily from the upper mantle with

oceanic continental crustal inputs.

+

230-245 Ma

Low- to high-K, I-type, calc-alkalic magmatism, compositionally diverse.

Subduction related, magma derived from asthenospheric and

lithospheric mantle with continental crust

components.

220-230 Ma

Bimodal, I-type magmatism, strong mantle signatures.

Subduction related with episodic extensions, magma derived from asthenospheric and

lithospheric mantle with minor crustal components.

210-220 Ma

Anorogenic, alkaline, bimodal, mildly A-type

granites.

Extensional tectonics possibly related to

slab-retreat.

INTE

RPR

ETAT

ION

S

0.7

0.8

0.9

1.0

1.1

1.2Peraluminous(S-type granite)

Metaluminous(I-type granite)

Mean MgO

AlO

/(CaO

+Na

O+K

O)

23

22

120 150 200 250 300 Ma

C. Anomaly plot: variations of MgO versus A/CNK of magmas from 120 to 320 Ma

Age

Figure 7.1: Te southeast Queensland of the northern New England Orogen between 320 and 120 Ma. A) Distribution of magmatism, B) K O contents, and C) Anomaly plot using MgO versus A/CNK. (The radiometric ages of the magmatic units are expressed in Ma, and data is tabulated in Appendix 7).

mporal geochemical changes in magmas of

2

Mount Mucki Diorite




Woonga Granodiorite

Other magmatic units


201

and bimodal granitoids between 220-210 Ma that consisted of gabbros and mildly A-type

granites.

The termination of calc-alkalic magmatism at 300 Ma and recommencing at 280

Ma reflected the cessation of the mid-Palaeozoic subduction and development of a new

west-dipping subduction zone to the east i.e. the Gympie arc (Sivell & McCulloch, 1993).

The bimodal magmatism between 280 and 260 Ma reflected changes in source region,

possibly related to a back-arc extensional tectonism (Sivell & McCulloch, 1993,1997).

Cawood (1984) suggested that a component of strike-slip plate motion might have

influenced early Permian volcanism at the Gondwana margin. Widespread calc-alkalic

magmatism between 260 and 220 Ma was characteristics of mantle-derived magma,

contaminated by components of crustal rocks (e.g. Stephens, 1991; Gust et al., 1993;

Kwiecien, 1996; Hanson, 1998). The Late Permian to Mid Triassic period was commonly

regarded as an overall contractional episode (Holcombe et al., 1997a). The plutonic

bodies emplaced during the calc-alkalic phase have volcanic arc affinities; implying

subduction-related magmatism possibly linked to a westward dipping subduction zone- the

Gympie arc. Bimodal magmatism dominated during the 230-220 Ma period, corresponding

to episodic extensional tectonics, whereas alkaline magmatism of Late Triassic granitoids

reflected extensions (Stephens, 1991).

Within the Triassic, magmatism during the period between 245 and 225 Ma was

dominated by plutons with mantle signatures (Figure 7.1). The change from a dominantly

calc-alkalic granodiorite composition of the Early-Middle Triassic to bimodal granite-

gabbro compositions in the Late Triassic, reflected significant changes in the source regions

as well as the tectonic regimes. Detailed geologic and petrogenetic study of the SCIC (227-

237 Ma) and the Neara Volcanics (240-242 Ma) provided additional insights into the

Triassic mantle as well as the tectonic framework of eastern Australia. This chapter

brings together the geological evidences to synthesis the petrogenetic and tectonic

evolution of eastern Australia during the Triassic era (Figure 7.2).

The Early Triassic

The widespread calc-alkalic magmatism of the Early Triassic had been linked to


202

episodes of contractions and extensions related to the Hunter Bowen Orogeny (Holcombe

et al., 1997a). The early Triassic Neara Volcanics is calc-alkalic and have typical

continental arc signatures derived from a depleted mantle or primitive lower crustal

sources, but isotopic ratios suggested substantial oceanic crust involvement. The presence

of oceanic crust within the lithospheric mantle during the early Triassic supported

evidence for a westward subduction during the Permian-Triassic period. The outboard

Gympie island arc probably sit to the east of the NNEO during the early Triassic period.

A rapid ascent of mantle melts to shallow level indicated an extensional regime in the

region behind the accreting Gympie arc.

Middle Triassic

The Middle Triassic Woolooga Granodiorite (234 Ma) and Station Creek

Granodiorite (231-232 Ma) are reversed zoned plutons that implied possible disruption of

vertically stratified magma chambers (Mahood & Cornejo, 1992). The reversed zonation

in plutons have been linked to magma resurgence (e.g. Nabelek et al., 1986; Fridrich &

Mahood, 1984; Allen, 1992) or related to active tectonics (e.g. Beard & Day, 1987

&1988; Mahood & Cornejo, 1992; McMurry, 2001). In the Rush Creek Granodiorite,

undeformed oligoclase mantled fractured andesine. The fractured cores were indicative of

episodic brittle deformation/strains after their initial crystallisation- possibly associated

with contractional deformation, followed by periods of tectonic quiescence during which

the undeformed rims and interstitial plagioclase crystallised.

The Woonga Granodiorite (237 Ma) has primitive isotopic signatures that

suggested a mantle-derived fractionate. The composition of the Woolooga and Rush

Creek Granodiorites reflected a combination of melts derived from the subduction zone

mantle, basaltic underplate and significant proportions of local crustal components. Their

chemistry is typical of continental-margin I-type granitoids, formed during active

subduction. Melting of crustal underplate required an input of hot mafic tholeiitic mantle-

melt (e.g. the parental magma for Woonga Granodiorite), which might be introduced

during episodic extensional tectonism in the terminal stage of subduction. Crustal

contaminants might be introduced into the lower crust, or assimilated during magmatic

residence in high-level magma chambers.


203

Figure 7.2: The Early-Triassic to Late-Triassic tectonic evolution of the eastern Australian continental margin

A. Early Triassic - The Neara Volcanics (240 to 242 Ma)

B. Middle Triassic - The Woolooga-Rush Creek Granodiorite group and the Woonga Granodiorite (231 to 237 Ma)

C. - The Mount Mucki Diorite - Gibraltar Quartz Monzodiorite Group and andesitic dykes.

Late Triassic


Magmat ism

Isotopic evidence

Geochemical evidences

Petrograph ic evidence

: Part ial melt ing of subducting oceanic plate to form the Neara Volcanics.

: Sr-Nd isotopic ratios correspond to the HIMU mantle reservoir.

: Volcanic arc-type magma, calc-alkaline, medium to high potassium, high alumina composition with high Ba and Sr. LREE enriched and has the Nb, Ta and Ti troughs typical of s u b d u c t i o n z o n e magmatism.

: Ear ly hornblende stabilisation. Hornblende geobarometry indicates crystallisation pressures >16 Kbars

Tectonics: Transpressional tectonics

Subducting plate

Subducting plate

Subducting plate

Slab fluids induces partial melting ofthe mantle wedge

Gabbroic underplating the lower continental crust

Partial melting ofthe subductingoceanic crust

Continental crust

Continental crust

Palaeozoic accretionary wedgeNeara Volcanics

Dehydration magmatisminduces partial melting ofthe mantle wedge


Magmatism

Isotopic evidence


Petrographic evidence

: Partial melting of the subduction zone upper

gabbroic underplate.

: Contamination of depleted mantle melt by j u v e n i l e c r u s t s a n d seawater.

: Volcanic arc-granite, calc-alkaline, high potassium, high alumina composition with elevated Ba and Sr. LREE and LIL enriched and has the Nb, Ta and Ti troughs typical of s u b d u c t i o n z o n e magmatism.

: High P-T melts at pressures < 8 Kbars

Tectonics: ? Change-over from contractional to extensional tectonism.

mantle and the


Magmatism

Isotopic evidence


Petrographi c evidence

: Partial melting of the upper

: Depleted mantle contaminated by juvenile crusts and seawater. Cf PREMA source

: Transitional tholeiitic, high potassium, high alumina composition, LREE and LIL enriched and has the Nb, Ta and Ti t r o u g h s t y p i c a l o f s u b d u c t i o n z o n e magmatism.

: Ear l y stabilisation of hornblende indicating high water content at P< 8 Kbars

Tectonics: Extensional tectonism.

mantle from water released from subducting plate.

Partial melting of subductionzone mantle with contributionsfrom the gabbroic underplate

Woonga Granodiorite

Woolooga-Rush CreekGranodiorite

Dehydration induces partial melting ofthe mantle wedge

Asthenospheric and lithospheric mantle melts manage to reach higher levels to form the MMD-GQM group

EXTENSION

Lithospheric mantle

Asthenospheric mantle

Slab fluids




204

Late Triassic

The Mount Mucki Diorite (227 Ma) and the Gibraltar Quartz Monzodiorite)

have a transitional tholeiitic characteristics that suggested a mantle fractionate. Arc-type

tholeiitic gabbro emplaced at shallow-level (<2 kbars) implies a subduction-related

extension regime and a higher heat source than the normal continental geothermal

gradient. Evidence of regional extension was supported by widespread dyking and the

formation of a 100 km dyke swarm from Brooyar Forest to the Rosedale area. The ages

of dyke ranged from 229 Ma (Roberts, 1992) in the NDB, to 222.6 (Ar/Ar, hornblende)

and 223.6 Ma (K/Ar whole rock) (Irwin, 1973) in the Esk Trough. Nash & Jones (1996)

suggested that the NW-trending dyke swarms were related to the Mount Perry Fault and

the Late Triassic crustal extension that provided pathways for the magma ascent. The

230-220 Ma Triassic plutonism was felsic and had A-type granite affinity, forming

discrete calderas with compositions suggesting derivation from older continental crust

(Holcombe et al. (1997a). These characteristics probably resulted from crustal melting in

an extensional environment established after the termination of the early Hunter-Bowen

Orogeny (Holcombe et al., 1997b; Allen et al., 1998).

Summary

The Late Permian to Mid Triassic period was commonly regarded as an overall

contractional episode (Holcombe et al., 1997a), with evidence of a western dipping

subducting oceanic plate (Figure 7.2). The geologic evidences from the SCIC and dykes

indicated a relatively tectonic quiet period at 237 Ma. The period between 237 and 232

Ma was punctuated by episodic brittle deformation possibly related to an overall

contractional tectonics. The 231-232 Ma period (ages of the Rush Creek Granodiorite)

represented a tectonically quiet time, possible during the changeover between

contractional to extensional tectonics. By 229 Ma (earliest age for dykes), regional

extension was established as evident from the reactivation of NW structures (Nash,

1986). The Mount Mucki Diorite (227 Ma) and the Gibraltar Quartz Monzodiorite were

emplaced during this period of active dyking. Both plutons have a transitional tholeiitic

characteristic hinting of mantle-sourced plutons. The migration of mafic magma to high

levels was most likely aided by extensional tectonics (e.g. Miller et al., 2000). The most


205

likely period for the transition from contraction- to extension-related magmatism occurred

in the Late Triassic (~227-229 Ma), marking the onset of the prolonged break-up of

Gondwana.

CONCLUSIONS

1. The Station Creek Igneous Complex consists of five discrete high-level plutons - the

Woolooga Granodiorite (234 Ma), Rush Greek Granodiorite (231-232 Ma), Mount

Mucki Diorite (227 Ma), Gibraltar Quartz Monzodiorite (227 Ma) and Woonga

Granodiorite (237 Ma). The plutons form three distinct geochemical groups - the

Woolooga-Rush Greek Granodiorites (W-RC), Woonga Granodiorite, and the Mount

Mucki Diorite-Gibraltar Quartz Monzodiorite (MMD-GQM) groups, which relate to

different source regions.

2. The Woolooga-Rush Greek Granodiorite group (W-RC) is high-K, and composition

ranges from biotite monzogranite to hornblende granodiorite and quartz

monzodiorite. Major and trace element geochemistry in combination with radiogenic

isotope data indicated the source of the W-RC group was derived from a juvenile yet

more evolved mafic source, and an isotopically evolved crustal source. The W-RC

group has higher SiO2 content (>65 wt%) and overall higher initial Sr ratios

(>0.70353) and lower εNd values (<1.8) than the MMD-GQM group. The W-RC

contains early-formed pyroxene, indicating that was initially relatively dry melt, with

the appearance of hornblende and the development of water saturation at shallow

crustal levels (<4 kbar pressure). The W-RC is LREE enriched, and has relatively flat

MREE-HREE pattern characterized by moderate negative Eu anomaly. The REE

pattern is consistent with a petrogenetic model involving partial melting of

lithospheric mantle at temperatures >900°C and at pressures of less than 8 kbars,

followed by the fractionation of clinopyroxene, hornblende, plagioclase and Fe- Ti

oxides. Addition components to the magma were from plagioclase-bearing basaltic

underplate and upper crust (10-14 wt%).


206

3. The early Late Triassic MMD-GQM group (87Sr/86Sr of 0.70312 to 0.70325) is

transitional tholeiitic to calc-alkalic, sourced mainly from depleted mantle source with

<<5% crustal component. Trace element and isotopic evidences suggested mixing of a

MORB- and OIB-type mantle, with the addition of LIL-enriched subduction fluids. The

MMD-GQM was a relatively hydrous magmatic system that fractionated hornblende,

augite, anorthite, magnetite and possibly olivine from a gabbroic parent. The MMD-

GQM has a relatively flat MREE-HREE pattern lacking Eu anomaly, which was

consistent with the involvement of hornblende as a fractionating phase. The absence

of steep REE pattern suggests that garnet was absent in the source region,

constraining the source to <8 kbars (depths <26 km). The petrogenetic model for the

MMD-GQM is from partial melting of lithospheric mantle mixed with asthenospheric

mantle (15-50 %) at temperatures >1000°C and at pressures of <8 kbars, followed by

low pressures (< 5 kb) crystal fractionation.

4. The mid Middle Triassic Woonga Granodiorite (237 Ma) is calc-alkalic and has

primitive isotopic values (87Sr/86Sr of 0.70318), suggesting a juvenile source with

mantle signatures. The granodiorite had been partly metasomatised.

5. The Neara Volcanics (241-242 Ma) is derived from the partial melting of upper-

mantle with additional component from the subducting oceanic plate. Isotopic and

geochemistry established that the volcanic unit is not co-magmatic to the Station

Creek Igneous Complex.

6. The dominantly calc-alkalic affinity of the SCIC is an indicator of an Andean-type

tectonic environment. The plutons are characteristic of continental island-arc

granitoids that suggested upper mantle-sourced melts with involvement of crustal

component (up to 14 wt%). The changes in magma chemistry between 237 to 227 Ma

reflected changes in source characteristics and tectonic styles. Diminishing crustal

component from 234 to 227 Ma suggested thinning of the subduction complex due to

crustal attenuation, leading to the Late Triassic extension. High-level emplacement of

mantle-fractionates at 227 Ma supported evidences for the termination of contraction

tectonics and the beginning of extension tectonism in the northern New England


207

Orogen.

7. The TDM model ages for the parental magma of the SCIC are 620-700 Ma, clearly

verifying the involvement of older lithospheric mantle. The SCIC has a narrow range

of initial 87Sr/86Sr ratios (0.70312 to 0.70391) and a wider range of εNd values (+1.35

to 4.2), which indicates a diverse source region. The relatively variable εNd values

and uniformly low initial 87Sr/S6Sr ratios suggest mixture of isotopically evolved

rocks with mantle-derived melts.

References

208

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APPENDICES

LIST OF APPENDICES APPENDIX 1 – ANALYTICAL METHODOLOGIES

I. SILICATE ROCK ANALYSIS BY ICP 1 II. LOSS ON IGNITION 3 III. DETERMINATION OF FERROUS AND FERRIC IRON 4 IV. DETERMINATION OF S, CO2 AND H2O+ 6

APPENDIX 2 – WHOLE ROCK GEOCHEMICAL DATA I. WHOLE ROCK GEOCHEMISTRY 8 II. STABLE ISOTOPE DATA FOR ORE DEPOSITS 22 III. RADIOMETRIC DATA 22 IV. COMPARISON OF GEOCHEMICAL RESULTS

USING THE DIFFERENT ANALYTICAL TECHNIQUES 22 V. GENERIC GEOCHEMISTRY (RECALCULATED) 23

APPENDIX 3 – PHASE CHEMISTRY DATA 30

APPENDIX 4 – PETROGRAPHIC DATA 38 MODAL COMPOSITION (POINT COUNTING)

APPENDIX 5 – PETROGENETIC MODELLING MATHEMATICAL EQUATIONS USED IN PETROGENETIC

MODELLING 40 FRACTIONAL CRYSTALLISATION MODELS 41 MIXING AND ASSIMILATION MODELS 49 ASSIMILATION-CRYSTAL FRACTIONATION MODELS 56 PARTIAL MELTING MODELS 60

AVERAGE GEOCHEMISTRY OF MAJOR SOURCE REGIONS 67 PARTITION COEFFICIENTS 68

APPENDIX 6 – REPRESENTATIVE PETROGRAPHY 70

APPENDIX 7 – RADIOMETRIC AGES, SOUTHEAST QUEENSLAND AGES OF LITHOLOGIC UNITS 77 GEOCHEMISTRY VERSUS AGES OF PLUTONIC ROCKS

IN SOUTHEAST QUEENSLAND 79

APPENDIX 8 – MINERALISATION POTENTIALS 83

Abbrevia tions: Amph. = amphoiblite Gt. = granite Rhyo. = rhyolite And. = andesite Mdio = monzodiorite Serp. = serpentine Bas = basalt Mgt. = monzogranite Ton. = tonalite Bas-an. = basaltic andesite Por. = porphyry Trach. = trachyte Cat. = cataclastic Mongab = monzogabbro Trand. = trachyandesite Dac. = dacite Monz = monzonite Trem.sch = tremolite schist Dio. = diorite QMD = quartz monzodiorite Dy = dyke QMG = quartz monzogabbro Fo. = foliated Qmonz = quartz monzonite Gd. = granodiorite Qtz dio. = quartz diorite

APPENDIX 1- ANALYTICAL METHODOLOGIES

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I. SILICATE ROCK ANALYSIS BY ICP

This procedure (Silicate 3/93) is a modification of an existing School of Natural Resource Sciences atomic absorption method of silicate rock analysis (Kwiecien, 1990) using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). The method allows for the determination of all-10 major oxides as well as strontium and barium, from the one sample solution using standard silicate reference materials. Iron is determined as total ferric iron (Fe2O3T). Sample Preparation A representative sample of silicate rock is to be crushed in the jaw crusher, split and finally ground in a

chrome-steel ring mill for about 3 to 4 minutes until approximately 150-200 mesh fineness. Reagents

Hydrofluoric Acid (AR grade or better) 50%. 4mls per sample. Aqua regia (1:3 Nitric / Hydrochloric Acid - AR grade). 1ml per sample. Boric Acid (AR grade or better) 50g/litre. 50mls per sample. (It will be necessary to heat to 70°C and

stir on magnetic stirrer to dissolve). Deionised water in preference to distilled water (check Si content of distilled water).

Calibrating Standards

USGS reference standards or other silicate rocks covering the expected compositional range of the rocks to be analysed.

Control Standard

Each student will be required to include at least one or two control standards (supplied by the School of Geology) in each batch of analysis. This will be used to monitor analytical technique, instrument calibration and drift.

Apparatus:

Digestion bottles: Nalgene 125ml polypropylene or low-density polyethylene (code number 2003-0004) with a machined gas tight tapered plastic screw cap.

Storage bottles: Nalgene 250ml low-density polyethylene storage bottles. 200ml borosilicate volumetric flask. 50mm polyethylene funnel. 10ml polyethylene pipette. 250ml polyethylene beaker. 25ml polyethylene measuring cylinder. 50ml polyethylene measuring cylinder. Pipette sucker. Wash bottle. Water bath.

Apparatus Preparation

(a) Preparation of storage bottles. Transfer approximately 20mls 1:3 nitric acid to a bottle, shake vigorously for about 30 seconds, and transfer to the next bottle. Rinse the bottle thoroughly at least 3 times removing all traces of nitric acid and oven dry at 50°C.

(b) Volumetric flasks.

Treat with nitric acid similar to the above procedure. PROCEDURE 1. Dry the powdered* rock sample in an oven at 105-110°C for 1 hour and allow to cool in a desiccator. *(This procedure relies on all of the constituents being ground extremely fine for complete dissolution

to occur) 2. Weigh exactly 0.2000g (± 0.1mg) of dry - 200* mesh rock powder into a glass weighing bottle and

quantitatively transfer to a pre-cleaned, labelled digestion bottle, and recap. Re-weigh the weighing bottle and calculate the exact weight of sample used. Write this weight on the digestion bottle if the weight is not 0.2000g.

APPENDIX 1 – ANALYTICAL METHODOLOGIES

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3. Premix the required volume of digestion acid in a polyethylene beaker allowing extra acid for the blank preparation. Prepare one blank for each batch of analysis. The ratio for 20mls of digestion acid (4 samples) is as follows: 1ml Nitric acid, 3mls hydrochloric acid and 16mls hydrofluoric acid.

4. Remove cap from the digestion bottle and lightly tap the corner of the bottle to consolidate the rock powder to one side (shown in the diagram below). Slowly rotate the bottle 180° and pipette in (plastic pipette) 5mls of acid mixture into the side of the bottle not allowing it to come in contact with the silicate sample. Recap the bottle tightly and swirl the contents. Allow the sample to stand overnight. Check for complete dissolution and if necessary the bottles may be heated in a water bath at 50°-60°C until the sample is dissolved

5. After digestion cool the bottles in a deep freeze (-15°C) for 15 minutes. Remove the bottles one at a

time to the fume cupboard and rapidly add 50mls (at 20°C) of boric acid solution (50g/litre). Alternatively and preferably, the digestion bottles may be transferred to the fume cupboard half submerged in a tray of ice during the addition of the boric acid solution. Recap the bottle and shake vigorously. Allow to stand for about 10 minutes and re-shake. If the solution is not completely clear heat the bottles to 60°C in a water bath for 30 minutes to dissolve all precipitated fluorides.

6. Remove the cap from digestion bottle and add approximately 30mls deionised water. Transfer the contents to a 200ml borosilicate volumetric flask via a 50mm polyethylene funnel. Rinse the bottle at least three times transferring the contents into the funnel. Make up to the mark, shake vigorously and rapidly transfer to a pre-cleaned 250ml polyethylene storage bottle. The final concentration of silicate rock is 0.2000g/200ml. Determine all 10 major oxides directly from this solution using silicate reference materials (calibrating standards) prepared in the same manner.

For each batch of samples, a solution blank must be prepared. (Carry out the above procedure without using any rock powder).

ICP DETERMINATION

The Silicate Rock Analysis method is stored on the hard disk in the ICP. This program has been optimised for the determination of all-10 major oxides and 2 trace metals, Sr and Ba. Three separate runs are carried out on each batch of analysis, for specific groups of elements have specific parameters for optimum precision, which is required for silicate analysis. Appropriate calibration standards and a blank are run first in order to obtain a calibration graph. The samples are run in batches of 10 and the ICP is then re-calibrated to minimise drift. One or 2 control standards are run with each batch of 10 samples to monitor calibration and drift. Should the calibration of any of the elements fail, an error message will appear informing the operator immediately. All data is to be stored to disk and at the end of the run, if necessary, the calibration may be adjusted and the results reprocessed. All the major oxides together with barium and strontium are run through the ICP at a concentration of 0.1g/100mls (1000 dilution).

HF-aqua regia mixture

Polyethylene 10 ml pipette

Consolidated rock powder not in contact with acid


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ICP PARAMETERS Element Wavelength

nm RF

Power kW

Plasma gas

L/Min

Aux Gas L/Min

Neb. Pressure

kpa

Pump Speed rpm

Viewing height mm

Integration Time

Si 288.158 1.3 13.5 0.75 180 20.0 7 3 x 6 sec Al 394.401 1.3 13.5 0.75 180 20.0 7 3 x 5 sec Fe 259.940 1.3 13.5 0.75 180 20.0 7 2 x 3 sec Ti 336.121 1.3 13.5 0.75 180 20.0 7 1 x 3 sec Ca 317.933 1.3 13.5 0.75 180 20.0 8 2 x 3 sec Mn

257.610 1.3 13.5 0.75 180 20.0 8 1 x 3 sec

Na 588.995 1.05 13.5 0.75 190 20.0 8 2 x 3 sec K 769.896 1.05 13.5 0.75 190 20.0 8 2 x 3 sec Mg 383.826 1.05 13.5 0.75 190 20.0 9 2 x 3 sec Ba 455.403 1.05 13.5 0.75 190 20.0 6 2 x 2 sec Sr

407.771 1.05 13.5 0.75 190 20.0 8 2 x 2 sec

P 177.495 1.40 13.5 0.75 140 20.0 5 2 x 4 sec

II. LOSS ON IGNITION Loss on Ignition (LOI) includes H2O+, CO2 and S (all volatile material is removed during ignition). PROCEDURES

Weigh accurately approximately 2.0000 to 3.0000g to ± 0.1mg of dried (105°C) rock powder into a pre-ignited silica crucible. Ignite to 900°C for 15-20 minutes. Cool in a desiccator and reweigh crucible and sample.

Record: (i) Weight of the crucible (ii) Weight of the crucible plus sample (iii) Weight of the crucible plus sample after ignition.

% L01 = ∆ weight x 100_____

Original weight of sample

LOI does not consider the additional weight gain due to the oxidation of Fe2+ to Fe3+. For high values of Fe2+ a negative weight loss can be obtained. If ferrous iron has been determined separately, the LOI can be corrected for the oxidation of Fe2+ as follows:

%LOI = W1 - [W2 - ((W1 x %FeO X 0.1113)/100)] x 100 W1

Where W1 = original weight of sample, W2 = weight of sample after ignition For the separate determination of H2O+, CO2 and S refer to the next section.

EXPLANATORY NOTES Step 4 of the Procedure When hydrofluoric acid reacts with silicates the silica is converted to volatile silicon tetrafluoride (SiF4) and therefore the reaction must take place in an enclosed vessel, or severe loss of silica will occur.


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Lightly consolidating the rock powder to one side of the digestion bottle prior to the addition of hydrofluoric acid (see diagram) will ensure minimal or no reaction will take place until the reaction vessel is sealed. Leaving the sample stand overnight at normal temperature will ensure no loss silicon tetrafluoride occurs and aids in the complete digestion of the sample. If prolonged heating is carried out the plastic bottles will soften and at the same time the internal pressure increases rapidly. If the lids are not retighten gaseous silicon tetrafluoride may be lost. Some metamorphic minerals, particularly kyanite and staurolite may not dissolve using this digestion technique. Step 5 of the procedure The digestion bottles are cooled in a deep freeze to -15°C prior to the addition of boric acid to create a negative pressure in the bottle when the cap is removed. This reduces the possibility of any silicon tetrafluoride loss. The addition of boric acid is a critical component of the analysis. It performs the following functions: (i) It reacts with residual hydrofluoric acid to form fluoroboric acid that does not immediately react with glass. This enables the final volume of solution (200ml) to be made up in a volumetric flask. (ii) It reacts with and stabilises the volatile silicon tetrafloride and prevents any further volatilisation losses of silica. (iii) It reacts with and dissolves the precipitated calcium and magnesium fluorides formed during the digestion. (iv) Does not introduce any analyte elements into the digestion. Loss on ignition Volatiles determined by loss on ignition will be most accurate for samples containing low concentrations of ferrous iron. The oxidation of ferrous iron during ignition increases the sample weight and if this is not subtracted from the LOI value, an incorrect result will be obtained. For samples containing low concentrations of volatiles and high concentrations of ferrous iron, the sample may actually gain weight rather than lose it after it has been ignited.

III. DETERMINATION OF FERROUS AND FERRIC IRON

The valency state of an analyte species cannot be determined by ICP-AES, AAS, or x-ray Fluorescence; instruments generally used for silicate rock analysis. Iron determined by the above methods is reported as total ferric iron and expressed as Fe2O3T regardless of oxidation state. For Norms and some other computations FeO and Fe2O3 must be reported separately. If ferrous iron is determined separately by titration, then the actual ferric iron concentration may be calculated by difference as follows:

2FeO + O Æ Fe2O3 2(71.85) + 16 Æ 159.70 143.70 + 16 Æ 159.70

therefore, Fe2O3 = Fe2O3T - 1.1113 FeO.

For silicates containing high concentrations of ferrous iron, the summation criterion of 100% for a "good" analysis will not necessarily apply, as a slightly higher result will be obtained if all of the ferrous iron is expressed as ferric iron. If a rock contains 10% FeO and the analysis is reported as Fe2O3T (total ferric) the sum of the major elements could legitimately add up to more than 101%. DETERMINATION OF FERROUS IRON Ferrous iron is determined on a separate HF digestion by the conventional titrimetric method using standard potassium dichromate solution with barium diphenylamine sulphonate as the indicator. A "spike" sample containing a small amount of ferrous ammonium sulphate may be added to the sample to facilitate end point detection, particularly for samples containing low concentrations of ferrous iron. This


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method assumes no oxidation of iron occurs during the digestion, or that manganese and vanadium do not interfere (see attached notes). Reagents (All reagents of analytical grade)

Sulphuric acid, 98%. Hydrofluoric acid, 50%. Barium diphenylamine sulphonate. Phosphoric acid, 85%. Ferrous ammonium sulphate. Potassium dichromate Boric acid

Reagent Preparation

Sulphuric acid, 1:3. Slowly add 1 volume of concentrated sulphuric acid to 3 volumes of water in a large beaker (to confine any boiling) with extreme caution, as the reaction is very exothermic. If boiling does occur, allow the solution to cool down for 15 to 20 minutes before adding the remainder of the sulphuric acid. Allow the solution to cool and transfer to a polyethylene storage bottle and label, Sulphuric acid-1:3

Potassium dichromate. Weigh out 2.728g AR grade potassium dichromate into a 2 litre volumetric flask and dilute to the mark. Transfer the solution to polyethylene storage bottle and label, Potassium Dichromate 2.728g/2 litres. This solution contains the equivalent of 2.00mg FeO per ml of potassium dichromate.

Barium diphenylamine sulphonate indicator (BDS). Dissolve 0.2g barium diphenylamine sulphonate in 1 litre of water and then add 1 litre of 85% phosphoric acid and mix well. Transfer to a polyethylene storage bottle and label, Indicator solution.

Ferrous ammonium sulphate. Dissolve approximately 0.5g ferrous ammonium sulphate in 500ml of water containing 10ml (measuring cylinder) concentrated sulphuric acid.

PROCEDURES

1. Weigh 0.500g of dried (105°C) powdered silicate sample into a 100ml platinum crucible and add 20ml 1:3 sulphuric acid. (Refer to explanatory notes regarding the grinding of the sample)

2. Cover the crucible with the platinum lid and carefully bring to the boil on an electric hotplate. 3. Add 10ml of HF from a plastic measuring cylinder, cover and again bring to the boil. Boil gently for

15 minutes. 4. While the sample in the crucible is digesting, add 400ml of water and approximately 10g of boric

acid to a 1 litre beaker. Stir on an electric hotplate to aid the dissolution of the boric acid. If the ferrous concentrations is very low and the titration is very small, at this stage add 5.00ml (pipette) of ferrous ammonium sulphate "spike" solution. (Refer to explanatory notes)

5. After the solution in the crucible has boiled for 15 minutes, leave the lid on and remove the crucible from the hotplate and immediately immerse the covered crucible and contents in the boric acid solution. The crucible should be kept covered until just before the titration.

6. Add 10ml of BDS indicator solution and titrate the solution with standard dichromate solution until a purple end point, which persists for 30 seconds.

7. For each batch of samples carry out a blank determination and subtract this value from each sample titration. If a spike sample has been used for low ferrous iron values, include this spike in the blank.

Calculation Calculate percent FeO in the sample as follows:

%FeO = (dichromate titn (ml)- blank) x 2.000 x 100


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500 (wt sample in mg)

EXPLANATORY NOTES It should be noted that in the determination of ferrous iron by titration it is really the net state of oxidation that is being determined. Carbonaceous matter if present will interfere and give a high ferrous iron value. Manganese dioxide will produce a low value and vanadium will produce a positive value, the correction being about twice the value of vanadium as vanadium pentoxide. During digestion the platinum lid should not be removed as sample oxidation may readily occur. Iron contamination from crushing equipment has been reported by Fitton and Gill (1970) who investigated this problem in detail. Their results are reported on a basalt ground in a tungsten carbide swing mill for various lengths of time. They indicate considerable atmospheric oxidation can occur if the samples are ground for longer than 1 minute; in their example the apparent FeO content of 6.8% falls to about 6% after 4 minutes grinding. This work showed that samples containing hydrated minerals such as biotite and chlorite were much more susceptible to oxidation than rocks in which the majority if iron was held in fresh anhydrous minerals such as olivine and pyroxene. It is therefore suggested samples to be analysed for ferrous iron content is mechanically ground for no longer than 1 minute. Since the particle size might not be as fine as would normally be accepted for chemical analysis, a small sub-sample should be reground for a few minutes in an agate mortar and pestle in acetone to prevent oxidation. The sample is then dried and ready for analysis. For critical work a blank using a sample of pure quartz should be ground in the swing mill for the same length of time as the sample and this value subtracted as the blank titration, particularly if a chrome-steel swing mill is used for crushing. If a large number of samples are being analysed it is more convenient to have the boric acid dissolved prior to analysis. Prepare the required volume of boric acid solution by dissolving 50g H3BO3/ litre, and use 200mls of this solution plus 200mls of deionised water per analysis. 200ml of this solution contain 10g of boric acid. Five litres will be required for 25 analyses. *Heat to 60°C and stir on an electric hotplate to aid the dissolution of the boric acid.

IV. DETERMINATION OF S, CO2 AND H2O+ All the above constituents may be determined individually by quantitative instrumental analysis. 1. SULPHUR Sulphur is determined on the LECO R432 Sulphur analyser, by oxidation of the powdered sample in an atmosphere of pure oxygen at 1050°C, and quantitatively measuring the evolved sulphur dioxide by infrared spectroscopy using appropriate calibrating standards.

Sample Preparation

To obtain significant results it is important the sample be ground extremely fine to ensure homogeneity of low concentration sulphides throughout the sample.

Sample Weight

Approximately 0.250-0.300g of dried (110°C) sample is required for the LECO R432 Sulphur analyser.

Analysis time

Approximately 3 minutes per sample plus 3 minutes per calibrating standard and blank.

2. CARBON DIOXIDE AND H2O+

Both water and carbon dioxide may be determined simultaneously on the LECO R412 Multiphase Determinator by oxidation of the sample in an atmosphere of pure oxygen at 1100°C. The evolved carbon


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dioxide and water vapour are quantitatively measured by infrared spectroscopy using appropriate calibrating standards. Sample Weight

Approximately 0.250-0.300g of dried (110°C) rock powder is required for the LECO R412 Multiphase Determinator.

Analysis time

Approximately 15 minutes per sample plus 15 minutes per calibrating standard and the blank. Note: Carbon dioxide is only measured as % carbon and hence the results must be multiplied 3.664.

(C=12.01, CO2= 44.01) REFERENCES ABBEY S. 1978. Calibration Standards. X-Ray Spectrometry 7, 99-121.

BERNAS B. 1968. A new method for decomposition and comprehensive analysis of silicates by atomic absorption spectrometry. Analytical Chemistry 40, 1682.

BUCKLEY D. E. & CRANSTON R. E. 1971. Atomic absorption analysis of 18 elements from a single decomposition of an aluminosilicate. Chemical Geology 7, 273-284.

EASTON A. J. 1972. Chemical analysis of silicate rocks. Elsevier Publishing Company, New York.

FITTON J. G. & GILL R. C. O. 1970. The oxidation of ferrous iron in rocks during mechanical grinding. Geochimica Cosmochimica Acta 34, 518-524.

FRENCH W. J. & ADAMS S. J. 1973. Polypropylene bottles in the decomposition of silicate rocks. Analytica Chimica Acta 62, 324-328.

KWIECIEN W. 1990. Silicate rock analysis by AAS. School of Geology, Queensland University of Technology, Australia.

LORING D. H. & RANTALA R. T. T. 1992. Manual for geochemical analysis of marine sediments and suspended particulate matter. Earth Science Reviews 32, 235-283.

MAGILL W. A. & SUEHLA G. I. 1974. The study on the elimination of interferences in the determination of calcium by atomic absorption spectrophotometry. Analytical Chemistry 268, 177-180.

POTTS P. J. 1987. A handbook of silicate rock analysis. Chapman and Hall, New York.

RANTALA R. T. T. & LORING, D. H. 1989. Teflon bomb decomposition of silicate materials in a microwave oven. Analytica Chimica Acta 220, 263-267.

SAMCHUK A. I. & PILIPENKO A. T. 1987. Analytical chemistry of minerals. VNU Sciences Press, Utrecht, Netherlands.

APPENDIX 2- WHOLE ROCK GEOCHEMICAL DATA

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I. WHOLE ROCK GEOCHEMISTRYSample SC043 SC063 SC065 SC073 SC082 SC094 SC100 SC106 SC112 SC142 SC143 SC144 SC145 SC163 SC195

Easting 433274 433520 433589 433544 433590 432930 432489 432170 432450 434631 434816 434896 435066 432500 434216Northing 7110881 7110938 7111367 7110310 7109122 7106609 7111083 7110590 7110784 7119646 7119668 7119756 7119726 7114844 7118620

Lithology Cat. gd Cat. gd And. Cat. gd And. And. Cat. gd Cat. gd Cat. gd Gd Gd. Gd. Gd. Cat.dio. Gd.Unit Fo. gd Fo. gd Neara Fo. Gd North Arm North Arm Fo. gd. Fo. Gd Fo. Gd. Woolooga Woolooga Woolooga Woolooga Fo. Dio. WooloogaSiO2 68.13 65.19 58.86 67.14 52.47 58.13 64.01 65.19 65.86 63.85 64.82 63.72 64.14 - 65.13TiO2 0.75 0.84 0.78 0.69 0.79 0.95 0.91 0.87 0.85 0.56 0.54 0.55 0.53 - 0.50Al2O3 13.28 13.56 16.83 13.42 15.08 16.76 14.37 13.56 13.83 15.25 15.36 14.99 15.22 - 15.04Fe2O3 5.42 5.24 6.68 5.84 2.30 6.92 6.21 5.24 5.82 4.88 4.50 4.76 4.71 - 4.47FeO - - - - 3.91 - - - - - - - - - -MnO 0.09 0.09 0.15 0.13 0.10 0.16 0.14 0.09 0.12 0.10 0.09 0.09 0.11 - 0.10MgO 1.72 1.81 3.16 2.04 4.83 2.58 2.30 2.06 2.06 2.58 2.31 2.42 2.37 - 2.32CaO 2.17 2.24 5.62 2.43 5.55 5.95 0.53 2.24 2.47 4.44 4.07 4.35 4.34 - 3.85Na2O 3.55 3.63 2.86 3.55 3.90 3.37 3.41 3.60 3.54 3.71 3.95 3.61 3.70 - 3.54K2O 2.18 3.04 1.73 1.33 1.76 2.46 2.47 2.43 2.29 2.85 2.92 2.86 2.85 - 3.25P2O5 0.15 0.12 0.25 0.13 0.20 0.24 0.12 0.17 0.14 0.08 0.08 0.10 0.14 - 0.09CO2 0.14 1.14 - 0.52 - - 0.32 0.37 0.21 0.00 0.09 0.25 0.13 - 0.34H2O 2.63 2.70 - 2.90 - - 3.54 2.81 2.83 1.37 1.21 1.40 1.14 - 1.31LOI 2.77 3.84 3.07 3.42 6.23 2.95 3.86 3.18 3.04 1.37 1.30 1.65 1.27 - 1.65TOTAL 100.22 99.59 99.98 100.13 97.13 100.47 98.32 98.63 100.01 99.67 99.94 99.10 99.38 - 99.94Ba 422 616 544 274 438 549 546 633 545 378 427 393 407 - 484Sr 187 210 774 187 455 624 172 214 241 345 381 334 345 - 345Ag - - - <5 1 - <2 1 - - - - - <2 1 - - -As 2 2 10 2 - 3.53 1 - 19.3 1 5 2 - 1 2 - - 1.31 1 - - 3 2

Au - - - <5 1 - <5 1 - - - - - <5 1 - - -Be - - - - 1.22 - - 1.27 - - - - - 0.58 -Br - - - <1 1 - <1 1 - - - - - <1 1 - - -Ce - - - 37.1 1 36.29 58.4 1 - 44.04 - - - 42.5 1 - 14.32 -Co - - - 14.9 1 24.99 18 1 - 18.54 - - - 13 1 - 56.46 -Cr - - - 213 1 78.95 225 1 - 168.04 - - - 211 1 - 68.30 -Cs - - - 1.88 1 2.21 1.9 1 - 1.78 - - - 4.1 1 - 1.77 -Cu - - - - 47.60 - - 48.93 - - - - - 100.08 -Dy - - - - 3.46 - - 5.41 - - - - - 4.60 -Er - - - - 2.00 - - 3.15 - - - - - 2.70 -Eu - - - 1.36 1 1.09 1.88 1 - 1.36 - - - 0.98 1 - 1.33 -Ga 17 2 15 2 - 17 2 17.34 - 17 2 18.32 17 2 - - 17 2 - 17.22 16 2

Gd - - - - 3.70 - - 5.45 - - - - - 4.18 -Hf - - - 7.05 1 3.85 4.49 1 - 7.05 - - - 3.86 1 - 2.51 -Ho - - - - 0.70 - - 1.11 - - - - - 0.96 -Ir - - - <5 1 - <5 1 - - - - - <5 1 - - -La - - - 17 1 16.35 25.9 1 - 21.04 - - - 19.4 1 - 5.32 -Li - - - - 37.05 - - 17.33 - - - - - 26.91 -Lu - - - 0.3 1 0.28 0.38 1 - 0.43 - - - 0.28 1 - 0.38 -Mo - - - <5 1 - <5 1 - - - - - <5 1 - - -Ni - - - - 29.46 - - 46.27 - - - - - 28.75 -Nb 6 2 8 2 - 8 2 4.84 - 8 2 8.55 8 2 - - 6 2 - 3.42 4 2

Nd - - - - 18.20 - - 22.82 - - - - - 11.19 -Pb 16 2 14 2 - 30 2 13.76 - 20 2 16.60 18 2 - - 10 2 - 1.38 12 2

Pr - - - - 4.67 - - 5.79 - - - - - 2.33 -Rb 78 2 96 2 - 49 2 57.93 64.2 1 78 2 72.90 70 2 - - 88.9 1 - 19.73 96 2

Sb - - - 2.27 1 - 4.4 1 - - - - - 0.4 1 - - -Sc - - - 16.3 1 19.447 18.5 1 - 16.56 - - - 11.8 1 - 36.29 -Se - <1 1 - <1 1 - - <1 1 - -Sm - - - 3.95 1 4.00 6.76 1 - 5.37 - - - 4.28 1 - 3.46 -Sn - - - - 1.16 - - 1.56 - - - - - 0.45 -Ta - - - 0.51 1 0.37 0.49 1 - 0.61 - - - 0.68 1 - 0.31 -Tb - - - 0.72 1 0.56 1.02 1 - 0.86 - - - 0.77 1 - 0.70 -Th 10 2 10 2 - 6 2 6.75 7.11 1 7 2 6.23 9 2 - - 12.3 1 - 0.39 14 2

Tm - - - - 0.29 - - 0.46 - - - - - 0.39 -U 2 2 2 2 - 2 2 1.92 <2 1 1 2 1.38 <1 2 - - <1 2 - 0.15 <1 2

V - - - - 149.89 - - 91.84 - - - - - 272.07 -W - - - <2 1 - <2 1 - - - - - <2 1 - - -Y 21 2 32 2 - 20 2 18.08 - 27 2 28.86 30 2 - - 18 2 - 24.05 18 2

Yb - - - 2.36 1 1.86 2.93 1 - 2.85 - - - 2.22 1 - 2.45 -Zn - - - 123 1 57.95 119 1 - 66.73 - - - 61.1 1 - 68.75 -Zr 236 244 - 246 144.21 - 236 269.34 208 - - 138 - 94.28 134δ O - - - - 0.2; -0.5 - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - 0.13411 - - 0.14276 - - - - - - -143Nd/144Nd - - - - 0.51275 - - 0.51258 - - - - - - -87Rb/86Sr - - - - 0.3412 - - 0.86264 - - - - - - -87Sr/86Sr - - - - 0.70269 - - 0.70909 - - - - - - -

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY

9

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC206 SC215E SC222 SC223 SC229 SC233 SC235B SC237 SC241 SC252 SC289 SC304 SC313 SC323 SC328Easting 434575 433563 434493 434457 434296 433972 434300 433234 434550 434019 434372 435053 435010 435226 434853Northing 7119168 7118725 7119127 7118923 7119359 7119240 7119491 7120091 7119845 7120677 7121518 7120543 7121319 7122414 7122802

Lithology Gd. Gd. Dac. Gd. Trach. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd.Unit Woolooga Woolooga Dyke Woolooga Dyke Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga WooloogaSiO2 63.83 63.95 63.54 63.48 55.72 64.34 64.13 63.93 63.36 66.41 66.33 63.74 63.99 63.17 64.23TiO2 0.50 0.54 0.45 0.56 0.92 0.50 0.52 0.52 0.52 0.55 0.42 0.48 0.51 0.47 0.52Al2O3 14.84 14.7 14.70 14.92 15.28 15.50 15.24 15.40 15.00 15.21 15.09 15.20 15.44 15.04 15.40Fe2O3 4.38 4.97 3.71 4.84 7.03 4.71 4.71 4.83 3.62 4.56 3.63 4.60 4.93 4.85 4.42FeO - - - - - - - - - - - - - - -MnO 0.08 0.08 0.08 0.09 0.13 0.07 0.10 0.07 0.07 0.09 0.07 0.08 0.08 0.08 0.10MgO 2.32 2.44 1.58 2.48 4.39 2.48 2.56 2.42 2.68 2.23 1.73 2.41 2.56 2.77 2.35CaO 4.19 3.71 3.86 3.88 6.12 4.56 4.40 4.64 4.61 4.37 3.74 4.08 4.59 3.93 4.27Na2O 3.91 3.64 3.90 3.72 3.01 3.80 3.77 3.62 3.71 3.51 3.73 3.85 3.70 3.96 3.70K2O 2.99 3.15 2.51 3.04 2.30 2.93 2.96 2.83 2.84 3.21 3.19 2.89 2.81 2.78 2.95P2O5 0.11 0.11 0.16 0.09 0.18 0.10 0.07 0.07 0.13 0.10 0.08 0.11 0.11 0.12 0.13CO2 0.69 0.12 2.68 0.20 1.70 0.08 0.18 0.00 0.58 0.00 0.07 0.08 0.07 0.08 0.06H2O 1.46 1.29 2.09 1.35 2.67 1.14 1.54 2.14 1.76 1.04 0.85 1.89 1.60 1.52 1.20LOI 2.15 1.41 4.77 1.55 4.37 1.22 1.72 2.14 2.34 1.04 0.92 1.97 1.67 1.60 1.26TOTAL 99.30 98.70 99.26 98.65 99.45 100.21 100.18 100.47 98.88 101.28 98.93 99.41 100.39 98.77 99.33

Ba 441 456 368 444 349 419 425 396 441 492 479 431 390 423 407Sr 381 327 422 324 474 336 369 358 356 307 296 338 355 379 354Ag - <2 1 - - - - - - - - - - - - -As 3 2 2.76 1 - - - - - - - - - - 3 2 - -Au - <5 1 - - - - - - - - - - - - -Be - - - - - - - - - - - - - - -Br - <1 1 - - - - - - - - - - - - -Ce - 50.6 1 - - - - - - - - - - - - -Co - 14.1 1 - - - - - - - - - - - - -Cr - 222 1 - - - - - - - - - - - - -Cs - 2.4 1 - - - - - - - - - - - - -Cu - - - - - - - - - - - - - - -Dy - - - - - - - - - - - - - - -Er - - - - - - - - - - - - - - -Eu - 1.03 1 - - - - - - - - - - - - -Ga 17 2 17 2 - - - - - - - - - - 17 2 - -Gd - - - - - - - - - - - - - - -Hf - 4.6 1 - - - - - - - - - - - - -Ho - - - - - - - - - - - - - - -Ir - <5 1 - - - - - - - - - - - - -La - 24.2 1 - - - - - - - - - - - - -Li - - - - - - - - - - - - - - -Lu - 0.33 1 - - - - - - - - - - - - -Mo - <5 1 - - - - - - - - - - - - -Ni - - - - - - - - - - - - - - -Nb 4 2 6 2 - - - - - - - - - - 4 2 - -Nd - - - - - - - - - - - - - - -Pb 10 2 14 2 - - - - - - - - - - 12 2 - -Pr - - - - - - - - - - - - - - -Rb 99 2 89.2 1 - - - - - - - - - - 103 2 - -Sb - 0.9 1 - - - - - - - - - - - - -Sc - 12.3 1 - - - - - - - - - - - - -Se - <1 1 - - - - - - - - - - - - -Sm - 4.81 1 - - - - - - - - - - - - -Sn - - - - - - - - - - - - - - -Ta - 0.66 1 - - - - - - - - - - - - -Tb - 0.75 1 - - - - - - - - - - - - -Th 15 2 15.4 1 - - - - - - - - - - 13 2 - -Tm - - - - - - - - - - - - - - -U 2 2 <2 1 - - - - - - - - - - 2 2 - -V - - - - - - - - - - - - - - -W - <2 1 - - - - - - - - - - - - -Y 16 2 20 2 - - - - - - - - - - 18 2 - -Yb - 2.48 1 - - - - - - - - - - - - -Zn - 82.6 1 - - - - - - - - - - - - -Zr 122 148 - - - - - - - - - - 136 - -δ O - 3.6 - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -


10

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC350 SC358 SC363 SC369 SC374 SC382 SC386 SC388 SC393 SC394 SC400 SC412 SC430 SC450 SC453Easting 434656 435644 436233 436175 436667 437434 438926 438889 435726 436347 436186 437251 436717 438694 438387Northing 7123710 7123131 7123030 7122068 7121274 7121187 7119096 7119004 7120476 7120665 7119711 7119391 7118810 7118661 7118124

Lithology Gd. Xenolith Gd. Gd. Gd. Gd. Mdio Gd. Gd. Gd. Gd. Gd. Gd. Mdio Gd.Unit Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Intrusive Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga WooloogaSiO2 64.21 58.93 63.13 63.47 64.19 64.52 56.63 63.54 62.68 63.53 64.54 62.22 63.07 59.56 62.65TiO2 0.52 0.61 0.46 0.47 0.51 0.48 0.77 0.52 0.49 0.50 0.53 0.57 0.50 0.72 0.58Al2O3 15.69 16.15 14.73 14.21 15.7 15.4 16.09 14.23 15.03 15.56 15.39 15.49 15.44 16.1 14.51Fe2O3 4.96 6.04 4.85 4.93 4.89 2.15 6.90 5.19 4.92 4.72 4.94 5.15 4.81 6.28 5.16FeO - - - - - 2.34 - - - - - - - - -MnO 0.09 0.09 0.07 0.08 0.09 0.08 0.11 0.08 0.08 0.09 0.08 0.10 0.09 0.13 0.09MgO 2.41 3.62 2.86 2.80 2.66 2.58 4.49 2.76 2.71 2.73 2.62 2.86 2.59 3.50 2.97CaO 4.58 3.63 4.23 4.23 4.17 4.28 6.07 4.44 4.20 3.72 4.32 4.57 4.15 5.57 4.40Na2O 3.54 5.72 4.09 3.86 4.01 3.70 4.79 3.78 3.81 4.49 3.80 3.76 3.81 4.41 4.03K2O 2.92 2.25 2.62 2.48 2.86 2.89 1.94 2.78 2.69 2.97 2.81 2.90 2.99 2.26 2.56P2O5 0.10 0.19 0.14 0.13 0.12 0.13 0.16 0.14 0.15 0.11 0.16 0.11 0.14 0.14 0.16CO2 0.07 0.43 0.08 0.11 0.16 0.20 0.09 0.04 0.10 0.09 0.14 0.12 0.42 0.10 0.11H2O 1.60 2.12 1.37 1.84 1.39 1.46 1.51 0.95 1.63 1.84 1.88 2.41 2.19 1.30 1.68LOI 1.67 2.55 1.45 1.95 1.55 1.66 1.60 0.99 1.73 1.93 2.02 2.53 2.61 1.40 1.79TOTAL 100.69 99.78 98.63 98.61 100.75 100.47 99.55 98.45 98.49 100.35 101.21 100.26 100.20 100.07 98.90Ba 395 369 404 412 412 405 271 498 413 419 397 406 494 527 416Sr 336 425 363 363 376 382 404 401 365 396 358 352 423 405 351Ag - <2 1 - - - <5 1 - - - - <5 1 - - - -As 3 2 5.93 1 - - 7 2 6.62 1 - - - - 2.19 1 - 4 2 4 2 -Au - <5 1 - - - <5 1 - - - - <5 1 - - - -Be - - - - - - - - - - - - - - -Br - <1 1 - - - <1 1 - - - - <1 1 - - - -Ce - 45.1 1 - - - 43.8 1 - - - - 45.8 1 - - - -Co - 20.8 1 - - - 13.5 1 - - - - 15.3 1 - - - -Cr - 140 1 - - - 184 1 - - - - 173 1 - - - -Cs - 2.8 1 - - - 4.59 1 - - - - 4.07 1 - - - -Cu - - - - - - - - - - - - - - -Dy - - - - - - - - - - - - - - -Er - - - - - - - - - - - - - - -Eu - 1.24 1 - - - 1.07 1 - - - - 1.09 1 - - - -Ga 17 2 - - - 17 2 - - - - - - - 17 2 18 2 -Gd - - - - - - - - - - - - - - -Hf - 3.45 1 - - - 4 1 - - - - 4 1 - - - -Ho - - - - - - - - - - - - - - -Ir - <5 1 - - - <5 1 - - - - <5 1 - - - -La - 19.4 1 - - - 19.4 1 - - - - 19.9 1 - - - -Li - - - - - - - - - - - - - - -Lu - 0.29 1 - - - 0.27 1 - - - - 0.29 1 - - - -Mo - <5 1 - - - <5 1 - - - - <5 1 - - - -Ni - - - - - - - - - - - - - - -Nb 6 2 - - - 6 2 - - - - - - - 4 2 4 2 -Nd - - - - - - - - - - - - - - -Pb 22 2 - - - 12 2 - - - - - - - 12 2 12 2 -Pr - - - - - - - - - - - - - - -Rb 96 2 80.4 1 - - 115 2 99.1 1 - - - - 108 1 - 99 2 65 2 -Sb - 3.1 1 - - - 1.5 1 - - - - 0.3 1 - - - -Sc - 14.7 1 - - - 12.4 1 - - - - 12.7 1 - - - -Se <1 1 - - <1 1 - - - - <1 1 - - -Sm - 5.13 1 - - - 4.05 1 - - - - 4.05 1 - - - -Sn - - - - - - - - - - - - - - -Ta - <0.3 1 - - - 0.62 1 - - - - 0.82 1 - - - -Tb - 0.8 1 - - - 0.63 1 - - - - 0.62 1 - - - -Th 14 2 7.06 1 - - 14 2 12 1 - - - - 12.5 1 - 15 2 8 2 -Tm - - - - - - - - - - - - - - -U 3 2 <2 1 - - 2 2 <2 1 - - - - <2 1 - 3 2 2 2 -V - - - - - - - - - - - - - - -W - <2 1 - - - <2 1 - - - - <2 1 - - - -Y 18 2 - - - 19 2 - - - - - - - 17 2 22 2 -Yb - 2.21 1 - - - 2.07 1 - - - - 2.07 1 - - - -Zn - 66.3 1 - - - 73.8 1 - - - - 74.4 1 - - - -Zr 138 - - - 134 - - - - - - - 124 162 -δ O - - - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -


11

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC456 SC472 SC483 SC492 SC494 SC496 SC497 SC503 SC503pt SC508 SC512 SC513 SC517 SC518 SC520Easting 438179 438696 439548 439810 439673 438543 439275 438367 438367 438712 439196 437863 439919 440252 440388Northing 7118283 7120037 7120526 7119881 7119342 7121852 7121200 7117114 7117114 7116448 7115804 7117563 7117429 7116947 7117907

Lithology Gd. QMD Gd. QMD Gd. Gd. QMD Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd.Unit Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga WooloogaSiO2 61.21 61.84 63.44 64.15 64.47 63.84 63.79 61.21 61.38 65.94 64.28 62.89 64.11 65.64 64.21TiO2 0.65 0.57 0.59 0.51 0.53 0.53 0.57 0.75 0.76 0.44 0.57 0.65 0.53 0.51 0.49Al2O3 15.67 14.6 15.20 14.50 15.26 15.41 14.83 15.63 15.54 15.08 15.09 15.20 15.47 15.56 15.57Fe2O3 5.72 4.98 5.13 5.12 4.68 5.63 4.87 6.08 5.89 4.34 4.89 5.66 4.90 4.34 4.93FeO - - - - - - - - - - - - - - -MnO 0.11 0.09 0.10 0.10 0.09 0.10 0.08 0.13 0.13 0.09 0.10 0.10 0.08 0.09 0.10MgO 3.18 3.04 2.73 2.63 2.64 2.60 2.79 3.11 3.24 2.06 2.61 2.97 2.73 2.10 2.46CaO 4.76 4.56 4.29 4.20 4.45 4.34 4.65 5.34 5.05 3.27 4.57 4.16 3.82 3.65 3.44Na2O 3.84 4.00 3.94 4.25 4.00 3.74 4.03 3.62 3.83 3.88 3.29 3.85 3.71 3.42 3.83K2O 2.37 2.98 2.84 3.07 2.75 3.12 3.08 2.65 2.57 3.18 2.83 2.83 2.98 3.08 3.25P2O5 0.13 0.17 0.13 0.15 0.14 0.15 0.13 0.18 0.16 0.12 0.02 0.14 0.13 0.13 0.12CO2 0.07 0.10 0.02 0.09 0.07 0.08 0.04 0.07 0.06 0.14 0.03 0.12 0.11 0.05 0.09H2O 1.39 2.03 1.99 1.37 1.48 0.64 0.35 1.59 1.43 1.76 1.18 1.02 0.94 1.47 1.13LOI 1.46 2.13 2.01 1.46 1.55 0.72 0.39 1.66 1.49 1.90 1.21 1.14 1.05 1.52 1.22TOTAL 99.10 98.96 100.40 100.14 100.56 100.18 99.21 100.36 100.04 100.30 99.46 99.59 99.51 100.04 99.62Ba 411 399 440 436 398 420 431 468 409 475 402 465 437 458 416Sr 353 349 344 369 361 324 337 370 377 292 313 406 362 307 330Ag <5 1 - - - - - - - - - - - - <5 1 -As 4.07 1 - - - - - - 5 2 - - - - - 5.52 1 -Au <5 1 - - - - - - - - - - - - <5 1 -Be - 1.34 - - - - - - - - - - - - -Br 1.89 1 - - - - - - - - - - - - <1 1 -Ce 49.1 1 44.19 - - - - - - - - - - - 48.5 1 -Co 17.8 1 15.63 - - - - - - - - - - - 12.4 1 -Cr 200 1 233.90 - - - - - - - - - - - 207 1 -Cs 4.46 1 4.18 - - - - - - - - - - - 3.46 1 -Cu - 24.80 - - - - - - - - - - - - -Dy - 3.78 - - - - - - - - - - - - -Er - 2.22 - - - - - - - - - - - - -Eu 1.25 1 1.00 - - - - - - - - - - - 1.1 1 -Ga - 17.24 - - - - - 18 2 - - - - - - -Gd - 3.99 - - - - - - - - - - - - -Hf 5.01 1 4.86 - - - - - - - - - - - 4.27 1 -Ho - 0.76 - - - - - - - - - - - - -Ir <5 1 - - - - - - - - - - - - <5 1 -La 20.8 1 20.07 - - - - - - - - - - - 21.2 1 -Li - 17.15 - - - - - - - - - - - - -Lu 0.33 1 0.34 - - - - - - - - - - - 0.29 1 -Mo <5 1 - - - - - - - - - - - - <5 1 -Ni - 21.57 - - - - - - - - - - - - -Nb - 6.06 - - - - - 4 2 - - - - - - -Nd - 20.61 - - - - - - - - - - - - -Pb - 14.37 - - - - - 20 2 - - - - - - -Pr - 5.52 - - - - - - - - - - - - -Rb 91.3 1 105.96 - - - - - 87 2 - - - - - 115 1 -Sb 0.5 1 - - - - - - - - - - - - 0.48 1 -Sc 15.7 1 13.11 - - - - - - - - - - - 10.6 1 -Se <1 1 - - - - - - - - - - - <1 1 -Sm 5.1 1 4.45 - - - - - - - - - - - 4.22 1 -Sn - 2.01 - - - - - - - - - - - - -Ta 0.79 1 0.57 - - - - - - - - - - - 0.62 1 -Tb 0.86 1 0.62 - - - - - - - - - - - 0.71 1 -Th 9.88 1 11.20 - - - - - 10 2 - - - - - 13 1 -Tm - 0.33 - - - - - - - - - - - - -U <2 1 3.20 - - - - - 2 2 - - - - - 3.38 1 -V - 97.15 - - - - - - - - - - - - -W <2 1 - - - - - - - - - - - - <2 1 -Y - 19.80 - - - - - 22 2 - - - - - - -Yb 2.53 1 2.20 - - - - - - - - - - - 2.18 1 -Zn 111 1 40.84 - - - - - - - - - - - 101 1 -Zr - 167.44 - - - - - 174 - - - - - - -δ O - 2.5 - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - 0.12697 - - - - - - - - - - - - -143Nd/144Nd - 0.51273 - - - - - - - - - - - - -87Rb/86Sr - 0.85029 - - - - - - - - - - - - -87Sr/86Sr - 0.70636 - - - - - - - - - - - - -


12


Lithology Gd. Gd. Gd. Gd. Dac. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Trach-dac Gd.Unit Woolooga Woolooga Woolooga Woolooga Dyke Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Highbury WooloogaSiO2 64.3 61.88 64.04 67.11 62.43 64.69 64.51 61.55 64.11 61.99 63.28 64.25 64.63 46.9 64.29TiO2 0.46 0.51 0.54 0.41 0.52 0.40 0.48 0.54 0.50 0.58 0.57 0.55 0.58 1.8 0.56Al2O3 15.58 15.03 15.43 14.05 15.63 14.53 15.03 15.76 15.45 15.80 15.85 14.75 15.09 15.17 15.15Fe2O3 4.86 4.90 4.91 3.13 5.17 4.05 3.96 4.96 4.92 5.04 5.39 5.04 5.11 13.55 5.15FeO - - - - - - - - - - - - - - -MnO 0.12 0.12 0.10 0.07 0.10 0.08 0.09 0.10 0.12 0.13 0.15 0.09 0.08 0.26 0.11MgO 2.40 2.40 1.66 2.69 2.63 2.13 2.11 2.40 2.35 3.11 2.87 2.62 2.57 6.52 2.67CaO 3.67 3.60 3.54 1.97 4.34 2.98 3.68 4.32 3.17 4.36 4.30 4.12 4.26 10.17 4.19Na2O 3.71 3.41 3.99 3.79 3.82 4.22 3.87 3.85 3.94 4.05 3.77 3.80 3.69 3.42 3.79K2O 3.25 3.00 3.73 3.34 3.16 3.03 2.90 2.99 3.16 2.91 3.08 3.22 3.30 0.39 3.26P2O5 0.15 0.10 0.12 0.09 0.15 0.12 0.11 0.14 0.17 0.16 0.15 0.16 0.14 0.17 0.12CO2 0.09 0.11 0.12 0.02 0.11 0.41 0.07 0.16 0.86 0.12 0.07 0.05 0.04 - 0.02H2O 1.13 1.90 0.78 0.69 0.57 0.58 1.45 1.43 2.24 1.72 1.09 1.97 0.27 - 1.13LOI 1.22 2.01 0.90 0.71 0.68 0.99 1.52 1.59 3.10 1.84 1.16 2.02 0.31 0.84 1.15TOTAL 99.72 96.96 98.96 97.36 98.63 97.22 98.26 98.20 100.99 99.97 100.57 100.62 99.76 99.19 100.44Ba 468 419 349 466 402 497 438 431 585 419 457 454 478 76 463Sr 311 370 221 359 301 362 314 321 449 405 386 365 337 269 348Ag - - - - - - - <2 1 - - <5 1 - - <2 1 <5 1

As - - - - - - - 3.93 1 - - 3.85 1 - - 23.5 1 3.5 1

Au - - - - - - - <5 1 - - <5 1 - - <5 1 <5 1

Be - - - - - - - - - - - - - - 1.39Br - - - - - - - <1 1 - - <1 1 - - 2.66 1 1.16 1

Ce - - - - - - - 48.4 1 - - 48.1 1 - - 13.4 1 42.93Co - - - - - - - 13.2 1 - - 17.9 1 - - 52.9 1 14.72Cr - - - - - - - 170 1 - - 201 1 - - 86.5 1 174.41Cs - - - - - - - 4.3 1 - - 4.35 1 - - 3 1 3.86Cu - - - - - - - - - - - - - - 52.19Dy - - - - - - - - - - - - - - 3.52Er - - - - - - - - - - - - - - 2.04Eu - - - - - - - 1.05 1 - - 1.23 1 - - 1.41 1 0.97Ga - - - - - - - 17 2 - - - - - - 17.41Gd - - - - - - - - - - - - - - 3.73Hf - - - - - - - 4.46 1 - - 4.38 1 - - 2.7 1 4.31Ho - - - - - - - - - - - - - - 0.71Ir - - - - - - - <5 1 - - <5 1 - - <5 1 <5 1

La - - - - - - - 22.7 1 - - 22 1 - - 5.16 1 19.71Li - - - - - - - - - - - - - - 21.13Lu - - - - - - - 0.33 1 - - 0.3 1 - - 0.42 1 0.31Mo - - - - - - - <5 1 - - <5 1 - - <5 1 <5 1

Ni - - - - - - - - - - - - - - 17.69Nb - - - - - - - 6 2 - - - - - - 6.01Nd - - - - - - - - - - - - - - 19.88Pb - - - - - - - 14 2 - - - - - - 15.31Pr - - - - - - - - - - - - - - 5.36Rb - - - - - - - 106 1 - - 108 1 - - <10 1 115.29Sb - - - - - - - 1.1 1 - - 0.88 1 - - 2.4 1 0.64 1

Sc - - - - - - - 12.2 1 - - 13.4 1 - - 43.1 1 11.69Se - - - - - - - <1 1 - - <1 1 - - <1 1 <1 1

Sm - - - - - - - 5.02 1 - - 4.95 1 - - 3.77 1 4.21Sn - - - - - - - - - - - - - - 1.80Ta - - - - - - - 0.55 1 - - 0.74 1 - - 0.44 1 0.58Tb - - - - - - - 0.81 1 - - 0.81 1 - - 0.87 1 0.57Th - - - - - - - 12.4 1 - - 11.5 1 - - 0.58 1 11.75Tm - - - - - - - - - - - - - - 0.31U - - - - - - - <2 1 - - <2 1 - - <2 1 2.88V - - - - - - - - - - - - - - 91.07W - - - - - - - <2 1 - - <2 1 - - <2 1 <2 1

Y - - - - - - - 21 2 - - - - - - 18.79Yb - - - - - - - 2.52 1 - - 2.2 1 - - 3.08 1 2.01Zn - - - - - - - 66.6 1 - - 106 1 - - 117 1 49.27Zr - - - - - - - 148 - - - - - - 149.99δ O - - - - - - - - - - - - - - 4.3δ D (Bio/Hb) - - - - - - - - - - - - - - -114147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -


13

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC583 SC588 SC589 SC590 SC592 SC593 SC595 SC596 SC597 SC598 SC603 SC604 SC607 SC609C SC611Easting 442101 441707 441061 439571 439137 438497 436605 436393 435757 435197 436384 436128 437232 436077 438389Northing 7122601 7122504 7121375 7122477 7122659 7122220 7122407 7123416 7123893 7124021 7124545 7124940 7124911 7126465 7123904

Lithology Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. Gd. QMD Gd. And. Gd.Unit Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga Dyke Woolooga Neara WooloogaSiO2 63.67 63.26 63.41 64.28 63.28 62.84 63.41 61.75 63.87 64.13 64.4 59.01 64.67 63.15 63.36TiO2 0.58 0.61 0.55 0.58 0.46 0.53 0.54 0.50 0.56 0.58 0.55 0.68 0.55 0.72 0.56Al2O3 15.67 15.53 15.40 15.68 15.93 15.64 15.19 14.92 15.44 15.71 15.39 16.04 15.28 15.20 15.56Fe2O3 4.99 5.19 4.68 4.9 4.70 5.56 4.90 4.95 5.09 4.96 4.87 6.25 4.55 5.17 4.86FeO - - - - - - - - - - - - - - -MnO 0.11 0.11 0.13 0.08 0.09 0.12 0.07 0.08 0.07 0.09 0.07 0.14 0.10 0.08 0.06MgO 2.57 2.65 2.71 2.57 2.68 2.54 2.82 2.66 2.67 2.52 2.82 4.15 2.75 2.66 2.79CaO 4.68 4.32 3.95 4.66 3.79 4.37 3.99 4.13 4.15 4.04 3.83 5.86 4.06 4.01 4.47Na2O 3.70 3.70 4.15 3.74 3.88 4.16 3.80 3.83 3.66 3.67 3.63 3.82 3.86 3.68 3.79K2O 2.88 2.97 3.14 2.77 2.99 2.83 2.85 2.85 3.05 2.93 2.99 1.92 2.92 2.36 2.67P2O5 0.15 0.13 0.14 0.16 0.11 0.14 0.13 0.14 0.18 0.12 0.13 0.17 0.14 0.21 0.18CO2 0.07 0.09 0.05 0.08 0.15 0.13 0.10 0.09 0.27 0.06 0.25 0.13 0.01 - 0.07H2O 1.39 1.45 1.56 1.71 1.68 0.81 1.45 3.30 1.14 0.67 0.99 1.60 0.45 - 1.43LOI 1.46 1.54 1.61 1.79 1.83 0.94 1.55 3.39 1.41 0.72 1.23 1.73 0.45 3.30 1.50TOTAL 100.46 100.01 99.87 101.21 99.74 99.67 99.25 99.20 100.15 99.47 99.91 99.77 99.33 100.54 99.80

Ba 497 475 516 439 381 384 375 385 431 378 438 291 398 434 351Sr 333 435 485 348 334 352 350 340 356 339 390 367 322 581 338Ag - - - <2 1 - - - - - - <2 1 - - - -As 4 2 7 2 - 4.46 1 - - - - - - 5.03 1 - - - -Au - - - <5 1 - - - - - - <5 1 - - - -Be - - - - - - - - - - - - - - -Br - - - <1 1 - - - - - - 1.35 1 - - - -Ce - - - 45 1 - - - - - - 45.4 1 - - - -Co - - - 14.7 1 - - - - - - 13.8 1 - - - -Cr - - - 163 1 - - - - - - 204 1 - - - -Cs - - - 5.1 1 - - - - - - 4.9 1 - - - -Cu - - - - - - - - - - - - - - -Dy - - - - - - - - - - - - - - -Er - - - - - - - - - - - - - - -Eu - - - 1 1 - - - - - - 0.97 1 - - - -Ga 17 2 17 2 - 17 2 - - - - - - - - - - -Gd - - - - - - - - - - - - - - -Hf - - - 3.98 1 - - - - - - 4.29 1 - - - -Ho - - - - - - - - - - - - - - -Ir - - - <5 1 - - - - - - <5 1 - - - -La - - - 20.1 1 - - - - - - 20.4 1 - - - -Li - - - - - - - - - - - - - - -Lu - - - 0.28 1 - - - - - - 0.3 1 - - - -Mo - - - <5 1 - - - - - - <5 1 - - - -Ni - - - - - - - - - - - - - - -Nb 4 2 4 2 - 6 2 - - - - - - - - - - -Nd - - - - - - - - - - - - - - -Pb 18 2 16 2 - 14 2 - - - - - - - - - - -Pr - - - - - - - - - - - - - - -Rb 103 2 103 2 - 102 1 - - - - - - 93 1 - - - -Sb - - - 0.7 1 - - - - - - 1.7 1 - - - -Sc - - - 13 1 - - - - - - 12.9 1 - - - -Se - - <1 1 - - - - - - <1 1 - - - -Sm - - - 4.2 1 - - - - - - 4.32 1 - - - -Sn - - - - - - - - - - - - - - -Ta - - - 0.49 1 - - - - - - 0.42 1 - - - -Tb - - - 0.62 1 - - - - - - 0.7 1 - - - -Th 15 2 14 2 - 11.8 1 - - - - - - 12.7 1 - - - -Tm - - - - - - - - - - - - - - -U 3 2 3 2 - 2.42 1 - - - - - - <2 1 - - - -V - - - - - - - - - - - - - - -W - - - <2 1 - - - - - - <2 1 - - - -Y 19 2 19 2 - 18 2 - - - - - - - - - - -Yb - - - 1.96 1 - - - - - - 2.13 1 - - - -Zn - - - 69.7 1 - - - - - - 112 1 - - - -Zr 144 144 - 130 - - - - - - - - - - -δ O - - - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -


14

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC612 SC614 SC617 SC620 SC623 SC627 SC628 SC631 SC631XeSC637 SC638 SC642 SC642A SC653 SC653AEasting 438933 439941 440479 439856 439897 439237 438631 438632 438632 439115 439105 438758 438758 437629 437629Northing 7124250 7125048 7125606 7125357 7126255 7125620 7126019 7127272 7127272 7114982 7114677 7115615 7115615 7114876 7114876

Lithology Gd. Gd. Gd. Trand. Gd. Gd. Gd. Dacite Xenolith Gd. Gd. Gd. Gd. Rhyolite RhyoliteUnit Woolooga Woolooga Woolooga Dyke Woolooga Woolooga Woolooga Neara Neara Woolooga Woolooga Woolooga Woolooga Oakview OakviewSiO2 65.8 67.03 65.3 64.03 68.19 64.55 66.18 57.58 62.47 62.11 63.25 64.38 63.11 49.9 49.65TiO2 0.47 0.47 0.53 0.51 0.43 0.56 0.52 0.84 0.84 0.65 0.58 0.55 0.54 1.99 1.90Al2O3 15.73 14.48 15.37 14.25 15.00 15.23 15.28 14.97 15.34 15.59 15.22 15.63 15.64 15.12 14.69Fe2O3 4.26 3.97 4.24 4.45 3.86 4.98 4.35 8.07 4.82 5.40 5 4.87 4.78 12.51 12.11FeO - - - - - - - - - - - - - - -MnO 0.05 0.06 0.07 0.08 0.10 0.09 0.08 0.15 0.09 0.08 0.10 0.09 0.09 0.21 0.20MgO 2.48 2.13 2.27 2.26 1.73 2.50 2.12 4.72 1.78 2.94 2.67 2.53 2.52 5.43 5.47CaO 3.54 2.86 3.16 2.85 2.38 3.73 3.84 4.11 4.33 4.55 4.13 4.09 3.94 10.08 9.68Na2O 4.05 3.58 3.85 3.94 3.57 3.74 3.78 3.27 3.72 3.60 3.59 3.87 3.92 3.82 3.94K2O 2.90 3.37 2.83 3.62 3.01 2.78 2.87 0.80 2.83 2.62 2.91 2.93 3.08 0.35 0.34P2O5 0.11 0.11 0.13 0.11 0.13 0.13 0.14 0.27 0.23 0.14 0.11 0.26 0.20 0.18 0.09CO2 - 0.01 - - - - - - - - - - - - -H2O - 1.35 - - - - - - - - - - - - -LOI 1.47 1.36 1.37 3.72 1.78 1.69 1.24 3.30 2.01 1.45 1.36 1.56 1.42 0.81 0.58TOTAL 100.86 99.42 99.12 99.82 100.18 99.99 100.40 98.07 98.45 99.12 98.92 100.76 99.24 100.40 98.64

Ba 433 358 403 424 450 445 382 329 1165 357 424 398 407 36 38Sr 320 308 356 362 341 388 338 506 605 334 337 348 350 231 231Ag - - <2 1 - - - - - - - <2 1 - - - -As - - 1.44 1 - - - - - - - 2.46 1 - - - -Au - - <5 1 - - - - - - - <5 1 - - - -Be - - - - - - - - - - - - - - -Br - - <1 1 - - - - - - - <1 1 - - - -Ce - - 43.9 1 - - - - - - - 49 1 - - - -Co - - 13.7 1 - - - - - - - 14.5 1 - - - -Cr - - 239 1 - - - - - - - 190 1 - - - -Cs - - 8.4 1 - - - - - - - 5.5 1 - - - -Cu - - - - - - - - - - - - - - -Dy - - - - - - - - - - - - - - -Er - - - - - - - - - - - - - - -Eu - - 0.92 1 - - - - - - - 1.06 1 - - - -Ga - - - - - - - - - - - - - - -Gd - - - - - - - - - - - - - - -Hf - - 3.47 1 - - - - - - - 4.76 1 - - - -Ho - - - - - - - - - - - - - - -Ir - - <5 1 - - - - - - - <5 1 - - - -La - - 20.6 1 - - - - - - - 22.2 1 - - - -Li - - - - - - - - - - - - - - -Lu - - 0.24 1 - - - - - - - 0.3 1 - - - -Mo - - <5 1 - - - - - - - <5 1 - - - -Ni - - - - - - - - - - - - - - -Nb - - - - - - - - - - - - - - -Nd - - - - - - - - - - - - - - -Pb - - - - - - - - - - - - - - -Pr - - - - - - - - - - - - - - -Rb - - 107 1 - - - - - - - 102 1 - - - -Sb - - 0.3 1 - - - - - - - 0.6 1 - - - -Sc - - 10.4 1 - - - - - - - 12.4 1 - - - -Se - - <1 1 - - - - - - - <1 1 - - - -Sm - - 3.81 1 - - - - - - - 4.55 1 - - - -Sn - - - - - - - - - - - - - - -Ta - - 0.62 1 - - - - - - - 0.61 1 - - - -Tb - - 0.64 1 - - - - - - - 0.8 1 - - - -Th - - 13 1 - - - - - - - 12.8 1 - - - -Tm - - - - - - - - - - - - - - -U - - 3.36 1 - - - - - - - 2.93 1 - - - -V - - - - - - - - - - - - - - -W - - <2 1 - - - - - - - <2 1 - - - -Y - - - - - - - - - - - - - - -Yb - - 1.93 1 - - - - - - - 2.3 1 - - - -Zn - - 59.5 1 - - - - - - - 87.1 1 - - - -Zr - - - - - - - - - - - - - - -δ O - - - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)

except for: 1 INAA (Becquerel Laboratories) and 2 XRF (ANU). Isotopes from Uni. Queensland.


15


Lithology Rhyolite QMB Trand. QMB Bas-trand. And. Trand. Bas-trand. QMG Fo. ton. Fo. ton. Dacite QMD MicroGd. And.Unit Oakview Gibraltar Gibraltar Gibraltar Dyke Neara Neara Neara Gibraltar Fo. Gd. Fo. Gd. Neara Gibraltar Gibraltar NearaSiO2 55.7 58.64 57.15 57.58 53.98 56.79 61.26 60.77 55.09 61.46 65.26 51.23 59.9 63.28 52.47TiO2 1.03 1.19 1.38 1.00 0.89 0.92 0.98 0.91 1.49 1.15 0.95 1.21 1.19 0.74 1.07Al2O3 17.37 16.62 16.92 16.75 19.88 15.42 17.24 17.19 17.72 14.54 14.39 18.89 17.35 15.78 17.64Fe2O3 7.66 6.50 7.13 7.78 5.91 7.67 4.98 5.85 4.62 8.62 6.46 9.74 6.61 4.37 9.43FeO - - - - - - - - 3.40 - - - - - -MnO 0.17 0.24 0.25 0.16 0.11 0.17 0.13 0.15 0.27 0.20 0.12 0.17 0.16 0.16 0.17MgO 3.40 2.09 2.52 3.15 1.91 4.98 1.50 1.80 3.15 2.92 2.13 3.51 2.39 1.53 3.81CaO 5.68 3.81 5.11 5.95 6.17 5.77 2.92 3.36 6.09 2.78 2.44 9.68 4.31 1.32 6.05Na2O 4.55 4.94 4.42 4.13 3.26 3.64 4.23 4.03 4.32 4.01 3.61 2.88 4.67 4.25 3.84K2O 2.01 3.16 2.85 2.68 4.24 0.75 5.28 4.69 2.20 1.49 2.19 1.65 3.20 4.39 2.19P2O5 0.24 0.00 0.11 0.04 0.50 0.08 1.08 0.42 0.17 0.05 0.47 0.65 0.00 0.26 0.59CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 3.20 1.91 1.44 1.27 2.14 3.26 1.31 1.67 1.82 3.12 2.02 0.86 1.58 2.69 2.6TOTAL 101.01 99.08 99.27 100.49 98.99 99.45 100.92 100.84 100.71 100.33 100.04 100.47 101.35 98.76 99.87

Ba 547 623 584 533 622 288 765 724 505 253 473 390 604 666 586Sr 518 668 1383 1070 1312 794 785 886 1637 271 346 1140 995 321 1235Ag <2 1 - - - - - - - <5 1 - - - - - -As 9.13 1 - - - - - - - 3.94 1 - - - - - -Au <5 1 - - - - - - - <5 1 - - - - - -Be - - - - - - - - 1.25 - - - - - -Br <1 1 - - - - - - - <1 1 - - - - - -Ce 42.9 1 - - - - - - - 59.76 - - - - - -Co 30.7 1 - - - - - - - 10.57 - - - - - -Cr 56.5 1 - - - - - - - 60.73 - - - - - -Cs 1.9 1 - - - - - - - 5.88 1 - - - - - -Cu - - - - - - - - 24.62 - - - - - -Dy - - - - - - - - 5.61 - - - - - -Er - - - - - - - - 3.00 - - - - - -Eu 1.46 1 - - - - - - - 2.57 - - - - - -Ga - - - - - - - - 19.64 - - - - - -Gd - - - - - - - - 7.20 - - - - - -Hf 4.25 1 - - - - - - - 2.81 - - - - - -Ho - - - - - - - - 1.09 - - - - - -Ir <5 1 - - - - - - - <5 1 - - - - - -La 19.2 1 - - - - - - - 25.45 - - - - - -Li - - - - - - - - 21.16 - - - - - -Lu 0.35 1 - - - - - - - 0.39 - - - - - -Mo <5 1 - - - - - - - <5 1 - - - - - -Ni - - - - - - - - 0.37 - - - - - -Nb - - - - - - - - 5.66 - - - - - -Nd - - - - - - - - 35.84 - - - - - -Pb - - - - - - - - 8.10 - - - - - -Pr - - - - - - - - 8.30 - - - - - -Rb 65.9 1 - - - - - - - 64.60 - - - - - -Sb 8.2 1 - - - - - - - 0.93 1 - - - - - -Sc 21.5 1 - - - - - - - 16.70 - - - - - -Se <1 1 - - - - - - - <1 1 - - - - - -Sm 5.22 1 - - - - - - - 8.00 - - - - - -Sn - - - - - - - - 1.49 - - - - - -Ta 0.43 1 - - - - - - - 0.38 - - - - - -Tb 0.89 1 - - - - - - - 0.97 - - - - - -Th 5.62 1 - - - - - - - 4.52 - - - - - -Tm - - - - - - - - 0.41 - - - - - -U <2 1 - - - - - - - 1.05 - - - - - -V - - - - - - - - 133.23 - - - - - -W <2 1 - - - - - - - <2 1 - - - - - -Y - - - - - - - - 27.21 - - - - - -Yb 2.72 1 - - - - - - - 2.52 - - - - - -Zn 118 1 - - - - - - - 115.83 - - - - - -Zr - - - - - - - - 98.87 - - - - - -δ O - - - - - - -0.8 - 0.4 - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - 0.13616 - - - - - -143Nd/144Nd - - - - - - - - 0.51279 - - - - - -87Rb/86Sr - - - - - - - - 0.10828 - - - - - -87Sr/86Sr - - - - - - - - 0.70360 - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



16


Lithology And. Trand. Trand. Monzab. QMD Gd. Gd Gd. Gd. Gd. Gd. Gd. Qtz dio. Gd. MonzgabUnit Neara Neara Dyke Gibraltar Gibraltar ?Jur intru. ?Jur intru. ?Jur intru. Woolooga Woolooga Woolooga Woolooga Woolooga Woolooga GibraltarSiO2 51.89 58.76 73.15 52.04 60.25 63.13 61.32 61.25 61.32 63.47 66.32 63.45 57.14 62.38 54.89TiO2 1.03 1.06 0.19 1.22 0.95 0.60 0.7 0.73 0.69 0.65 0.62 0.61 0.89 0.67 0.8Al2O3 17.83 15.80 13.40 16.46 16.91 15.16 15.7 15.59 15.93 15.73 15.50 15.18 16.96 15.54 18.46Fe2O3 8.90 6.96 1.15 9.65 5.63 5.14 5.45 5.69 5.69 5.11 3.98 2.41 6.84 5.22 7.9FeO - - - - - - - - - - - 2.34 - - -MnO 0.17 0.18 0.05 0.30 0.15 0.15 0.13 0.13 0.14 0.09 0.10 0.12 0.12 0.11 0.19MgO 3.49 1.99 0.19 3.84 1.72 2.73 2.75 2.80 2.79 2.62 1.29 2.45 3.87 2.46 2.64CaO 7.18 4.85 1.66 7.05 4.11 4.15 4.37 4.60 4.79 4.41 2.93 4.00 6.29 4.05 7.65Na2O 3.53 4.40 3.60 3.80 4.39 3.62 3.48 3.89 3.50 3.58 4.22 3.55 3.87 3.73 4.05K2O 2.08 2.87 3.97 2.27 3.44 2.82 2.95 2.71 2.66 2.86 3.91 3.04 1.69 3.07 1.58P2O5 0.66 0.50 0.08 0.79 0.09 0.09 0.36 0.15 0.06 0.11 0.15 0.12 0.09 0.09 0.00CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 2.244 1.63 2.25 1.47 1.07 1.6 1.5 1.08 0.63 1.61 0.56 1.5 1.05 1.67 1.08TOTAL 98.99 99.01 99.66 98.88 98.72 99.19 98.71 98.62 98.19 100.24 99.58 99.02 98.80 98.99 99.22

Ba 466 617 515 455 1112 420 447 377 370 397 533 402 287 412 387Sr 1191 763 178 1260 812 386 421 350 363 351 513 325 459 402 907Ag - - - - - - <5 1 - - <2 1 - - - - <5 1

As - - - - - - 1.43 1 - - 3.63 1 - - - - <5 1

Au - - - - - - <5 1 - - 8.7 1 - - - - <5 1

Be - - - - - - - - - - - - - - -Br - - - - - - <1 1 - - <1 1 - - - - <1 1

Ce - - - - - - 55 1 - - 50.8 1 - - - - 60.1 1

Co - - - - - - 16 1 - - 13.3 1 - - - - 15.7 1

Cr - - - - - - 148 1 - - 175 1 - - - - 83 1

Cs - - - - - - 3.65 1 - - 4.7 1 - - - - 1.15 1

Cu - - - - - - - - - - - - - - -Dy - - - - - - - - - - - - - - -Er - - - - - - - - - - - - - - -Eu - - - - - - 1.27 1 - - 1.15 1 - - - - 2.09 1

Ga - - - - - - - - - - - - - - -Gd - - - - - - - - - - - - - - -Hf - - - - - - 5.51 1 - - 4.69 1 - - - - 3.44 1

Ho - - - - - - - - - - - - - - -Ir - - - - - - <5 1 - - <5 1 - - - - <5 1

La - - - - - - 23.3 1 - - 23.1 1 - - - - 24.4 1

Li - - - - - - - - - - - - - - -Lu - - - - - - 0.28 1 - - 0.27 1 - - - - 0.3 1

Mo - - - - - - <5 1 - - <5 1 - - - - <5 1

Ni - - - - - - - - - - - - - - -Nb - - - - - - - - - - - - - - -Nd - - - - - - - - - - - - - - -Pb - - - - - - - - - - - - - - -Pr - - - - - - - - - - - - - - -Rb - - - - - - 88.9 1 - - 93.2 1 - - - - 51.9 1

Sb - - - - - - 0.7 1 - - 1.2 1 - - - - <0.2 1

Sc - - - - - - 12.6 1 - - 11.5 1 - - - - 11.1 1

Se - - - - - - <1 1 - - <1 1 - - - - <1 1

Sm - - - - - - 5.19 1 - - 5.03 1 - - - - 6.53 1

Sn - - - - - - - - - - - - - - -Ta - - - - - - 0.77 1 - - 0.55 1 - - - - <0.3 1

Tb - - - - - - 0.83 1 - - 0.8 1 - - - - 0.99 1

Th - - - - - - 12.8 1 - - 12.1 1 - - - - 6.76 1

Tm - - - - - - - - - - - - - - -U - - - - - - 2.6 1 - - 2.34 1 - - - - <2 1

V - - - - - - - - - - - - - - -W - - - - - - <2 1 - - <2 1 - - - - <2 1

Y - - - - - - - - - - - - - - -Yb - - - - - - 2.12 1 - - 2.09 1 - - - - 2.35 1

Zn - - - - - - 93.6 1 - - 71.9 1 - - - - 92.6 1

Zr - - - - - - - - - - - - - - -δ O - - - - - - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



17


Lithology Monzgab. Gd. Meta-bas. Dacite Serp. Fo. Gd. Volcanics Gd. Fo. Gd. Trand.por. Bas-trand. Fo.Gd. Cat. Gd. Syenite Trand.Unit Gibraltar Woolooga Neara Neara Mt Mia Fo. Gd. Neara Intrusive Fo. Gd. Intrusive Dyke Fo. Gd. Fo. Gd. Fo. Gd. Mt MuckiSiO2 51.65 66.23 65.52 65.24 - 69.74 60.61 68.4 66.35 63.24 59.24 66.01 64.64 59.23 47.33TiO2 1.09 0.65 0.69 0.95 - 0.62 1.03 0.73 0.89 0.62 1.05 0.89 0.95 0.99 1.18Al2O3 18.24 15.78 13.92 14.62 - 13.36 14.38 13.42 14.06 15.89 16.24 14.4 14.58 16.92 15.51Fe2O3 9.30 1.53 7.00 5.90 - 4.27 8.77 4.88 6.05 4.69 8.01 5.86 6.27 6.40 14FeO - 2.29 - - - - - - - - - - - - -MnO 0.19 0.10 0.10 0.10 - 0.07 0.16 0.09 0.11 0.08 0.28 0.11 0.13 0.15 0.24MgO 3.51 1.24 2.72 1.67 - 1.30 3.32 1.38 1.93 2.52 2.31 1.84 2.22 1.96 6.15CaO 8.94 2.79 1.31 2.58 - 1.36 4.72 1.93 2.77 3.33 4.90 2.84 2.28 3.41 12.38Na2O 3.82 4.20 3.42 2.76 - 4.11 3.53 4.07 3.46 4.80 4.23 3.27 3.44 4.22 2.11K2O 1.68 3.99 2.30 2.62 - 3.39 1.32 3.28 2.76 2.75 3.55 3.26 2.88 4.57 1.01P2O5 0.17 0.18 0.22 0.21 - 0.16 0.25 0.18 0.21 0.25 0.61 0.18 0.21 0.48 0.14CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 0.46 1.17 2.88 4.31 - 1.19 2.04 1.62 2.33 2.49 0.68 0.88 1.97 1.47 1.01TOTAL 99.05 100.40 100.08 100.96 - 99.57 100.13 99.98 100.92 100.66 101.10 99.54 99.57 99.80 101.06

Ba 384 520 493 776 - 446 307 551 592 464 695 456 831 829 199Sr 918 513 197 186 - 122 332 163 225 780 835 247 274 738 755Ag - <2 1 - - - - - - - <2 1 - <2 1 - - -As - 4.6 1 - - - - - - - 7.28 1 - 4.7 1 - - -Au - <5 1 - - - - - - - <5 1 - <5 1 - - -Be - 1.53 - - 0.01 - - - - 1.64 - - - - 0.43Br - <1 1 - - - - - - - <1 1 - <1 1 - - -Ce - 49.17 - - 0.15 - - - - 44.75 - 61.4 1 - - 11.31Co - 38.03 - - 67.35 - - - - 12.42 - 13.1 1 - - 43.56Cr - 51.06 - - 3232.21 - - - - 111.71 - 227 1 - - 64.47Cs - 4.50 - - 0.01 - - - - 1.22 - 6.2 1 - - 2.37Cu - 21.61 - - 2.33 - - - - 23.65 - - - - 215.52Dy - 3.86 - - 0.07 - - - - 3.03 - - - - 2.33Er - 2.16 - - 0.07 - - - - 1.73 - - - - 1.24Eu - 1.02 - - 0.02 - - - - 1.15 - 1.3 1 - - 0.78Ga - 17.56 - - 1.22 - - - - 20.59 - - - - 18.15Gd - 4.27 - - 0.05 - - - - 3.66 - - - - 2.43Hf - 4.18 - - 0.01 - - - - 4.13 - 7.21 1 - - 1.52Ho - 0.76 - - 0.02 - - - - 0.60 - - - - 0.47Ir - <5 1 - - - - - - - <5 1 - <5 1 - - -La - 22.40 - - 0.12 - - - - 21.00 - 27.4 1 - - 4.90Li - 13.41 - - 1.03 - - - - 18.76 - - - - 8.32Lu - 0.31 - - 0.02 - - - - 0.26 - 0.56 1 - - 0.17Mo - <5 1 - - - - - - - <5 1 - <5 1 - - -Ni - 17.95 - - 1927.67 - - - - 18.70 - - - - 18.68Nb - 7.53 - - 0.03 - - - - 6.23 - - - - 3.01Nd - 23.1 - - 0.22 - - - - 22.22 - - - - 7.74Pb - 17.21 - - 0.04 - - - - 13.05 - - - - 11.38Pr - 6.16 - - 0.05 - - - - 5.84 - - - - 1.65Rb - 110.46 - - 0.12 - - - - 64.65 - 120 1 - - 25.75Sb - 0.7 1 - - - - - - - 0.3 1 - 0.4 1 - - -Sc - 11.18 - - 11.61 - - - - 9.90 - 14.8 1 - - 35.39Se - <1 1 - - - - - - <1 1 - <1 1 - -Sm - 4.85 - - 0.05 - - - - 4.49 - 6.91 1 - - 2.25Sn - 3.10 - - 0.00 - - - - 2.23 - - - - 1.17Ta - 0.83 - - 0.01 - - - - 0.43 - 0.65 1 - - 0.25Tb - 0.65 - - 0.01 - - - - 0.51 - 1.2 1 - - 0.38Th - 11.85 - - 0.01 - - - - 6.53 - 9.14 1 - - 2.40Tm - 0.32 - - - - - - - 0.25 - - - - 0.18U - 2.89 - - 0.00 - - - - 2.05 - <2 1 - - 0.74V - 89.15 - - 44.85 - - - - 82.34 - - - - 443.37W - <2 1 - - - - - - - <2 1 - <2 1 - - -Y - 19.95 - - 0.60 - - - - 15.53 - - - - 11.27Yb - 2.05 - - 0.09 - - - - 1.64 - 4.16 1 - - 1.12Zn - 81.42 - - 34.23 - - - - 59.40 - 86.7 1 - - 88.75Zr - 146.00 - - 0.29 - - - - 157.28 - - - - 52.00δ O - 3.8 - - 5.4 - - - - - - - - - -δ D (Bio/Hb) - - - - - - - - - - - - - - -147Sm/144Nd - - - - - - - - - - - - - - -143Nd/144Nd - - - - - - - - - - - - - - -87Rb/86Sr - - - - - - - - - - - - - - -87Sr/86Sr - - - - - - - - - - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



18

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC944 SC944B SC985 SC987 SC999 SC1001 SC1008 SC1018 SC1018xCSC1018xDSC1018xeSC1018xFSC1021 SC1030 SC1030Easting 441000 441000 440474 441963 442100 441663 440139 440696 440650 440625 440696 440563 429200 432506 432506Northing 7113346 7113346 7114263 7114444 7112875 7113136 7112241 7110988 7110887 7110600 7110988 7110688 7107500 7105427 7105427

Lithology Bas-an. Bas-an. Meta-bas. Dolerite Gabbro Gabbro Trand. QMD Xenolith Xenolith Xenolith And. Tonalite Trach. XenolithUnit Dyke Dyke Fo. Dio. Gibraltar Mt Mucki Mt Mucki Dyke Gibraltar Gibraltar Gibraltar Gibraltar Gibraltar Intrusive North Arm North ArmSiO2 52.85 53 50.34 63.06 52.43 52.97 55.85 61.74 45.85 50.25 52.06 50.34 49.01 57.68 56.48TiO2 0.75 0.75 1.46 0.62 1.05 1.09 0.92 0.84 0.90 1.19 1.28 1.17 1.04 1.03 0.86Al2O3 21.26 21.31 15.01 15.63 16.15 16.28 18.92 16.84 14.06 14.91 16.05 15.33 19.07 16.99 17.43Fe2O3 6.94 7.13 10.98 4.48 6.06 10.47 6.57 5.08 14.31 12.24 10.62 12.03 9.02 7.34 7.76FeO - - - - 4.63 - - - - - - - - - -MnO 0.15 0.15 0.20 0.08 0.17 0.20 0.14 0.13 0.40 0.29 0.23 0.24 0.19 0.11 0.13MgO 2.69 2.71 6.71 2.42 4.12 4.60 1.92 1.82 7.89 4.66 4.22 4.71 4.21 3.71 2.56CaO 9.64 9.26 9.60 3.34 8.92 9.81 6.68 5.21 8.27 9.04 7.44 8.45 8.42 5.82 6.28Na2O 3.14 3.33 2.72 4.43 3.16 2.83 3.08 3.83 2.37 2.65 3.79 3.22 3.05 4.53 4.48K2O 1.90 1.92 0.27 2.65 1.55 1.58 4.82 3.64 1.12 2.09 2.28 1.94 2.69 2.11 1.03P2O5 0.60 0.62 0.19 0.21 0.31 0.20 0.54 0.26 0.14 0.27 0.31 0.27 0.45 0.30 0.41CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 1.03 1.03 0.88 1.23 0.90 0.95 0.98 0.92 2.85 1.22 0.86 0.94 2.06 1.16 1.41TOTAL 100.95 101.21 98.34 98.15 99.97 100.98 100.42 100.31 98.15 98.81 99.14 98.63 99.21 100.78 98.83

Ba 385 400 214 447 218 221 832 553 327 358 362 440 594 365 300Sr 1541 1611 204.5 758 889 764 1178 846 521.5 759.2 837 704.9 1209 362 686Ag - - - <2 1 <2 1 - - <2 1 - - <2 1 - - <2 1 <2 1

As - - - 4.61 1 6.93 1 - - 7.64 1 - - 8.72 1 - - 23.7 1 37.1 1

Au - - - <5 1 7.7 1 - - <5 1 - - <5 1 - - <5 1 28 1

Be - - - - 0.98 - 2.06 1.412 - - - - - - -Br - - - <1 1 <1 1 - - 1.78 1 - - 1.57 1 - - <1 1 1.89 1

Ce - - - 67.2 1 33.72 - 71.36 54.40 - - 41.5 1 - - 51.7 1 51.5 1

Co - - - 15.5 1 30.25 - 14.68 12.78 - - 25.9 1 - - 20.2 1 15.4 1

Cr - - - 86 1 65.09 - 51.92 119.98 - - 82.1 1 - - 146 1 94.1 1

Cs - - - 5.4 1 1.67 - 3.69 2.23 - - 1.8 1 - - 7.5 1 3.3 1

Cu - - - - 50.58 - 90.17 70.81 - - - - - - -Dy - - - - 3.59 - 4.41 4.33 - - - - - - -Er - - - - 2.16 - 2.48 2.52 - - - - - - -Eu - - - 1.76 1 1.22 - 1.87 1.58 - - 1.54 1 - - 1.7 1 1.3 1

Ga - - - - 19.13 - 20.24 18.11 - - - - - - -Gd - - - - 3.83 - 5.79 4.92 - - - - - - -Hf - - - 5.42 1 2.40 - 4.72 4.43 - - 1.66 1 - - 3.93 1 5.11 1

Ho - - - - 0.74 - 0.86 0.87 - - - - - - -Ir - - - <5 1 <5 1 - - <5 1 - - <5 1 - - <5 1 <5 1

La - - - 30.9 1 15.97 - 32.49 26.24 - - 18.7 1 - - 24 1 23.2 1

Li - - - - 7.88 - 10.86 10.23 - - - - - - -Lu - - - 0.36 1 0.33 - 0.35 0.37 - - 0.4 1 - - 0.36 1 0.28 1

Mo - - - <5 1 <5 1 - - <5 1 - - <5 1 - - <5 1 <5 1

Ni - - - - 9.03 - 14.29 6.46 - - - - - - -Nb - - - - 5.79 - 9.95 8.18 - - - - - - -Nd - - - - 17.56 - 36.88 26.67 - - - - - - -Pb - - - - 9.94 - 14.23 14.31 - - - - - - -Pr - - - - 4.36 - 9.39 6.94 - - - - - - -Rb - - - 118 1 35.52 - 98.30 86.51 - - 75.6 1 - - 74.3 1 29.3 1

Sb - - - 0.7 1 0.8 1 - - 2.7 1 - - 3.2 1 - - 3.5 1 6.2 1

Sc - - - 11.5 1 11.89 - 11.29 10.49 - - 20.1 1 - - 18.9 1 15.2 1

Se - - - <1 1 <1 1 - <1 1 - - <1 1 - - <1 1 <1 1

Sm - - - 6.95 1 4.04 - 7.29 5.49 - - 6.31 1 - - 6.21 1 5.76 1

Sn - - - - 2.12 - 2.22 1.59 - - - - - - -Ta - - - 0.69 1 0.42 - 0.62 0.60 - - 0.5 1 - - 0.39 1 0.84 1

Tb - - - 1.04 1 0.57 - 0.77 0.72 - - 1.09 1 - - 1 1 1 1

Th - - - 10.3 1 4.93 - 9.81 8.70 - - 5.71 1 - - 6.15 1 11.2 1

Tm - - - - 0.33 - 0.36 0.36 - - - - - - -U - - - <2 1 1.68 - 2.81 1.67 - - <2 1 - - <2 1 <2 1

V - - - - 288.56 - 148.03 127.87 - - - - - - -W - - - <2 1 <2 1 - - <2 1 - - <2 1 - - <2 1 <2 1

Y - - - - 19.03 - 22.45 22.85 - - - - - - -Yb - - - 2.79 1 2.13 - 2.30 2.39 - - 3.04 1 - - 2.55 1 2.44 1

Zn - - - 93.7 1 72.62 - 82.53 78.25 - - 139 1 - - 75.1 1 75.1 1

Zr - - - - 81.78 - 186.43 160.02 - - - - - - -δ O - - - - 7.3 - - - - - - - - - -δ D (Bio/Hb) - - - - -111 - - - - - - - - - -147Sm/144Nd - - - - 0.14082 - 0.12135 0.12557 - - - - - - -143Nd/144Nd - - - - 0.51285 - 0.5128 0.51279 - - - - - - -87Rb/86Sr - - - - 0.11394 - - 0.30639 - - - - - - -87Sr/86Sr - - - - 0.70346 - - 0.70417 - - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



19


Lithology QMD QMD QMD Dacite Ton-Gd. And. QMD Tonalite Monzgab. Qmonz. QMD Gd. Gd. Gd. DaciteUnit Woolooga Woolooga Woolooga Highbury Woonga Highbury Woolooga Woonga Mt Mucki Woolooga Woonga Woonga Woonga Woonga HighburySiO2 60.17 58.99 60.62 49.68 67.37 48.81 58.57 66.99 52.4 64.78 65.09 66.5 67.04 66.96 48.65TiO2 0.7 0.75 0.98 1.1 0.39 1.25 0.80 0.40 1.13 0.88 0.24 0.43 0.42 0.27 1.37Al2O3 15.27 16.15 17.01 14.68 17.14 17.73 16.49 16.76 19.26 15.71 15.43 15.29 16.01 14.95 14.4Fe2O3 5.5 6.64 6.42 9.99 3.44 10.49 6.52 3.25 8.50 4.87 2.52 3.90 1.80 3.38 11.86FeO - - - - - - - - - - - - 1.75 - -MnO 0.09 0.14 0.17 0.20 0.09 0.17 0.12 0.07 0.14 0.15 0.04 0.08 0.07 0.07 0.20MgO 2.71 3.29 2.40 9.20 1.78 4.02 3.66 1.76 2.86 1.12 1.07 1.71 1.61 0.97 8.51CaO 4.54 5.59 5.11 9.14 2.27 7.47 6.00 2.40 8.35 2.57 3.84 3.52 3.78 3.75 11.20Na2O 3.80 4.15 4.26 3.62 4.81 3.20 3.85 5.05 4.06 4.24 4.71 4.17 4.47 4.16 2.88K2O 2.75 2.20 3.18 0.21 1.94 3.62 1.89 1.58 2.25 5.33 2.78 2.48 2.60 2.93 0.11P2O5 0.21 0.27 0.52 0.15 0.11 0.58 0.24 0.11 0.35 0.31 0.08 0.12 0.11 0.12 0.13CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 1.48 0.90 0.61 0.99 1.71 1.28 1.50 1.48 1.35 0.39 3.47 0.93 0.95 2.49 0.95TOTAL 97.22 99.07 101.28 98.96 101.05 98.62 99.64 99.85 100.65 100.35 99.27 99.12 100.80 100.05 100.26

Ba 403 328 712 23 418 667 333 341 409 980 354 488 571 507 28Sr 378 433 911 93.4 459 1014 475 493 938 509 441 510 592 374 160Ag <2 1 <2 1 - <2 1 <2 1 - - - - <2 1 <2 1 - <2 1 <2 1 <2 1

As 6.72 1 6.98 1 - 12.6 1 2.53 1 - - - - <1 1 <1 1 - 2.11 1 1.86 1 <1 1

Au <5 1 <5 1 - <5 1 24.3 1 - - - - <5 1 <5 1 - <5 1 <5 1 <5 1

Be 1.69 - - - - 1.73 - - - - - - 1.16 - -Br <1 1 1.19 1 - <1 1 <1 1 - - - - <1 1 <1 1 - <1 1 <1 1 <1 1

Ce 50.34 50.6 1 - 5.17 1 16.7 1 76.68 - - - 84 1 19.5 1 - 22.03 36.2 1 8.54 1

Co 15.93 19.2 1 - 49.3 1 7.86 1 33.67 - - - 5.47 1 6.1 1 - 8.28 7.84 1 52.6 1

Cr 192.91 150 1 - 624 1 222 1 20.83 - - - 139 1 196 1 - 240.05 193 1 393 1

Cs 4.26 3.9 1 - 1 1 3.4 1 7.09 - - - 3.5 1 5.6 1 - 2.95 9.3 1 0.9 1

Cu 32.44 - - - - 56.12 - - - - - - 7.88 - -Dy 3.83 - - - - 4.57 - - - - - - 1.78 - -Er 2.12 - - - - 2.45 - - - - - - 1.05 - -Eu 1.14 1.27 1 - 0.78 1 0.6 1 2.08 - - - 2.09 1 0.54 1 - 0.65 0.82 1 1.09 1

Ga 18.57 - - - - 19.25 - - - - - - 16.13 - -Gd 4.33 - - - - 6.16 - - - - - - 1.83 - -Hf 5.21 5.39 1 - 1.69 1 2.45 1 4.03 - - - 6.21 1 2.27 1 - 2.92 3.6 1 2 1

Ho 0.74 - - - - 0.87 - - - - - - 0.36 - -Ir <5 1 <5 1 - <5 1 <5 1 - - - - <5 1 <5 1 - <5 1 <5 1 <5 1

La 22.53 22.3 1 - 1.98 1 9.6 1 34.06 - - - 36.8 1 9.65 1 - 13.61 18.9 1 3.47 1

Li 17.00 - - - - 20.61 - - - - - - 27.73 - -Lu 0.31 0.27 1 - 0.34 1 0.17 1 0.32 - - - 0.56 1 0.11 1 - 0.18 0.23 1 0.39 1

Mo <5 1 <5 1 - <5 1 <5 1 - - - - <5 1 <5 1 - <5 1 <5 1 <5 1

Ni 21.56 - - - - 11.03 - - - - - - 11.06 - -Nb 7.61 - - - - 13.44 - - - - - - 5.67 - -Nd 23.56 - - - - 38.77 - - - - - - 10.16 - -Pb 13.72 - - - - 16.79 - - - - - - 7.48 - -Pr 6.30 - - - - 9.92 - - - - - - 2.87 - -Rb 111.17 80.7 1 - <10 1 94.2 1 88.52 - - - 115 1 94.8 1 - 67.46 119 1 <10 1

Sb 0.7 1 0.9 1 - 4.9 1 0.7 1 - - - - 0.3 1 <0.2 1 - 0.5 1 0.4 1 <0.2 1

Sc 12.14 14.7 1 - 34.9 1 6.62 1 18.55 - - - 10.5 1 6 1 - 6.90 7.29 1 44.8 1

Se <1 1 <1 1 - <1 1 <1 1 - - - <1 1 <1 1 - <1 1 <1 1 <1 1

Sm 5.00 5.64 1 - 2.31 1 1.92 1 7.78 - - - 9.39 1 1.77 1 - 2.00 3.02 1 2.91 1

Sn 2.76 - - - - 2.53 - - - - - - 1.20 - -Ta 0.67 0.57 1 - <0.3 1 0.35 1 0.79 - - - 0.86 1 0.44 1 - 0.42 0.65 1 0.33 1

Tb 0.64 0.8 1 - 0.55 1 <0.5 1 0.82 - - - 1.48 1 <5 1 - 0.29 <5 1 0.77 1

Th 12.35 10.1 1 - <0.2 1 3.74 1 9.07 - - - 10.5 1 3.98 1 - 5.74 6.86 1 <2 1

Tm 0.31 - - - - 0.34 - - - - - - 0.16 - -U 3.69 <2 1 - <2 1 <2 1 2.42 - - - <2 1 <2 1 - 1.31 2.82 1 <2 1

V 95.39 - - - - 219.74 - - - - - - 54.05 - -W <2 1 <2 1 - <2 1 4.2 1 - - - - <2 1 17.4 1 - <2 1 <2 1 <2 1

Y 19.55 - - - - 22.11 - - - - - - 9.51 - -Yb 2.00 2.01 1 - 2.39 1 1.15 1 2.13 - - - 4.03 1 0.82 1 - 1.08 1.73 1 2.72 1

Zn 60.26 64 1 - 123 1 95.1 1 92.94 - - - 89.6 1 <50 1 - 29.83 51.3 1 115 1

Zr 192.33 - - - - 164.20 - - - - - - 107.75 - -δ O 4.0 - - - - 4.6 - - - 6.5 - - 8.0 - -δ D (Bio/Hb) -124 - - - - - - - - - - - -113 - -147Sm/144Nd 0.12796 - - - - - - - - - - - - - -143Nd/144Nd 0.51272 - - - - - - - - - - - - - -87Rb/86Sr 4.66097 - - - - - - - - - - - 0.41417 - -87Sr/86Sr 0.71943 - - - - - - - - - - - 0.70458 - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



20


Lithology Mgt Mgt Mgt Mgt Mgt Gd. Gd. Mgt Gd. Mgt Gd. Gd. Mdio Mgt MgtUnit Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Rush Ck Intrusive Rush Ck Rush CkSiO2 70.12 73.57 69.99 74.55 68.91 69.09 64.45 74.02 72.32 70.92 71.48 72.93 53.89 71.9 72.61TiO2 0.35 0.23 0.36 0.18 0.40 0.44 0.58 0.19 0.30 0.33 0.27 0.25 0.99 0.21 0.28Al2O3 14.12 13.47 14.31 13.37 14.24 13.87 14.74 13.48 14.10 14.25 14.23 14.12 17.29 13.48 13.54Fe2O3 2.93 2.02 2.68 1.61 3.34 1.59 4.92 1.69 1.09 2.83 2.32 2.37 9.15 2.01 2.43FeO - - - - - 1.79 - - 1.16 - - - - - -MnO 0.06 0.04 0.06 0.03 0.07 0.06 0.09 0.05 0.05 0.08 0.06 0.06 0.18 0.04 0.06MgO 1.25 0.71 1.41 0.46 1.72 1.70 2.73 0.47 0.98 1.27 0.95 0.74 3.47 0.68 0.99CaO 2.50 1.65 2.71 1.18 2.98 3.13 4.41 1.56 2.28 2.34 2.14 1.62 8.00 1.51 2.00Na2O 3.70 3.52 3.56 3.32 3.63 3.64 3.83 3.34 3.82 3.87 3.74 4.13 3.61 3.50 3.42K2O 4.13 4.50 3.94 4.41 3.71 3.28 2.77 4.32 3.67 3.94 3.79 3.55 1.75 4.44 4.40P2O5 0.08 0.00 0.09 - 0.10 0.09 0.15 0.03 0.06 0.10 0.06 0.09 0.40 0.04 0.05CO2 - - - - - - - - - - - - - - -H2O - - - - - - - - - - - - - - -LOI 0.36 0.34 0.84 0.67 0.70 0.73 0.87 0.35 0.66 0.82 0.77 0.67 0.13 0.40 0.32TOTAL 99.60 100.05 99.94 99.78 99.81 99.63 99.53 99.50 100.62 100.75 99.81 100.53 98.86 98.21 100.10

Ba 372 698 462 367 450 378 353 228 361 405 402 571 476 257 303Sr 205 146 234 123 234 248 320 133 210 226 220 208 698.2 133 166Ag <2 1 - <2 1 <2 1 - <2 1 <2 1 - - <2 1 <2 1 - <2 1 <2 1 -As 1.81 1 - 9.03 1 2.97 1 - 3.94 1 7.9 1 - - 6.61 1 5.91 1 - <1 1 3.57 1 -Au <5 1 - <5 1 <5 1 - <5 1 <5 1 - - <5 1 <5 1 - <5 1 <5 1 -Be - - - 1.83 - - 1.48 - - 1.52 - - 1.38 - -Br <1 1 - 2.97 1 1.38 1 - 1.93 1 1.82 1 - - 1.83 1 <1 1 - <1 1 <1 1 -Ce 39 1 - 34.5 1 42.01 - 21.8 1 47.34 - - 48.28 50 1 - 55.30 50.3 1 -Co 8.23 1 - 7.46 1 2.94 - 9.93 1 13.54 - - 5.51 5.14 1 - 22.42 4.42 1 -Cr 267 1 - 258 1 286.30 - 255 1 227.68 - - 291.48 265 1 - 63.91 261 1 -Cs 5.3 1 - 5.1 1 8.39 - 7.8 1 5.74 - - 9.33 5.3 1 - 2.09 10.7 1 -Cu - - - 28.16 - - 31.67 - - 10.74 - - 42.55 - -Dy - - - 2.02 - - 3.54 - - 2.91 - - 4.74 - -Er - - - 1.36 - - 2.11 - - 1.91 - - 2.69 - -Eu 0.72 1 - 0.68 1 0.42 - 0.77 1 0.88 - - 0.66 0.73 1 - 1.85 0.48 1 -Ga - - - 13.68 - - 17.28 - - 14.88 - - 21.74 - -Gd - - - 1.96 - - 3.66 - - 2.89 - - 5.77 - -Hf 4.09 1 - 3.87 1 3.55 - 4.15 1 4.06 - - 3.96 3.79 1 - 3.68 3.38 1 -Ho - - - 0.43 - - 0.72 - - 0.62 - - 0.95 - -Ir <5 1 - <5 1 <5 1 - <5 1 <5 1 - - <5 1 <5 1 - <5 1 <5 1 -La 19.9 1 - 16.2 1 22.68 - 9.27 1 23.14 - - 24.39 24.2 1 - 23.97 25.1 1 -Li - - - 20.88 - - 23.38 - - 44.20 - - 9.07 - -Lu 0.25 1 - 0.26 1 0.27 - 0.24 1 0.33 - - 0.36 0.31 1 - 0.38 0.3 1 -Mo <5 1 - <5 1 <10 1 - <5 1 <5 1 - - <10 1 <5 1 - <5 1 <5 1 -Ni - - - 7.78 - - 23.09 - - 11.12 - - 9.40 - -Nb - - - 7.23 - - 6.58 - - 7.03 - - 5.15 - -Nd - - - 14.07 - - 20.33 - - 18.54 - - 31.11 - -Pb - - - 19.48 - - 19.67 - - 17.45 - - 8.22 - -Pr - - - 4.50 - - 5.63 - - 5.50 - - 7.49 - -Rb 147 1 - 128 1 187.59 - 134 1 80.52 - - 146.67 146 1 - 51.15 181 1 -Sb 0.6 1 - 1.8 1 0.8 1 - 0.8 1 1.30 - - 1.30 0.9 1 - <0.2 1 0.7 1 -Sc 6.45 1 - 5.9 1 2.39 - 8.21 1 11.50 - - 5.31 4.18 1 - 16.28 3.51 1 -Se <1 1 - <1 1 <1 1 - <1 1 <1 1 - - <1 1 <1 1 - <1 1 <1 1 -Sm 3.16 1 - 2.93 1 2.44 - 2.95 1 4.19 - - 3.41 3.33 1 - 6.76 3.07 1 -Sn - - - 2.61 - - 3.07 - - 2.52 - - 2.32 - -Ta 0.72 1 - 0.95 1 1.06 - 0.81 1 0.67 - - 0.81 0.78 1 - 0.31 1.34 1 -Tb 5 1 - 0.54 1 0.32 - 0.55 1 0.57 - - 0.46 0.61 1 - 0.81 0.53 1 -Th 20.8 1 - 18 1 22.85 - 20 1 16.06 - - 19.41 19.4 1 - 6.18 31.9 1 -Tm - - - 0.22 - - 0.32 - - 0.31 - - 0.39 - -U 3.18 1 - 3.73 1 7.06 - 4.06 1 2.65 - - 4.83 4.5 1 - 1.32 11.1 1 -V - - - 11.63 - - 88.34 - - 29.80 - - 186.73 - -W <2 1 - <2 1 3.23 1 - 4.1 1 <2 1 - - <2 1 <2 1 - <2 1 <2 1 -Y - - - 12.70 - - 19.18 - - 17.12 - - 23.48 - -Yb 1.65 1 - 1.91 1 1.61 - 1.85 1 2.12 - - 2.20 2.16 1 - 2.49 2.11 1 -Zn 61.5 1 - 59.7 1 16.19 - 63.3 1 43.59 - - 27.87 56.7 1 - 91.04 - -Zr - - - 95.12 - - 135.43 - - 124.84 - - 137.72 - -δ O - - - 8.7 - 7.6 - - - 8.5 - - 7.3 - -δ D (Bio/Hb) - - - - - - - - - -129 - - - - -147Sm/144Nd - - - 0.10295 - - - - - 0.11471 - - - - -143Nd/144Nd - - - 0.51270 - - - - - 0.51271 - - - - -87Rb/86Sr - - - 0.81735 - - - - - 1.99758 - - - - -87Sr/86Sr - - - 0.70635 - - - - - 0.71043 - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



21

APPENDIX 2: WHOLE ROCK GEOCHEMISTRY (CONTINUED)Sample SC1225 SC1227 SC1258 SC1267 SC1285 SC1286 SC1287 SC1288 SC550 STD550ASTD550BSTD550CEasting 434825 434200 434340 431110 428675 427100 421400 421350 442087 442087 442087 442087Northing 7093741 7094923 7111832 7112688 7128550 7099050 7125625 7125720 7119413 7119413 7119413 7119413

Lithology Trem.sch. Gd. Amph. Amph. Qtz dio. Ton.-Gd. Gd. QMG Gd. Gd. Gd. Gd.Unit Widgee Rush Ck Fo. Gd. Manumbar Yorkeys Black SnakeBoogooramunyaBoonara Woolooga Woolooga Woolooga WooloogaSiO2 - 64.85 54.94 50.09 51.13 63.52 63.57 53.48 64.29 64.51 63.54 63.72TiO2 - 0.57 1.06 1.16 0.94 0.57 0.62 0.86 0.57 0.57 0.58 0.57Al2O3 - 15.22 14.28 15.54 16.7 16.07 15.86 15.88 15.40 15.82 15.78 15.40Fe2O3 - 4.92 9.01 10.25 10.24 4.59 5.09 9.78 5.03 5.03 4.78 4.93FeO - - - - - - - - - - - -MnO - 0.09 0.16 0.21 0.18 0.09 0.09 0.21 0.08 0.08 0.07 0.07MgO - 2.61 5.45 7.47 6.04 3.06 2.30 5.39 2.56 2.56 2.66 2.56CaO - 4.06 6.95 9.22 9.08 3.52 4.47 8.37 4.37 4.37 4.05 4.18Na2O - 3.64 3.27 3.57 2.89 4.83 3.05 2.59 3.74 3.79 3.79 3.70K2O - 3.05 1.32 1.03 1.11 2.43 3.56 1.81 2.83 2.87 2.90 2.93P2O5 - 0.16 0.17 0.21 0.38 0.24 0.18 0.29 0.13 0.10 0.14 0.16CO2 - - - - - - - - 0.09 0.12 0.09 -H2O - - - - - - - - 1.25 1.01 1.25 -LOI - 0.89 2.21 1.43 2.54 1.32 1.22 1.23 1.34 1.13 1.34 1.35TOTAL - 100.06 98.82 100.18 101.23 100.24 100.01 99.89 100.34 100.83 99.63 99.57

Ba - 418 391 120 310 433 409 347 415 463 387 386Sr - 338 228.9 218 698 676 416 745 351 349 357 344Ag - - <2 1 - - <2 1 - - - - - -As - - 1.77 1 - - 7.15 1 - - - - - -Au - - <5 1 - - <5 1 - - - - - -Be 0.08 - - - 0.71 1.37 - - - - - -Br - - <1 1 - - <1 1 - - - - - -Ce 1.32 - 36.8 1 - 31.09 40.44 - - - - - -Co 82.10 - 32.7 1 - 33.87 12.91 - - - - - -Cr 1762.17 - 289 1 - 82.37 161.51 - - - - - -Cs 1.66 - 2.16 1 - 4.26 4.12 - - - - - -Cu 75.23 - - - 43.73 12.34 - - - - - -Dy 1.30 - - - 3.91 2.64 - - - - - -Er 0.78 - - - 2.22 1.53 - - - - - -Eu 0.17 - 1.58 1 - 1.30 0.94 - - - - - -Ga 5.84 - - - 17.82 18.63 - - - - - -Gd 1.03 - - - 4.15 2.94 - - - - - -Hf 0.76 - 5.46 1 - 1.51 3.46 - - - - - -Ho 0.28 - - - 0.79 0.53 - - - - - -Ir - - <5 1 - - <5 1 - - - - - -La 0.33 - 14.2 1 - 13.33 19.33 - - - - - -Li 8.29 - - - 14.28 27.05 - - - - - -Lu 0.12 - 0.56 1 - 0.31 0.23 - - - - - -Mo - - <5 1 - - <5 1 - - - - - -Ni 1227.03 - - - 23.22 30.38 - - - - - -Nb 0.73 - - - 2.26 6.62 - - - - - -Nd 1.81 - - - 18.51 18.19 - - - - - -Pb 2.79 - - - 6.14 10.24 - - - - - -Pr 0.30 - - - 4.31 4.91 - - - - - -Rb 1.01 - 46 1 - 30.61 55.43 - - - - - -Sb - - 1.45 1 - - 5.2 1 - - - - - -Sc 16.71 - 31.4 1 - 25.81 10.76 - - - - - -Se - <1 1 - <1 1 - - - - - -Sm 0.72 - 6.17 1 - 4.33 3.58 - - - - - -Sn 0.13 - - - 1.79 1.82 - - - - - -Ta 0.09 - 0.4 1 - 0.13 0.50 - - - - - -Tb 0.19 - 1.28 1 - 0.63 0.43 - - - - - -Th 0.09 - 3.94 1 - 1.74 5.69 - - - - - -Tm - - - - 0.32 0.23 - - - - - -U 0.02 - <2 1 - 0.53 1.66 - - - - - -V 79.13 - - - 221.40 70.83 - - - - - -W - - <2 1 - - <2 1 - - - - - -Y 6.70 - - - 19.71 13.61 - - - - - -Yb 0.74 - 4.13 1 - 2.01 1.48 - - - - - -Zn 35.82 - 112 1 - 78.17 54.68 - - - - - -Zr 27.01 - - - 50.78 127.77 - - - - - -δ O - - - - 5.5 - - - - - - -δ D (Bio/Hb) - - - - -116 -130 - - - - - -147Sm/144Nd - - - - - 0.11690 - - - - - -143Nd/144Nd - - - - - 0.51268 - - - - - -87Rb/86Sr - - - - - 0.26598 - - - - - -87Sr/86Sr - - - - - 0.70430 - - - - - -Methodology: Major elements as well as Ba and Sr by ICP-AES (Queensland Uni. Tech.); trace elements by ICP-MS (Uni. Queensland)



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II. STABLE ISOTOPIC DATA FOR ORE DEPOSITSδ 18OWR Low Qtz High Qtz Pyrite Stibnite Galena

12.9 -64 -94 3.50 - -4.4 -87 -118 -1.00 -4.10 -10.3 - - 1.30 - -2.702.8 - - -1.60 - -3.8020.3 - - - - -

(Analytical results from the Stable Isotope Laboratory, University of Queensland)

III. RADIOMETRIC DATA: K/Ar (Results from the University of Queensland)

1. Sample name = SC 806 2. Sample name = SC 999Lab number = QA 781 Lab number = QA 782Sample type = Mineral separate Sample type = Mineral separateSample preparation = None Sample preparation = NoneSample analyzed = Hornblende Sample analyzed = HornblendeSample weight analyzed (g) = 0.1351 Sample weight analyzed (g) = 0.5467K2O analysis 1 (wt%) = 0.72 K2O analysis 1 (wt%) = 0.52K2O analysis 2 (wt%) = 0.69 K2O analysis 2 (wt%) = 0.60K2O average used for age calculation (wt%) = 0.705 K2O average used for age calculation (wt%) = 0.5640Ar radiogenic (%) = 66.7313 40Ar radiogenic (%) = 78.173940Ar radiogenic (moles/gram) = 2.07152E-10 40Ar radiogenic (moles/gram) = 1.79373E-10Minimum age (Ma) = 193.4 Minimum age (Ma) = 210Calculated 1 sigma error (plus or minus Ma) = 5.1 Calculated 1 sigma error (plus or minus Ma) = 21

IV. COMPARISON OF GEOCHEMICAL RESULTS USING THE DIFFERENT ANALYTICAL TECHNIQUES

Analytical Method ICP-MS INNA ICP-MS INNA ICP-MS INNA XRF INNA ICP-MS INNA ICP-MS INNAElement Ce 33.72 34.8 42.93 47.2 42.01 50.7 39.03 42.40 14.66 15.6

Co 30.25 29.1 14.72 15.4 2.94 2.9 32.10 35.20 52.02 53.9Cr 65.09 63.6 174.41 175.0 286.30 289.0 11.00 ND 74 54Cs 1.67 2.0 3.86 3.8 8.39 8.4 1.88 1.21 0.46 NDEu 1.22 1.3 0.97 1.1 0.42 0.5 1.26 1.40 0.75 0.84Ga 19.13 17.41 13.68 17Hf 2.40 2.5 4.31 4.5 3.55 3.4 3.67 3.51 1.48 1.42La 15.97 17.4 19.71 20.4 22.68 26.0 18.45 18.40 6.29 6.54Lu 0.33 0.3 0.31 0.3 0.27 0.3 0.42 0.36 0.26 0.23Nb 5.79 6.01 7.23 6Pb 9.94 15.31 19.48 14Rb 35.52 37.6 115.29 116.0 187.59 181.0 90 89.2 51.00 51.00 11 12Sc 11.89 13.1 11.69 12.5 2.39 2.6 18.00 19.70 36 33.1Sm 4.04 4.6 4.21 4.5 2.44 2.9 4.55 4.59 2.23 2.45Ta 0.42 0.5 0.58 0.7 1.06 0.9 0.65 0.65 0.35 0.35Tb 0.57 0.8 0.57 0.8 0.32 0.5 0.77 0.81 0.44 0.48Th 4.93 5.3 11.75 12.7 22.85 25.5 17 15.4 4.09 5.03 1.22 0.93U 1.68 <2 2.88 <2 7.06 5.4 3 1.06 ND 0.4 0.4Y 19.03 18.79 12.70 20Yb 2.13 2.4 2.01 2.2 1.61 2.0 2.61 2.54 1.62 1.60Zn 72.62 84.8 49.27 89.8 16.19 <50 88.00 114.00 90 128Zr 81.78 149.99 95.12 148

INAA results are from the Becquerel Laboratories, Lucas Heights, NSW. ND- Not determinedICP-MS results are from the Radiometric Laboratory of the Earth Sciences Department, University of Queensland. XRF results are from the Austalian National University, Canberra.

215EQuartz diorite Granodiorite Granite Granodiorite

Kilkivan Hg vein

ShamrockYorkeysMt VictorGreen Rock

2.00-3.60

-

Sphalerite

-

δ D (SMOW)Ore Deposit

-

δ 34S (CDT) o/oo

Becquerel Laboratories StandardsSAMPLE NUMBERLithology

12NT2 12NT31 Standard 1 1 Standard 2

SC999 SC582 SC1153


23

V. GENERIC GEOCHEMISTRY (RECALCULATED)

SAMPLE SC043 SC063 SC065 SC073 SC082 SC094 SC100 SC106 SC112 SC142 SC143 SC144 SC145 SC195 SC206Rock unit Cat. gd Cat. gd Neara Cat. gd North Arm North Arm Cat. gd Cat. gd Cat. gd WooloogaWoolooga WooloogaWoolooga Woolooga Woolooga

SiO2 (%) 69.92 68.08 60.74 69.43 57.45 59.61 67.76 68.3 67.91 64.95 65.71 65.39 65.38 66.26 65.7Ti (ppm) 4614 5259 4826 4278 5158 5840 5775 5464 5254 3415 3282 3384 3239 3050 3085MOLESAl2O3 0.13 0.14 0.17 0.14 0.16 0.17 0.15 0.14 0.14 0.15 0.15 0.15 0.15 0.15 0.15K2O 0.02 0.03 0.02 0.01 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.03CaO 0.04 0.04 0.10 0.04 0.11 0.11 0.01 0.04 0.05 0.08 0.07 0.08 0.08 0.07 0.08Na2O 0.06 0.06 0.05 0.06 0.07 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06INDICESAlkali index 5.73 6.67 4.59 4.88 5.66 5.83 5.88 6.03 5.83 6.56 6.87 6.47 6.55 6.79 6.9Felsic index 0.72 0.75 0.45 0.67 0.5 0.49 0.92 0.73 0.7 0.6 0.63 0.6 0.6 0.64 0.62Mafic index 0.76 0.74 0.68 0.74 0.58 0.73 0.73 0.72 0.74 0.65 0.66 0.66 0.67 0.66 0.65Solidification In. 13.36 13.2 21.9 15.99 28.18 16.83 15.99 15.46 15.03 18.4 16.89 17.73 17.39 17.08 17.06Alkali No. 68.46 68.74 65.77 66.53 58.13 66.91 65.85 67.59 66.84 69.36 71.44 69.91 70.58 71.12 71.04Mg No. 38.60 40.63 48.37 40.90 59.03 42.48 42.32 43.78 41.22 51.16 50.42 50.18 49.92 50.7 51.20CIPW NORMQ 32.04 28.05 18.01 34.36 6.11 12.54 31.38 28.46 28.34 18.2 18.71 19.59 19.31 20.76 18.96C 1.75 3.06 0.43 3.23 0 0 6.38 2.13 1.78 0 0 0 0 0 0Zr 0.05 0.05 - 0.05 - - 0.05 - 0.04 - - 0.03 - 0.03 0.03Or 13.3 18.87 10.59 8.18 10.92 15 15.55 15.1 14.04 17.19 17.55 17.44 17.22 19.64 18.28Ab 30.94 32.19 25.05 31.18 34.68 29.37 30.67 32.03 31.01 32.04 33.98 31.44 32.01 30.56 34.15An 9.53 3.95 27.94 8.61 19.39 24.1 0.23 8.61 10.78 16.92 15.86 16.75 16.92 15.9 14.59Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di - - - - 6.79 4.37 - - - 4.31 3.15 2.86 3.02 0.96 1.72Hy 7.69 7.76 12.55 9.08 10.08 8.75 9.95 8.38 8.82 7.63 7.18 7.88 7.67 8.36 7.98Ol - - - - - - - - - - - - - - -Mt 2.83 2.79 3.51 3.08 10.13 3.62 3.35 2.8 3.06 2.53 2.32 2.49 2.44 2.31 2.29Hm - - - - - - - - - - - - - - -Il 1.47 1.67 1.54 1.36 1.57 1.86 1.84 1.74 1.67 1.09 1.04 1.08 1.03 0.97 0.98Ap 0.37 0.3 0.61 0.32 0.5 0.59 0.32 0.43 0.35 0.19 0.19 0.25 0.34 0.22 0.27

Differentiation index76.28 79.11 53.65 73.72 51.71 56.91 77.6 75.59 73.39 67.43 70.24 68.47 68.54 70.96 71.39

Q % 37.34 33.77 22.07 41.73 8.59 15.48 40.32 33.8 33.67 21.58 21.73 22.99 22.6 23.9 22.05A % 15.5 22.72 12.98 9.94 15.36 18.52 19.98 17.93 16.68 20.38 20.38 20.46 20.15 22.61 21.26P % 47.16 43.51 64.95 48.33 76.05 66 39.7 48.27 49.65 58.04 57.89 56.55 57.25 53.49 56.69

V. GENERIC GEOCHEMISTRY (RECALCULATED)

SAMPLE SC215E SC222 SC223 SC229 SC233 SC235B SC237 SC241 SC252 SC289 SC304 SC313 SC323 SC328 SC350Unit Woolooga Dyke Woolooga Dyke Woolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga Woolooga Woolooga

SiO2 (%) 65.73 67.25 65.38 58.6 65 65.13 65.02 65.63 66.25 67.68 65.41 64.82 65.01 65.49 64.85Ti (ppm) 3327 2855 3457 5801 3028 3166 3170 3229 3289 2569 2953 3097 2900 3179 3148MOLESAl2O3 0.15 0.15 0.15 0.16 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.16K2O 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03CaO 0.07 0.07 0.07 0.11 0.08 0.08 0.08 0.09 0.08 0.07 0.07 0.08 0.07 0.08 0.08Na2O 0.06 0.07 0.06 0.05 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.06 0.06INDICESAlkali index 6.79 6.41 6.76 5.31 6.73 6.73 6.45 6.55 6.72 6.92 6.74 6.51 6.74 6.65 6.46Felsic index 0.65 0.62 0.64 0.46 0.6 0.6 0.58 0.59 0.61 0.65 0.62 0.59 0.63 0.61 0.59Mafic index 0.67 0.7 0.66 0.62 0.66 0.65 0.67 0.57 0.67 0.68 0.66 0.66 0.64 0.65 0.67Solidification index 17.18 13.5 17.61 26.24 17.82 18.29 17.66 20.86 16.51 14.09 17.53 18.29 19.29 17.51 17.43Alkali No. 69 75.95 69.38 58.97 70.57 69.85 70.39 71.31 71.43 75.97 70.72 69.7 68.55 71.54 70.56Mg No. 49.31 45.76 50.38 55.30 51.06 51.85 49.81 59.46 49.21 48.56 50.93 50.71 53.08 51.3 49.05CIPW NORMQ 19.37 28.38 18.65 13.26 17.91 18.14 18.72 19.16 20.98 22.2 18.31 18.26 17.2 19.07 18.93C 0 4.93 0 0.76 0 0 0 0 0 0 0 0 0 0 0Zr 0.03 - - - - - - - - - - 0.03 - - 0.03Or 19.24 15.74 18.56 14.37 17.55 17.82 17.07 17.43 18.98 19.28 17.58 16.92 16.96 17.83 17.52Ab 31.76 35.01 32.52 26.91 32.58 32.5 31.25 32.59 29.71 32.28 33.53 31.81 34.59 32.02 30.35An 14.95 2.68 15.58 20.56 16.84 16.26 17.81 16.54 16.32 15.4 16.16 17.53 15.59 17.12 18.57Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 2.34 - 2.24 - 4.25 3.79 4.46 2.45 4.1 2.37 3.06 3.88 2.92 2.97 2.98Hy 8.37 6.63 8.44 16.03 7.25 7.75 7.12 7.96 6.41 5.6 7.75 7.83 9 7.41 7.88Ol - - - - - - - - - - - - - - -Mt 2.6 2 2.54 3.77 2.42 2.43 2.5 1.91 2.32 1.88 2.4 2.54 2.54 2.29 2.55Hm - - - - - - - - - - - - - - -Il 1.06 0.91 1.1 1.85 0.96 1.01 1.01 1.03 1.04 0.82 0.94 0.98 0.92 1.01 1Ap 0.27 0.4 0.22 0.45 0.24 0.17 0.17 0.32 0.24 0.2 0.27 0.27 0.3 0.32 0.24


Q 22.7 34.69 21.86 17.66 21.1 21.41 22.06 22.35 24.4 24.9 21.4 21.6 20.39 22.16 22.17A 22.55 19.24 21.76 19.13 20.68 21.03 20.12 20.33 22.07 21.62 20.54 20.02 20.11 20.72 20.52P 54.75 46.07 56.38 63.21 58.22 57.55 57.82 57.31 53.53 53.48 58.06 58.38 59.5 57.11 57.3


24

SAMPLE SC358 SC363 SC369 SC374 SC382 SC386 SC388 SC393 SC394 SC400 SC412 SC430 SC450 SC453 SC456Unit Xenolith WooloogaWoolooga WooloogaWoolooga Intrusive Woolooga WooloogaWoolooga WooloogaWoolooga WooloogaIntrusive Woolooga Woolooga

SiO2 (%) 60.61 64.96 65.66 64.71 65.3 57.82 65.2 64.78 64.55 65.07 63.67 64.63 60.36 64.51 62.69Ti (ppm) 3761 2838 2915 3082 2912 4713 3199 3036 3046 3203 3497 3072 4375 3581 3991MOLESAl2O3 0.16 0.15 0.14 0.16 0.15 0.16 0.14 0.15 0.16 0.15 0.16 0.16 0.16 0.15 0.16K2O 0.02 0.03 0.03 0.03 0.03 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.03 0.03CaO 0.07 0.08 0.08 0.08 0.08 0.11 0.08 0.08 0.07 0.08 0.08 0.08 0.10 0.08 0.09Na2O 0.09 0.07 0.06 0.07 0.06 0.08 0.06 0.06 0.07 0.06 0.06 0.06 0.07 0.07 0.06INDICESAlkali index 7.97 6.71 6.34 6.87 6.59 6.73 6.56 6.5 7.46 6.61 6.66 6.8 6.67 6.59 6.21Felsic index 0.69 0.61 0.6 0.62 0.61 0.53 0.6 0.61 0.67 0.6 0.59 0.62 0.54 0.6 0.57Mafic index 0.63 0.63 0.64 0.65 0.65 0.61 0.65 0.64 0.63 0.65 0.64 0.65 0.64 0.63 0.64Solidification index 20.53 19.83 19.9 18.45 18.53 24.78 19.02 19.18 18.31 18.49 19.5 18.24 21.28 20.18 21.05Alkali No. 64.66 67.76 67.03 69.74 69.99 60.34 66.6 68.59 69.63 69.33 68.06 69.84 64.41 66.16 65.95Mg No. 54.28 53.88 52.95 51.87 51.83 56.32 51.30 52.18 53.40 51.24 52.39 51.62 52.47 53.28 52.41CIPW NORMQ 4.32 16.78 19.25 16.98 2 2.91 18.26 17.67 14.15 18.66 15.62 17.36 8.87 16.6 14.92C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Zr - - - 0.03 - - - - - - - 0.03 0.03 - -Or 13.76 15.99 15.22 17.14 16.92 11.76 16.92 16.49 17.89 16.84 17.6 18.21 13.62 15.64 14.44Ab 49.98 35.73 33.9 34.31 30.95 41.57 32.93 33.43 38.72 32.52 32.66 33.14 37.97 35.23 33.4An 12.16 14.59 14.7 16.6 16.71 17.13 14.1 16.6 13.83 16.85 17.31 16.68 17.8 14.44 19.07Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 2.35 4.86 4.77 2.33 1.99 10.07 6.34 3.05 3.27 2.66 3.89 1.07 7.43 5.46 3.45Hy 12.19 8.29 8.31 8.77 5.43 11.1 7.48 8.84 8.46 8.48 8.81 9.32 9.34 8.38 10.18Ol - - - - - - - - - - - - - - -Mt 3.16 2.54 2.6 2.51 6.3 3.59 2.71 2.59 2.44 2.54 2.68 2.51 3.24 2.71 2.98Hm - - - - 0.35 - - - - - - - - - -Il 1.2 0.9 0.93 0.98 0.9 1.5 1.02 0.96 0.97 1.02 1.11 0.98 1.39 1.14 1.27Ap 0.47 0.34 0.32 0.29 0.31 0.39 0.34 0.37 0.27 0.39 0.27 0.34 0.34 0.39 0.32


Q 5.39 20.19 23.17 19.97 3 3.97 22.21 20.99 16.73 21.99 18.78 20.33 11.33 20.27 18.23A 17.15 19.24 18.32 20.16 25.41 16.03 20.58 19.59 21.15 19.84 21.16 21.33 17.4 19.09 17.65P 77.46 60.56 58.5 59.87 71.58 80.01 57.21 59.43 62.12 58.17 60.07 58.34 71.26 60.64 64.12

SAMPLE SC472 SC483 SC492 SC494 SC496 SC497 SC503 SC508 SC512 SC513 SC517 SC518 SC520 SC525 SC526Unit Woolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga Woolooga Woolooga

SiO2 (%) 63.86 64.48 65.01 65.11 64.19 64.55 62.02 67.01 65.42 63.88 65.11 66.63 65.25 65.28 65.17Ti (ppm) 3529 3595 3098 3209 3195 3458 4555 2681 3478 3958 3227 3103 2985 2800 3220MOLESAl2O3 0.15 0.15 0.14 0.15 0.15 0.15 0.16 0.15 0.15 0.15 0.15 0.15 0.16 0.16 0.16K2O 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.03CaO 0.08 0.08 0.08 0.08 0.08 0.08 0.10 0.06 0.08 0.08 0.07 0.07 0.06 0.07 0.07Na2O 0.07 0.06 0.07 0.07 0.06 0.07 0.06 0.06 0.05 0.06 0.06 0.06 0.06 0.06 0.06INDICESAlkali index 6.98 6.78 7.32 6.75 6.86 7.11 6.27 7.06 6.12 6.68 6.69 6.5 7.08 6.96 6.41Felsic index 0.6 0.61 0.64 0.6 0.61 0.6 0.54 0.68 0.57 0.62 0.64 0.64 0.67 0.65 0.64Mafic index 0.62 0.65 0.66 0.64 0.68 0.64 0.66 0.68 0.65 0.66 0.64 0.67 0.67 0.67 0.67Solidification index 20.27 18.65 17.45 18.76 17.23 18.89 20.12 15.3 19.16 19.4 19.06 16.23 17 16.88 17.51Alkali No. 66.4 68.14 67.69 69.6 68.09 67.93 65.33 72.72 68.97 66.13 69.09 73.01 70.32 70.78 69.84Mg No. 54.74 51.32 50.44 52.78 47.78 53.16 50.33 48.46 51.40 50.97 52.47 48.94 49.71 49.45 49.25CIPW NORMQ 14.29 16.65 15.77 17.71 16.85 15.57 14.18 20.92 20.68 16.33 18.52 22.51 17.84 18.36 19.28C 0 0 0 0 0 0 0 0 0 0 0 0.27 0 0 0Zr - - - - - - 0.04 - - - - - - - -Or 18.25 17.12 18.45 16.47 18.61 18.48 15.73 19.16 17.08 17.05 17.95 18.58 19.59 19.56 18.74Ab 35.07 34 36.56 34.29 31.93 34.62 32.07 33.46 28.42 33.21 31.98 29.46 33.04 31.97 30.49An 13.59 15.75 11.65 15.8 16.23 13.51 18.44 14.66 18.47 16.19 17.12 17.63 16.05 16.61 17.84Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 6.85 4.32 6.8 4.51 3.57 7.4 5.53 0.44 3.7 2.9 0.82 - 0.27 0.62 -Hy 7.8 8.15 6.79 7.49 8.57 6.57 9.14 7.92 8 9.77 9.71 8.08 9.42 9.12 9.73Ol - - - - - - - - - - - - - - -Mt 2.62 2.65 2.64 2.41 2.88 2.51 3.09 2.24 2.53 2.93 2.53 2.24 2.55 2.51 2.63Hm - - - - - - - - - - - - - - -Il 1.12 1.14 0.98 1.02 1.02 1.1 1.46 0.85 1.11 1.26 1.03 0.99 0.95 0.89 1.02Ap 0.42 0.32 0.36 0.34 0.36 0.31 0.41 0.29 0.05 0.34 0.32 0.32 0.29 0.36 0.25


Q 17.6 19.94 19.13 21.02 20.15 18.95 17.63 23.72 24.43 19.73 21.64 25.53 20.62 21.23 22.33A 22.48 20.5 22.38 19.54 22.26 22.49 19.56 21.72 20.18 20.6 20.98 21.07 22.64 22.61 21.7P 59.93 59.57 58.49 59.44 57.59 58.57 62.81 54.56 55.39 59.68 57.38 53.4 56.74 56.16 55.97


25

SAMPLE SC533 SC534 SC535 SC538 SC540 SC542 SC550 SC552 SC555 SC556 SC568 SC571 SC572 SC582 SC583Unit Woolooga WooloogaDyke WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaHighbury Woolooga Woolooga

SiO2 (%) 65.31 69.44 63.74 67.22 66.68 63.71 64.94 65.49 63.17 63.66 65.16 64.99 47.69 64.75 64.31Ti (ppm) 3301 2543 3183 2492 2975 3351 3452 3062 3543 3437 3344 3496 10972 3381 3512MOLESAl2O3 0.15 0.14 0.16 0.15 0.15 0.16 0.15 0.15 0.16 0.16 0.15 0.15 0.15 0.15 0.16K2O 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.00 0.03 0.03CaO 0.06 0.04 0.08 0.06 0.07 0.08 0.08 0.06 0.08 0.08 0.07 0.08 0.18 0.08 0.08Na2O 0.07 0.06 0.06 0.07 0.06 0.06 0.06 0.06 0.07 0.06 0.06 0.06 0.06 0.06 0.06INDICESAlkali index 7.72 7.13 6.98 7.25 6.77 6.84 6.57 7.1 6.96 6.85 7.02 6.99 3.81 7.05 6.58Felsic index 0.69 0.78 0.62 0.71 0.65 0.61 0.6 0.69 0.61 0.61 0.63 0.62 0.27 0.63 0.58Mafic index 0.75 0.54 0.66 0.66 0.65 0.67 0.66 0.68 0.62 0.65 0.66 0.67 0.68 0.66 0.66Solidification index 11.62 20.77 17.79 15.86 16.43 16.9 18.08 16.35 20.58 18.99 17.85 17.52 27.3 17.96 18.18Alkali No. 73.44 71.27 69.19 72.41 73.2 70.65 69.33 70.6 67.75 68.07 68.18 68.67 45.67 68.33 69.71Mg No. 40.11 63.00 50.19 51.03 51.35 48.94 50.21 48.62 55.01 51.34 50.74 49.91 48.8 50.67 50.50CIPW NORMQ 16.66 24.22 15.16 19.86 20.32 15.29 18.6 20.39 13.58 15.69 17.6 17.8 0 16.9 17.46C 0 0.8 0 0 0 0 0 2.02 0 0 0 0 0 0 0Zr - - - - - 0.03 - - - - - - - - 0.03Or 22.56 20.47 19.13 18.66 17.77 18.4 16.95 19.14 17.59 18.42 19.37 19.68 2.36 19.52 17.29Ab 34.54 33.25 33.11 37.21 33.94 33.83 32.07 34.17 35.04 32.2 32.72 31.5 29.69 32.41 31.73An 13.51 9.76 16.6 12.3 15.67 17.57 17.14 10.04 16.75 17.42 13.96 15.04 25.55 14.88 17.91Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 2.62 - 3.35 0.08 1.96 2.53 3.05 - 3.21 2.51 4.77 4.46 20.53 4.52 3.73Hy 6.17 8.93 8.56 8.27 7.08 8.27 8.18 9.34 9.69 9.58 7.61 7.53 0.16 7.87 7.89Ol - - - - - - - - - - - - 10.81 - -Mt 2.55 1.65 2.69 2.14 2.08 2.61 2.59 2.56 2.61 2.76 2.6 2.62 7.05 2.64 2.57Hm - - - - - - - - - - - - - - -Il 1.05 0.81 1.01 0.79 0.94 1.06 1.1 0.97 1.13 1.09 1.06 1.11 3.51 1.07 1.12Ap 0.29 0.22 0.37 0.3 0.27 0.35 0.31 0.42 0.39 0.36 0.39 0.34 0.41 0.29 0.36


Q 19.09 27.62 18.05 22.56 23.17 17.97 21.94 24.35 16.37 18.74 21.04 21.19 - 20.19 20.69A 25.85 23.34 22.77 21.2 20.26 21.62 20 22.86 21.2 22 23.16 23.42 - 23.32 20.49P 55.06 49.04 59.18 56.24 56.57 60.41 58.06 52.79 62.43 59.26 55.8 55.39 - 56.49 58.82

SAMPLE SC588 SC589 SC590 SC592 SC593 SC595 SC596 SC597 SC598 SC603 SC604 SC607 SC609C SC611 SC612Unit Woolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaWoolooga WooloogaDyke WooloogaNeara Woolooga Woolooga

SiO2 (%) 64.24 64.53 64.65 64.63 63.65 64.9 64.45 64.69 64.94 65.26 60.19 65.4 64.94 64.46 66.2Ti (ppm) 3714 3356 3497 2817 3218 3314 3129 3400 3521 3341 4158 3335 4439 3415 2835MOLESAl2O3 0.15 0.15 0.15 0.16 0.16 0.15 0.15 0.15 0.16 0.15 0.16 0.15 0.15 0.16 0.16K2O 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.03 0.03 0.03 0.03CaO 0.08 0.07 0.08 0.07 0.08 0.07 0.08 0.07 0.07 0.07 0.11 0.07 0.07 0.08 0.06Na2O 0.06 0.07 0.06 0.06 0.07 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.07INDICESAlkali index 6.67 7.29 6.51 6.87 6.99 6.64 6.68 6.71 6.61 6.62 5.73 6.78 6.04 6.46 6.95Felsic index 0.61 0.65 0.58 0.64 0.62 0.62 0.62 0.62 0.62 0.63 0.49 0.63 0.6 0.59 0.66Mafic index 0.66 0.63 0.66 0.64 0.69 0.64 0.65 0.66 0.66 0.63 0.6 0.62 0.66 0.64 0.63Solidification index 18.26 18.46 18.38 18.81 16.83 19.6 18.58 18.44 17.9 19.71 25.71 19.51 19.18 19.78 18.12Alkali No. 68.76 69.47 69.91 70.44 68.77 68.35 68.56 68.87 70.01 68.65 62.4 69.41 68.08 68.99 71.85Mg No. 50.29 53.43 50.96 53.04 47.51 53.27 51.56 50.96 50.16 53.43 56.81 54.49 50.48 53.21 53.56CIPW NORMQ 17.15 15.05 18.27 16.78 14.82 17.78 16.44 18.24 18.72 19.26 11.21 18.29 2 17.61 19.21C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Zr 0.03 - 0.03 - - - - - - - - - - - -Or 17.93 18.95 16.56 18.11 17 17.3 17.64 18.32 17.59 18 11.62 17.51 14.39 16.11 17.29Ab 31.9 35.85 31.93 33.63 35.78 33.02 33.94 31.47 31.55 31.22 33.1 33.13 32.13 32.73 34.57An 17.35 14.46 18 17.69 15.94 16.44 15.86 17.01 18.07 17.18 21.49 16.01 18.62 17.96 16.37Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 2.82 3.85 3.38 0.18 3.84 2.22 3.61 1.18 1.19 0.07 5.41 3.07 0.86 2.78 0.78Hy 8.7 8.11 7.87 9.92 8.34 9.31 8.55 9.44 8.95 10.18 12.13 8.36 9.53 8.81 8.54Ol - - - - - - - - - - - - - - -Mt 2.68 2.42 2.51 2.44 2.87 2.55 2.63 2.62 2.56 2.51 3.25 2.34 2.71 2.52 2.18Hm - - - - - - - - - - - - - - -Il 1.18 1.07 1.11 0.89 1.02 1.05 0.99 1.08 1.12 1.06 1.32 1.06 1.41 1.09 0.9Ap 0.32 0.34 0.38 0.27 0.34 0.32 0.35 0.44 0.29 0.32 0.41 0.34 0.52 0.44 0.26


Q 20.34 17.85 21.55 19.46 17.74 21.03 19.6 21.45 21.79 22.48 14.48 21.53 2.98 20.86 21.97A 21.26 22.48 19.54 21.01 20.35 20.46 21.03 21.54 20.47 21.01 15.01 20.61 21.43 19.09 19.77P 58.4 59.67 58.91 59.53 61.91 58.5 59.37 57.01 57.74 56.5 70.51 57.85 75.59 60.05 58.26


26

SAMPLE SC614 SC617 SC620 SC623 SC627 SC628 SC631 SC631Xe SC637 SC638 SC642 SC653 SC657 SC664 SC677Unit Woolooga WooloogaDyke WooloogaWoolooga WooloogaNeara Xenolith Woolooga WooloogaWoolooga Oakview Oakview Gibraltar Gibraltar

SiO2 (%) 68.36 66.8 66.63 69.3 65.67 66.74 60.76 64.78 63.59 64.83 64.9 50.11 56.95 60.34 58.41Ti (ppm) 2873 3250 3182 2620 3416 3144 5295 5244 3989 3564 3324 11979 6313 7340 8456MOLESAl2O3 0.14 0.15 0.15 0.15 0.15 0.15 0.15 0.16 0.16 0.15 0.15 0.15 0.17 0.17 0.17K2O 0.04 0.03 0.04 0.03 0.03 0.03 0.01 0.03 0.03 0.03 0.03 0.00 0.02 0.03 0.03CaO 0.05 0.06 0.05 0.04 0.07 0.07 0.08 0.08 0.08 0.08 0.07 0.18 0.10 0.07 0.09Na2O 0.06 0.06 0.07 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.08 0.08 0.07INDICESAlkali index 6.94 6.68 7.56 6.58 6.52 6.65 4.07 6.55 6.22 6.5 6.8 4.17 6.56 8.1 7.27Felsic index 0.71 0.68 0.73 0.73 0.64 0.63 0.5 0.6 0.58 0.61 0.62 0.29 0.54 0.68 0.59Mafic index 0.65 0.65 0.66 0.69 0.67 0.67 0.63 0.73 0.65 0.65 0.66 0.7 0.69 0.76 0.74Solidification index 16.3 17.23 15.84 14.19 17.86 16.16 28 13.54 20.19 18.84 17.82 24.56 19.3 12.52 14.89Alkali No. 72.4 72.2 70.28 75.28 69.45 72.52 56.22 72.34 67.28 68.68 70.12 48.39 63.81 68.75 66.25Mg No. 51.53 51.47 50.15 47.03 49.86 49.12 53.69 42.18 51.89 51.41 50.72 46.23 46.79 38.91 41.18CIPW NORMQ 23.67 21.5 18.14 27.82 19.94 21.56 18.92 18.83 16.93 18.35 17.14 0 4.06 6.13 5.88C 0 0.43 0 1.77 0 0 1.82 0 0 0 0 0 0 0 0Zr - - - - - - - - - - - - - - -Or 20.37 17.2 22.33 18.13 16.77 17.16 4.99 17.38 15.91 17.73 18.09 2.08 12.23 19.3 17.3Ab 30.97 33.42 34.79 30.78 32.3 32.35 29.33 32.77 31.3 31.24 33.56 33.49 39.56 43.19 38.4An 13.84 15.59 11.01 11.55 16.95 16.48 20.39 17.57 19.19 17.33 16.65 22.69 21.66 14.37 18.48Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 0.16 - 2.73 - 1.19 1.82 - 3.28 2.77 2.72 2.12 21.56 5.12 4.54 6.19Hy 7.85 8.42 7.48 6.94 9 7.2 18.03 5.67 9.59 8.75 8.49 8.2 10.98 6.87 7.33Ol - - - - - - - - - - - 1.58 - - -Mt 2.06 2.21 2.36 2 2.58 2.23 4.34 2.54 2.82 2.61 2.49 6.37 3.99 3.41 3.71Hm - - - - - - - - - - - - - - -Il 0.91 1.03 1.01 0.83 1.09 1 1.69 1.67 1.27 1.13 1.05 3.77 2.01 2.33 2.69Ap 0.27 0.32 0.27 0.32 0.32 0.34 0.67 0.57 0.34 0.27 0.56 0.33 0.59 - 0.27


Q 26.64 24.51 21.03 31.51 23.2 24.63 25.7 21.76 20.32 21.68 20.06 - 5.24 7.39 7.34A 22.93 19.61 25.88 20.54 19.51 19.6 6.78 20.08 19.09 20.95 21.17 - 15.78 23.26 21.61P 50.43 55.88 53.09 47.95 57.29 55.77 67.53 58.16 60.59 57.38 58.77 - 78.98 69.36 71.05

SAMPLE SC681 SC690 SC699 SC700 SC707 SC710 SC711 SC719 SC725 SC729 SC743 SC760 SC788 SC789 SC790Unit Gibraltar Dyke Neara Neara Neara Gibraltar Cat. gd Cat. gd Neara Gibraltar Gibraltar Neara Neara Neara Dyke

SiO2 (%) 58.03 55.74 59.04 61.51 61.28 55.7 63.22 66.58 51.43 60.03 65.86 53.94 53.63 60.35 75.07Ti (ppm) 6042 5509 5734 5899 5501 9032 7091 5810 7282 7150 4617 6595 6364 6526 1169MOLESAl2O3 0.17 0.20 0.16 0.17 0.17 0.18 0.15 0.14 0.19 0.17 0.16 0.18 0.18 0.16 0.13K2O 0.03 0.05 0.01 0.06 0.05 0.02 0.02 0.02 0.02 0.03 0.05 0.02 0.02 0.03 0.04CaO 0.11 0.11 0.11 0.05 0.06 0.11 0.05 0.04 0.17 0.08 0.02 0.11 0.13 0.09 0.03Na2O 0.07 0.05 0.06 0.07 0.07 0.07 0.07 0.06 0.05 0.08 0.07 0.06 0.06 0.07 0.06INDICESAlkali index 6.81 7.5 4.39 9.51 8.72 6.52 5.5 5.8 4.53 7.87 8.64 6.03 5.61 7.27 7.57Felsic index 0.53 0.55 0.43 0.77 0.72 0.52 0.66 0.7 0.32 0.65 0.87 0.5 0.44 0.6 0.82Mafic index 0.71 0.76 0.61 0.77 0.76 0.73 0.75 0.75 0.74 0.73 0.74 0.71 0.72 0.78 0.86Solidification index 17.76 12.47 29.23 9.38 11 17.43 17.14 14.8 19.74 14.17 10.52 19.77 19.39 12.27 2.13Alkali No. 63.59 74.63 56.68 75.14 72.28 63.24 59.42 65.96 62.3 68.43 75.22 60.49 62.38 67.41 92.44Mg No. 44.51 39.03 56.26 37.37 37.87 42.63 40.16 39.51 41.66 41.74 40.96 44.48 43.69 36.16 24.66CIPW NORMQ 5.94 2.49 12.44 9.14 8.85 5.4 20.5 27.43 3.24 7.01 16.71 2.23 2.96 9.76 33.87C 0 0 0 1.2 0.04 0 1.39 2.55 0 0 2.15 0 0 0 0.27Zr - - - - - - - - - - - - - - -Or 16.05 25.98 4.63 31.44 28.06 12.74 9.11 13.26 9.85 19.04 27.09 13.42 12.75 17.5 24.1Ab 35.4 28.59 32.18 36.05 34.52 35.73 35.1 31.3 24.62 39.77 37.54 33.63 31.09 38.41 31.28An 19.57 28.19 24.64 9.34 15.13 22.04 14.11 10.08 34.16 17.12 5.68 25.35 27.8 15.42 8.22Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 8.65 1.19 4.16 - - 5.69 - - 9.31 3.99 - 2.48 5.07 5.85 -Hy 8.56 7.85 16 6.31 7.95 5.05 12.94 9.25 10.31 7.6 6.59 14.77 12.38 6.42 1.19Ol - - - - - - - - - - - - - - -Mt 4 3.11 4.07 2.55 3 7.34 4.52 3.36 4.99 3.38 2.31 4.95 4.69 3.64 0.6Hm - - - - - 3.15 - - - - - - - - -Il 1.92 1.75 1.83 1.87 1.75 2.77 2.26 1.85 2.32 2.27 1.47 2.1 2.03 2.08 0.37Ap 0.1 1.24 0.2 2.62 1.02 0.4 0.12 1.15 1.56 - 0.66 1.47 1.63 1.23 0.2


Q 7.72 2.92 16.84 10.63 10.22 7.11 26.01 33.42 4.51 8.45 19.2 2.99 3.97 12.04 34.75A 20.85 30.48 6.27 36.57 32.42 16.78 11.56 16.16 13.71 22.96 31.13 17.98 17.09 21.58 24.73P 71.43 66.6 76.9 52.8 57.36 76.1 62.43 50.42 81.79 68.59 49.67 79.03 78.94 66.38 40.53


27

SAMPLE SC792 SC794 SC806 SC808 SC809 SC812 SC820 SC825 SC826 SC830 SC832 SC836 SC852 SC854 SC871Unit Gibraltar Gibraltar Intrusive Intrusive Intrusive WooloogaWoolooga WooloogaWooloogaWooloogaWoolooga Gibraltar Gibraltar WooloogaNeara

SiO2 (%) 53.42 61.71 64.69 63.08 62.79 62.85 64.35 66.98 65.06 58.45 64.1 55.92 52.39 66.74 67.41Ti (ppm) 7508 5833 3686 4317 4487 4240 3951 3754 3750 5458 4127 4886 6628 3927 4256MOLESAl2O3 0.17 0.17 0.15 0.16 0.16 0.16 0.16 0.15 0.15 0.17 0.16 0.18 0.18 0.16 0.14K2O 0.02 0.04 0.03 0.03 0.03 0.03 0.03 0.04 0.03 0.02 0.03 0.02 0.02 0.04 0.03CaO 0.13 0.08 0.08 0.08 0.08 0.09 0.08 0.05 0.07 0.11 0.07 0.14 0.16 0.05 0.02Na2O 0.06 0.07 0.06 0.06 0.06 0.06 0.06 0.07 0.06 0.06 0.06 0.07 0.06 0.07 0.06INDICESAlkali index 6.07 7.83 6.44 6.43 6.6 6.16 6.44 8.13 6.59 5.56 6.8 5.63 5.5 8.19 5.72Felsic index 0.46 0.66 0.61 0.6 0.59 0.56 0.59 0.74 0.62 0.47 0.63 0.42 0.38 0.75 0.81Mafic index 0.72 0.77 0.65 0.66 0.67 0.67 0.66 0.76 0.67 0.64 0.68 0.75 0.73 0.77 0.72Solidification index 19.63 11.33 19.08 18.8 18.56 19.06 18.49 9.63 17.44 23.79 16.99 16.33 19.17 9.19 17.62Alkali No. 58.25 72.62 68.05 67.95 67.11 67.69 69.23 77.23 69.42 63.3 69.34 67.48 62.22 77.5 62.5Mg No. 44.08 37.70 51.27 49.99 49.36 49.28 50.39 39.10 49.21 52.85 48.28 39.83 42.78 37.61 43.50CIPW NORMQ 1.46 9.92 18.19 16.35 14.41 16.04 18.07 18.5 19.79 8.92 16.45 4.87 0 18.85 29.3C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3.93Zr - - - - - - - - - - - - - - -Or 13.86 20.9 17.14 18.04 16.48 16.17 17.23 23.4 17.99 10.26 18.71 9.58 10.13 23.27 14.05Ab 33.22 38.18 31.49 30.4 33.87 30.47 30.81 36.15 30.08 33.65 32.54 35.09 32.99 35 29.91An 21.92 16.84 17.31 19.14 17.61 20.52 18.75 12.01 16.57 24.62 17.16 28.24 28.28 12.28 5.68Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 8.56 3.46 2.91 1.24 4.26 3.08 2.52 1.82 2.23 5.78 2.68 9.05 13.45 0.56 -Hy 12.04 5.94 9 9.93 8.72 9.35 8.56 4.68 5.08 11.36 8.32 7.65 7.1 2.78 11.69Ol - - - - - - - - - - - - 0.9 - -Mt 5.06 2.94 2.68 2.86 2.97 2.97 2.64 2.04 6.17 3.57 2.73 4.11 4.82 5.7 3.67Hm - - - - - - - - 0.76 - - - - 0.08 -Il 2.39 1.85 1.17 1.37 1.43 1.35 1.26 1.19 1.16 1.74 1.31 1.56 2.11 1.22 1.35Ap 1.95 0.22 0.22 0.89 0.37 0.15 0.27 0.36 0.29 0.22 0.22 - 0.41 0.43 0.55

Differentiation index48.54 69 66.82 64.79 64.76 62.68 66.11 78.05 67.86 52.83 67.7 49.54 43.12 77.12 73.26

Q 2.07 11.56 21.62 19.48 17.49 19.28 21.29 20.54 23.44 11.52 19.38 6.26 - 21.09 37.12A 19.67 24.35 20.37 21.49 20.01 19.44 20.3 25.98 21.31 13.25 22.05 12.32 - 26.03 17.8P 78.26 64.1 58.01 59.03 62.5 61.29 58.4 53.48 55.25 75.24 58.57 81.42 - 52.89 45.08

SAMPLE SC874 SC885 SC886 SC892 SC896 SC901 SC908 SC911 SC928 SC933 SC936 SC944 SC985 SC987 SC999Unit Neara Cat. gd Neara Intrusive Cat. gd Intrusive Dyke Cat. gd Cat. gd Cat. gd Mt Mucki Dyke Fol.dio Gibraltar Mt Mucki

SiO2 (%) 67.5 70.89 61.79 69.54 67.3 64.42 58.99 66.91 66.23 60.24 47.31 52.89 51.65 65.06 52.92Ti (ppm) 5893 3778 6295 4449 5412 3786 6268 5408 5835 6036 7071 4500 8950 3835 6354MOLESAl2O3 0.15 0.13 0.14 0.13 0.14 0.16 0.16 0.14 0.15 0.17 0.15 0.21 0.15 0.16 0.16K2O 0.03 0.04 0.01 0.04 0.03 0.03 0.04 0.04 0.03 0.05 0.01 0.02 0.00 0.03 0.02CaO 0.05 0.02 0.09 0.04 0.05 0.06 0.09 0.05 0.04 0.06 0.22 0.17 0.18 0.06 0.16Na2O 0.05 0.07 0.06 0.07 0.06 0.08 0.07 0.05 0.06 0.07 0.03 0.05 0.05 0.07 0.05INDICESAlkali index 5.38 7.5 4.85 7.35 6.22 7.55 7.78 6.53 6.32 8.79 3.12 5.04 2.99 7.08 4.71Felsic index 0.68 0.85 0.51 0.79 0.69 0.69 0.61 0.7 0.73 0.72 0.2 0.34 0.24 0.68 0.35Mafic index 0.78 0.77 0.73 0.78 0.76 0.65 0.78 0.76 0.74 0.77 0.69 0.72 0.62 0.65 0.73Solidification index 12.9 9.95 19.6 10.14 13.59 17.07 12.76 12.93 14.99 11.43 26.43 18.34 32.45 17.31 20.56Alkali No. 69.27 73.7 57.9 71.58 67.17 70.72 65.1 68.45 66.28 70.16 47.03 71.89 47.74 71.22 55.33Mg No. 35.93 37.62 42.86 35.91 38.73 51.56 36.36 38.35 41.23 37.76 46.53 43.44 54.77 51.69 42.14CIPW NORMQ 31.23 27.74 19.04 25.58 26.15 13.74 7.46 24.93 24.86 6.58 0 2.94 4.53 16.24 6.98C 3.01 0.75 0 0 0.71 0 0 0.63 2.04 0 0 0 0 0 0Zr - - - - - - - - - - - - - - -Or 16.09 20.42 8 19.77 16.61 16.63 21 19.65 17.51 27.59 6.02 11.33 1.65 16.26 8.85Ab 24.26 35.45 30.63 35.12 29.81 41.5 35.83 28.15 29.95 36.47 18.01 27.52 23.76 38.79 25.78An 12.38 6.15 20.03 8.88 13.07 14.05 14.92 13.55 10.79 14.11 30.16 38.15 28.92 15.51 24.44Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di - - 2.28 0.07 - 1.52 5.49 - - 0.87 25.52 5.19 15.56 0.71 13.23Hy 7.69 5.81 12.99 6.32 8.44 8.54 8.14 8.03 9.39 8.31 5.54 8.8 16.6 8.62 3.77Ol - - - - - - - - - - 5.13 - - - -Mt 3.11 2.21 4.56 2.53 3.13 2.43 4.07 3.03 3.27 3.32 7.17 3.59 5.76 2.35 11.99Hm - - - - - - - - - - - - - - 2.54Il 1.87 1.2 2.01 1.41 1.72 1.2 2 1.72 1.86 1.92 2.26 1.43 2.86 1.22 1.92Ap 0.52 0.39 0.61 0.44 0.51 0.61 1.46 0.44 0.52 1.18 0.34 1.46 0.46 0.52 0.71


Q 37.2 30.9 24.5 28.63 30.53 15.99 9.42 28.89 29.91 7.76 - 3.68 7.7 18.71 10.57A 19.16 22.75 10.3 22.13 19.4 19.36 26.51 22.77 21.07 32.55 - 14.17 2.8 18.73 13.4P 43.64 46.35 65.2 49.24 50.07 64.65 64.07 48.33 49.02 59.68 - 82.15 89.5 62.56 76.03


28

SAMPLE SC1001 SC1008 SC1018SC1018xCSC1018xDSC1018xeSC1018xFSC1021 SC1030SC1030xeSC1037 SC1069 SC1071 SC1074 SC1086Unit Mt Mucki Dyke Gibraltar Xenolith Xenolith Xenolith Xenolith Intrusive North ArmXenolith Woolooga WooloogaWooloogaHighbury Woonga

SiO2 (%) 52.95 56.16 62.12 48.11 51.49 52.97 51.53 49.01 57.9 57.98 62.85 60.09 60.22 50.71 67.82Ti (ppm) 6533 5546 5067 5652 7298 7808 7198 1.04 6198 5292 4383 4580 5836 6731 2354MOLESAl2O3 0.16 0.19 0.17 0.14 0.15 0.16 0.15 19.07 0.17 0.18 0.16 0.16 0.17 0.15 0.17K2O 0.02 0.05 0.04 0.01 0.02 0.02 0.02 2.69 0.02 0.01 0.03 0.02 0.03 0.00 0.02CaO 0.17 0.12 0.09 0.15 0.17 0.14 0.15 8.42 0.10 0.11 0.08 0.10 0.09 0.17 0.04Na2O 0.05 0.05 0.06 0.04 0.04 0.06 0.05 3.05 0.07 0.07 0.06 0.07 0.07 0.06 0.08INDICESAlkali index 4.41 7.9 7.47 3.49 4.74 6.07 5.16 6.64 5.51 6.55 6.35 7.44 3.83 6.75Felsic index 0.31 0.54 0.59 0.3 0.34 0.45 0.38 0.53 0.47 0.59 0.53 0.59 0.3 0.75Mafic index 0.69 0.77 0.74 0.64 0.72 0.72 0.72 0.66 0.75 0.67 0.67 0.73 0.52 0.66Solidification index 23.61 11.71 12.67 30.71 21.53 20.18 21.51 20.97 16.17 18.36 20.21 14.76 39.97 14.87Alkali No. 55.22 72.4 73.47 41.66 50.75 55.37 51.59 62.86 66.6 67.4 64.52 68.67 43.95 78.49Mg No. 46.54 36.67 41.51 52.19 42.99 44.05 43.67 48.04 50.03 39.52 49.40 49.54 42.55 64.60 50.62CIPW NORMQ 4.36 3.13 12.38 0 1.89 0 0.1 5.62 9.12 14.42 10.01 9.53 0 23.8C 0 0 0 0 0 0 0 0 0 0 0 0 0 3.16Zr - - - - - - - - - - - - - -Or 9.4 28.77 21.75 7.01 12.74 13.84 11.8 12.61 6.29 17.08 13.34 18.75 1.28 11.6Ab 24.1 26.32 32.71 21.27 23.2 32.86 28.08 38.66 39.11 33.71 35.93 35.95 31.47 41.06An 27.27 23.89 18.23 25.9 23.39 20.58 22.41 19.99 25.23 17.31 19.4 17.93 23.83 11.03Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 17.05 6.04 5.64 13.81 17.85 13 16.11 6.25 4.09 4.35 6.27 4.18 17.51 -Hy 10.08 5.81 4.69 14.52 11.72 11.04 12.45 10.59 9.63 8.44 9.67 7.66 9.37 6.69Ol - - - 7.77 - 0.15 - - - - - - 8.83 -Mt 5.35 3.37 2.6 7.69 6.42 5.52 6.3 3.76 4.06 2.93 3.45 3.25 5.21 1.76Hm - - - - - - - - - - - - - -Il 2.08 1.76 1.61 1.81 2.33 2.49 2.3 1.97 1.69 1.39 1.46 1.86 2.15 0.75Ap 0.48 1.3 0.63 0.35 0.66 0.76 0.66 0.72 1.01 0.52 0.66 1.24 0.37 0.27

Differentiation index37.86 58.22 66.84 28.28 37.83 46.7 39.98 56.89 54.52 65.21 59.28 64.23 32.75 76.46

Q 6.69 3.81 14.55 - 3.09 - 0.16 7.31 11.44 17.47 12.72 11.6 - 27.2A 14.43 35.04 25.57 - 20.81 - 18.91 16.4 7.89 20.7 16.95 22.82 - 13.26P 78.87 61.15 59.88 - 76.1 - 80.93 76.29 80.68 61.83 70.32 65.58 - 59.54

SAMPLE SC1098 SC1101 SC1116 SC1119 SC1121 SC1125 SC1128 SC1129 SC1132 SC1134 SC1144 SC1148 SC1149 SC1153 SC1157Unit Highbury WooloogaWoonga Mt Mucki WooloogaWoonga Woonga Woonga Woonga Highbury Rush CreekRush CreekRush CreekRush CreekRush Creek

SiO2 (%) 50.14 59.68 68.1 52.77 64.81 67.94 67.72 67.14 68.63 48.99 70.66 73.78 70.62 75.22 69.54Ti (ppm) 7686 4887 2438 6822 5278 1502 2625 2522 1659 8270 2114 1383 2178 1089 2420MOLESAl2O3 0.18 0.16 0.17 0.19 0.15 0.16 0.15 0.16 0.15 0.14 0.14 0.13 0.14 0.13 0.14K2O 0.04 0.02 0.02 0.02 0.06 0.03 0.03 0.03 0.03 0.00 0.04 0.05 0.04 0.05 0.04CaO 0.14 0.11 0.04 0.15 0.05 0.07 0.06 0.07 0.07 0.20 0.04 0.03 0.05 0.02 0.05Na2O 0.05 0.06 0.08 0.07 0.07 0.08 0.07 0.07 0.07 0.05 0.06 0.06 0.06 0.05 0.06INDICESAlkali index 6.82 5.74 6.63 6.31 9.57 7.49 6.65 7.07 7.09 2.99 7.83 8.02 7.5 7.73 7.34Felsic index 0.48 0.49 0.73 0.43 0.79 0.66 0.65 0.65 0.65 0.21 0.76 0.83 0.73 0.87 0.71Mafic index 0.72 0.64 0.65 0.75 0.81 0.7 0.7 0.7 0.78 0.58 0.7 0.74 0.66 0.78 0.66Solidification index 18.85 22.99 15.12 16.19 7.2 9.66 13.95 12.96 8.48 36.43 10.41 6.6 12.17 4.69 13.87Alkali No. 58.49 63.93 78.62 66.35 75.54 83.2 75.63 77.33 80.78 42.84 79.35 85.23 79.35 88.57 75.73Mg No. 43.18 52.65 51.76 40.00 31.30 45.69 46.49 46 36.25 58.7 45.81 41.05 51.04 36.14 50.50CIPW NORMQ 0 10.93 23.48 0 12.65 18.7 22.46 20.91 22.8 0 25.61 30.9 26.33 34.96 24.74C 0 0 2.57 0 0 0 0 0 0 0 0 0 0 0.96 0Zr - - - - - - - - - - - - - - -Or 22.14 11.43 9.51 13.47 31.66 17.22 14.97 15.16 17.84 0.66 24.7 26.71 23.59 26.4 22.18Ab 23.93 33.34 43.53 34.79 36 41.67 36.02 37.22 36.16 24.73 31.61 29.91 30.44 28.37 31.06An 24.22 22.69 11.79 28.09 8.17 13.36 16.07 15.74 13.86 26.44 9.82 7.75 11.57 6.04 11.77Ne 2.19 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 9.4 5.42 - 10.16 2.82 5.19 1.15 1.93 4.01 23.48 1.97 0.57 1.39 - 2.29Hy - 10.83 6.52 3.62 4.06 1.97 6.34 3.05 2.88 10.34 4.01 2.79 4.49 2.15 5.34Ol 9.12 - - 2.74 - - - - - 5.32 - - - - -Mt 5.51 3.39 1.68 4.37 2.48 1.34 2.02 4.53 1.76 6.11 1.5 1.03 1.37 0.83 1.71Hm - - - - - - - 0.56 - - - - - - -Il 2.45 1.55 0.77 2.17 1.68 0.48 0.83 0.78 0.53 2.64 0.67 0.44 0.69 0.35 0.77Ap 1.43 0.58 0.27 0.84 0.75 0.2 0.29 0.26 0.29 0.31 0.19 - 0.22 - 0.24


Q - 13.94 26.59 - 14.3 20.56 25.09 23.49 25.15 - 27.92 32.43 28.64 36.5 27.57A - 14.58 10.77 - 35.78 18.93 16.72 17.03 19.68 - 26.92 28.04 25.66 27.57 24.71P - 71.48 62.64 - 49.92 60.51 58.19 59.49 55.17 - 45.16 39.53 45.7 35.93 47.72


29

SAMPLE SC1160 SC1166 SC1177 SC1179 SC1185 SC1189 SC1199 SC1204 SC1211 SC1216 SC1227 SC1258 SC1267 SC1285 SC1286Unit Rush CreekRush CreekRush CreekRush CreekRush CreekRush CreekRush CreekIntrusive Rush CreekRush CreekRush CreekCat. gd ManumbarYorkeys Black Snake

SiO2 (%) 69.87 65.32 74.65 72.35 70.97 72.17 73.03 54.58 73.51 72.77 65.39 56.87 50.72 51.81 64.21Ti (ppm) 2668 3524 1149 1799 1980 1634 1501 6011 1287 1682 3446 6596 7042 5710 3454MOLESAl2O3 0.14 0.15 0.13 0.14 0.14 0.14 0.14 0.17 0.14 0.13 0.15 0.15 0.15 0.17 0.16K2O 0.04 0.03 0.05 0.04 0.04 0.04 0.04 0.02 0.05 0.05 0.03 0.01 0.01 0.01 0.03CaO 0.06 0.08 0.03 0.04 0.04 0.04 0.03 0.14 0.03 0.04 0.07 0.13 0.17 0.16 0.06Na2O 0.06 0.06 0.05 0.06 0.06 0.06 0.07 0.06 0.06 0.06 0.06 0.05 0.06 0.05 0.08INDICESAlkali index 6.92 6.6 7.66 7.49 7.81 7.53 7.68 5.36 7.94 7.82 6.69 4.59 4.6 4 7.26Felsic index 0.69 0.6 0.83 0.77 0.77 0.78 0.83 0.4 0.84 0.8 0.62 0.4 0.33 0.31 0.67Mafic index 0.68 0.64 0.78 0.71 0.69 0.71 0.76 0.73 0.75 0.71 0.65 0.62 0.58 0.63 0.6Solidification index 13.93 19.16 4.79 9.03 10.66 8.8 6.86 19.3 6.4 8.81 18.35 28.61 33.47 29.78 20.52Alkali No. 74.62 67.91 88.25 82.69 79.72 83.29 84.4 61.41 85.55 81.95 69.1 51.73 48.15 53.05 69.16Mg No. 48.48 52.36 35.52 44.93 47.06 44.79 38.22 42.91 40.13 44.66 51.24 54.52 59.08 53.89 56.91CIPW NORMQ 26.79 18.61 33.87 29.6 26.11 28.93 30.26 4.66 30.45 29.84 19.23 8.88 0 2.33 13.66C 0 0 0.51 0 0 0.15 0.66 0 0.22 0 0 0 0 0 0Zr - - - - - - - - - - - - - - -Or 19.31 16.68 25.78 21.45 23.4 22.71 21.04 10.56 26.94 26.1 18.24 8.16 6.21 6.69 14.59Ab 30.59 32.95 28.53 31.96 32.83 32 35.05 31.14 30.32 29.05 31.16 28.8 30.8 24.95 41.44An 11.75 15.11 7.75 10.41 9.92 10.59 7.79 26.33 7.55 8.66 16.41 21.26 23.81 29.95 15.25Ne 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Di 2.62 5.26 - 0.48 1.11 - - 10.05 - 0.94 2.68 11.15 17.47 11.52 1.22Hy 3 7.48 2.3 2.19 4.43 3.86 3.41 9.9 3.04 3.58 8.41 14.58 4.85 16.75 9.99Ol - - - - - - - - - - - - 8.92 - -Mt 4.61 2.54 0.87 3 1.44 1.19 1.21 4.73 1.04 1.24 2.53 4.76 5.3 5.3 2.36Hm 0.38 - - 0.29 - - - - - - - - - - -Il 0.83 1.12 0.36 0.56 0.63 0.52 0.48 1.92 0.41 0.53 1.09 2.1 2.25 1.82 1.1Ap 0.21 0.36 0.07 0.14 0.24 0.15 0.22 0.97 0.1 0.12 0.39 0.43 0.51 0.92 0.58


Q 30.29 22.33 35.31 31.68 28.3 30.7 32.14 6.41 31.97 31.86 22.61 13.23 - 3.65 16.08A 21.83 20.01 26.87 22.96 25.36 24.1 22.35 14.53 28.28 27.87 21.45 12.16 - 10.47 17.18P 47.87 57.66 37.82 45.35 46.34 45.2 45.51 79.06 39.75 40.27 55.94 74.61 - 85.89 66.74

SAMPLE SC1287 SC1288Unit Bogooramunya Boonara

SiO2 (%) 64.35 54.21Ti (ppm) 3762 5226MOLESAl2O3 0.16 0.16K2O 0.04 0.02CaO 0.08 0.15Na2O 0.05 0.04INDICESAlkali index 6.61 4.4Felsic index 0.6 0.34Mafic index 0.69 0.64Solidification index 16.43 27.54Alkali No. 70.76 53.84Mg No. 47.24 52.20CIPW NORMQ 18.89 6.16C 0 0Zr - -Or 21.37 10.91Ab 26.21 22.36An 19.42 26.94Ne 0 0Di 1.93 11.49Hy 8.07 14.92Ol - -Mt 2.62 5.06Hm - -Il 1.2 1.67Ap 0.44 0.7

Differentiation index66.47 39.43

Q 21.99 9.28A 24.88 16.44P 53.13 74.28

APPENDIX 3: EMP DATA

30

Electron microprobe data of mineral phases within the plutons of Station Creek igneous Complex, porphyritic stocks, Highbury Volcanics, Neara Volcanics, North Arm Volcanics and dykes, and the country rocks.

EMP DATA FOR MINERAL PHASESSAMPLE UNIT Mineral Core/ Host SiO2 TiO2 Al2O3 FeO MgO CaO MnO Na2O K2O P2O5 Cr2O3 Cl F Total

Rim215D-1A Woolooga Horn. Core 48.20 1.94 6.50 12.20 16.13 11.44 0.04 1.49 0.76 0.00 0.00 - - 98.70215D-1B Woolooga Horn. Rim 48.82 1.95 6.22 11.55 16.28 11.45 0.22 1.27 0.71 0.00 0.00 - - 98.47215D-1C Woolooga Ilmenite Exsol Matrix 0.17 96.42 0.00 2.44 0.00 0.44 0.06 0.00 0.00 0.00 0.10 - - 99.63215D-1D Woolooga Magnetite Exsol Matrix 0.37 0.85 0.20 94.71 0.04 0.00 0.09 0.00 0.00 0.00 0.00 - - 96.26215D-2A Woolooga Plag-zone Core 58.14 0.00 25.41 0.32 0.12 9.12 0.05 6.22 0.39 0.00 0.01 - - 99.78215D-2B Woolooga Plag-zone Interm 56.54 0.00 26.04 0.21 0.16 9.77 0.00 5.83 0.35 0.00 0.02 - - 98.92215D-2C Woolooga Plag-zone Rim 59.17 0.00 23.15 0.31 0.00 7.82 0.00 7.16 0.46 0.00 0.00 - - 98.07215D-3A Woolooga Plag-zone Core 58.48 0.00 24.77 0.17 0.13 8.62 0.00 6.56 0.33 0.00 0.00 - - 99.06215D-3B Woolooga Plag-zone Interm 60.30 0.00 24.03 0.20 0.18 6.44 0.00 7.51 0.74 0.00 0.00 - - 99.40215D-3C Woolooga Plag-zone Rim 58.88 0.08 24.70 0.17 0.06 8.07 0.00 6.77 0.24 0.00 0.00 - - 98.97215D-4A Woolooga Horn. Core 55.85 0.46 1.19 9.54 19.84 11.55 0.48 0.58 0.07 0.00 0.00 - - 99.56215D-4B Woolooga Horn. Rim 54.87 0.61 1.65 10.58 19.39 11.41 0.41 0.23 0.16 0.00 0.00 - - 99.31215D-4C Woolooga Biotite Core 37.86 5.33 12.91 16.40 16.25 0.09 0.22 0.00 7.74 0.00 0.00 0.250 <0.005 96.80215D-4D Woolooga Biotite? Rim 29.12 0.03 19.23 19.24 22.29 0.08 0.37 0.00 0.00 0.00 0.00 0.248 <0.005 90.36215D-4D Woolooga Biotite? Rim 28.46 0.19 18.78 18.42 22.21 0.05 0.45 0.01 0.03 0.00 0.00 - - 88.60215D-5A Woolooga Plag-unzone Core 58.94 0.15 24.10 0.37 0.00 7.83 0.00 6.68 0.40 0.00 0.00 - - 98.47215D-5B Woolooga Plag-unzone Interm 59.21 0.06 24.39 0.15 0.11 7.91 0.00 6.88 0.32 0.00 0.00 - - 99.03215D-5C Woolooga Plag-unzone Rim 60.64 0.00 23.92 0.14 0.23 7.06 0.17 7.34 0.30 0.00 0.00 - - 99.80215D-6A Woolooga Horn. Core 46.75 2.13 7.00 12.90 15.05 11.35 0.27 1.44 0.87 0.00 0.00 - - 97.76215D-6B Woolooga Horn. Rim 48.46 1.64 5.67 12.65 15.62 11.30 0.25 1.25 0.69 0.00 0.00 0.135 <0.005 97.53215D-6C Woolooga Horn. Core 45.52 2.53 8.42 13.58 14.47 11.54 0.11 1.94 0.72 0.00 0.00 0.162 <0.005 98.83215D-6D Woolooga Horn. Core 47.56 1.98 6.66 12.41 15.28 11.41 0.28 1.48 0.76 0.00 0.00 - - 97.82235-1A Woolooga Horn. Core 54.22 0.12 0.97 7.92 15.38 21.85 0.19 0.44 0.00 0.00 0.00 - - 101.09235-1B Woolooga Horn. Core 53.55 0.00 1.03 7.75 14.73 21.66 0.38 0.17 0.00 0.00 0.00 - - 99.27235-1C Woolooga Horn. Interm 52.67 0.19 0.84 7.92 14.73 21.10 0.23 0.01 0.00 0.00 0.01 - - 97.70235-1D Woolooga Horn. Rim 54.68 0.12 0.76 9.43 15.22 19.92 0.53 0.35 0.00 0.00 0.00 - - 101.01235-1E Woolooga Magnetite Includ. Horn 4.05 0.10 0.00 74.45 0.20 0.11 0.00 0.00 0.00 0.00 0.00 - - 78.91235-1F Woolooga Ilmenite Includ. Horn 0.28 2.46 1.18 93.71 0.09 0.00 0.29 0.00 0.00 0.00 0.16 - - 98.17235-1G Woolooga Magnetite Includ. Horn 0.33 0.07 0.20 96.41 0.02 0.00 0.02 0.13 0.00 0.00 0.20 - - 97.38235-1H Woolooga Plag-unzone Rim 62.94 0.13 22.90 0.33 0.54 4.75 0.00 8.85 0.73 0.00 0.00 - - 101.17235-1I Woolooga Plag-unzone Interm 57.51 0.00 27.54 0.24 0.16 10.14 0.00 6.12 0.30 0.00 0.00 - - 102.01235-2A Woolooga Plag-zone Core 58.92 0.08 25.76 0.05 0.33 8.40 0.00 7.15 0.49 0.00 0.00 - - 101.18235-2B Woolooga Plag-zone Interm 57.88 0.00 25.22 1.54 2.00 6.79 0.08 6.87 0.56 0.00 0.00 - - 100.94235-2C Woolooga Plag-zone Rim 62.71 0.00 23.84 0.13 0.11 6.05 0.00 7.64 0.69 0.00 0.00 - - 101.17235-2D Woolooga Plag-zone Rim 58.64 0.00 26.34 0.11 0.25 8.95 0.00 6.48 0.42 0.00 0.00 - - 101.19235-2E Woolooga Or-Perthite Matrix 67.68 0.00 19.02 0.09 0.38 0.32 0.04 7.21 6.77 0.00 0.03 - - 101.54235-3A Woolooga Plag-zone Core 59.22 0.00 26.53 0.18 0.25 9.13 0.00 6.60 0.45 0.00 0.00 - - 102.36235-3B Woolooga Plag-zone Interm 59.23 0.00 25.01 0.03 0.05 7.79 0.00 7.10 0.43 0.00 0.00 - - 99.64235-3C Woolooga Plag-zone Rim 65.36 0.03 21.30 0.00 0.21 2.69 0.00 9.75 0.44 0.00 0.00 - - 99.78235-3D Woolooga Or-Perthite Matrix 66.29 0.00 17.91 0.08 0.37 0.24 0.01 3.33 12.30 0.00 0.00 - - 100.53235-3G Woolooga Pyrx-c Core . 56.49 0.03 0.60 20.03 25.24 0.72 1.16 0.05 0.00 0.00 0.00 - - 104.32235-5A Woolooga Biotite Core 37.85 5.69 12.21 12.99 16.17 0.00 0.09 0.00 9.19 0.00 0.00 - - 94.19235-5B Woolooga Biotite Core 36.80 5.60 12.17 12.90 15.96 0.00 0.24 0.00 8.82 0.00 0.00 - - 92.49235-5C Woolooga Biotite Rim 37.84 4.87 11.85 13.02 16.26 0.00 0.00 0.00 8.82 0.00 0.00 - - 92.66235-5D Woolooga Magnetite Includ. Biotite 3.13 0.49 1.71 85.04 1.62 0.09 0.06 0.60 0.47 0.00 0.16 - - 93.37235-5E Woolooga Magnetite Includ. Biotite 0.11 2.82 0.62 89.56 0.05 0.00 0.56 0.00 0.00 0.00 0.28 - - 94.00235-5F Woolooga Magnetite Includ. Biotite 0.30 0.90 0.35 91.92 0.11 0.00 0.16 0.00 0.00 0.00 0.16 - - 93.90328-1A Woolooga Pyrx-c Relict Horn 54.71 0.01 0.01 6.89 15.34 23.41 0.70 0.00 0.02 0.00 0.00 - - 101.09

328-1B Woolooga Horn. Mantle 51.20 1.37 4.44 11.39 17.41 11.71 0.16 0.28 0.37 0.00 0.00 0.004 <0.005 98.33328-1C Woolooga Horn. Rim . 55.15 0.00 0.00 8.23 16.21 23.24 0.34 0.00 0.00 0.00 0.00 0.032 <0.005 103.17328-1D Woolooga Magnetite Horn 0.40 3.46 0.72 91.03 0.27 0.00 0.73 0.43 0.00 0.07 0.06 - - 97.17328-1E Woolooga Apatite Mag. 0.00 0.00 0.16 1.97 0.22 53.31 0.00 0.52 0.01 42.20 0.00 1.670 3.351 98.39328-1F Woolooga Ilmenite Exsol Mag. 0.14 95.37 0.23 4.74 0.00 0.14 0.00 0.00 0.00 0.00 0.02 - - 100.64328-1G Woolooga Sphene Exsol Ilmenite 12.74 46.84 0.67 26.41 0.00 10.27 4.14 0.12 0.10 0.00 0.00 - - 101.29328-1H Woolooga Ilmenite Horn 0.28 51.67 0.00 44.40 0.35 0.06 5.78 0.00 0.01 0.00 0.01 - - 102.56328-1I Woolooga Magnetite Matrix 0.27 3.94 0.94 92.20 0.44 0.00 0.87 0.00 0.00 0.00 0.17 - - 98.83328-1J Woolooga Apatite Mag. 0.00 0.05 0.00 1.59 0.00 53.17 0.07 0.38 0.00 42.83 0.00 - - 98.09328-1K Woolooga Ilmenite Matrix 0.23 51.00 0.22 41.15 0.21 0.00 8.64 0.00 0.00 0.00 0.00 - - 101.45328-1L Woolooga Magnetite Matrix 0.14 2.87 0.46 92.15 0.10 0.00 0.47 0.00 0.00 0.00 0.01 - - 96.20328-1M Woolooga Biotite Sec Core 39.08 4.54 12.81 13.37 18.40 0.00 0.00 0.00 8.50 0.00 0.00 0.234 <0.005 96.70328-1N Woolooga Biotite Sec Rim 34.78 1.04 14.27 18.86 22.53 0.30 0.09 0.00 0.57 0.00 0.00 0.186 <0.005 92.44328-2A Woolooga Plag-unzone Rim 59.22 0.01 24.30 0.02 0.00 8.37 0.05 6.04 0.52 0.00 0.00 - - 98.53328-2B Woolooga Plag-unzone Interm 59.40 0.00 24.50 0.31 0.00 8.71 0.00 6.22 0.49 0.00 0.00 - - 99.63328-2C Woolooga Plag-unzone Rim 59.80 0.02 24.51 0.22 0.00 8.92 0.00 6.89 0.50 0.00 0.00 - - 100.86328-2D Woolooga Horn. Matrix 52.74 0.86 2.81 11.94 17.71 11.06 0.18 0.00 0.17 0.00 0.00 - - 97.47328-2E Woolooga Horn. Matrix 53.44 0.67 2.32 11.46 18.17 11.38 0.24 0.47 0.24 0.00 0.00 - - 98.39328-2F Woolooga Or-Perthite Matrix 67.80 0.00 17.19 0.19 0.07 0.12 0.00 5.61 8.75 0.00 0.00 - - 99.73328-2G Woolooga Plag-unzone Core 59.02 0.00 23.42 0.32 0.00 8.08 0.00 7.01 0.48 0.00 0.13 - - 98.46328-3A Woolooga Plag-zone Core 56.61 0.01 26.79 0.00 0.00 10.59 0.00 5.65 0.42 0.00 0.00 - - 100.07328-3B Woolooga Plag-zone Interm 60.48 0.09 25.32 0.52 0.00 8.55 0.00 6.66 0.71 0.00 0.00 - - 102.33328-3C Woolooga Plag-zone Rim 64.31 0.03 22.32 0.32 0.00 4.84 0.00 8.27 0.58 0.00 0.04 - - 100.71328-3D Woolooga Pyrx-c Includ. 63.80 0.00 0.00 0.72 31.48 0.35 0.00 0.00 0.00 0.00 0.00 - - 96.35328-4A Woolooga Plag-unzone Core 59.95 0.15 24.31 0.19 0.00 7.70 0.16 6.57 0.42 0.00 0.00 - - 99.45328-4B Woolooga Plag-unzone Rim 59.13 0.00 24.38 0.00 0.09 7.83 0.00 6.58 0.50 0.00 0.00 - - 98.51382-1A Woolooga Plag-zone Core 58.82 0.01 26.23 0.17 0.00 10.02 0.00 6.06 0.49 0.00 0.03 - - 101.83382-1C Woolooga Plag-zone Interm 59.52 0.06 24.69 0.18 0.30 8.65 0.00 6.61 0.67 0.00 0.00 - - 100.68382-1D Woolooga Plag-zone Rim 60.07 0.00 24.26 0.36 0.07 7.71 0.00 7.15 0.26 0.00 0.00 - - 99.88382-1E Woolooga Or-Perthite Matrix 69.40 0.05 18.54 0.00 0.14 1.10 0.00 11.01 0.00 0.00 0.00 - - 100.24382-1G Woolooga CPX include Core Plag. 55.16 0.00 0.00 8.59 14.55 24.64 0.31 0.28 0.02 0.00 0.03 - - 103.58382-1H Woolooga CPX include Core Plag. 56.16 0.14 0.00 7.72 15.85 23.86 0.14 0.00 0.00 0.00 0.00 - - 103.87382-2A Woolooga Magnetite Matrix 0.45 0.16 0.27 96.44 0.01 0.00 0.07 0.22 0.00 0.06 0.29 - - 97.97382-2C Woolooga Horn. Core 55.02 0.62 2.30 12.32 17.92 11.65 0.43 0.47 0.21 0.00 0.00 - - 100.94382-2D Woolooga Sphene Core Matrix 31.71 28.26 5.99 2.59 0.01 28.63 0.00 0.13 0.00 0.00 0.00 - - 97.32382-3A Woolooga Horn. Core 55.16 0.31 1.26 12.00 18.93 10.75 0.49 0.71 0.08 0.00 0.00 - - 99.69382-3B Woolooga Horn. Rim 54.34 0.54 2.13 11.52 18.56 11.27 0.46 0.60 0.24 0.00 0.00 - - 99.66382-4A Woolooga Or-Perthite Matrix 66.21 0.01 17.18 0.00 0.09 0.00 0.04 0.43 16.44 0.00 0.00 - - 100.40382-5A Woolooga Plag-zone Core 60.41 0.00 23.86 0.31 0.04 7.64 0.00 6.40 0.79 0.00 0.02 - - 99.47382-5B Woolooga Plag-zone Interm 59.77 0.00 24.73 0.29 0.11 8.47 0.00 6.65 0.64 0.00 0.00 - - 100.66382-5C Woolooga Plag-zone Rim 68.54 0.00 18.49 0.08 0.16 0.87 0.02 11.31 0.28 0.00 0.00 - - 99.75450-1A Woolooga CPX Core 60.39 0.24 0.00 8.74 17.53 11.56 0.45 0.39 0.11 0.00 0.00 0.000 0.000 99.41450-1B Woolooga Pyrx-Horn Rim 59.85 0.27 0.17 9.29 17.45 10.95 0.35 0.44 0.07 0.00 0.00 0.000 0.000 98.84450-1C Woolooga Pyrx-Horn Core 60.07 0.32 0.33 9.08 17.61 11.42 0.34 0.42 0.12 0.00 0.00 0.000 0.000 99.71450-1D Woolooga Biotite Sec Core 37.50 2.45 13.80 19.22 18.25 0.14 0.12 0.49 2.61 0.00 0.10 0.000 0.000 94.68450-1E Woolooga Magnetite Matrix 0.36 0.59 0.21 90.73 0.34 0.00 0.00 0.00 0.00 0.00 0.50 0.000 0.000 92.73450-1EB Woolooga Magnetite Matrix 0.46 0.47 0.20 91.36 0.02 0.00 0.20 0.00 0.00 0.00 0.00 0.000 0.000 92.71


31

EMP DATA OF MINERAL PHASESSAMPLE UNIT Mineral Core/ Host SiO2 TiO2 Al2O3 FeO MgO CaO MnO Na2O K2O P2O5 Cr2O3 Cl F Total

Rim450-1F Woolooga Ilmenite Matrix 0.19 41.54 0.13 46.23 0.20 0.00 4.66 0.28 0.02 0.00 0.00 0.000 0.000 93.25450-2A Woolooga Plag-zone Core 62.93 0.11 22.18 0.29 0.12 9.83 0.07 4.42 0.32 0.00 0.00 0.000 0.000 100.27450-2B Woolooga Plag-zone Interm 63.54 0.00 21.56 0.46 0.00 9.38 0.10 4.50 0.40 0.00 0.00 0.000 0.000 99.94450-2C Woolooga Plag-zone Rim 67.28 0.00 20.14 0.28 0.17 7.14 0.00 5.18 0.28 0.00 0.00 0.000 0.000 100.47450-3A. Woolooga Plag-zone Core 63.42 0.00 21.94 0.27 0.00 9.92 0.00 4.15 0.25 0.00 0.00 0.000 0.000 99.95450-3B Woolooga Plag-zone Rim 79.72 0.00 14.67 0.15 0.00 0.23 0.00 7.67 0.08 0.00 0.00 0.000 0.000 102.52450-3C Woolooga Or-Perthite 75.04 0.00 17.31 0.05 0.18 3.07 0.02 6.95 0.17 0.00 0.00 0.000 0.000 102.79450-4A Woolooga Pyrx relict Core 59.57 0.47 0.24 9.04 17.54 11.07 0.31 0.48 0.16 0.00 0.00 0.000 0.000 98.88450-4B Woolooga Pyrx relict Rim 59.78 0.25 0.45 8.97 17.70 11.47 0.44 0.46 0.15 0.00 0.00 0.000 0.000 99.67450-4D Woolooga Pyrx sec Interm 60.40 0.18 0.00 8.69 17.60 10.97 0.39 0.39 0.12 0.00 0.00 0.000 0.000 98.74450-4F Woolooga Magnetite Includ. Cpx 0.43 0.47 0.22 91.28 0.10 0.00 0.04 0.00 0.00 0.12 0.31 0.000 0.000 92.97494-1A Woolooga Horn. Core 50.40 0.89 3.74 13.80 16.49 10.86 0.40 1.20 0.35 0.00 0.00 - - 98.13494-1B Woolooga Horn. Core 50.62 1.29 3.55 14.80 15.77 10.01 0.55 1.53 0.39 0.00 0.01 - - 98.52494-1C Woolooga Horn. Core 51.78 0.79 3.65 13.58 16.64 10.84 0.43 1.09 0.30 0.00 0.00 - - 99.10494-1D Woolooga Horn. Rim 50.90 0.81 3.55 13.72 16.45 10.92 0.50 0.99 0.30 0.00 0.00 - - 98.14494-1E Woolooga Magnetite Matrix 0.41 1.75 0.53 92.60 0.17 0.00 0.13 0.43 0.00 0.00 0.10 - - 96.12494-1F Woolooga Ilmenite Includ. Horn 0.52 46.32 0.00 45.76 0.19 0.62 6.22 0.10 0.00 0.00 0.00 - - 99.73494-1G Woolooga Or-Perthite Matrix 66.91 0.00 17.47 0.21 0.00 0.32 0.00 6.46 6.87 0.00 0.00 - - 98.24494-2A. Woolooga Plag-zone Core 59.35 0.00 24.53 0.40 0.00 8.41 0.00 6.67 0.38 0.00 0.00 - - 99.74494-2B Woolooga Plag-zone Interm 58.51 0.00 25.20 0.30 0.07 9.00 0.00 5.98 0.39 0.00 0.00 - - 99.45494-2C Woolooga Plag-zone Rim 59.04 0.00 23.93 0.24 0.00 7.64 0.00 6.90 0.55 0.00 0.01 - - 98.31494-3A Woolooga Plag-zone Core 57.02 0.00 25.13 0.27 0.25 9.15 0.00 5.73 0.57 0.00 0.00 - - 98.12494-3B Woolooga Plag-zone Interm 58.79 0.00 24.16 0.23 0.14 8.32 0.00 6.33 0.49 0.00 0.00 - - 98.46494-3C Woolooga Plag-zone Interm 56.92 0.02 25.25 0.41 0.14 9.21 0.00 5.94 0.42 0.00 0.00 - - 98.31494-3D Woolooga Plag-zone Rim 57.97 0.03 24.62 0.22 0.21 8.58 0.00 6.54 0.61 0.00 0.00 - - 98.78494-4A Woolooga Horn. Core 51.45 0.92 3.16 14.24 16.01 10.90 0.48 1.08 0.30 0.00 0.00 - - 98.54494-4B Woolooga Horn. Core 50.58 0.65 3.78 13.40 16.25 10.95 0.34 1.31 0.52 0.00 0.00 - - 97.78494-4C Woolooga Horn. Core 50.54 0.90 3.62 14.38 15.79 10.89 0.47 1.31 0.35 0.00 0.00 - - 98.25494-4D Woolooga Horn. Core 50.92 1.04 3.03 14.70 15.70 10.44 0.42 1.32 0.30 0.00 0.00 - - 97.87494-4E Woolooga Horn. Rim 50.73 0.89 3.59 13.99 15.81 10.87 0.32 1.20 0.44 0.00 0.00 - - 97.84494-4F Woolooga Or-Perthite Matrix 64.77 0.00 19.40 0.10 0.41 2.34 0.00 10.27 0.31 0.00 0.00 - - 97.60494-4F2 Woolooga Or-Perthite Matrix 67.22 0.06 18.45 0.10 0.16 0.70 0.12 11.01 0.28 0.00 0.00 - - 98.10494-4G Woolooga Magnetite Includ. Horn 0.42 2.17 0.26 93.43 0.06 0.00 0.10 0.00 0.00 0.00 0.31 - - 96.75494-5A Woolooga Horn. Core 52.94 0.82 2.24 13.30 16.79 10.84 0.50 0.79 0.23 0.00 0.01 - - 98.46494-5B Woolooga Horn. Interm 52.17 0.95 2.86 13.70 16.53 10.80 0.41 1.07 0.27 0.00 0.00 - - 98.76494-5C Woolooga Horn. Rim 53.99 0.28 1.41 12.43 17.19 11.49 0.21 0.33 0.17 0.00 0.00 - - 97.50497-1A Woolooga Plag-unzone Core 59.34 0.00 23.85 0.04 0.00 8.67 0.18 6.65 0.53 0.00 0.00 - - 99.26497-1B Woolooga Plag-unzone Interm 59.46 0.00 23.44 0.29 0.00 7.92 0.00 7.03 0.44 0.00 0.00 - - 98.58497-1C Woolooga Plag-unzone Rim 63.40 0.19 20.94 0.04 0.00 4.98 0.00 8.43 0.37 0.00 0.00 - - 98.35497-2A Woolooga Horn. Core 54.86 0.68 1.17 9.69 19.09 11.69 0.43 0.10 0.13 0.00 0.00 - - 97.84497-2B Woolooga Horn. Core 53.46 0.80 2.02 10.36 18.84 11.64 0.32 0.73 0.25 0.00 0.01 - - 98.43497-2C Woolooga Horn. Rim 53.64 0.52 2.72 11.01 18.11 12.22 0.28 0.42 0.18 0.00 0.00 - - 99.10497-2D Woolooga Sphene Exsol Mag-Ilm 30.40 39.00 0.00 1.58 0.00 28.13 0.00 0.36 0.00 0.00 0.00 - - 99.47497-2E Woolooga Magn-Ilmn Mean 1.18 51.72 0.00 41.27 0.16 1.07 1.03 0.00 0.00 0.00 0.02 - - 96.45497-2F Woolooga Magnetite Horn 0.46 0.97 0.13 94.45 0.23 0.00 0.06 0.09 0.00 0.00 0.00 - - 96.39497-2G Woolooga Ilmenite Exsol Mag. 0.21 91.30 0.06 5.70 0.10 0.40 0.03 0.00 0.00 0.00 0.00 - - 97.80497-2H Woolooga Apatite Mag. 0.00 0.00 0.00 2.92 0.00 52.71 0.00 0.12 0.00 41.83 0.00 - - 97.58497-4A Woolooga Magnetite Matrix 0.34 0.81 0.11 94.16 0.08 0.00 0.05 0.00 0.00 0.00 0.08 - - 95.63497-4B Woolooga Biotite Sec Mantle 30.34 0.46 15.07 20.71 20.96 0.08 0.34 0.00 0.12 0.00 0.00 0.018 <0.005 88.08497-4C Woolooga Horn. Core 51.61 0.84 3.25 11.01 17.59 11.60 0.37 0.79 0.29 0.00 0.00 0.047 <0.005 97.35497-4D Woolooga Magnetite Includ. Horn 0.45 1.28 0.18 92.97 0.00 0.00 0.10 0.00 0.00 0.00 0.21 - - 95.19497-4E Woolooga Sphene Includ. Horn 30.93 36.74 0.62 1.09 0.00 27.47 0.00 0.00 0.14 0.00 0.01 0.023 <0.005 97.00497-5A Woolooga Ilmenite Exsol Mag. 0.38 49.57 0.08 33.85 0.27 0.43 16.71 0.00 0.00 0.00 0.00 - - 101.29497-5B Woolooga Magnetite Ilmenite 0.31 0.71 0.16 95.09 0.00 0.00 0.11 0.00 0.00 0.00 0.02 - - 96.40497-5C Woolooga Horn. Core 52.71 0.77 2.57 10.75 17.90 11.73 0.37 0.35 0.30 0.00 0.00 0.092 <0.005 97.45497-5D Woolooga Horn. Rim 53.20 0.74 2.56 10.75 18.56 11.58 0.38 0.46 0.21 0.00 0.00 - - 98.44497-6A Woolooga Plag-zone Core 59.07 0.00 24.69 0.19 0.07 8.07 0.00 6.81 0.33 0.00 0.00 - - 99.23497-6B Woolooga Plag-zone Rim 59.07 0.08 24.07 0.22 0.06 7.52 0.00 6.90 0.43 0.00 0.00 - - 98.35497-7A Woolooga Biotite Prim Core 39.33 4.86 12.51 15.14 16.44 0.00 0.10 0.00 9.54 0.00 0.00 0.245 <0.005 97.92497-7B Woolooga Biotite Prim Rim 38.61 4.43 12.82 15.35 16.12 0.00 0.09 0.00 8.86 0.00 0.00 0.249 <0.005 96.28497-7C Woolooga Horn. Core 52.52 1.12 2.69 10.93 18.09 11.35 0.35 0.64 0.25 0.00 0.00 - - 97.94497-7D Woolooga Horn. Rim 52.70 0.69 2.51 10.40 18.31 11.38 0.30 0.77 0.21 0.00 0.00 - - 97.27582-1A Woolooga Plag-unzone Core 55.86 0.00 26.14 0.18 0.08 10.38 0.00 5.46 0.24 0.00 0.00 - - 98.34582-1B Woolooga Plag-unzone Interm 56.10 0.00 26.32 0.18 0.04 10.15 0.00 5.61 0.33 0.00 0.00 - - 98.73582-1C Woolooga Plag-unzone Rim 59.55 0.00 23.72 0.15 0.23 7.61 0.00 7.29 0.26 0.00 0.00 - - 98.81582-1D Woolooga Magnetite Matrix 0.49 2.24 0.29 91.65 0.00 0.00 0.42 0.00 0.00 0.00 0.18 - - 95.27582-2A Woolooga Horn. Core 54.17 0.36 1.08 13.77 16.66 11.36 0.43 0.13 0.14 0.00 0.00 0.086 <0.005 98.10582-2B Woolooga Horn. Interm 52.16 0.73 2.32 13.42 16.18 11.30 0.58 0.37 0.33 0.00 0.08 0.172 <0.005 97.47582-2C Woolooga Horn. Rim 52.70 0.98 2.34 12.27 17.24 11.29 0.53 0.50 0.25 0.00 0.00 - - 98.10582-2D Woolooga Ilmenite Matrix 0.18 47.91 0.03 45.09 0.30 0.00 6.67 0.24 0.00 0.00 0.01 - - 100.43582-2E Woolooga Magnetite Matrix 0.30 1.15 0.18 94.50 0.15 0.00 0.11 0.00 0.00 0.00 0.06 - - 96.45582-2F Woolooga Apatite Includ. Mag. 0.00 0.04 0.07 2.00 0.00 53.10 0.00 0.19 0.00 41.82 0.00 - - 97.22582-2G Woolooga Apatite Matrix 0.00 0.03 0.00 0.12 0.00 54.54 0.00 0.01 0.03 42.83 0.00 0.630 3.560 97.56582-3A Woolooga Biotite Core 37.62 5.40 12.31 18.26 13.89 0.01 0.15 0.00 9.16 0.00 0.00 0.208 <0.005 96.80582-3B Woolooga Biotite Rim 38.42 4.39 12.43 17.73 14.32 0.05 0.21 0.05 9.24 0.00 0.00 0.316 <0.005 96.84582-3C Woolooga Ilmenite Exsol Ilmenite 0.13 96.41 0.08 3.09 0.07 0.00 0.00 0.00 0.00 0.00 0.00 - - 99.78582-3D Woolooga Ilmenite Matrix 0.09 47.92 0.08 46.04 0.23 0.05 6.32 0.05 0.00 0.00 0.00 - - 100.78582-3E Woolooga Magnetite Matrix 0.34 1.07 0.23 94.08 0.01 0.00 0.11 0.32 0.00 0.00 0.00 - - 96.16582-4A Woolooga Biotite Prim Core 38.25 5.25 12.11 17.67 14.11 0.00 0.24 0.00 9.22 0.00 0.00 - - 96.85582-4B Woolooga Biotite Prim Rim 38.64 5.12 12.33 17.48 14.49 0.00 0.11 0.00 8.94 0.00 0.00 - - 97.11582-5A Woolooga Horn. Core 51.92 0.68 2.61 13.31 16.92 11.01 0.35 0.78 0.20 0.00 0.00 - - 97.78582-5B Woolooga Horn. Rim 54.73 0.40 1.36 11.31 18.18 11.19 0.42 0.33 0.13 0.00 0.00 - - 98.05582-6A Woolooga Plag-unzone Core 57.87 0.02 24.53 0.36 0.00 8.42 0.00 6.33 0.45 0.00 0.00 - - 97.98582-6B Woolooga Plag-unzone Interm 57.05 0.10 25.31 0.26 0.03 9.18 0.02 6.42 0.37 0.00 0.00 - - 98.74582-6C Woolooga Plag-unzone Rim 59.92 0.00 23.62 0.36 0.04 7.28 0.00 7.25 0.36 0.00 0.00 - - 98.83582-7A Woolooga Plag-zone Core 57.75 0.00 24.90 0.26 0.00 8.92 0.00 6.19 0.35 0.00 0.00 - - 98.37582-7B Woolooga Plag-zone Rim 57.83 0.02 24.54 0.31 0.15 8.63 0.00 6.40 0.28 0.00 0.00 - - 98.16582-7C Woolooga Plag-zone Interm 58.58 0.00 24.45 0.29 0.14 8.05 0.00 6.85 0.27 0.00 0.00 - - 98.63588-1A Woolooga Biotite Core 37.68 4.79 14.17 19.36 13.41 0.13 0.16 0.05 9.19 0.00 0.05 - - 98.99588-1A2 Woolooga Or-Perthite Matrix 62.59 0.36 17.46 0.16 0.13 0.04 0.00 2.18 13.35 0.00 0.00 - - 96.27588-1B Woolooga Plag-unzone Rim 65.81 0.00 18.80 0.00 0.33 0.67 0.00 11.12 0.09 0.00 0.00 - - 96.82588-1C Woolooga Biotite Rim 37.67 4.35 12.11 18.23 13.45 0.00 0.07 0.00 8.78 0.00 0.00 - - 94.66588-1D Woolooga Ilmenite incl Includ. Biotite 0.30 52.09 0.12 44.82 0.24 0.00 8.30 0.06 0.00 0.00 0.00 - - 105.93588-2A Woolooga Plag-zone Interm 56.79 0.00 24.66 0.34 0.40 7.85 0.00 6.78 0.54 0.00 0.00 - - 97.36588-2B Woolooga Plag-zone Interm 57.31 0.00 24.32 0.26 0.24 7.52 0.00 6.98 0.45 0.00 0.07 - - 97.15588-2C Woolooga Plag-zone Rim 47.73 0.36 11.17 1.67 1.03 1.68 0.00 3.26 4.04 0.00 0.00 - - 70.94588-2D Woolooga Plag-zone Core 55.49 0.10 25.76 0.19 0.20 9.59 0.00 5.81 0.46 0.00 0.00 - - 97.60588-3A Woolooga Plag-zone Core 58.07 0.00 23.99 0.30 0.34 7.16 0.04 7.26 0.54 0.00 0.00 - - 97.70588-3A Woolooga Plag-zone Core 57.13 0.08 26.24 0.31 0.25 9.12 0.00 6.06 0.41 0.00 0.00 - - 99.60588-3B Woolooga Plag-zone Interm 55.06 0.00 26.01 0.18 0.19 9.30 0.00 6.06 0.36 0.00 0.00 - - 97.16588-3C Woolooga Plag-zone Rim 58.89 0.11 24.01 0.06 0.29 6.86 0.00 7.38 0.41 0.00 0.00 - - 98.01


32


Rim588-3D Woolooga Magnetite Includ. Plag. 0.45 0.72 0.13 91.00 0.00 0.22 0.00 0.00 0.00 0.00 0.00 - - 92.52588-3E Woolooga Plag-zone Interm 55.20 0.00 26.70 0.30 0.30 9.80 0.00 5.77 0.41 0.00 0.00 - - 98.48588-3F Woolooga Plag-zone Interm 55.00 0.00 26.50 0.21 0.00 9.75 0.00 5.70 0.34 0.00 0.00 - - 97.50588-3G Woolooga Plag-zone Interm 55.12 0.00 26.97 0.25 0.23 10.09 0.00 5.42 0.25 0.00 0.00 - - 98.33588-3H Woolooga Plag-zone Rim 61.08 0.00 24.11 0.27 0.41 6.32 0.04 7.68 0.29 0.00 0.00 - - 100.20588-4A Woolooga Horn. Core 51.71 0.94 4.82 14.60 16.15 11.37 0.27 1.54 0.34 0.00 0.00 - - 101.74588-4A Woolooga Horn. Core 51.06 0.44 3.75 12.92 15.39 11.13 0.15 1.09 0.29 0.00 0.00 - - 96.22588-4B Woolooga Horn. Rim 60.42 0.03 8.68 2.03 2.48 2.50 0.00 3.65 2.16 0.00 0.00 - - 81.95588-4C Woolooga Horn. Interm 52.24 0.27 3.08 13.12 15.84 11.54 0.34 0.28 0.25 0.00 0.00 - - 96.96588-4D Woolooga Horn. Rim 53.48 0.45 3.63 14.25 15.74 11.22 0.38 0.71 0.21 0.00 0.00 - - 100.07588-4E Woolooga Apatite Includ. Horn 0.00 0.09 0.00 0.40 0.00 52.01 0.00 0.43 0.02 39.17 0.00 - - 92.12588-5A Woolooga Pyrx-Horn Core 53.68 0.35 1.67 9.19 14.87 20.73 0.06 0.35 0.04 0.00 0.00 - - 100.94588-5B Woolooga Horn. Rim 49.71 0.85 4.58 13.86 15.06 10.87 0.28 1.37 0.40 0.00 0.00 - - 96.98588-5C Woolooga Horn-Cpx Interm 53.21 0.26 1.27 9.34 14.79 21.17 0.23 0.36 0.00 0.00 0.00 - - 100.63588-5D Woolooga Ilmenite Includ. Horn 0.34 36.24 0.15 61.00 0.09 0.30 1.26 0.00 0.00 0.00 0.00 - - 99.38588-5D2 Woolooga Magnetite Includ. Horn 0.30 28.93 0.01 66.84 0.01 0.14 1.05 0.28 0.02 0.00 0.00 - - 97.58588-5E Woolooga Horn-Cpx Rim 51.28 0.76 4.58 13.71 15.99 11.04 0.26 1.02 0.38 0.00 0.00 - - 99.02588-5F Woolooga Horn-Cpx Core 52.54 0.44 1.27 9.35 14.93 20.78 0.20 0.50 0.00 0.00 0.00 - - 100.01588-5G Woolooga Horn. Rim 50.54 0.78 4.97 13.79 15.50 10.59 0.52 1.17 0.44 0.00 0.00 - - 98.30588-5H Woolooga Magnetite Includ. Horn 0.36 6.05 0.13 86.66 0.00 0.20 0.74 0.00 0.00 0.00 0.32 - - 94.46588-5I Woolooga Magnetite Includ. Horn 0.30 0.47 0.74 91.89 0.25 0.32 0.12 0.00 0.00 0.00 0.22 - - 94.31588-5J Woolooga Magnetite Includ. Horn 0.22 0.32 0.57 91.26 0.36 0.22 0.18 0.00 0.00 0.00 0.12 - - 93.25588-5K Woolooga Horn. Interm 51.85 0.29 1.34 9.16 14.50 20.47 0.42 0.39 0.00 0.00 0.00 - - 98.42588-6A Woolooga Horn. Core 51.97 0.85 4.51 13.34 16.46 10.91 0.51 1.17 0.28 0.00 0.00 - - 100.00588-6B Woolooga Horn. Interm 52.95 0.33 2.40 13.49 16.34 11.93 0.13 0.40 0.17 0.00 0.00 - - 98.14588-6C Woolooga Horn. Rim 52.50 0.95 3.78 11.28 17.49 11.20 0.20 0.99 0.21 0.00 0.00 - - 98.60588-6D Woolooga Magnetite Includ. Horn 0.26 3.38 0.06 89.48 0.18 0.00 0.53 0.00 0.00 0.00 0.74 - - 94.63588-6E Woolooga Magnetite Matrix 0.18 4.27 0.04 90.27 0.00 0.19 0.57 0.00 0.00 0.10 0.05 - - 95.67588-6F Woolooga Horn. Interm 52.32 0.83 4.62 13.91 16.26 10.72 0.48 1.39 0.33 0.00 0.00 - - 100.86588-6G Woolooga Biotite Sec 37.89 5.01 13.50 19.47 12.19 0.00 0.10 0.06 9.18 0.00 0.00 - - 97.40588-7A Woolooga Horn.? 50.64 0.02 4.54 17.89 20.73 0.91 0.53 0.21 0.33 0.00 0.00 - - 95.80588-7B Woolooga Horn.? 52.91 0.13 2.27 17.53 20.91 1.93 0.69 0.04 0.06 0.00 0.00 - - 96.47588-7D Woolooga Magnetite Includ. Amp. 0.09 4.72 0.10 91.52 0.18 0.00 0.17 0.27 0.00 0.00 0.14 - - 97.19617-1A Woolooga Biotite Pri Core 38.65 3.53 12.71 16.41 15.85 0.00 0.25 0.00 9.26 0.00 0.00 0.230 <0.005 96.66617-1B Woolooga Biotite Pri Rim 38.39 3.13 13.28 16.54 16.40 0.11 0.36 0.00 8.16 0.00 0.00 0.197 <0.005 96.37617-1C Woolooga Biotite Sec 38.44 3.47 12.61 15.97 15.36 0.12 0.20 0.01 9.02 0.00 0.00 - - 95.20617-1D Woolooga Biotite Pri Rim 37.56 2.89 12.86 16.05 16.01 0.03 0.37 0.24 8.95 0.00 0.00 - - 94.96617-1D2 Woolooga Biotite Pri Rim 38.97 2.97 12.44 15.90 15.62 0.08 0.21 0.25 9.19 0.00 0.00 - - 95.63617-1E Woolooga Magnetite Matrix 0.28 0.13 0.17 94.92 0.08 0.00 0.11 0.12 0.00 0.00 0.37 - - 96.18617-2A Woolooga Plag-zone Core 62.05 0.00 22.43 0.00 0.21 5.38 0.00 8.71 0.09 0.00 0.00 - - 98.87617-2B Woolooga Plag-zone Interm 59.48 0.02 23.84 0.23 0.30 7.08 0.00 7.47 0.36 0.00 0.00 - - 98.78617-2C Woolooga Plag-zone Rim 64.09 0.00 20.68 0.00 0.15 3.50 0.00 9.50 0.12 0.00 0.00 - - 98.04617-3A Woolooga Plag-zone Core 58.72 0.00 23.91 0.18 0.00 7.51 0.00 6.83 0.35 0.00 0.00 - - 97.50617-3B Woolooga Plag-zone Interm 58.93 0.00 24.16 0.05 0.16 7.86 0.00 7.16 0.23 0.00 0.00 - - 98.55617-3C Woolooga Plag-zone Rim 60.61 0.00 23.45 0.13 0.15 6.98 0.06 8.01 0.25 0.00 0.00 - - 99.64617-3D Woolooga Plag-unzone Core 59.70 0.00 23.70 0.26 0.00 7.29 0.00 7.19 0.41 0.00 0.00 - - 98.55617-3E Woolooga Plag-unzone Rim 61.12 0.05 22.17 0.00 0.00 5.74 0.00 7.89 0.29 0.00 0.00 - - 97.26617-3F Woolooga Biotite Sec Mantle Mag. 38.80 3.32 12.70 16.65 14.92 0.05 0.36 0.00 9.17 0.00 0.00 - - 95.97617-4A Woolooga Horn Pri Core 54.51 0.45 1.18 9.13 19.93 10.38 0.81 0.27 0.10 0.00 0.00 0.035 <0.005 96.76617-4B Woolooga Horn Sec 54.79 0.00 0.00 8.86 20.06 10.22 1.15 0.19 0.01 0.00 0.00 0.035 <0.05 95.28707-1A Neara Plag-unzone Core Matrix 54.30 0.07 27.30 0.53 0.28 10.90 0.00 4.98 0.58 0.00 0.00 0.000 98.94707-1B Neara Plag-unzone Rim Matrix 58.20 0.14 22.60 2.64 0.96 4.07 0.17 5.19 4.28 0.00 0.00 0.030 98.25707-2A Neara Plag-unzone Rim Matrix 53.50 0.00 28.20 0.68 0.50 11.70 0.05 4.40 0.46 0.00 0.00 0.000 99.49707-2B Neara Plag-unzone Core Matrix 54.00 0.00 27.50 0.58 0.25 11.00 0.16 4.83 0.54 0.00 0.00 0.040 98.86707-5A Neara Plag-zone Core Matrix 64.70 0.00 21.20 0.92 0.57 1.26 0.04 8.92 1.33 0.00 0.00 0.020 98.94707-5B Neara Plag-zone Rim Matrix 65.70 0.00 19.30 0.81 0.88 1.43 0.03 9.15 1.60 0.00 0.00 0.010 98.90707-5C Neara Magnetite 1.08 10.00 0.24 77.90 0.06 0.76 0.06 0.46 0.04 0.07 0.00 0.120 90.67707-5D Neara Magnetite 1.66 13.60 0.19 71.70 0.20 0.69 0.82 0.01 0.01 0.00 0.00 0.110 88.88710-1A Gibraltar Sphene Core 30.28 37.55 0.17 1.48 0.00 28.21 0.00 0.00 0.00 0.00 0.00 0.019 <0.005 97.69710-1B Gibraltar Epidote Core 38.60 0.40 21.52 13.04 0.00 22.30 0.49 0.00 0.01 0.00 0.00 0.002 - 102.97710-2A Gibraltar Plag-unzone Core 67.57 0.09 18.96 0.00 0.03 1.41 0.00 10.75 0.17 0.00 0.00 - - 97.85710-2B Gibraltar Ilmenite Matrix 0.89 50.85 0.09 41.37 0.13 0.93 8.63 0.06 0.02 0.00 0.00 - - 97.28710-2C Gibraltar Sphene Exsol Ilmenite 30.46 36.58 1.00 1.34 0.00 28.43 0.00 0.04 0.00 0.00 0.00 - - 99.8710-2D Gibraltar Or-Perthite Matrix 64.38 0.05 16.49 0.00 0.00 0.00 0.00 0.46 15.90 0.00 0.00 - - 99.99710-2D Gibraltar Perthite Grano. Matrix 67.20 0.00 19.00 0.16 0.00 0.61 0.11 6.23 6.41 0.00 0.00 0.010 0.005 98.22710-2D rpt Gibraltar Perthite Grano. Matrix 67.00 0.05 18.70 0.16 0.00 0.82 0.08 4.60 8.55 0.00 0.00 0.000 - 98.32710-3A Gibraltar Amphibole Core 55.83 0.29 0.71 9.17 20.09 10.87 0.80 0.33 0.13 0.00 0.00 0.018 - 97.64710-3B Gibraltar Magnetite 0.44 0.05 0.06 97.76 0.00 0.00 0.01 0.00 0.00 0.00 0.00 - - 99.77710-3C Gibraltar Apatite Core Matrix 0.61 0.00 0.00 0.31 0.00 53.00 0.28 0.43 0.00 42.10 0.00 1.357 - 99.96710-4A Gibraltar Magnetite Matrix 0.46 3.15 0.76 92.20 0.23 0.00 0.72 0.12 0.00 0.00 0.00 - - 103.97710-4B Gibraltar Sphene Exsol Ilmenite 32.30 31.50 4.60 2.75 0.00 28.51 0.00 0.10 0.01 0.00 0.00 - 1.468 100.46710-4C Gibraltar Ilmenite Exsol Sphene 0.33 53.38 0.00 38.71 0.16 0.21 11.18 0.00 0.00 0.00 0.00 - - 98.13710-5A Gibraltar Horn. Core 54.06 1.22 2.73 9.25 19.62 11.47 0.53 1.25 0.33 0.00 0.00 0.108 1.095 97.67710-5A2 Gibraltar Horn. Core 52.35 0.85 3.06 9.61 19.02 10.82 0.53 1.42 0.38 0.00 0.09 - 99.99710-5B Gibraltar Horn. Rim 53.77 0.74 2.01 9.14 19.46 11.10 0.73 0.53 0.19 0.00 0.00 0.075 98.35725-1A Neara Pyrx Core 52.50 0.15 1.48 7.95 14.50 22.20 1.05 0.13 0.00 0.00 0.00 0.040 97.95725-2A Neara Plag. Core 55.20 0.01 26.70 0.49 0.17 10.30 0.00 5.12 0.28 0.00 0.02 0.010 100.72725-2B Neara Plag. Rim 54.60 0.00 27.00 0.54 0.11 10.30 0.00 5.07 0.24 0.00 0.00 0.020 101.91725-3A Neara Pyrx Core 53.20 0.15 1.21 7.33 14.30 23.20 1.03 0.18 0.00 0.00 0.10 0.000 96.31725-3B Neara Pyrx Rim 54.10 0.31 1.13 7.11 15.80 22.40 0.64 0.22 0.00 0.00 0.10 0.050 90.01725-3C Neara Ilmenite 2.21 43.30 0.42 44.30 0.63 0.59 4.80 0.00 0.00 0.00 0.00 0.010 86.21725-3D Neara Magnetite 0.27 2.59 0.72 85.80 0.11 0.11 0.00 0.18 0.00 0.08 0.00 0.110 99.19725-3E Neara Chlorite 30.30 0.00 15.50 17.10 21.40 0.91 0.30 0.41 0.00 0.00 0.00 0.070 98.33725-4A Neara Plag. Core 55.90 0.00 26.60 0.21 0.23 9.66 0.09 5.94 0.38 0.00 0.00 0.080 99.97725-4B Neara Pyrx 53.10 0.19 3.20 14.20 14.10 12.40 0.79 0.00 0.13 0.00 0.00 0.070 98.46725-5A Neara Plag. Core 50.30 0.00 30.50 0.57 0.36 14.70 0.17 2.99 0.04 0.18 0.00 0.030 91.29725-5B Neara Plag. Rim 49.90 0.00 29.40 1.28 0.85 13.30 0.04 3.19 0.29 0.00 0.00 0.040 100.19725-6A Neara Magnetite 0.35 3.22 0.58 86.40 0.16 0.11 0.00 0.23 0.00 0.20 0.00 0.080 88.55725-7A Neara Ilmenite 0.40 0.00 0.00 0.05 0.00 54.40 0.00 0.00 0.00 44.30 0.01 0.890 95.71725-7B Neara Magnetite 0.01 2.60 0.15 85.40 0.08 0.00 0.00 0.14 0.00 0.01 0.00 0.130 95.71788-1A Neara Horn. 37.70 0.11 21.70 12.90 0.10 22.60 0.41 0.06 0.00 0.00 0.01 0.050 98.42788-2A Neara Horn.? 38.00 0.00 21.90 12.70 0.00 22.90 0.07 0.00 0.01 0.00 0.00 0.010 90.70788-2B Neara Epidote? 53.50 0.09 3.24 12.40 15.70 12.30 0.92 0.14 0.04 0.00 0.00 0.050 98.14788-3A Neara Magnetite 1.73 1.71 0.39 85.50 0.05 1.12 0.00 0.07 0.00 0.00 0.00 0.090 96.45788-4A Neara Horn. Core 53.30 0.21 3.44 13.00 15.10 12.00 0.85 0.00 0.08 0.00 0.00 0.000 98.68788-7A Neara Horn. Core 38.00 0.18 21.30 13.20 0.29 22.70 0.33 0.24 0.00 0.00 0.00 0.010 96.79788-7B Neara Horn. Rim 52.70 0.06 3.06 15.00 14.10 12.50 1.00 0.04 0.08 0.00 0.00 0.010 97.57788-7C Neara Horn. Rim 38.30 0.00 21.50 13.10 0.38 22.80 0.35 0.07 0.00 0.00 0.02 0.090 98.49788-8C Neara Epidote 51.00 0.01 5.18 15.00 12.40 12.40 0.95 0.28 0.19 0.00 0.00 0.050 97.58788-9A Neara Plag. Core 52.80 0.00 28.00 0.76 0.30 11.70 0.02 4.22 0.59 0.00 0.00 0.020 - 98.82788-9B Neara Plag. Rim 54.40 0.00 26.40 0.69 0.64 8.65 0.10 4.65 1.95 0.00 0.00 0.000 - 99.37


33


Rim791-1A Gibraltar Plag. Core 56.9 0 26.1 0.3 0.16 8.83 0.14 6.06 0.36 0 0 0.000 - 99.74791-1B Gibraltar Plag. Rim 64.1 0 22.1 0.23 0.14 2.98 0 9.37 0.19 0 0.16 0.000 - 98.97791-2A Gibraltar Plag. Core 54.6 0.07 27.8 0.27 0.34 11.1 0.07 5.14 0.15 0 0.04 0.000 - 90.96791-2B Gibraltar Plag. Rim 60 0 24.3 0.13 0.06 6.86 0.11 7.06 0.31 0 0.15 0.000 - 97.63791-4A Gibraltar Magnetite 0.01 0.33 0 90.4 0 0.03 0 0 0 0.07 0 0.080 - 99.85791-4B Gibraltar Sphene Core 30 36.5 1.77 1.87 0.02 26.8 0.03 0.04 0.08 0.37 0 0.000 - 91.24791-5A Gibraltar Ilmenite 0.13 54 0 30.4 0.1 0.29 14.8 0 0.03 0.03 0 0.000 - 98.4791-5B Gibraltar Magnetite 0.09 0.95 0 89.8 0 0.01 0 0 0 0.2 0 0.130 - 97.79791-6A Gibraltar Horn. Core 54.2 0.33 2.13 12.5 16 11.7 1.07 0.23 0.13 0 0 0.000 - 98.09791-6B Gibraltar Horn. Rim 54.1 0.29 2.3 10.9 16.6 12.3 0.69 0.15 0.04 0.08 0 0.140 - 98.46791-7A Gibraltar Horn. Core 53.2 0.44 2.75 11.7 16.5 11.9 0.88 0.38 0.1 0.07 0 0.070 - 97.88792-1A Gibraltar Plag-zone Core 55.00 0.08 26.51 0.45 0.33 10.47 0.00 5.43 0.19 0.00 0.00 - - 97.36792-1B Gibraltar Plag-zone Interm 66.85 0.00 18.74 0.00 0.09 1.44 0.01 10.43 0.32 0.00 0.00 - - 97.34792-1C Gibraltar Plag-zone Rim 60.50 0.00 22.49 0.29 0.14 5.80 0.00 7.82 0.32 0.00 0.00 - - 97.69792-1D Gibraltar Horn. Core 55.58 0.42 0.41 10.46 18.05 11.53 0.84 0.00 0.05 0.00 0.00 - - 95.21792-1E Gibraltar Horn. Rim 55.44 0.27 0.59 10.35 18.30 11.45 0.82 0.43 0.04 0.00 0.00 - - 96.06792-1F Gibraltar Magnetite Matrix 0.41 0.90 0.18 93.42 0.21 0.07 0.02 0.00 0.00 0.00 0.00 - - 95.91792-2A Gibraltar Magnetite 0.51 0.65 0.17 94.31 0.12 0.00 0.30 0.00 0.00 0.00 0.00 - - 98.64792-2B Gibraltar Magn-Ilmn Bulk Matrix 0.40 3.04 0.21 90.69 0.27 0.00 1.08 0.08 0.01 0.13 0.00 - - 94.23792-2C1 Gibraltar Ilmenite Exsol Mag. 1.03 40.27 0.00 37.13 0.10 0.67 19.29 0.12 0.00 0.00 0.03 - - 96.90792-2C2 Gibraltar Ilmenite Exsol Mag. 0.39 54.88 2.77 34.01 0.29 0.00 0.65 1.24 0.00 0.00 0.00 - - 97.01792-2D Gibraltar Magnetite 0.42 1.23 0.38 94.24 0.16 0.00 0.46 0.01 0.00 0.00 0.00 - - 97.79792-3A Gibraltar Horn Pri Core 54.21 0.18 0.77 10.78 17.80 12.03 0.78 0.41 0.05 0.00 0.00 - - 97.28792-3B Gibraltar Horn Pri Rim 53.72 0.17 1.56 11.74 17.41 11.82 0.64 0.66 0.07 0.00 0.00 - - 98.29792-3C Gibraltar Horn Sec Core 53.76 0.14 1.49 11.60 17.40 11.83 0.65 0.37 0.04 0.00 0.00 - - 97.49792-3D Gibraltar Horn Sec Rim 54.13 0.20 2.21 10.75 18.22 11.33 0.64 0.68 0.13 0.00 0.00 - - 97.84792-4A Gibraltar Horn. Core 53.94 0.43 0.55 13.03 16.53 11.77 0.88 0.26 0.10 0.00 0.00 - - 95.27792-4B Gibraltar Horn. Rim 54.11 0.37 1.41 11.62 17.04 11.79 0.76 0.65 0.09 0.00 0.00 - - 97.34792-4C Gibraltar Magnetite Includ. Horn 0.54 0.00 0.16 94.11 0.35 0.00 0.00 0.01 0.01 0.00 0.09 - - 98.00792-5A Gibraltar Plag-unzone Core 57.15 0.06 24.50 0.37 0.06 8.50 0.00 6.35 0.35 0.00 0.00 - - 98.09792-5B Gibraltar Plag-unzone Rim 66.53 0.00 18.89 0.04 0.18 2.18 0.00 9.69 0.48 0.00 0.01 - - 100.24792-6A Gibraltar Plag-unzone Core 49.56 0.00 29.98 0.61 0.24 14.59 0.00 3.03 0.08 0.00 0.00 - - 98.30794-1A Gibraltar Plag-zone Core 61.90 0.07 23.59 0.18 0.15 6.65 0.00 7.34 0.36 0.00 0.00 - - 100.53794-1B Gibraltar Plag-zone Interm 61.01 0.00 21.33 0.32 0.18 5.34 0.04 5.57 4.51 0.00 0.00 - - 94.83794-1C Gibraltar Plag-zone Rim 61.98 0.00 23.17 0.30 0.09 6.47 0.08 7.45 0.99 0.00 0.00 - - 98.38794-1D Gibraltar Biotite Includ. Plag. 37.04 5.63 12.71 15.03 15.08 0.06 0.28 0.11 8.89 0.00 0.00 - - 103.60794-1E Gibraltar Ilmenite Includ. Plag. 0.34 44.77 0.04 46.05 0.33 0.13 6.68 0.00 0.00 0.00 0.04 - - 98.89794-1F Gibraltar Sphene Matrix 32.36 40.14 0.00 1.48 0.00 29.40 0.00 0.22 0.00 0.00 0.00 - - 97.22794-1G Gibraltar Or-Perthite Matrix 66.53 0.01 17.35 0.10 0.01 0.11 0.00 5.13 9.64 0.00 0.01 - - 97.80794-1H Gibraltar Plag-unzone Core 59.96 0.01 22.56 0.13 0.07 6.13 0.37 7.16 0.83 0.00 0.00 - - 96.54794-1I Gibraltar Plag-unzone Rim 61.29 0.00 22.02 0.10 0.29 5.61 0.00 8.00 0.49 0.00 0.00 - - 95.68794-2A Gibraltar Horn. 53.25 0.36 1.61 11.50 17.56 11.10 0.80 0.19 0.17 0.00 0.00 - - 100.02794-2B Gibraltar Epidote Matrix 38.14 0.26 22.23 12.15 0.00 22.49 0.26 0.12 0.03 0.00 0.00 - - 100.11794-2C Gibraltar Plag-unzone Core 62.01 0.00 22.38 0.20 0.37 6.04 0.19 8.11 0.72 0.00 0.00 - - 98.43794-2D Gibraltar Plag-unzone Rim 62.42 0.18 22.12 0.16 0.51 5.10 0.00 8.60 1.02 0.00 0.00 - - 100.70794-3A Gibraltar Plag-unzone Core 60.01 0.00 23.27 0.37 0.13 6.86 0.00 7.31 0.48 0.00 0.00 - <0.005 96.92794-3B Gibraltar Plag-unzone Rim 64.55 0.08 21.80 0.35 0.08 4.74 0.00 8.42 0.68 0.00 0.00 - <0.005 98.88794-4A Gibraltar Biotite Prim Matrix 38.21 6.23 12.58 14.43 15.79 0.00 0.40 0.13 9.15 0.00 0.00 0.034 0.498 97.17794-4B Gibraltar Sphene Matrix 30.46 39.19 0.00 1.37 0.00 27.76 0.00 0.10 0.00 0.00 0.00 0.001 - 95.17794-4C Gibraltar Horn. 54.27 0.21 1.00 10.83 17.83 11.54 0.53 0.80 0.16 0.00 0.00 0.014 - 28.27816-1A Woolooga Epidote Core 37.90 0.03 22.87 11.27 0.00 22.34 0.68 0.06 0.02 0.00 0.00 - <0.005 95.19816-1B Woolooga Spinel? Epidote 12.56 0.05 8.22 1.86 0.35 4.83 0.08 0.28 0.00 0.00 0.04 - - 94.47816-1C Woolooga Sphene Core 29.93 36.37 0.30 1.25 0.00 27.34 0.00 0.00 0.00 0.00 0.00 0.021 - 81.10816-1D Woolooga Epidote Rim 37.68 0.04 22.83 11.11 0.00 22.69 0.08 0.04 0.00 0.00 0.00 - - 98.79816-1E Woolooga Magnetite Matrix 4.95 0.00 0.01 75.58 0.31 0.13 0.12 0.00 0.00 0.00 0.00 - - 98.86816-2A Woolooga Plag-unzone Core 60.53 0.03 23.13 0.37 0.19 6.58 0.00 7.61 0.35 0.00 0.00 - - 98.29816-2B Woolooga Plag-unzone Rim 64.06 0.00 21.12 0.08 0.12 4.07 0.00 8.98 0.43 0.00 0.00 - - 98.35816-3A Woolooga Plag-zone Core 61.46 0.01 22.44 0.24 0.07 5.90 0.01 7.31 0.85 0.00 0.00 - - 98.67816-3B Woolooga Plag-zone Interm 61.46 0.01 22.14 0.43 0.08 5.88 0.00 7.41 0.94 0.00 0.00 - - 95.62816-3C Woolooga Plag-zone Rim 60.19 0.00 23.17 0.18 0.32 6.71 0.00 7.82 0.28 0.00 0.00 - - 99.55816-3D Woolooga Magnetite Matrix 0.56 0.62 0.18 93.64 0.18 0.00 0.30 0.06 0.00 0.08 0.00 - 4.207 96.71816-3E Woolooga Ilmenite Exsol Matrix 0.47 49.84 0.00 38.43 0.14 0.53 10.05 0.09 0.00 0.00 0.00 - 0.214 97.66816-3F Woolooga Apatite Mag. 0.00 0.02 0.00 0.19 0.00 54.02 0.00 0.29 0.00 42.19 0.00 0.389 - 97.34816-4A Woolooga Horn. Core 54.02 0.42 1.66 10.01 18.42 11.66 0.73 0.54 0.20 0.00 0.00 0.037 0.008 97.00816-4B Woolooga Horn. Interm 54.23 0.22 1.41 9.39 18.54 11.98 0.69 0.78 0.10 0.00 0.00 - 0.172 97.37816-4C Woolooga Horn. Rim 52.42 0.14 2.52 12.82 15.32 12.21 1.00 0.46 0.11 0.00 0.00 0.034 0.113 97.56816-5A Woolooga Horn. Core 53.26 0.58 2.04 9.88 18.45 11.75 0.52 0.67 0.22 0.00 0.00 0.068 - 97.50816-5B Woolooga Horn. Rim 53.13 0.65 2.15 10.78 17.58 11.53 0.84 0.59 0.31 0.00 0.00 0.215 0.075 97.86816-6A Woolooga Horn. Core 54.37 0.33 1.00 10.19 18.30 11.86 0.70 0.59 0.16 0.00 0.00 - - 98.37816-6B Woolooga Horn. Rim 54.82 0.15 1.13 10.91 17.86 11.73 0.64 0.44 0.18 0.00 0.00 0.034 - 98.31820-1A Woolooga Plag-unzone Core 58.08 0.04 24.55 0.27 0.00 8.37 0.03 6.50 0.53 0.00 0.00 - - 97.18820-1B Woolooga Plag-unzone Interm 57.45 0.00 25.13 0.22 0.00 9.05 0.00 6.04 0.42 0.00 0.00 - - 97.89820-1C Woolooga Plag-unzone Rim 78.79 0.00 8.96 0.09 0.04 0.13 0.07 1.12 7.98 0.00 0.00 - - 97.60820-2A Woolooga Plag-zone Core 55.88 0.04 25.66 0.30 0.13 9.42 0.00 5.96 0.50 0.00 0.00 - - 98.56820-2B Woolooga Plag-zone Interm 57.60 0.00 24.28 0.36 0.00 8.34 0.00 6.34 0.61 0.00 0.07 - - 99.20820-2C Woolooga Plag-zone Rim 59.07 0.07 23.86 0.45 0.11 7.33 0.00 7.22 0.45 0.00 0.00 - <0.005 93.16820-3A Woolooga Pyrx Includ. Plag. 52.92 0.20 0.00 9.26 15.30 21.16 0.26 0.10 0.00 0.00 0.00 - - 98.89820-3B Woolooga Biotite Matrix 36.35 4.43 13.14 14.40 18.00 0.34 0.09 0.00 6.41 0.00 0.00 0.102 - 98.71820-4A Woolooga Plag-zone Core 54.85 0.00 27.18 0.38 0.21 11.15 0.00 4.81 0.30 0.00 0.01 - - 97.57820-4B Woolooga Plag-zone Interm 56.43 0.00 26.11 0.24 0.01 10.03 0.00 5.40 0.49 0.00 0.00 - 0.196 97.64820-4C Woolooga Plag-zone Rim 60.46 0.04 22.70 0.18 0.21 5.70 0.00 7.81 0.47 0.00 0.00 - <0.005 98.06820-5A Woolooga Horn. Core 54.91 0.41 0.79 9.99 18.80 12.02 0.37 0.27 0.07 0.00 0.01 0.055 0.254 97.20820-5B Woolooga Horn. Rim 55.35 0.37 1.29 8.94 20.32 11.14 0.08 0.37 0.20 0.00 0.00 0.156 - 95.68820-5C Woolooga Horn. Core 55.23 0.33 1.13 8.98 19.91 10.94 0.25 0.29 0.14 0.00 0.00 0.094 - 101.54820-5D Woolooga Magnetite Horn 0.47 2.26 0.43 92.01 0.11 0.00 0.13 0.09 0.00 0.00 0.18 - <0.005 98.69820-5E Woolooga Ilmenite Exsol Mag. 0.31 51.02 0.17 42.98 0.45 0.07 6.36 0.18 0.00 0.00 0.00 - <0.05 96.83820-5F Woolooga Sphene Exsol Ilmenite 30.28 39.87 0.00 0.86 0.00 27.64 0.00 0.00 0.04 0.00 0.00 0.009 <0.05 98.47820-6A Woolooga Horn Prim Core 53.95 0.11 0.64 12.91 16.38 12.57 0.27 0.00 0.00 0.00 0.00 0.012 - 75.92820-6B Woolooga Horn Prim Rim 55.33 0.08 0.17 13.59 16.25 12.18 0.38 0.42 0.07 0.00 0.00 0.052 - 97.11820-6C Woolooga Horn Sec Core 36.39 0.07 3.88 14.62 13.27 6.92 0.30 0.39 0.08 0.00 0.00 - - 94.52820-6D Woolooga Horn Sec Rim 50.43 0.25 4.28 14.60 17.32 9.82 0.34 0.03 0.04 0.00 0.00 - - 99.97852-1A Gibraltar Biotite Sec 38.32 5.43 12.40 12.84 16.42 0.10 0.00 0.03 8.98 0.00 0.00 - - 97.41852-1B Gibraltar Ilmenite Matrix 0.48 45.95 0.28 47.70 0.29 0.00 5.27 0.00 0.00 0.00 0.00 - - 100.00852-1B2 Gibraltar Ilmenite Matrix 0.47 45.63 0.00 45.32 0.13 0.09 5.69 0.00 0.00 0.08 0.00 - - 97.91852-1C Gibraltar Magnetite Matrix 0.51 0.58 0.37 98.32 0.17 0.00 0.05 0.00 0.00 0.00 0.00 - - 95.09852-1D Gibraltar Ilmenite Includ. Horn 0.27 48.10 0.20 45.23 0.13 0.01 3.97 0.00 0.00 0.00 0.00 - - 98.26852-1E Gibraltar Magnetite Includ. Horn 0.43 1.87 2.03 89.83 0.35 0.00 0.17 0.37 0.00 0.04 0.00 - - 94.05852-1F Gibraltar Ilmenite Includ. Horn 0.34 47.78 0.07 45.90 0.00 0.00 4.12 0.00 0.00 0.05 0.00 - - 92.60852-1G Gibraltar Magnetite Includ. Horn 0.51 1.85 1.77 89.55 0.19 0.00 0.18 0.00 0.00 0.00 0.00 - - 92.81852-1H Gibraltar Apatite Includ. Ilmenite 0.00 4.42 0.07 3.01 0.00 47.49 0.33 0.34 0.00 36.94 0.00 - - 97.61852-1I Gibraltar Magnetite Matrix 0.45 0.24 0.37 91.39 0.12 0.01 0.23 0.00 0.00 0.00 0.00 - - 97.10


34


Rim852-2A Gibraltar Plag-unzone Core 54.68 0.00 26.04 0.31 0.22 10.33 0.10 4.98 0.95 0.00 0.00 - - 97.91852-2B Gibraltar Plag-unzone Interm 51.49 0.01 27.63 0.47 0.26 12.69 0.00 3.65 0.90 0.00 0.00 - - 96.92852-2C Gibraltar Plag-unzone Rim 67.22 0.00 18.77 0.19 0.04 4.11 0.00 7.38 0.20 0.00 0.00 - - 98.26852-3A Gibraltar Plag-zone Core 50.41 0.02 29.22 0.35 0.00 13.75 0.00 3.01 0.16 0.00 0.00 - - 99.10852-3B Gibraltar Plag-zone Rim 50.81 0.00 29.64 0.37 0.11 13.77 0.00 3.40 0.16 0.00 0.00 - - 98.31852-4A Gibraltar Horn-Cpx Core 52.41 0.39 1.24 7.88 16.24 20.53 0.21 0.20 0.00 0.00 0.00 - - 95.89852-4B Gibraltar Horn-Cpx Rim 52.43 0.31 0.00 10.76 14.49 19.62 0.43 0.22 0.05 0.00 0.00 - - 95.86852-4C Gibraltar Magnetite Matrix 1.16 5.42 0.80 87.04 0.51 0.00 0.87 0.09 0.00 0.00 0.00 - - 88.48852-4D Gibraltar Magnetite Matrix 0.23 2.22 0.72 92.21 0.30 0.00 0.18 0.00 0.00 0.00 0.00 - - 95.16852-4E Gibraltar Biotite Sec Core 37.05 1.91 9.95 17.13 14.90 0.38 0.24 0.00 6.92 0.00 0.00 - - 94.51852-5A Gibraltar Magnetite Includ. Cpx 0.54 8.36 3.99 80.75 0.14 0.05 1.33 0.00 0.00 0.00 0.00 - - 98.96852-5B Gibraltar Magnetite Includ. Cpx 0.27 0.74 1.23 92.06 0.15 0.00 0.06 0.00 0.00 0.00 0.00 - - 94.79852-5C Gibraltar Horn-Cpx Core 51.57 0.68 1.68 8.31 15.40 20.59 0.44 0.29 0.00 0.00 0.00 - - 99.94852-5D Gibraltar Magnetite Matrix 0.32 1.33 0.29 92.23 0.18 0.00 0.37 0.07 0.00 0.00 0.00 - - 97.92852-5F Gibraltar Pyrx-c Rim 52.78 0.20 0.00 10.55 14.04 21.20 0.62 0.55 0.00 0.00 0.00 - - 97.62852-6A Gibraltar Plag-zone Core 49.76 0.00 30.06 0.50 0.09 14.61 0.00 2.88 0.02 0.00 0.00 - - 96.35852-6B Gibraltar Plag-zone Rim 58.29 0.05 23.96 0.32 0.27 7.42 0.00 7.01 0.30 0.00 0.00 - - 97.72852-6C Gibraltar Magnetite Includ. Plag. 0.38 1.85 2.48 90.46 0.82 0.08 0.28 0.00 0.00 0.00 0.00 - - 98.86852-6D Gibraltar Pyrx-c Includ. Plag. 43.25 2.51 9.85 12.09 15.04 11.30 0.24 2.55 0.89 0.00 0.00 - - 98.85852-7A Gibraltar Pyrx-c sec Core 51.94 0.57 1.36 8.01 15.67 20.83 0.39 0.00 0.04 0.00 0.05 - - 99.86852-7B Gibraltar Pyrx-c sec Rim 51.88 0.57 1.59 7.90 15.96 20.72 0.16 0.07 0.00 0.00 0.00 - - 98.14852-7C Gibraltar Pyrx-c pri Core 52.08 0.71 1.77 8.07 15.83 20.62 0.14 0.64 0.00 0.00 0.00 - - 94.35852-7D Gibraltar Pyrx-c pri Rim 51.99 0.15 0.00 10.20 14.24 20.59 0.70 0.27 0.00 0.00 0.00 - - 94.56852-7E Gibraltar Biotite Pri Core 38.57 5.40 12.52 11.40 17.15 0.06 0.00 0.00 9.25 0.00 0.00 - - 93.91852-7F Gibraltar Biotite Sec Rim 37.96 5.81 12.09 14.76 14.75 0.05 0.04 0.00 9.05 0.00 0.05 - 100.87852-7G Gibraltar Magnetite Matrix 0.29 5.15 2.13 84.86 0.16 0.00 0.97 0.28 0.07 0.00 0.00 - 98.78886-00E Neara Plag. Core 63.80 0.00 22.40 1.10 0.36 3.09 0.07 8.91 1.00 0.00 0.01 0.070 98.57886-00F Neara Plag. Core 64.90 0.00 21.40 0.47 0.04 1.46 0.00 9.35 1.12 0.00 0.00 0.030 98.56886-1A Neara Plag. Core 64.00 0.39 21.20 0.36 0.23 1.47 0.11 9.63 1.13 0.00 0.02 0.010 97.91886-1A Neara Pyrx Core 51.80 0.14 4.30 13.80 14.90 12.20 0.53 0.66 0.09 0.00 0.00 0.030 98.68886-1B Neara Pyrx Rim 51.00 0.79 4.12 15.90 12.70 12.30 0.52 0.31 0.14 0.00 0.00 0.110 96.90886-2B Neara Plag. Rim 64.30 0.00 21.10 0.40 0.23 2.12 0.05 9.69 0.80 0.00 0.00 0.000 99.40886-3A Neara Horn. Core 38.30 0.07 24.00 10.20 0.00 23.70 0.16 0.22 0.00 0.00 0.10 0.020 - 99.77886-4A Neara Horn. Core 47.60 4.52 6.65 15.90 10.10 13.50 0.51 0.21 0.14 0.00 0.06 0.080 - 100.09901-1A Neureum Plag. Core 61.2 0 24.1 0.07 0.05 6.22 0.06 7.64 0.36 0 0 0.020 - 97.12901-1B Neureum Plag. Rim 61.2 0.05 24.1 0.26 0.12 6.14 0 7.72 0.35 0.01 0 0.030 - 98.43901-2A Neureum Plag. Core 57.9 0 26.6 0.25 0.41 1.26 0.19 5.83 4.59 0 0 0.010 - 99901-3A Neureum Horn. Core 46.1 1.97 10.2 10.2 16.3 10.9 0.11 1.77 0.51 0.01 0.14 0.020 - 98901-3B Neureum Horn. Rim 44.2 1.52 11.5 14.9 12.6 11 0.32 2.25 0.52 0 0.03 0.090 - 98.71901-4A Neureum Horn. Core 46.3 1.74 10.3 9.44 16.8 11 0.09 1.75 0.48 0 0 0.010 - 98.99901-4B Neureum Horn. Rim 46.5 1.71 10.3 9.03 17 11.2 0.11 1.99 0.56 0.12 0.1 0.000 - 94.48901-5A Neureum Chlorite 42.7 2.12 12.6 13.7 13 11.5 0.2 2.37 0.54 0 0.01 0.000 - 91.63901-6A Neureum Ilmen-magn 0.05 41 0 52.6 0.08 0.07 0.29 0.06 0.02 0.21 0 0.000 - 98.42901-6B Neureum Magnetite 0 2.13 0.37 88.4 0.09 0 0 0.49 0 0.1 0 0.030 - 91.43901-7A Neureum Ilmenite L. Amp. 0.09 85.5 0.04 12 0.07 0.03 0.21 0.05 0.03 0.09 0.23 0.000 - 99.05901-7B Neureum Magnetite L.Amp. 0 12.3 0 78.4 0 0 0.52 0.08 0 0 0 0.010 - 100.01936-1A Mt Mucki Plag. Core 45.5 0 33.1 0.93 0.29 18 0.05 1 0.12 0 0 0.050 - 99.16936-1B Mt Mucki Plag. Rim 54.1 0.08 28.2 0.24 0.3 11.6 0.15 5.07 0.12 0 0.1 0.000 - 92.32936-2A Mt Mucki Ilmenite 0.05 49.1 0 43.8 0.06 0.15 5.89 0 0 0.02 0 0.000 - 90.75936-2B Mt Mucki Magnetite 0.09 0 0 91.9 0.13 0 0 0 0.02 0.1 0 0.070 - 99.78936-2C Mt Mucki Magnetite 0.16 0.66 0.09 89.2 0.07 0.09 0 0.31 0 0.09 0 0.100 - 99.14936-3A Mt Mucki Pyrx-horn? 51.6 0.37 3.48 9.56 14.1 19.2 0.64 0.4 0.13 0 0.06 0.080 - 98.86936-4A Mt Mucki Horn. Core 45.2 2.81 10 11.8 14.8 11.2 0.44 2.18 0.41 0 0 0.070 - 99.82936-4B Mt Mucki Horn. Rim 49.7 1.29 5.9 12.5 15.7 11.7 0.45 0.98 0.36 0 0.04 0.090 - 99.62936-5A Mt Mucki Pyrx Core 53 0.15 1.15 6.48 14.3 23.9 0.51 0.2 0 0 0.05 0.000 - 98.8936-6A Mt Mucki Plag. Core 46.7 0 32.6 0.62 0.26 17.5 0.05 1.8 0.07 0 0 0.000 - 100936-6B Mt Mucki Plag. Rim 54.1 0 27.7 0.46 0.16 11.3 0.12 4.58 0.2 0 0.04 0.020 - 99.89936-7A Mt Mucki Plag. Core 54.5 0.03 28 0.48 0.3 11.1 0.15 5.21 0.11 0 0 0.030 - 99.63936-8A Mt Mucki Pyrx 52 0.51 2.69 8.65 14.8 19.8 0.3 0.76 0.11 0.13 0 0.040 - 99.96936-8B Mt Mucki Horn. Rim Mantle 55 0 2.55 11.1 16.6 13.3 0.63 0.12 0.09 0 0.15 0.000 - 99.23936-9A Mt Mucki Sphene Core 30.1 39.3 1.03 0.58 0 28.6 0.12 0 0 0.07 0.09 0.000 - 98.47999-1A Mt Mucki Horn. Core 47.03 1.79 6.82 13.22 14.88 11.43 0.41 1.11 0.71 0.00 0.00 0.095 - 95.03999-1B Mt Mucki Horn. Rim 43.53 2.57 9.57 15.55 12.05 11.76 0.21 1.36 0.93 0.00 0.00 0.132 - 97.84999-1C Mt Mucki Magnetite Matrix 0.46 0.00 0.16 94.26 0.15 0.00 0.00 0.00 0.00 0.00 0.00 - - 95999-1E Mt Mucki Plag-unzone Core Horn 56.42 0.13 25.44 0.25 0.00 9.71 0.00 5.72 0.17 0.00 0.00 - - 96.54999-1F Mt Mucki Apatite Matrix 0.29 0.00 0.00 0.00 0.00 52.30 0.00 0.00 0.23 41.10 0.00 0.090 - 97.40999-1SP Mt Mucki Sphene Matrix 30.22 37.42 0.04 0.99 0.00 27.77 0.00 0.10 0.00 0.00 0.00 - - 99.42999-2B Mt Mucki Horn. Core 48.55 1.21 5.32 13.26 15.28 11.84 0.35 1.03 0.53 0.00 0.03 - - 97.87999-3C Mt Mucki Sphene 29.30 39.50 1.08 0.84 0.00 28.50 0.11 0.00 0.08 0.00 0.01 0.000 - 99.87999-4A Mt Mucki Horn. Rim 44.66 2.92 9.49 13.13 13.62 11.82 0.28 1.39 0.56 0.00 0.00 - - 99.20999-4B Mt Mucki Horn. Core 49.59 1.15 5.13 13.12 15.20 11.85 0.31 0.95 0.55 0.00 0.00 - - 98.28999-4C Mt Mucki Plag-unzone Core 52.50 0.00 28.92 0.49 0.05 13.11 0.00 3.93 0.20 0.00 0.00 - - 98.78999-4D Mt Mucki Plag-unzone Rim 56.57 0.02 26.06 0.00 0.05 9.73 0.00 5.68 0.17 0.00 0.00 - - 99.46999-4E Mt Mucki Plag-zone Core 59.22 0.00 24.34 0.26 0.00 7.92 0.00 6.76 0.28 0.00 0.00 - - 99.88999-4F Mt Mucki Plag-zone Rim 58.48 0.00 25.15 0.00 0.33 8.62 0.00 6.72 0.16 0.00 0.00 - - 99.74999-4G Mt Mucki Oroclase Core 66.00 0.00 18.00 0.13 0.07 0.00 0.09 0.99 14.60 0.00 0.00 0.000 - 98.14999-4H Mt Mucki Oroclase Core 65.50 0.00 18.10 0.16 0.28 0.11 0.10 0.79 14.70 0.00 0.00 0.000 - 98.41999-5A Mt Mucki Plag. Matrix Matrix 57.90 0.00 24.92 0.47 0.04 8.29 0.00 6.39 0.13 0.00 0.00 0.000 <0.005 99.06999-5B Mt Mucki Plag. Matrix Matrix 60.49 0.03 23.12 0.22 0.23 6.41 0.00 7.85 0.06 0.00 0.00 - <0.005 98.63999-5C Mt Mucki Horn. Core 46.92 2.25 7.71 12.61 15.10 11.66 0.53 1.63 0.65 0.00 0.00 0.101 2.966 101.05999-5D Mt Mucki Horn. Rim 50.69 1.07 4.56 13.00 15.96 12.01 0.21 0.75 0.38 0.00 0.00 0.070 - 99.521000-1A Mt Mucki Ilmenite Matrix 0.39 45.57 0.00 46.59 0.00 0.00 7.45 0.00 0.00 0.00 0.00 - - 94.211000-1B Mt Mucki Magnetite Matrix 0.25 0.04 0.00 93.75 0.00 0.00 0.01 0.00 0.00 0.00 0.00 - - 97.191000-1C Mt Mucki Magnetite Matrix 0.34 0.08 0.33 93.01 0.16 0.00 0.29 0.00 0.00 0.00 0.00 - - 100.921000-1D Mt Mucki Sphene Exsol Mag. 27.67 42.40 0.51 1.71 0.01 24.89 0.00 0.00 0.00 0.00 0.00 - - 95.901000-1E Mt Mucki Ilmenite Exsol Mag. 0.33 49.16 0.00 40.78 0.06 0.16 10.23 0.20 0.00 0.00 0.00 - - 99.061000-1F Mt Mucki Magnetite Matrix 0.48 0.27 0.21 94.51 0.10 0.00 0.23 0.08 0.00 0.02 0.00 - - 96.111000-2A Mt Mucki Horn Sec Core 45.35 2.96 9.56 11.85 15.37 11.01 0.35 2.23 0.37 0.00 0.01 - <0.05 95.041000-2A2 Mt Mucki Horn Sec Core 43.60 2.71 9.11 11.91 15.09 10.84 0.30 2.06 0.49 0.00 0.00 - <0.05 97.351000-2B Mt Mucki Horn Sec Rim 48.11 1.37 5.02 12.69 14.97 11.21 0.45 0.61 0.61 0.00 0.00 0.133 - 96.401000-2C Mt Mucki Horn Pri Rim 46.57 1.24 5.71 8.97 13.37 21.35 0.02 0.12 0.00 0.00 0.00 0.007 - 95.801000-2D Mt Mucki Horn Pri Core 46.07 1.27 5.50 9.12 13.11 21.22 0.11 0.00 0.00 0.00 0.00 - - 96.581000-2E Mt Mucki Plag. Core Horn 52.32 0.00 26.77 0.14 0.00 11.67 0.00 4.81 0.09 0.00 0.00 - - 97.491000-2F Mt Mucki Plag. Rim Horn 53.47 0.07 26.39 0.45 0.00 10.95 0.00 5.22 0.03 0.00 0.00 - - 98.571000-2G Mt Mucki Plag. Core Horn 46.31 0.00 31.44 0.77 0.00 17.16 0.00 1.73 0.08 0.00 0.00 - - 98.541000-2H Mt Mucki Plag. Rim Horn 46.37 0.00 31.74 1.30 0.42 17.57 0.00 1.14 0.03 0.00 0.00 - - 98.251000-3A Mt Mucki Horn. Core 44.50 2.89 9.92 11.62 15.49 11.11 0.19 2.41 0.41 0.00 0.00 - - 99.361000-3B Mt Mucki Horn. Rim 44.36 2.78 9.82 12.35 14.87 11.45 0.37 1.90 0.35 0.00 0.00 - - 99.721000-3C Mt Mucki Horn. Rim 48.25 1.07 5.27 8.73 13.62 22.28 0.10 0.00 0.01 0.00 0.03 - - 98.031000-3D Mt Mucki Horn. Core 47.53 1.16 5.97 9.31 13.65 21.89 0.00 0.20 0.01 0.00 0.00 - - 100.561000-3E Mt Mucki Horn. Core 45.21 2.34 8.58 12.06 14.94 11.72 0.33 2.03 0.82 0.00 0.00 - - 99.14


35


Rim1000-3F Mt Mucki Horn. Rim 54.31 0.00 0.00 6.34 15.04 24.01 0.45 0.41 0.00 0.00 0.00 - - 98.081000-3G Mt Mucki Plag. Core Horn 46.59 0.04 32.35 0.71 0.13 17.89 0.00 1.39 0.00 0.00 0.04 - - 100.441000-3H Mt Mucki Plag. Rim Horn 45.38 0.04 32.57 0.93 0.00 18.30 0.00 0.86 0.00 0.00 0.00 - - 98.481000-4A Mt Mucki Horn. Core 52.78 0.25 1.07 5.22 16.00 24.91 0.21 0.00 0.00 0.00 0.00 - <0.005 98.111000-4B Mt Mucki Horn. Rim 47.87 1.07 5.46 8.60 13.50 21.92 0.04 0.01 0.01 0.00 0.00 - - 96.771000-4C Mt Mucki Horn. Core 44.43 2.91 9.64 11.87 15.33 10.90 0.21 2.43 0.39 0.00 0.00 0.065 <0.005 97.111000-4D Mt Mucki Horn. Rim 48.91 1.37 5.18 13.02 15.40 11.28 0.35 0.73 0.53 0.00 0.00 - <0.005 96.821000-4E Mt Mucki Horn. Core 53.32 0.26 2.18 11.87 16.51 12.44 0.11 0.26 0.16 0.00 0.00 0.015 - 98.151000-4F Mt Mucki Horn. Rim 50.60 0.25 4.17 13.21 15.43 12.30 0.40 0.34 0.12 0.00 0.00 0.019 - 98.531000-4G Mt Mucki Plag. Rim 57.84 0.00 24.41 0.26 0.18 8.36 0.01 6.92 0.17 0.00 0.00 - - 101.041000-5A Mt Mucki Plag. Core 45.93 0.00 32.72 0.76 0.00 18.24 0.00 0.88 0.00 0.00 0.00 - - 97.781000-5A2 Mt Mucki Plag. Interm 46.99 0.00 33.36 0.80 0.12 18.53 0.00 1.24 0.00 0.00 0.00 - - 97.561000-5A3 Mt Mucki Plag. Core 39.41 0.07 23.10 11.79 0.09 23.20 0.11 0.00 0.01 0.00 0.00 - - 98.591000-5B Mt Mucki Plag. Interm 52.98 0.00 27.67 0.38 0.00 11.83 0.00 4.50 0.20 0.00 0.00 - - 98.661000-5C Mt Mucki Plag. Rim 61.79 0.00 22.11 0.25 0.01 5.68 0.00 8.57 0.18 0.00 0.00 - - 96.061000-5C2 Mt Mucki Plag. Rim 63.53 0.00 21.45 0.05 0.14 4.41 0.00 8.93 0.15 0.00 0.00 - - 99.031001-1A Mt Mucki Plag-zone . 46.58 0.07 26.30 0.76 0.00 20.76 0.00 1.45 0.14 0.00 0.00 - - 99.161001-1B Mt Mucki Plag-zone 54.13 0.00 27.71 0.29 0.00 11.97 0.00 4.80 0.13 0.00 0.00 - - 98.091001-1C Mt Mucki Plag. Matrix Matrix 55.69 0.15 26.46 0.47 0.27 10.49 0.00 5.58 0.05 0.00 0.00 - - 97.961001-1D Mt Mucki Horn. Core 52.20 0.37 3.45 11.99 16.85 12.35 0.33 0.46 0.09 0.00 0.00 - - 95.571001-1E Mt Mucki Horn. Rim 51.79 0.31 3.55 12.21 16.53 12.28 0.41 0.57 0.31 0.00 0.00 - - 100.191001-1F Mt Mucki Magnetite Includ. Horn 0.30 0.02 0.16 94.96 0.07 0.00 0.00 0.06 0.00 0.00 0.00 - - 96.871001-2A Mt Mucki Ilmenite Exsol Sphene 7.95 79.79 0.00 3.74 0.00 6.89 1.47 0.22 0.05 0.00 0.08 - - 100.011001-2B Mt Mucki Magnetite Ilmenite 0.29 0.18 0.36 95.70 0.20 0.00 0.00 0.14 0.00 0.00 0.00 - - 99.661001-3A Mt Mucki Plag-zone Core 48.23 0.07 32.07 0.50 0.01 17.29 0.00 1.76 0.08 0.00 0.00 - - 98.041001-3B Mt Mucki Plag-zone Rim 62.56 0.00 22.02 0.37 0.52 5.64 0.00 8.38 0.17 0.00 0.00 - - 97.691001-3C Mt Mucki Horn. Core 51.36 0.26 4.07 13.01 15.96 12.36 0.33 0.43 0.26 0.00 0.00 - - 100.101001-3D Mt Mucki Horn. Rim 52.59 0.23 3.24 12.42 16.34 12.22 0.37 0.08 0.20 0.00 0.00 - - 97.651001-4A Mt Mucki Pyrx-Horn Core 52.11 0.56 1.95 7.53 15.64 22.31 0.00 0.00 0.00 0.00 0.00 - - 100.921001-4B Mt Mucki Pyrx-Horn 51.58 2.13 3.23 10.51 16.84 12.62 0.38 0.06 0.30 0.00 0.00 - - 99.351001-4C Mt Mucki Pyrx-c Relict 54.74 0.06 0.00 5.26 15.80 24.81 0.25 0.00 0.00 0.00 0.00 - - 98.231018D-1A Xenolith Horn. Core 44.7 0.08 2.23 10.2 13.3 28.1 1.11 0.02 0.04 0 0 0.050 - 99.961018D-2A Xenolith Horn. Core 41.3 0.12 3.93 11.2 11.9 29.6 0.86 0.57 0.19 0 0.03 0.140 - 100.011018D-2B Xenolith Horn. Rim 51.5 0.05 4.99 14.4 14.8 12.5 0.73 0.51 0.25 0 0 0.060 - 98.951018D-3A Xenolith Plag. Core 59.8 0 25 0.38 0.08 7.29 0.01 7.27 0.13 0 0 0.000 - 99.481018D-4A Xenolith Or Core 65.1 0 18.3 0.06 0.2 0.28 0.07 1.32 13.5 0 0 0.040 - 91.341018D-5A Xenolith Plag. Core 59.5 0 24.6 0.24 0.15 7.58 0.07 6.94 0.35 0 0 0.000 - 100.791018D-6A Xenolith Magnetite 0 0.06 0 91 0.06 0.01 0 0 0 0.02 0 0.150 - 90.721018D-6B Xenolith Sphene 30.7 38.2 1.65 1.5 0 28.5 0.04 0 0 0.05 0.01 0.000 - 98.421018D-6C Xenolith Magnetite 0 0.25 0 90.3 0 0.01 0 0.01 0 0.06 0 0.120 - 95.021018F-1A Xenolith Pyrx Core 50.6 0.15 5.97 12.7 14.7 12.4 0.71 0.63 0.34 0 0 0.110 - 98.451018F-3A Xenolith Epidote Core 37.5 0 21.8 12.6 0 22.7 0.23 0 0 0 0.05 0.030 - 98.621018F-5A Xenolith Horn. Core 52.8 0.13 3.25 14.1 14.6 12 0.84 0.32 0.1 0.02 0 0.090 - 99.231018F-6A Xenolith Plag. Core 59.8 0 23.9 0.19 0.17 6.69 0 7.3 0.41 0 0 0.050 - 89.781018F-7A Xenolith Horn. Core 52.7 0.48 3.71 12.9 15.3 12 0.9 0.42 0.15 0.3 0.02 0.140 - 99.951018F-8A Xenolith Sphene Core 27.5 33.1 1.79 2.77 0 23.4 0.16 0.02 0 0.98 0 0.000 - 98.461018F-8Arpt Xenolith Sphene Core 30.6 36.8 1.99 3.08 0 26.1 0.18 0.02 0 1.09 0 0.000 - 98.441018F-9A Xenolith Plag. Core 60.4 0.1 23.5 0.18 0.14 5.96 0.07 7.68 0.34 0 0 0.050 - 98.341030-1A Xenolith Plag. Core 56.50 0.01 26.10 0.33 0.10 9.17 0.00 5.82 0.41 0.00 0.00 0.000 - 98.931030-1B Xenolith Plag. Rim 57.30 0.03 25.60 0.20 0.10 8.53 0.00 6.11 0.36 0.00 0.00 0.050 - 99.681030-2A Xenolith Plag. Core 59.13 0.11 23.14 0.51 0.13 12.19 0.00 3.42 0.30 0.00 0.00 - - 89.891030-2C Xenolith Plag. Rim 60.01 0.15 23.32 0.37 0.19 11.05 0.00 3.85 0.65 0.00 0.09 - - 91.351030-3A Xenolith Chalcopyrite 0.51 1.78 0.09 86.74 0.07 0.00 0.70 0.00 0.00 0.00 0.00 - 95.861030-4A Xenolith Magnetite Matrix 0.33 0.28 0.07 90.67 0.00 0.00 0.00 0.00 0.00 0.00 0.00 - - 92.791030-4A North Arm Epidote 37.50 0.00 22.10 12.80 0.10 22.90 0.30 0.00 0.00 0.00 0.00 0.050 - 90.011030-4B Xenolith Ilmenite Exsol Mag. 0.26 43.31 0.23 42.35 0.31 0.00 6.29 0.00 0.00 0.04 0.00 - - 100.091030-4C Xenolith Magnetite Exsol Ilmenite 0.42 2.58 0.25 85.69 0.18 0.00 0.80 0.09 0.00 0.00 0.00 - - 100.091030-5A Xenolith Plag-zone Core 71.14 0.00 17.83 0.10 0.00 4.46 0.00 6.13 0.43 0.00 0.00 - - 100.161030-5B Xenolith Plag-zone Interm 71.43 0.00 17.46 0.10 0.23 4.26 0.00 6.24 0.37 0.00 0.00 - - 99.301030-5C Xenolith Plag-zone Core 70.98 0.00 18.06 0.00 0.00 5.61 0.04 5.38 0.09 0.00 0.00 - - 100.131030-5D Xenolith Plag-zone Rim 62.55 0.00 21.87 0.31 0.24 9.77 0.00 4.32 0.24 0.00 0.00 - 99.471030-6A Xenolith Plag-unzone Core 68.82 0.00 19.01 0.14 0.07 5.97 0.00 5.68 0.44 0.00 0.00 - - 100.151030-6A North Arm Pyrx Core 53.60 0.08 3.40 14.10 14.50 12.40 0.63 0.60 0.09 0.00 0.00 0.010 98.121030-6B North Arm Plag-unzone Interm 69.04 0.04 18.72 0.06 0.20 5.97 0.08 5.85 0.19 0.00 0.00 - - 100.141030-6B North Arm Pyrx Rim 52.00 0.00 3.31 15.80 13.10 12.30 0.97 0.37 0.10 0.00 0.00 0.030 97.821030-6C North Arm Plag-unzone Rim 69.69 0.00 18.77 0.13 0.09 5.32 0.00 5.88 0.26 0.00 0.00 - <0.005 100.001030-8A North Arm Pyrx? Core 52.60 0.06 3.18 15.20 13.60 12.00 0.84 0.12 0.00 0.00 0.00 0.050 - 100.001069-1A Woolooga Horn. Core 55.99 0.19 1.09 13.41 16.97 11.35 0.54 0.37 0.09 0.00 0.00 0.095 - 100.001069-1B Woolooga Horn. Core 56.19 0.25 1.55 11.95 18.45 10.69 0.66 0.23 0.03 0.00 0.00 - - 99.051069-1C Woolooga Magnetite Includ. Horn 0.40 2.09 0.28 96.79 0.14 0.00 0.30 0.00 0.00 0.00 0.00 - <0.005 97.841069-1D Woolooga Magnetite Matrix 0.15 1.87 0.22 96.16 0.20 0.00 0.36 0.00 0.00 0.07 0.02 - - 100.011069-1E Woolooga Apatite Includ. Mag. 0.00 0.03 0.00 0.66 0.00 55.48 0.00 0.17 0.00 41.50 0.00 0.205 - 99.981069-2A Woolooga Plag-unzone Core 57.42 0.00 26.36 0.36 0.19 9.55 0.00 5.77 0.36 0.00 0.00 - - 100.001069-2B Woolooga Plag-unzone Interm 57.17 0.00 26.44 0.26 0.35 9.04 0.00 6.25 0.47 0.00 0.00 - - 99.991069-2C Woolooga Plag-unzone Inter 57.63 0.00 26.11 0.30 0.29 8.99 0.00 6.30 0.38 0.00 0.00 - - 100.021069-2D Woolooga Plag-unzone Rim 57.88 0.08 26.05 0.15 0.21 8.82 0.00 6.41 0.39 0.00 0.00 - - 100.001069-3A Woolooga Plag-zone Core 57.53 0.00 26.54 0.39 0.26 8.73 0.00 6.34 0.23 0.00 0.00 - - 100.001069-3B Woolooga Plag-zone Interm 57.83 0.01 25.96 0.45 0.27 8.69 0.00 6.53 0.26 0.00 0.00 - - 99.981069-3C Woolooga Plag-zone Rim 66.57 0.00 20.48 0.00 0.57 1.90 0.00 10.31 0.17 0.00 0.00 - - 99.981069-3D Woolooga Plag-unzone Core 56.93 0.07 26.67 0.25 0.46 9.09 0.08 6.20 0.23 0.00 0.00 - - 100.001069-3E Woolooga Plag-unzone Interm 55.84 0.00 27.02 0.54 0.38 10.05 0.00 5.75 0.40 0.00 0.00 - - 99.381069-3F Woolooga Plag-unzone Rim 57.99 0.00 26.31 0.28 0.17 8.70 0.00 6.47 0.08 0.00 0.00 - - 99.981069-3G Woolooga Perthite Grano. Matrix 65.40 0.42 17.90 0.00 0.00 0.09 0.27 0.83 14.20 0.00 0.00 0.100 - 99.971069-4A Woolooga Plag-unzone Core 57.89 0.00 26.15 0.51 0.23 8.61 0.00 6.23 0.36 0.00 0.00 - - 99.991069-4B Woolooga Plag-unzone Interm 55.59 0.04 27.47 0.54 0.44 10.20 0.00 5.38 0.31 0.00 0.00 - - 100.001069-4C Woolooga Plag-unzone Rim 66.30 0.00 20.58 0.07 0.24 2.19 0.00 10.20 0.41 0.00 0.00 - - 97.621069-4D Woolooga Ilmenite Exsol Matrix 0.40 49.09 0.16 44.58 0.28 0.17 5.30 0.00 0.02 0.00 0.00 - - 100.221069-4E Woolooga Magnetite Exsol Matrix 0.44 2.04 0.38 94.47 0.07 0.00 0.22 0.00 0.00 0.00 0.00 - - 99.71069-4F Woolooga Perthite Grano. Matrix 67.40 0.00 20.20 0.33 0.10 1.81 0.00 9.95 0.37 0.00 0.00 0.000 <0.005 99.991069-4F rpt Woolooga Perthite Grano. Matrix 66.00 0.00 20.90 0.08 0.00 2.57 0.01 9.01 1.07 0.00 0.00 0.070 <0.005 99.981069-5A Woolooga Horn. Core 57.23 0.00 0.50 12.48 17.73 11.38 0.62 0.05 0.00 0.00 0.00 0.135 - 100.011069-5B Woolooga Horn. Rim 54.44 0.45 3.49 12.12 17.11 11.18 0.31 0.66 0.22 0.00 0.00 0.122 - 99.861069-5C Woolooga Horn. Core 56.29 0.28 1.47 11.74 18.45 11.19 0.27 0.18 0.14 0.00 0.00 - - 99.981069-5D Woolooga Horn. Core 57.14 0.16 1.35 11.07 19.15 10.51 0.45 0.00 0.03 0.00 0.00 - 1.220 100.001069-5E Woolooga Magnetite Matrix 0.28 2.93 0.22 95.77 0.00 0.00 0.61 0.00 0.00 0.00 0.17 - - 100.001069-5F Woolooga Sphene Mantle Mag. 30.59 39.04 1.97 1.13 0.00 27.14 0.07 0.05 0.01 0.00 0.00 0.042 - 99.991086-1A Woonga Sphene Matrix 30.92 38.32 1.16 0.85 0.00 28.53 0.00 0.16 0.00 0.00 0.06 - - 99.991086-1B Woonga Plag-zone Core 59.25 0.00 25.38 0.00 0.15 7.80 0.00 7.12 0.29 0.00 0.00 - - 100.001086-1C Woonga Plag-zone Interm 60.52 0.00 24.57 0.00 0.24 6.85 0.00 7.56 0.25 0.00 0.00 - - 100.011086-1D Woonga Plag-zone Rim 59.11 0.00 25.27 0.09 0.39 7.63 0.00 7.27 0.24 0.00 0.00 - - 100.001086-3A Woonga Plag-zone Core 60.65 0.00 24.23 0.25 0.30 6.42 0.01 7.72 0.43 0.00 0.00 - - 100.01


36


Rim1086-3B Woonga Plag-zone Interm 62.98 0.00 22.73 0.17 0.22 4.86 0.00 8.73 0.31 0.00 0.00 - - 96.821086-3C Woonga Plag-zone Rim 68.54 0.00 18.95 0.00 0.60 0.13 0.02 11.67 0.10 0.00 0.00 - - 100.011098-1A Highbury Plag. Core 50.00 0.00 30.80 1.30 0.57 7.24 0.00 1.84 5.01 0.00 0.02 0.020 - 99.991098-1B Highbury Plag. Core 51.90 0.00 29.90 0.18 0.02 13.70 0.11 3.78 0.15 0.00 0.10 0.030 - 89.471098-1C Highbury Plag. Rim 48.00 0.01 32.40 0.16 0.37 16.60 0.14 2.22 0.00 0.00 0.04 0.000 - 98.061098-3D Highbury Magnetite 0.06 0.84 0.00 88.30 0.08 0.06 0.00 0.00 0.09 0.00 0.00 0.040 - 99.761098-3E Highbury Ilmenite 0.12 46.90 0.00 46.10 0.06 0.17 4.48 0.06 0.18 0.00 0.00 0.000 - 98.641098-4A Highbury Plag. Core 56.80 0.05 26.60 0.26 0.16 9.40 0.00 6.25 0.19 0.00 0.00 0.000 - 90.241098-5A Highbury Ilmenite 0.12 48.10 0.00 46.00 0.21 0.19 3.63 0.18 0.12 0.07 0.00 0.010 - 101.621098-5B Highbury Magnetite 0.16 0.72 0.00 88.80 0.08 0.11 0.00 0.00 0.08 0.27 0.00 0.060 - 99.471098-6A Highbury Pyrx 53.50 0.00 1.29 8.37 13.90 23.30 0.89 0.26 0.02 0.00 0.00 0.000 - 98.301098-6B Highbury Pyrx Rim 53.20 0.36 3.68 11.30 17.10 12.60 0.64 0.34 0.21 0.00 0.00 0.010 - 98.121098-6C Highbury Chlorite 47.20 0.79 5.70 11.90 14.60 13.80 0.52 0.84 0.50 2.18 0.00 0.080 - 99.121098-6D Highbury Horn-Biotite 51.50 0.17 4.82 12.60 15.00 12.60 0.60 0.45 0.09 0.00 0.15 0.000 - 100.001101-1A Woolooga Plag-unzone Core 58.04 0.00 24.92 0.21 0.26 8.84 0.00 6.19 0.66 0.00 0.00 - - 99.991101-1B Woolooga Plag-unzone Rim 56.12 0.12 26.74 0.44 0.11 10.82 0.00 5.33 0.32 0.00 0.00 - - 100.001101-1C Woolooga Plag-unzone Core 56.69 0.00 26.52 0.36 0.11 10.37 0.00 5.59 0.35 0.00 0.00 - - 99.991101-1D Woolooga Plag-unzone Rim 62.18 0.00 22.95 0.23 0.15 6.32 0.00 7.63 0.54 0.00 0.00 - - 99.981101-1E Woolooga Perthite Grano. Matrix 65.60 0.18 18.70 0.15 0.19 0.34 0.34 2.94 11.40 0.00 0.00 0.020 - 99.981101-2A Woolooga Plag-unzone Core 62.87 0.01 22.51 0.14 0.20 5.63 0.00 7.69 0.93 0.00 0.00 - - 99.971101-2B Woolooga Plag-unzone Rim 57.35 0.00 26.06 0.22 0.29 9.71 0.00 5.95 0.40 0.00 0.00 - - 100.461101-2C Woolooga Magnetite Matrix 0.48 4.02 0.78 93.98 0.04 0.00 0.59 0.08 0.00 0.00 0.00 - - 100.011101-2E Woolooga Perthite Grano. Matrix 66.00 0.13 18.00 0.03 0.00 0.00 0.16 0.30 15.70 0.00 0.00 0.010 <0.005 98.131101-3A Woolooga Pyrx-c Relict 53.25 0.12 0.00 10.05 13.50 22.64 0.36 0.09 0.00 0.00 0.00 - - 99.991101-3B Woolooga Horn-Cpx Core 54.10 0.06 0.50 16.65 14.14 12.09 0.30 0.25 0.04 0.00 0.00 0.023 - 100.081101-3C Woolooga Pyrx-c Relict 53.32 0.11 0.00 10.00 14.12 21.81 0.38 0.25 0.00 0.00 0.00 - - 100.031101-3D Woolooga Ilmenite Matrix 0.30 45.49 0.00 50.57 0.12 0.00 3.38 0.19 0.03 0.00 0.00 - <0.005 99.351101-3D2 Woolooga Ilmenite Matrix 0.63 1.71 0.53 96.39 0.07 0.00 0.47 0.01 0.00 0.00 0.22 - <0.005 100.021101-4A Woolooga Horn A Core 52.62 0.27 0.75 21.50 11.54 11.18 1.13 0.32 0.04 0.00 0.00 0.108 - 99.891101-4B Woolooga Horn B Core 51.68 0.87 4.04 14.93 15.74 11.00 0.17 1.17 0.42 0.00 0.00 0.154 - 100.181101-4C Woolooga Granophyre Grano. Matrix 58.80 0.00 25.20 0.43 0.12 8.62 0.00 6.24 0.44 0.00 0.00 0.000 - 99.871101-4D Woolooga L.Amphibole Grano. Matrix 52.40 0.03 33.90 0.95 1.37 0.36 0.08 0.35 10.70 0.00 0.00 0.000 <0.005 99.991101-4D M Woolooga Matrix for 4C Grano. Matrix 58.50 0.06 25.60 0.16 0.09 9.19 0.00 5.87 0.36 0.00 0.00 0.040 <0.005 96.601129-1A Woonga Sphene Matrix 31.11 37.96 1.14 2.00 0.00 27.78 0.00 0.00 0.00 0.00 0.00 0.021 - 97.201129-1B Woonga Horn. Core 50.41 0.85 4.19 12.09 16.03 11.16 0.82 0.75 0.30 0.00 0.00 0.036 <0.005 95.351129-1C Woonga Horn. Interm 51.24 0.67 3.61 11.61 17.00 11.42 0.64 0.74 0.27 0.00 0.00 - - 100.001129-1D Woonga Horn. Interm 50.71 0.33 3.68 11.36 16.44 11.36 0.69 0.59 0.19 0.00 0.00 0.061 - 94.351129-1E Woonga Magnetite Includ. Horn 0.44 0.09 0.29 98.94 0.00 0.00 0.24 0.00 0.00 0.00 0.00 - <0.005 94.741129-1MagnetiteWoonga Magnetite Matrix 0.49 0.01 0.23 93.07 0.16 0.00 0.33 0.00 0.00 0.00 0.06 - <0.005 93.451129-2A Woonga Biotite Core 36.48 4.36 13.50 17.07 13.70 0.00 0.40 0.14 9.09 0.00 0.00 0.078 - 93.161129-2B Woonga Biotite Interm 35.88 3.92 13.35 17.78 14.04 0.01 0.37 0.00 8.10 0.00 0.00 0.058 - 99.81129-2C Woonga Biotite Rim 35.65 3.60 13.46 17.90 14.84 0.02 0.45 0.17 7.07 0.00 0.00 - - 96.531129-2D Woonga Granophyre Matrix 63.00 0.05 23.20 0.25 0.21 2.67 0.00 9.37 0.98 0.00 0.00 0.030 - 97.421129-3A Woonga Plag-zone Core 58.12 0.00 23.81 0.00 0.09 6.64 0.00 7.70 0.17 0.00 0.00 - - 96.881129-3B Woonga Plag-zone Interm 58.67 0.01 24.04 0.22 0.22 6.54 0.00 7.50 0.22 0.00 0.00 - - 97.691129-3C Woonga Plag-zone Rim 57.87 0.00 24.37 0.00 0.25 6.97 0.00 7.24 0.18 0.00 0.00 - - 96.981129-4A Woonga Plag-zone Core 60.75 0.00 22.49 0.11 0.23 5.74 0.00 8.05 0.32 0.00 0.00 - - 99.761129-4B Woonga Plag-zone Rim 59.80 0.04 22.66 0.11 0.00 6.37 0.00 7.71 0.29 0.00 0.00 - - 99.981129-5A Woonga Granophyre Matrix 58.90 0.00 25.30 0.26 0.07 8.25 0.13 6.48 0.35 0.00 0.00 0.000 - 99.981129-5B Woonga Granophyre Matrix 65.60 0.00 21.70 0.07 0.00 3.69 0.04 8.70 0.08 0.00 0.00 0.000 - 99.271129-5B M Woonga L.Amphibole Matrix 67.00 0.00 20.80 0.00 0.07 2.48 0.24 9.10 0.12 0.00 0.00 0.090 - 97.601144-1A Rush Creek Horn. Core 55.49 0.96 3.41 11.36 15.38 10.91 0.57 0.88 0.31 0.00 0.00 - - 99.301144-1B Rush Creek Horn. Rim 56.70 0.37 1.64 10.85 15.44 11.89 0.28 0.32 0.11 0.00 0.00 - - 97.821144-1C Rush Creek Horn B Core 53.14 1.23 4.71 12.84 14.10 10.97 0.56 1.29 0.46 0.00 0.00 - - 91.381144-1D Rush Creek Horn B Rim 55.25 0.89 2.79 11.43 15.17 10.94 0.50 0.55 0.30 0.00 0.00 - - 87.051144-1E Rush Creek Magnetite Includ. Horn 0.47 0.05 0.20 90.32 0.22 0.00 0.10 0.00 0.00 0.00 0.02 - - 97.661144-1F Rush Creek Ilmenite Includ. Horn 0.27 81.08 0.10 5.34 0.15 0.11 0.00 0.00 0.00 0.00 0.00 - - 97.371144-2A Rush Creek Plag-zone Core 62.44 0.04 21.14 0.27 0.07 9.05 0.00 4.45 0.18 0.00 0.02 - - 99.781144-2B Rush Creek Plag-zone Interm 63.34 0.00 20.29 0.32 0.06 8.39 0.06 4.57 0.34 0.00 0.00 - - 96.321144-2C Rush Creek Plag-zone Rim 64.56 0.00 21.15 0.20 0.08 8.84 0.04 4.61 0.30 0.00 0.00 - - 99.061144-3A Rush Creek Biotite Core 40.22 5.06 12.07 17.47 12.42 0.03 0.03 0.00 9.02 0.00 0.00 - - 93.411144-3B Rush Creek Biotite Rim 42.36 5.15 12.55 16.28 13.18 0.00 0.09 0.04 9.41 0.00 0.00 - - 87.811144-3C Rush Creek Magnetite Matrix 0.45 0.00 0.27 92.33 0.13 0.00 0.13 0.10 0.00 0.00 0.00 - - 90.701144-3D Rush Creek Ilmenite Exsol Matrix 0.30 78.08 0.07 9.09 0.14 0.00 0.13 0.00 0.00 0.00 0.00 - - 92.761144-3E Rush Creek Ilmenite Matrix 0.28 43.81 0.00 41.88 0.00 0.00 4.70 0.00 0.03 0.00 0.00 - - 90.571144-4A Rush Creek Magnetite Matrix 0.47 0.00 1.01 91.22 0.00 0.00 0.01 0.00 0.05 0.00 0.00 - - 99.261144-4B Rush Creek Ilmentite Includ. Mag. 0.30 42.57 0.66 42.12 0.13 0.09 4.58 0.12 0.00 0.00 0.00 - - 100.901148-1A Rush Creek Horn. Core 56.48 0.63 2.34 11.55 15.32 11.13 0.58 0.96 0.27 0.00 0.00 - - 93.481148-1B Rush Creek Horn. Rim 59.19 0.37 1.17 9.89 17.09 11.98 0.54 0.51 0.16 0.00 0.00 - - 94.301148-1C Rush Creek Magnetite 0.38 0.24 0.38 92.35 0.13 0.00 0.00 0.00 0.00 0.00 0.00 - - 102.321148-1E Rush Creek Biotite Includ. Plag. 40.39 4.45 12.04 15.24 13.28 0.22 0.18 0.00 8.43 0.00 0.07 - - 101.111148-1F Rush Creek Plag. Core Matrix 75.62 0.00 16.70 0.09 0.10 2.62 0.01 6.83 0.35 0.00 0.00 - - 100.701148-2A Rush Creek Plag-fct Core 64.01 0.00 22.19 0.35 0.15 9.44 0.00 4.56 0.41 0.00 0.00 - - 101.951148-2B Rush Creek Plag-fct Interm 65.19 0.00 21.17 0.38 0.02 8.77 0.00 4.85 0.32 0.00 0.00 - - 96.921148-2C Rush Creek Plag-fct Rim 75.19 0.00 16.61 0.00 0.16 2.81 0.02 6.71 0.45 0.00 0.00 - - 100.681148-2D Rush Creek Biotite 40.24 4.81 12.22 16.90 13.06 0.08 0.32 0.00 9.29 0.00 0.00 - - 101.981148-3A Rush Creek Plag-zone Core 65.35 0.00 21.30 0.22 0.08 8.60 0.00 4.72 0.33 0.00 0.08 - - 102.531148-3B Rush Creek Plag-zone Interm 72.65 0.00 17.77 0.21 0.12 4.37 6.44 0.42 0.00 0.00 0.00 - - 97.481148-3C Rush Creek Plag-zone Rim 77.68 0.00 15.74 0.00 0.15 1.36 0.00 7.39 0.21 0.00 0.00 - - 99.671148-3D Rush Creek Or-Perthite Matrix 66.61 0.00 13.88 0.22 0.00 0.05 0.00 0.69 16.03 0.00 0.00 - - 100.131148-4A Rush Creek Plag-zone Core 65.20 0.00 20.49 0.22 0.09 8.18 0.00 4.92 0.57 0.00 0.00 - - 100.731148-4B Rush Creek Plag-zone Interm 64.59 0.03 21.24 0.28 0.15 8.65 0.03 4.75 0.41 0.00 0.00 - - 94.821148-4C Rush Creek Plag-zone Rim 68.09 0.00 19.72 0.14 0.33 6.61 0.00 5.56 0.28 0.00 0.00 - - 92.981148-5A Rush Creek Biotite Pri Core 39.56 4.61 11.95 15.93 13.34 0.05 0.20 0.00 9.18 0.00 0.00 - 0.133 98.971148-5B Rush Creek Biotite Sec Core 40.06 3.54 11.31 15.05 13.81 0.04 0.04 0.12 9.01 0.00 0.00 - - 99.471149-1A Rush Creek Horn. Core 56.82 0.31 1.87 10.76 16.10 11.70 0.46 0.72 0.23 0.00 0.00 0.112 0.213 99.701149-1B Rush Creek Horn. Rim 57.46 0.20 2.23 10.49 16.12 11.81 0.29 0.52 0.27 0.00 0.08 - - 99.051149-1C Rush Creek Horn. Rim 58.67 0.32 1.51 10.09 16.31 12.01 0.22 0.36 0.21 0.00 0.00 0.084 - 100.361149-1D Rush Creek Horn. Core 55.24 0.83 2.73 12.59 15.05 11.13 0.29 0.88 0.31 0.00 0.00 - - 93.071149-1E Rush Creek Horn. Core 58.47 0.36 1.35 11.17 16.32 11.63 0.44 0.50 0.12 0.00 0.00 - - 100.971149-1F Rush Creek Magnetite Includ. Horn 0.40 0.30 0.90 91.25 0.00 0.00 0.18 0.00 0.00 0.00 0.04 - - 100.811149-2A Rush Creek Plag-unzone Core 65.12 0.00 21.55 0.12 0.21 8.68 0.10 4.91 0.28 0.00 0.00 - - 100.591149-2B Rush Creek Plag-unzone Interm 65.64 0.14 21.24 0.11 0.17 8.37 0.06 4.76 0.32 0.00 0.00 - 0.136 97.901149-2C Rush Creek Plag-unzone Rim 63.32 0.00 22.34 0.09 0.13 10.13 0.00 4.35 0.23 0.00 0.00 - - 97.211149-3A Rush Creek Biotite Core 41.27 4.95 12.24 15.69 14.49 0.03 0.02 0.09 9.12 0.00 0.00 0.263 0.064 96.881149-3B Rush Creek Biotite Interm 41.11 5.21 12.15 15.50 14.05 0.00 0.04 0.00 9.15 0.00 0.00 - - 97.681149-3C Rush Creek Biotite Rim 41.34 4.44 12.39 15.18 13.94 0.01 0.15 0.04 9.39 0.00 0.00 0.273 - 97.551149-3D Rush Creek Biotite Core 40.75 5.06 12.36 15.65 14.28 0.07 0.26 0.00 9.25 0.00 0.00 - - 92.481149-3E Rush Creek Biotite Rim 41.07 4.99 13.01 15.30 13.71 0.03 0.14 0.00 9.30 0.00 0.00 - - 93.251149-3F Rush Creek Ilmenite Includ. Biotite 0.29 39.81 0.27 45.60 0.15 0.00 6.36 0.00 0.00 0.00 0.00 - - 98.831149-3G Rush Creek Magnetite Includ. Biotite 0.38 0.21 0.80 91.63 0.09 0.00 0.08 0.00 0.00 0.00 0.06 - - 100.46


37


Rim1149-3H Rush Creek Or-Perthite Matrix 68.23 0.01 14.13 0.00 0.09 0.09 0.00 1.26 15.02 0.00 0.00 - - 99.491149-4A Rush Creek Plag-zone Core 66.63 0.00 20.41 0.17 0.17 7.40 0.00 5.27 0.38 0.00 0.03 - - 100.881149-4B Rush Creek Plag-zone Interm 63.19 0.00 22.04 0.09 0.23 9.36 0.00 4.24 0.34 0.00 0.00 - - 99.451149-4C Rush Creek Plag-zone Rim 65.25 0.07 21.47 0.06 0.19 8.71 0.03 4.86 0.24 0.00 0.00 - - 99.341153-1A Rush Creek Plag-zone Core 58.62 0.11 24.92 0.49 0.06 8.36 0.00 6.50 0.39 0.00 0.00 - - 99.031153-1B Rush Creek Plag-zone Interm 59.78 0.07 24.50 0.30 0.00 7.81 0.00 6.61 0.27 0.00 0.00 - 0.318 98.561153-1C Rush Creek Plag-zone Rim 64.91 0.00 20.75 0.08 0.00 3.78 0.00 9.17 0.34 0.00 0.00 - 0.180 98.781153-2A Rush Creek Horn. Core 54.01 0.54 2.01 10.97 17.97 11.31 1.09 0.52 0.14 0.00 0.00 0.033 0.580 98.531153-2B Rush Creek Horn. Rim 53.16 0.48 2.66 10.89 18.27 11.60 0.83 0.56 0.33 0.00 0.00 0.098 0.625 95.271153-2C Rush Creek Biotite Core 39.49 5.13 12.91 15.04 15.98 0.00 0.39 0.04 9.55 0.00 0.00 0.236 - 95.881153-2D Rush Creek Biotite Rim 38.22 5.08 12.40 14.63 15.10 0.12 0.39 0.00 9.33 0.00 0.00 0.205 - 97.361153-2E Rush Creek Magnetite Matrix 0.43 0.11 0.26 94.84 0.02 0.00 0.20 0.00 0.00 0.00 0.02 - - 98.661166-1A Rush Creek Plag-unzone Core 56.78 0.07 24.78 0.19 0.42 8.46 0.00 6.33 0.30 0.00 0.03 - - 97.991166-1B Rush Creek Plag-unzone Interm 58.47 0.00 24.31 0.25 0.19 8.12 0.00 6.89 0.43 0.00 0.00 - - 97.031166-1C Rush Creek Plag-unzone Rim 57.25 0.01 25.08 0.00 0.15 8.85 0.00 6.33 0.32 0.00 0.00 - - 98.471166-1D Rush Creek Or-Perthite Matrix 64.42 0.02 16.65 0.00 0.10 0.10 0.00 1.78 13.96 0.00 0.00 - - 97.821166-2A Rush Creek Horn. Core 49.22 1.59 5.25 12.99 15.74 11.51 0.21 1.39 0.57 0.00 0.00 - - 99.061166-2B Rush Creek Horn. Rim 52.01 0.99 3.02 12.17 16.98 11.11 0.33 0.96 0.17 0.00 0.08 - - 99.901166-3A Rush Creek Plag-zone Core 58.89 0.00 24.62 0.05 0.11 8.33 0.00 6.63 0.43 0.00 0.00 - - 99.081166-3B Rush Creek Plag-zone Rim 64.43 0.00 21.51 0.04 0.21 4.48 0.00 8.78 0.45 0.00 0.00 - 0.003 97.881166-3C Rush Creek Plag-zone Interm 58.93 0.00 24.48 0.19 0.17 8.05 0.00 6.91 0.35 0.00 0.00 - <0.005 98.101166-4A Rush Creek Horn-Cpx Core 54.54 0.44 1.44 10.13 18.56 11.88 0.25 0.56 0.08 0.00 0.00 0.086 - 100.621166-4B Rush Creek Horn. Rim 51.43 0.94 3.56 11.79 17.23 11.56 0.34 0.86 0.39 0.00 0.00 0.115 - 95.881166-4C Rush Creek Ilmenite Includ. Horn 0.35 46.85 0.10 48.01 0.10 0.00 5.21 0.00 0.00 0.00 0.00 - <0.005 96.921166-4D Rush Creek Magnetite Includ. Horn 0.43 0.17 0.32 94.78 0.10 0.00 0.02 0.01 0.00 0.00 0.05 - - 99.981166-4E Rush Creek Biotite Sec Core 39.01 4.41 12.47 16.28 15.36 0.00 0.07 0.00 9.32 0.00 0.00 0.284 - 97.81185-1A Rush Creek Perthite Grano. Matrix 66.60 0.00 17.80 0.16 0.00 0.07 0.02 2.24 13.00 0.00 0.00 0.010 - 98.91185-3A Rush Creek Horn. Core 39.00 4.60 13.40 16.00 14.80 0.07 0.56 0.00 0.84 0.00 0.00 0.280 - 99.981185-3B Rush Creek Altered Horn Rim 56.10 0.05 1.84 9.18 18.10 12.40 1.09 0.00 0.00 0.00 0.00 0.010 - 99.981185-4A Rush Creek Plag. Core 59.30 0.03 25.00 0.37 0.00 8.66 0.05 6.16 0.34 0.00 0.00 0.000 - 99.91185-4B Rush Creek Plag. Rim 68.40 0.02 19.60 0.05 0.02 3.48 0.03 8.03 0.26 0.00 0.00 0.090 - 1001185-5A Rush Creek Perthite Grano. 66.60 0.00 18.30 0.00 0.14 0.29 0.09 3.01 11.50 0.00 0.00 0.010 - 96.751185-5rpt Rush Creek Perthite Grano. 66.70 0.00 17.70 0.00 0.00 0.17 0.09 2.07 13.10 0.00 0.00 0.080 - 97.151185-6A Rush Creek Biotiteite Core 38.40 5.14 12.70 15.90 14.50 0.20 0.54 0.36 8.68 0.00 0.00 0.210 - 97.811185-6B Rush Creek Biotiteite Rim 38.30 4.58 13.00 16.20 15.20 0.37 0.69 0.41 7.94 0.00 0.01 0.220 - 99.631185-7 Rush Creek Biotiteite Core 38.20 5.30 13.10 16.40 14.20 0.14 0.74 0.38 8.93 0.00 0.00 0.240 - 99.611286-1A Black Snake Plag-unzone Core 58.80 0.00 24.61 0.02 0.21 7.99 0.00 7.02 0.24 0.00 0.00 - - 99.821286-1B Black Snake Plag-zone Core 58.32 0.00 23.94 0.16 0.00 8.02 0.00 6.76 0.19 0.00 0.00 - - 97.761286-1B2 Black Snake Plag-unzone Core 59.95 0.01 24.45 0.21 0.20 7.77 0.00 7.05 0.12 0.00 0.06 - - 98.861286-1C Black Snake Plag-unzone Rim 56.91 0.00 24.96 0.31 0.00 9.36 0.00 5.93 0.29 0.00 0.00 - - 99.741286-2A Black Snake Plag-unzone Core 57.67 0.00 25.75 0.00 0.00 9.06 0.00 6.28 0.10 0.00 0.00 - - 95.511286-2B Black Snake Plag-unzone Interm 58.09 0.04 25.37 0.13 0.00 8.86 0.00 7.04 0.21 0.00 0.00 - <0.005 97.771286-2C Black Snake Plag-unzone Rim 56.97 0.00 24.02 0.00 0.00 8.14 0.00 6.17 0.21 0.00 0.00 - - 95.401286-3A Black Snake Horn. Core 44.83 1.73 10.86 11.17 15.87 10.57 0.11 2.16 0.43 0.00 0.04 0.043 0.091 97.411286-3A2 Black Snake Horn. Core 44.31 1.90 10.97 10.51 15.07 10.83 0.00 1.59 0.22 0.00 0.00 - - 95.271286-3B Black Snake Horn. Rim 49.09 1.62 6.15 11.58 16.56 10.93 0.22 0.92 0.33 0.00 0.01 0.088 - 97.011286-3C Black Snake Magnetite Includ. Horn 0.33 0.04 0.20 93.29 0.26 0.02 0.06 0.23 0.00 0.00 0.84 - <0.005 96.711286-3D Black Snake Apatite Mag. 0.00 0.00 0.00 0.90 0.00 53.68 0.00 0.26 0.00 42.17 0.00 - <0.005 96.451286-4A Black Snake Biotite Core 38.33 3.49 14.62 13.63 16.80 0.08 0.26 0.00 9.50 0.00 0.00 0.098 3.239 98.531286-4B Black Snake Biotite Rim 37.63 3.47 14.14 16.61 15.25 0.03 0.42 0.00 8.90 0.00 0.00 0.0871286-4C Black Snake Apatite Biotite 0.00 0.00 0.08 0.24 0.00 55.00 0.00 0.04 0.00 43.17 0.00 0.743

Abbreviation: Amp = amphibole; Cpx = clinopyroxene; Exsol = exsolution; Fct = fractured; Grano = granophyre; Horn = hornblende; Ilm = ilmenite; Includ = inclusion; Interm = intermediate; L.Amp = late amphibole; Mag = magnetite; Or = orthoclase; Pert = perthite; Plag = plagioclase; Pri = primary; Pyrx = pyroxene; Sec = secondary.

APPENDIX 4: MODAL MINERALOGY

38

Modal mineral percentages of representative samples for the various plutons based on point counting

APPENDIX 4: MODAL MINERALOGY

39

APPENDIX 5 PETROGENETIC MODELS

40

MATHEMATICAL EQUATIONS USED IN PETROGENETIC MODELING

Mathematical models tested various magmatic processes that may operate on the

SCIC magmas using the Igpet and NewPet programs. The equations of the various

magmatic processes summarised below are adapted from Allergre & Minster (1978)* and

from the Igpet program#. Fractional crystallisation process (Rayleigh fractionation)*: CL = concentration of an element in the residual liquid,

CL CO = initial concentration of an element in the liquid, ---- = F (D-1) F = weight fraction of liquid remaining, and CO D = bulk partition coefficient of an element between solid and

liquid. Partial melting process (equilibrium or batch melting)*: CL = concentration of an element in the melt, CL 1 CO = initial concentration of an element in the source, ---- = --------------- F = weight fraction of melt, and CO D + F(1-D) D = bulk partition coefficient of an element at the time of melt

extraction. Simple magma-mixing process# (lever-rule): CL =concentration of an element in contaminated magma,

CL = C1α + C2(1-α) C1 = concentration of an element in the source, C2 = concentration of an element in the contaminant, and α = weight proportion of source magma.

Contamination before fractional crystallisation CL = concentration of an element in the residual

liquid, CL = [α Co + Cc (1- α)] F (D-1) CO = initial concentration of an element in the liquid,

Cc = concentration of an element in the contaminant, α = weight proportion of source magma,

F = weight fraction of liquid remaining, and D = bulk partition coefficient of an element between

solid and liquid. Assimilation-Fractional crystallisation (AFC) process: CL = concentration of an element in the liquid,

CL Ca Co = initial concentration of an element in the liquid,

--- = Fz + (R/(R-1)) x ----- x (1-Fz) Ca = concentration of an element in the assimilant, Co zCo F = weight fraction of liquid remaining,

R = mass of assimilant (Ma) divided by the mass of crystallisation (Mc), and

z = (R+D-1)/(R-1), where D is the bulk partition coefficient at the time of melt extraction.


41

A flow chart of fractional crystallisation models within and between units of the Station Creek Igneous Complex. Arrow indicates a parent-to-daughter fractionation trend. Samples of a pluton are arranged vertically with increasing SiO2 content from top to bottom. Accompanying the modelled fractionation path is:

a. the sum of least squares (R2) for the model, and b. crystallising phases between the parent to daughter compositions.

A good model has R2 < 0.2 and is depicted on the flow chart by a solid arrow, whereas a poor model (R2>0.2) is shown as a dashed-arrow. The “geologic feasibility” is based on field relationship and intrusive timing, and “geologically infeasible” means that the daughter product cannot be a direct fractionate of the parent. However, the modelling does not discount the possibility that the daughter product could fractionate from similar composition(s) within the pluton that is not exposed or sampled. The details of the respective models calculated by IGPET (1996) program are present below.

SC936 (47.98)

SC1129 (67.39)

SC999 (53.53) SC1204

(55.09) SC710 (56.18)

SC1069 (60.50)

SC1018 (62.44)

SC472 (64.20)

SC854 (67.02)

SC1166 (65.65)

SC1185 (71.17)

SC1153 (75.31)

MODEL 13 R2 = 1.032 - Opx, cpx, mgt, plag

MODEL 10 R2 = 0.069 - Hb, bio, mgt, plag

MODEL 11 R2 = 0.125 - Hb, bio, mgt, plag

MODEL 1 R2 = 0.036 - Cpx, hb, mgt, plag, sph. MODEL 2

R2 = 0.164 - Cpx, mgt, plag

MODEL 6 R2 = 0.479 - Hb, mgt, ilm, plag

MODEL 3 R2 = 0.185 - Cpx, mgt, ilm, plag

MODEL 8 R2 = 0.076 -Hb, mgt, plag

MODEL 5 R2 = 0.154 - Hb, mgt, ilm, plag, K-feld

Mt. Mucki Diorite




Woonga Granodiorite

FRACTIONAL CRYSTALLISATION MODELS

Increase SiO2 (Wt %)

Units

MODEL 4 R2 = 0.190 - Hb, mgt, ilm, plag

MODEL 9 R2 = 0.153 -Hb, bio, mgt, plag

MODEL 7 R2 = 0.198 -Hb, mgt, plag

MODEL 12 R2 = 0.069 - Cpx, hb, mgt, plag

SC681 (58.49)

SC112 (65.39)

R2 = 0.123 - Hb, mgt, ilm, plag

EXPLANATION

Sample number

SiO2 wt % (anhydrous)


Fractionating phases

Poor fractional crystallisation model

Geologically infeasible


42

FRACTIONAL CRYSTALLISATION MODELS

FC MODEL 1 To test closed system fractional crystallisation within the Mount Mucki Diorite from a primitive parental gabbroic magma (SC936) to diorite (SC999) Parent (Co) is SC936 (Mount Mucki Diorite = parental magma) Coef. %Cum Mineral 0.053 10.5 936-CPX 0.216 43.0 1000-HB 0.049 09.7 936-MGT 0.178 35.5 936-PLAG 0.006 01.3 936-SPH 0.496 (F) SC999 Daughter (CL) (Fractionated Mount Mucki Diorite) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Parent SC936 Obs 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Calc 48.07 1.20 15.70 12.77 0.17 6.22 12.53 2.07 0.87 0.16 Diff* Wt -0.04 -0.01 0.01 0.00 0.08 0.01 0.02 0.07 0.15 -0.02 Sum of squares of residuals R2 = 0.036 D Co Co’ Co-Co’ Co-Co’/Co SC999(CL) Ba 0.27 201.7 133 68.7 0.34 222.6 Nb 0.45 3.05 4.01 -0.96 -0.31 5.91 La 0.46 4.97 11.2 -6.23 -1.25 16.3 Sr 0.86 765.4 820.1 -54.72 -0.07 907.6 Zr 0.25 52.7 49.4 3.3 0.06 83.5 Eu 1.18 0.79 1.41 -0.63 -0.80 1.25 Yb 0.86 1.14 1.97 -0.83 -0.73 2.18(Using basaltic partition coefficients)

FC MODEL 2 To test if the Gibraltar Quartz Monzodiorite sample (SC710) is the result of closed system fractional crystallisation from diorite of the Mount Mucki Diorite (SC999). Parent (Co) is SC999 (Mount Mucki Diorite) Coef %Cum Mineral 0.124 52.1 936-CPX 0.036 15.1 936-MGT 0.078 32.8 936-PLAG 0.766 (F) SC710 Daughter (CL) (Gibraltar Quartz Monzodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 Parent SC999 Obs 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Calc 53.24 1.18 16.59 10.30 0.28 4.28 9.16 3.48 1.73 0.14 Diff* Wt 0.12 -0.11 -0.05 0.00 -0.11 -0.07 -0.06 -0.25 -0.15 0.18 Sum of squares of residuals R2 = 0.164 D Co Co’ Co-Co’ Co-Co’/Co SC710 (CL) Ba 0.09 222.6 404.0 -181.44 -0.82 515.0 Nb 0.07 5.91 4.50 1.41 0.24 5.77 La 0.30 16.3 21.6 -5.25 -0.32 26.0 Sr 0.63 907.6 1513.5 -605.84 -0.67 1669.4 Zr 0.08 83.5 78.9 4.56 0.05 100.8 Eu 0.71 1.25 2.42 -1.17 -0.94 2.62 Yb 0.43 2.18 2.20 -0.03 -0.01 2.57 Sc 1.19 12.1 17.9 -5.78 -0.48 17.0 (Using basaltic partition coefficients)


43

FC MODEL 3 To test if the more silicic Gibraltar Quartz Monzodiorite sample (SC681) is the result of closed system fractional crystallisation from more basic magma of the same pluton (SC710). Parent (Co) is SC710 (Gibraltar Quartz Monzodiorite) Coef %Cum Mineral 0.022 09.3 710-CPX 0.014 05.9 710-IL 0.046 19.6 710-MGT 0.155 65.3 791-PLAG 0.758 (F) SC681 Daughter (CL) (Gibraltar Quartz Monzodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 58.49 1.02 17.02 7.11 0.16 3.20 6.04 4.20 2.72 0.04 Parent SC710 Obs 54.30 1.47 17.47 10.80 0.27 3.10 6.00 4.26 2.17 0.17 Calc 54.51 1.46 17.00 10.80 0.28 2.90 6.22 4.14 2.12 0.03 Diff* Wt -0.08 0.01 0.23 0.00 -0.01 0.20 -0.21 0.12 0.05 0.14 Sum of squares of residuals R2 = 0.185 D Co Co’ Co-Co’ Co-Co’/Co SC681 (CL) Ba 0.11 497.7 422.8 74.9 0.15 541.4 Sr 1.19 1613.5 1144.3 469.2 0.29 1087.0 (Using andesitic partition coefficients)

FC MODEL 4 To test if a Gibraltar Quartz Monzodiorite sample (SC1018) resulted from closed system fractional crystallisation of less evolved magma of the same pluton (SC681). Parent (Co) is SC681 (Gibraltar Quartz Monzodiorite) Coef %Cum Mineral 0.089 29.8 710-HB 0.006 02.1 710-IL 0.027 09.2 710-MGT 0.176 58.9 791-PLAG 0.700 (F) SC1018 Daughter (CL) (Gibraltar Quartz Monzodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 62.44 0.85 17.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Parent SC681 Obs 58.49 1.02 17.02 7.11 0.16 3.20 6.04 4.20 2.72 0.04 Calc 58.61 1.00 16.82 7.11 0.22 3.05 6.26 3.91 2.67 0.18 Diff* Wt -0.05 0.01 0.10 0.00 -0.06 0.15 -0.22 0.29 0.05 -0.14 Sum of squares of residuals R2 = 0.190 D Co Co’ Co-Co’ Co-Co’/Co SC1018 (CL) Ba 0.12 541.4 409.4 132.0 0.24 559.3 Sr 1.13 1087.0 895.9 191.0 0.18 855.6 (Using andesitic partition coefficients)

FC MODEL 5 To test if the Woonga Granodiorite (SC1129) is the result of closed system fractional crystallisation from the Gibraltar Quartz Monzodiorite (SC1018) Parent (Co) is SC1018 (Net-veined complex of the Gibraltar Quartz Monzodiorite) Coef %Cum Mineral 0.043 14.0 1129-HB 0.010 03.3 710-IL 0.107 34.5 710-KFEL 0.013 04.1 710-MGT 0.137 44.2 792-PLAG


44

0.686 (F) SC1129 Daughter (CL) (Woonga Granodiorite) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5

Daughter 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 Parent SC1018 Obs 62.44 0.85 17.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Calc 62.54 0.84 17.25 4.62 0.17 1.86 5.16 3.59 3.57 0.08 Diff* Wt -0.04 0.00 -0.11 0.00 -0.04 -0.02 0.11 0.28 0.11 0.19 Sum of squares of residuals R2 = 0.154

D Co Co’ Co-Co’ Co-Co’/Co SC1129(CL) Ba 2.28 559.3 930.7 -371.46 -0.66 574.00 Nb 0.23 8.27 4.27 4 0.48 5.70 La 0.27 26.5 10.4 16.1 0.61 13.70 Sr 2.62 855.6 1096.5 -240.88 -0.28 595.10 Zr 0.07 161.8 76.2 85.6 0.53 108.30 Eu 1.85 1.6 0.9 0.69 0.43 0.66 Yb 0.78 2.41 1 1.41 0.59 1.09(Using dacite-andesite partition coefficients)

FC MODEL 6 To test if Woolooga Granodiorite (SC1069) is the result of closed system fractional crystallisation from a less evolved magma of the Gibraltar Quartz Monzodiorite (SC710). Parent (Co) is SC710 (Gibraltar Quartz Monzodiorite) Coef %Cum Mineral 0.028 09.2 710-HB 0.018 06.0 710-IL 0.056 18.3 710-MGT 0.203 66.5 791-PLAG 0.686 (F) SC1069 Daughter (CL) (Woolooga Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28 Parent SC710 Obs 54.30 1.47 17.47 10.80 0.27 3.10 6.00 4.26 2.17 0.17 Calc 54.75 1.46 16.81 10.80 0.30 2.90 6.08 4.20 1.63 0.19 Diff* Wt -0.18 0.01 0.33 0.00 -0.03 0.21 -0.08 0.05 0.54 -0.02 Sum of squares of residuals R2 = 0.479 D Co Co’ Co-Co’ Co-Co’/Co SC1069 (CL) Ba 0.12 497.7 241.4 256.4 0.52 336.4 La 0.32 25.1 17.7 7.37 0.29 22.9 Sr 1.22 1613.5 482.5 1131.0 0.70 444.1 Eu 1.23 2.53 1.42 1.11 0.44 1.30 Yb 0.61 2.48 1.78 0.70 0.28 2.06 Sc 1.93 16.5 21.4 -4.94 -0.30 15.1 (Using andesitic partition coefficients)

FC MODEL 7 To test closed system fractional crystallisation within the Woolooga Granodiorite (from quartz monzodiorite (SC1069) to quartz monzodiorite-granodiorite (SC472) Parent (Co) is SC1069 (Woolooga Granodiorite) Coef %Cum Mineral 0.050 18.5 1069-HB 0.021 07.9 582-MGT 0.199 73.6 1069-PLAG 0.722 (F) SC472 Daughter (CL) (Woolooga Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 64.20 0.59 15.16 4.65 0.09 3.16 4.73 4.15 3.09 0.18 Parent SC1069 Obs 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28


45

Calc 60.63 0.46 16.26 6.13 0.10 3.23 5.87 4.16 2.31 0.13 Diff* Wt -0.05 0.31 0.15 0.00 0.05 0.14 -0.14 0.10 -0.05 0.15 Sum of squares of residuals R2 = 0.198

D Co Co’ Co-Co’ Co-Co’/Co SC472 (CL) Ba 0.14 336.4 312.7 23.7 0.07 414.20 La 0.31 22.9 16.7 6.2 0.27 20.80 Sr 1.37 444.1 408.5 35.6 0.08 362.30 Eu 1.55 1.3 1.24 0.07 0.05 1.03 Yb 0.95 2.06 2.25 -0.18 -0.09 2.28(Using andesite partition coefficients)

FC MODEL 8 To test closed system fractional crystallisation within the Woolooga Granodiorite from quartz monzodiorite-granodiorite (SC472) to granodiorite (SC854) Parent (Co) is SC472 (Woolooga Granodiorite) Coef %Cum Mineral 0.128 54.4 582-HB 0.000 00.2 582-MGT 0.107 45.5 582-PLAG 0.765 (F) SC854 Daughter (CL) (Woolooga Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 67.02 0.66 15.97 3.71 0.10 1.25 2.82 4.25 4.04 0.18 Parent SC472 Obs 64.20 0.59 15.16 4.65 0.09 3.16 4.73 4.15 3.09 0.18 Calc 64.22 0.58 15.31 4.65 0.14 3.14 4.75 3.90 3.14 0.14 Diff* Wt -0.01 0.01 -0.08 0.00 -0.04 0.02 -0.01 0.25 -0.05 0.04 Sum of squares of residuals R2 = 0.076

D Co Co’ Co-Co’ Co-Co’/Co SC854 (CL) Ba 0.13 414.2 416.5 -2.27 -0.01 526.20 Nb 0.72 6.29 7.07 -0.78 -0.12 7.62 La 0.41 20.8 19.4 1.49 0.07 22.70 Sr 0.94 362.3 511.3 -149.02 -0.41 519.10 Zr 0.77 173.8 138.8 35 0.20 147.70 Eu 2.42 1.03 1.51 -0.48 -0.47 1.03 Yb 2.68 2.28 3.26 -0.98 -0.43 2.08 (Using andesite partition coefficients)

FC MODEL 9 To test if the Rush Creek granodiorite sample (SC1166) could result from closed system fractional crystallisation of Woolooga Granodiorite (SC472). Parent (Co) is SC472 (Woolooga Granodiorite) Coef %Cum Mineral 0.029 31.0 1166-BIO 0.008 8.8 1166-HB 0.001 01.3 1166-MGT 0.055 58.9 1166-PLAG 0.904 (F) SC1166 Daughter (CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Parent SC472 Obs 64.20 0.59 15.16 4.65 0.09 3.16 4.73 4.15 3.09 0.18 Calc 64.29 0.69 15.42 4.65 0.09 3.17 4.64 3.90 2.87 0.14 Diff* Wt -0.04 -0.10 -0.13 0.00 0.01 -0.02 0.09 0.26 0.22 0.04 Sum of squares of residuals R2 = 0.153 D Co Co’ Co-Co’ Co-Co’/Co SC1166 (CL) Ba 2.08 414.2 400.6 13.6 0.03 359.6 Nb 2.12 6.29 7.49 -1.20 -0.19 6.70 La 0.22 20.8 21.8 -0.96 -0.05 23.6


46

Sr 1.12 362.3 329.8 32.5 0.09 325.9 Zr 0.50 173.8 131.3 42.6 0.25 137.9 Eu 1.07 1.03 0.91 0.13 0.13 0.90 Yb 0.51 2.28 2.05 0.23 0.10 2.16 Sc 5.14 13.6 17.8 -4.15 -0.31 11.7 (Using andesitic partition coefficients)

FC MODEL 10 To test closed system fractional crystallisation within the Rush Creek Granodiorite from granodiorite (SC1166) to granite (SC1185) Parent (Co) is SC1166 (Rush Creek Granodiorite) Coef %Cum Mineral 0.004 01.4 1166-BIO 0.103 33.3 1166-HB 0.015 04.8 1166-MGT 0.186 60.5 1166-PLAG 0.691 (F) SC1185 Daughter (CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 71.17 0.33 14.30 2.56 0.08 1.27 2.35 3.88 3.95 0.10 Parent SC1166 Obs 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Calc 65.60 0.37 15.02 4.51 0.08 2.83 4.46 3.99 2.87 0.07 Diff* Wt 0.02 0.22 -0.01 0.00 0.01 -0.05 0.03 -0.09 -0.05 0.08 Sum of squares of residuals R2 = 0.069

D Co Co’ Co-Co’ Co-Co’/Co SC1185 (CL) Ba 0.34 359.6 318.7 40.9 0.11 406.40 Nb 0.59 6.7 6.06 0.64 0.10 7.06 La 0.4 23.6 19.6 4 0.17 24.50 Sr 1.8 325.9 304.5 21.4 0.07 226.80 Zr 0.14 137.9 91 46.9 0.34 125.30 Eu 2.44 0.9 1.12 -0.22 -0.24 0.66 Yb 1.69 2.16 2.85 -0.69 -0.32 2.20(Using dacite-andesite partition coefficients)

FC MODEL 11 To test closed system fractional crystallisation within the Rush Creek Granodiorite from a granite (SC1185) to a more siliceous granite (SC1153) Parent (Co) is SC1185 (Rush Creek Granodiorite) Coef %Cum Mineral 0.020 11.1 1166-BIO 0.028 15.8 1166-HB 0.008 04.4 1166-MGT 0.122 68.7 1166-PLAG 0.821 (F) SC1153 Daughter (CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 75.31 0.18 13.51 1.46 0.03 0.46 1.19 3.35 4.46 0.04 Parent SC1185 Obs 71.17 0.33 14.30 2.56 0.08 1.27 2.35 3.88 3.95 0.10 Calc 71.21 0.28 14.54 2.56 0.03 1.25 2.37 3.57 3.90 0.03 Diff* Wt -0.01 0.05 -0.12 0.00 0.05 0.02 -0.02 0.31 0.05 0.07 Sum of squares of residuals R2 = 0.125

D Co Co’ Co-Co’ Co-Co’/Co SC1153 (CL) Ba 1.3 406.4 393.3 13.1 0.03 370.70 Nb 1.49 7.06 8.05 -0.99 -0.14 7.30 La 0.74 24.5 21.8 2.72 0.11 22.90 Sr 3.08 226.8 187.3 39.5 0.17 124.30 Zr 0.87 125.3 93.6 31.7 0.25 96.10 Eu 2.33 0.66 0.54 0.12 0.18 0.42


47

Yb 1.42 2.2 1.76 0.44 0.20 1.63(Using rhyolite partition coefficients)

FC MODEL 12 To test if the monzodiorite intrusion (SC1204) is the result of fractional crystallisation from a primitive magma similar to the Mount Mucki Diorite (SC936) Parent (Co) is SC936 (Mount Mucki Diorite) Coef %Cum Min/Rock 0.102 17.5 936-CPX 0.209 35.6 1000-HB 0.069 11.7 1204-MGT 0.207 35.2 1204-PLAG 0.412 (F) SC1204 Daughter (CL) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 55.09 1.01 17.68 8.42 0.18 3.55 8.18 3.69 1.79 0.41 Parent SC936 Obs 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Calc 48.02 1.24 15.67 12.77 0.17 6.22 12.55 2.23 0.80 0.18 Diff* Wt -0.02 -0.04 0.03 0.00 0.07 0.02 0.00 -0.09 0.23 -0.04 Sum of squares of residuals R2 = 0.069

D Co Co’ Co-Co’ Co-Co’/Co SC1204 (CL) Ba 0.1 201.7 218.3 -16.57 -0.08 486.6Nb 0.64 3.05 3.82 -0.77 -0.25 5.26La 0.29 4.97 13.1 -8.11 -1.63 24.5Sr 0.73 765.4 562.4 203 0.27 713.8Zr 0.55 52.7 94.8 -42.1 -0.80 140.8Eu 1.82 0.79 3.93 -3.14 -3.97 1.9Yb 1.89 1.14 5.63 -4.5 -3.95 2.55(Using andesite partition coefficients)

FC MODEL 13 To test if the Rush Creek Granodiorite (SC1166) is the result of fractional crystallisation from a primitive monzodiorite rock exposed at the centre of the pluton (SC1204) Parent (Co) is SC1204 (Monzodiorite intrusion into the Rush Creek Granodiorite) Coef %Cum Mineral 0.060 14.7 1204-CPX 0.008 01.9 1204-IL 0.039 09.6 1204-MGT 0.038 09.3 1204-OPX 0.264 64.5 1204-PLAG 0.578 (F) SC1166 Daughter (CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Parent SC1204 Obs 55.09 1.01 17.68 8.42 0.18 3.55 8.18 3.69 1.79 0.41 Calc 55.61 1.02 17.52 8.42 0.14 3.33 8.13 2.79 1.63 0.10 Diff* Wt -0.21 0.00 0.08 0.00 0.04 0.22 0.05 0.90 0.16 0.31 Sum of squares of residuals R2 = 1.032 D Co Co’ Co-Co’ Co-Co’/Co SC1166 (CL) Ba 0.24 486.6 236.8 249.9 0.51 359.6 Nb 0.19 5.26 4.29 0.97 0.18 6.70 La 0.22 24.5 15.4 9.12 0.37 23.6 Sr 1.85 713.8 518.6 195.2 0.27 325.9 Zr 0.06 140.8 82.3 58.5 0.42 137.9 Eu 1.47 1.90 1.16 0.73 0.38 0.90 Yb 0.21 2.55 1.40 1.15 0.45 2.16(Using dacite-andesite partition coefficients)


48

Model 1: SC936 to SC999 (SiO 47.98 to 53.53 wt %)

2

Modeling within the Mount Mucki Diorite

Models 3-4: SC710 to SC1018 (SiO 56.18 to 62.44 wt %)

2

Model within the Gibraltar Quartz Monzodiorite

(C

o-C

o’)/C

o

0

1.0

-1.0

Mount Mucki Diorite-Gibraltar Quartz Monzodiorite Group

TRACE-ELEMENT MODELING IN FRACTIONAL CRYSTALLISATION PROCESS

FRACTIONAL CRYSTALLISATION


2


2


2

Modeling within the Rush Creek Granodiorite


2


2

Modeling within the Woolooga Granodiorite

(Co-

Co’

)/Co

0

1.0

-1.0

Woolooga and Rush Creek Granodiorite Group

Differences between calculated and observed trace element concentrations established by fractional crystallisation normalised to the observed parent compositions) for plutonic rocks of the Station Creek Igneous Complex. The trace elements are arranged from left to right in order of increasing compatibility. Good petrogenetic models established by major element chemistry (R < 0.2) are depicted with solid lines and poor models (R > 0.2) are depicted with broken lines. The major and trace element data and calculations used in the plots are presented in Appendix 5.

2 2

model (

(Co-Co’)/Co = Difference between calculated and observed trace-element concentration in parentObserved concentration in parent

A good model has Co'-Co)/Co << 0.5, whereas a bad model has Co'-Co)/Co > 0.5


2

Model between the Gibraltar Quartz Monzodiorite and the Woolooga Granodiorite


2

Model between the Gibraltar Quartz Monzodiorite and the Woonga Granodiorite


2

Model between the Mt Mucki Diorite and the Gibraltar Quartz Monzodiorite

(Co-

Co’

)/Co 0

1.0

-1.0

Intraplutonic crystal fractionation models


2

Model between the Woolooga and the Rush Creek Granodiorite


49

Petrogenetic models to test the probabilities of generating hybrid compositions by magma mixing or assimilation of a rock into magma in the Station Creek Igneous Complex. A. Mixing models between parental magma (SC936) and a upper crustal partial melt (SC106)

for the probable generation of magma for the various compositions of the SCIC. B. Four mixing combinations between the Mt. Mucki Diorite (SC936, SC999), the Woonga

Granodiorite (SC1129) and the Gibraltar Quartz Monzodiorite (SC710). C. Two mixing combinations between the Mt. Mucki Diorite (SC936, SC999) and the Woonga

Granodiorite (SC1129). D. Magma mixing-model between granite (SC1153) of Rush Creek Granodiorite and a

monzodiorite intrusion (SC1204) at the centre of the pluton.

MIXING AND ASSIMILATION MODELS

B. The possible combinations of magma mixing or assimilation to generate a hybrid magma of SC1018 composition

SC936 (47.98)

SC710 (56.18)

SC1129 (67.39)

R2 = 2.77

R2 = 2.65

R2 = 2.47

R2 = 2.43

SC999 (53.53)

C. The possible combinations of magma mixing or assimilation to generate a hybrid magma of SC710 composition

SC936 (47.98)

SC1129 (67.39)

R2 = 5.22

R2 = 3.17

SC999 (53.53)

D. A mixing model to test if granodiorite (SC1185) of the Rush Creek Granodiorite is a hybrid from mixing monzodiorite (SC1204) and granite (SC1153).

SC1153 (75.31)

SC1204 (55.09)

R2 = 0.34

R2 = Least square mass balance for the mixing models

Explanations for the model

The intersection between the domains of the different plutons represents hybrid magma or assimilation of rocks from a pluton into the magma of another. The sum of least squares (R2) is the difference between an observed composition and the calculated hybrid composition from magma mixing.

SC999 (53.53)

SC010

SC020

R2 = 1.1

PLUTON A

PLUTON B

PLUTON C

Sample number

SiO2 wt % (Anhydrous)

Fractional crystallisation between end-members

Shaded region: Magma mixing between Pluton A and Pluton B

Shaded overlap region: Magma mixing between Plutons A, B and C

Fractionated daughter

Parental composition


MIX

Sample descriptions SC1018 (quartz monzodiorite): Net-veined complex. SC936 (gabbro) and SC999 (diorite) of Mount Mucki Diorite. SC710 (quartz monzodiorite): Gibraltar Quartz Monzodiorite. SC1129 (granodiorite): Woonga Granodiorite. SC1153 (granite), SC1166 (granodiorite): Rush Creek Granodiorite. SC1204 (monzodiorite) intrusion into Rush Creek Granodiorite.

SC936 Parental magma (Mount Mucki Diorite)

Woolooga Granodiorite 87Sr/86Sri = 0.70353

R2 = 3.64

Woonga Granodiorite 87Sr/86Sri = 0.70318

R2 = 6.56

Rush Ck. Granodiorite 87Sr/86Sri = 0.70366

R2 = 3.27

Mt Mucki Diorite 87Sr/86Sri = 0.70312

R2 = 1.37

Gibraltar Qtz Monzodiorite 87Sr/86Sri = 0.70317

R2 = 6.67

Monzodiorite intrusion R2 = 4.25

SC106 Upper crust

contamination 87Sr/86Sri =

0.70534

Parent Magma

SCIC plutons Crustal contaminant

A. Mixing models to test the probability of forming the various plutons of the SCIC by mixing parental magma (SC936) with an upper crustal partial melt (SC106)

Figure above relates to Models 1 to 6

Refers to Models 7 to 10 Refers to Models 11 and 12 Refers to Model 13


50

MAGMA-MIXING MODELS

MIXING MODEL 1

a. To test if the diorite of the Mount Mucki Diorite (SC999) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC999 (CL) Coef %Cum Rock 0.323 32.6 SC106 (C2) 0.667 (α) 67.4 SC936 (C1) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC999 (CL) Obs 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Calc 54.15 1.09 15.09 10.12 0.19 4.86 9.13 2.65 1.51 0.15 Diff* Wt -0.25 -0.02 0.70 0.18 -0.02 -0.65 -0.02 0.58 0.07 0.16 Sum of squares of residuals R2 = 1.371 b. To test if the diorite of the Mount Mucki Diorite (SC999) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) followed by fractional crystallisation Hybrid lava SC999 (CL) Coef %Cum Rock/Mineral -0.072 -07.2 936-CPX F = 1-Σ(Coef minerals) -0.211 -21.1 1000-HB -0.044 -04.4 936-MGT -0.147 -14.7 936-PLAG 0.171 17.1 SC106 (Cc) 1.303 (α) 130.3 SC936 (Co) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 936-CPX 53.45 0.15 1.16 6.00 0.51 14.42 24.10 0.20 0.00 0.00 1000-HB 47.87 1.89 6.97 10.69 0.20 15.38 15.38 1.31 0.30 0.00 936-MGT 0.10 0.00 0.00 99.63 0.00 0.14 0.00 0.00 0.02 0.11 936-PLA 45.96 0.00 33.44 0.94 0.05 0.29 18.18 1.01 0.12 0.00 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Obs SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Calc SC999 53.58 1.31 16.46 10.30 0.25 4.17 9.11 3.00 1.69 0.21 Diff* Wt -0.02 -0.23 0.01 0.00 -0.07 0.04 0.00 0.23 -0.11 0.11 Sum of squares of residuals R2 = 0.138 (Bad model due to non-logical modes for phases and components)

MIXING MODEL 2

a. To test if the diorite of the Gibraltar Quartz Monzodiorite (SC710) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC710 (CL) Coef %Cum Rock 0.566 58.8 SC106 (C2) 0.396 (α) 41.2 SC936 (C1) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 (C1) 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC710 (CL) Obs (SC710) 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17


51

Calc (SC710) 57.84 0.99 14.30 7.86 0.15 3.69 6.30 2.99 1.85 0.16 Diff* Wt -0.67 0.53 1.88 -0.16 0.13 -0.48 -0.09 1.41 0.39 0.02 Sum of squares of residuals R2 = 6.698 (Bad model) b. To test if the diorite of the Gibraltar Quartz Monzodiorite (SC710) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) followed by fractional crystallisation Hybrid lava SC710 (CL) Coef %Cum Rock 0.082 08.5 1000-HB F = 1-Σ(Coef minerals) 0.036 03.7 710-MGT 0.249 25.8 792-PLAG 0.582 60.3 SC106 (Cc) 0.017 (α) 01.8 SC936 (Co) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 1000-HB 47.87 1.89 6.97 10.69 0.20 15.38 15.38 1.31 0.30 0.00 710-MGT 0.45 0.05 0.06 99.43 0.01 0.00 0.00 0.00 0.00 0.00 792-PLA 50.53 0.00 30.56 0.62 0.00 0.24 14.87 3.09 0.08 0.00 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Obs SC710) 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 Calc (SC710) 57.31 0.71 16.76 7.71 0.08 2.69 6.55 3.12 1.55 0.11 Diff* Wt -0.45 0.81 0.65 0.00 0.20 0.53 -0.34 1.28 0.69 0.07 Sum of squares of residuals R2 = 3.845 (Poor model)

MIXING MODEL 3

a. To test if the diorite of the Woonga Granodiorite (SC1129) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC1129 (CL) Coef %Cum Rock 0.982 99.3 SC106 (C2) 0.007 (α) 00.7 SC936 (C1) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC1129 (CL) Obs 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 Calc 67.75 0.91 14.13 4.96 0.09 2.17 2.40 3.74 2.52 0.18 Diff* Wt -0.14 -0.49 0.98 -1.58 -0.02 -0.55 1.40 0.76 0.09 -0.07 Sum of squares of residuals R2 = 6.563 (poor model) b. To test if the diorite of the Woonga Granodiorite (SC1129) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) followed by fractional crystallisation Hybrid lava SC1129 (CL) Coef %Cum Rock -0.162 -16.2 999-HB F = 1-Σ(Coef minerals) -0.035 -03.5 1129-MGT -0.046 -04.6 936-PLAG 0.885 88.3 SC106 (Cc) 0.360 (α) 35.9 SC936 (Co) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 999-HB 51.39 1.08 4.62 13.18 0.21 16.18 12.18 0.76 0.39 0.00 1129-MG 0.52 0.01 0.24 98.71 0.35 0.17 0.00 0.00 0.00 0.00


52

936-PLA 45.96 0.00 33.44 0.94 0.05 0.29 18.18 1.01 0.12 0.00 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Obs (SC1129) 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 Calc (SC1129) 67.58 1.06 16.01 3.38 0.12 1.52 3.79 3.96 2.57 0.21 Diff* Wt -0.08 -0.64 0.04 0.00 -0.05 0.10 0.01 0.54 0.05 -0.10 Sum of squares of residuals R2 = 0.734 (Poor model due to non-logical modes for component and phases)

MIXING MODEL 4

a. To test if the diorite of the Woolooga Granoodiorite (SC1069) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC1069 (CL) Coef %Cum Rock 0.695 71.0 SC106 (C2) 0.283 (α) 29.0 SC936 (C1) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC1069 (CL) Obs 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28 Calc 61.30 0.98 14.38 7.07 0.13 3.27 5.19 3.24 2.07 0.16 Diff* Wt -0.32 -0.21 -1.09 -0.94 0.01 0.10 0.54 1.02 0.19 0.11 Sum of squares of residuals R2 = 3.604 (poor model) b. To test if the diorite of the Woolooga Granoodiorite (SC1069) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) followed by fractional crystallisation Hybrid lava SC1069 (CL) Coef %Cum Rock -0.061 -06.1 382-CPX F = 1-Σ(Coef minerals) 0.076 07.6 1069-HB -0.003 -00.3 936-MGT 0.188 19.0 1069-PLAG 0.535 54.0 SC106 (Cc) 0.255 (α) 25.8 SC936 (Co) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 382-CPX 54.07 0.13 0.00 7.43 0.13 15.26 22.97 0.00 0.00 0.00 1069-HB 56.59 0.18 1.19 12.10 0.51 18.20 11.00 0.17 0.06 0.00 936-MGT 0.10 0.00 0.00 99.63 0.00 0.14 0.00 0.00 0.02 0.11 1069-PL 57.41 0.00 26.36 0.36 0.00 0.19 9.55 5.77 0.36 0.00 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Obs (SC1069) 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28 Calc (SC1069) 60.81 0.80 16.71 6.13 0.14 3.24 5.70 3.67 1.70 0.13 Diff* Wt -0.13 -0.03 -0.07 0.00 0.00 0.13 0.03 0.58 0.55 0.15 Sum of squares of residuals R2 = 0.706 (Poor model due to non-logical modes for component and phases)

MIXING MODEL 5

a. To test if the diorite of the Rush Creek Granodiorite (SC1166) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC1166 (CL) Coef %Cum Rock 0.878 88.6 SC106 (C2) 0.113 (α) 11.4 SC936 (C1)


53

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC1166 (CL) Obs 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Calc 65.73 0.94 14.32 5.80 0.11 2.61 3.49 3.57 2.36 0.17 Diff* Wt -0.03 -0.35 0.35 -1.29 -0.02 0.17 1.00 0.33 0.46 -0.02 Sum of squares of residuals R2 = 3.272 (poor model) b. To test if the diorite of the Rush Creek Granodiorite (SC1166) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) followed by fractional crystallisation Hybrid lava SC1166 (CL) Coef %Cum Rock -0.011 -01.1 1166-HB F = 1-Σ(Coef minerals) -0.024 -02.4 1166-MGT -0.022 -02.2 1166-PLAG 0.726 72.5 SC106 (Cc) 0.331 (α) 33.1 SC999 (Co) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 1166-HB 52.79 1.04 3.41 11.80 0.23 17.50 11.90 1.00 0.34 0.00 1166-MG 0.45 0.18 0.33 98.90 0.02 0.10 0.00 0.01 0.00 0.00 1166-PL 58.34 0.07 25.46 0.20 0.00 0.43 8.69 6.50 0.31 0.00 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Obs (SC1166) 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Calc (SC1166) 65.74 1.00 15.23 4.51 0.12 2.77 4.42 3.67 2.37 0.23 Diff* Wt -0.04 -0.41 -0.11 0.00 -0.03 0.01 0.08 0.23 0.45 -0.08 Sum of squares of residuals R2 = 0.453 (Poor model due to non-logical modes for component and phases)

MIXING MODEL 6

To test if the monzodiorite intrusion (SC1204) is a hybrid of mixing parental magma (SC936) and an upper crustal partial melt (SC106) Hybrid lava SC1204 (CL) Coef %Cum Rock 0.446 45.6 SC106 (C2) 0.531 (α) 54.4 SC936 (C1) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC106 68.68 0.92 14.28 4.97 0.09 2.17 2.36 3.79 2.56 0.18 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC1204 (CL) Obs 55.09 1.01 17.68 8.42 0.18 3.55 8.18 3.69 1.79 0.41 Calc 56.08 1.04 14.71 8.99 0.17 4.28 7.71 2.83 1.68 0.16 Diff* Wt -0.39 -0.03 1.48 -0.58 0.01 -0.73 0.47 0.86 0.10 0.25 Sum of squares of residuals R2 = 4.254

MIXING MODEL 7

To test if Gibraltar Quartz Monzodiorite (SC1018) is a hybrid from the assimilation of Woonga Granodiorite (SC1129) into the Mount Mucki Diorite (SC936) Hybrid lava SC1018 (CL) Coef %Cum Rock 0.832 84.8 SC1129 (C2) 0.149 (α) 15.2 SC936 (C1)


54

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC1018 (CL) Obs 62.44 0.85 17.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Calc 63.19 0.53 15.72 4.71 0.09 2.27 5.03 4.06 2.33 0.11 Diff* Wt -0.30 0.32 0.65 -0.09 0.04 -0.43 0.24 -0.18 1.36 0.15 Sum of squares of residuals R2 = 2.766 (poor model)

MIXING MODEL 8

To test if the Gibraltar Quartz Monzodiorite (SC1018) is a hybrid from assimilation of Woonga Granodiorite (SC1129) into the Mount Mucki Diorite (SC999) Hybrid lava SC1018 (CL) Coef %Cum Rock 0.758 77.2 SC1129 (C2) 0.224 (α) 22.8 SC999 (C1)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Hybrid SC1018 (CL) Obs 62.44 0.85 17.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Calc 63.09 0.56 15.90 4.87 0.09 2.17 4.92 4.13 2.34 0.15 Diff* Wt -0.26 0.29 0.57 -0.25 0.04 -0.33 0.35 -0.26 1.34 0.11 Sum of squares of residuals R2 = 2.652 (poor model)

MIXING MODEL 9

To test if the Gibraltar Quartz Monzodiorite (SC1018) is a hybrid from assimilation of Woonga Granodiorite (SC1129) into magma of Gibraltar Quartz Monzodiorite (SC710) Hybrid lava SC1018 (CL) Coef %Cum Rock 0.363 (α) 36.6 SC710 (C1) 0.628 63.4 SC1129 (C2)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC710 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 Hybrid SC1018 (CL) Obs 62.44 0.85 7.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Calc 62.72 0.82 16.67 4.92 0.14 2.18 4.64 4.42 2.46 0.13 Diff* Wt -0.11 0.03 0.18 -0.30 -0.01 -0.34 0.63 -0.55 1.23 0.13 Sum of squares of residuals R2 = 2.467 (poor model)

MIXING MODEL 10

To test if SC1018 of the Gibraltar Quartz Monzodiorite is a hybrid from combination of magma mixing between the Mount Mucki Diorite and early magma of the Gibraltar Quartz Monzodiorite, in addition to the assimilation of the Woonga Granodiorite Hybrid lava SC1018 (CL) Coef %Cum Rock 0.263 26.6 SC710 (C1) 0.661 66.8 SC1129 (C2) 0.065 (α) 06.6 SC999 (C1’)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5


55

SC710 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Hybrid SC1018 (CL) Obs 62.44 0.85 17.03 4.62 0.13 1.84 5.27 3.87 3.68 0.26 Calc 62.80 0.75 16.46 4.93 0.13 2.19 4.74 4.34 2.42 0.14 Diff* Wt -0.15 0.10 0.28 -0.31 0.00 -0.35 0.53 -0.47 1.26 0.12 Sum of squares of residuals R2 = 2.433 (poor model)

MIXING MODEL 11

To test if the Gibraltar Quartz Monzodiorite (SC710) is a hybrid from the assimilation of the Woonga Granodiorite (SC1129) into the Mount Mucki Diorite (SC936) Hybrid lava SC710 (CL) Coef %Cum Rock 0.574 59.3 SC1129 (C2) 0.394 (α) 40.7 SC936 (C1)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 SC936 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Hybrid SC710 (CL) Obs 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 Calc 57.58 0.71 15.43 6.97 0.14 3.38 7.12 3.42 1.90 0.12 Diff* Wt -0.56 0.81 1.32 0.74 0.14 -0.17 -0.91 0.98 0.34 0.05 Sum of squares of residuals R2 = 5.218 (poor model)

MIXING MODEL 12

To test if the Gibraltar Quartz Monzodiorite (SC710) is a hybrid from the assimilation of the Woonga Granodiorite (SC1129) into the Mount Mucki Diorite (SC999) Hybrid lava SC710 (CL) Coef %Cum Rock 0.371 38.1 SC1129 (C2) 0.603 (α) 61.9 SC999 (C1)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC1129 67.39 0.42 16.09 3.38 0.07 1.62 3.80 4.49 2.61 0.11 SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Hybrid SC710 (CL) Obs 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 Calc 57.27 0.80 15.91 7.46 0.13 3.14 6.90 3.61 1.92 0.23 Diff* Wt -0.44 0.72 1.08 0.25 0.14 0.08 -0.69 0.79 0.32 -0.06 Sum of squares of residuals R2 = 3.168 (poor model)

MIXING MODEL 13

To test if the granodiorite of the Rush Creek Granodiorite (SC1185) is a hybrid of mixing granite (SC1153) of the pluton and a monzodiorite intrusion (SC1204) Hybrid lava SC1185 (CL) Coef %Cum Rock 0.179 (α) 18.0 SC1204 (Monzodiorite intrusion) (C1) 0.816 82.0 SC1153 (Granite of the Rush Creek Granodiorite) (C2) SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 SC1204 55.09 1.01 17.68 8.42 0.18 3.55 8.18 3.69 1.79 0.41 SC1153 75.31 0.18 13.51 1.46 0.03 0.46 1.19 3.35 4.46 0.04 Hybrid SC1185 (CL)


56

Obs 71.17 0.33 14.30 2.56 0.08 1.27 2.35 3.88 3.95 0.10 Calc 71.32 0.33 14.18 2.70 0.06 1.01 2.43 3.40 3.95 0.11 Diff* Wt -0.06 0.00 0.06 -0.14 0.02 0.26 -0.09 0.49 0.00 -0.01 Sum of squares of residuals R2 = 0.340 CL

(Observed) CL’

(Calculated) CL – CL’

(R) C1

SC1204 C2

SC1153 CL – CL’ /

CL La 24.5 23.1 1.4 24.5 22.9 0.06 Nd 18.6 17.3 1.3 31.8 14.2 0.07 Sm 3.4 3.2 0.2 6.9 2.5 0.06 Eu 0.7 0.7 0 1.9 0.4 0.00 Yb 2.2 1.8 0.4 2.5 1.6 0.18 Lu 0.4 0.3 0.1 0.4 0.3 0.25 Rb 147.2 164 -16.9 52.3 189.5 -0.11 Sr 226.8 228.9 -2.1 713.8 124.3 -0.01 Ba 406.4 389.6 16.8 486.6 370.7 0.04 Y 17.2 14.8 2.4 24 12.8 0.14 Nb 7.1 6.9 0.2 5.3 7.3 0.03 Zr 125.3 103.6 21.7 140.8 96.1 0.17 Th 19.5 20 -0.5 6.3 23.1 -0.03 (Using dacite-andesite partition coefficients)

ASSIMILATION-CRYSTAL FRACTIONATION MODELS

AFC MODEL 1

To test if the Gibraltar Quartz Monzodiorite (SC710) resulted from AFC processes of assimilation of a supra-crustal melt (SC106- composition similar to the foliated S-type granite) in the Mount Mucki Diorite (SC936) Parent (Co) is SC936 (Mount Mucki Diorite) Coef %Cum Mineral 0.156 24.5 936-CPX 0.167 26.3 999-HB 0.067 10.5 936-MGT 0.246 38.7 936-PLAG 0.357 SC710 Daughter (CL) (Gibraltar Quartz Monzodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 56.18 1.52 18.07 7.71 0.28 3.21 6.21 4.41 2.24 0.17 Parent SC936 (Co) Obs 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Calc 48.28 0.75 15.63 12.77 0.23 6.18 12.48 1.98 0.90 0.07 Diff* Wt -0.12 0.45 0.05 0.00 0.02 0.05 0.07 0.16 0.13 0.07 Sum of squares of residuals R2 = 0.274 AFC MODEL PARAMETERS Fraction of liquid (F): 0.619 Rate of assimilation (R): 0.2

D SC710(CL) Assim Ca (SC106)

Calc(Co') SC936(Co) Co-Co'/Co

Ba 0.09 515 633 99.61 201.70 0.51 Nb 0.53 6 8.55 2.38 3.01 0.21 La 0.26 26 21.04 9.07 4.97 -0.82 Sr 0.78 1707.8 244.82 1602.15 765.40 -1.09 Zr 0.43 101 269.3 7.56 52.70 0.86 Eu 1.60 3 1.36 7.79 0.78 -8.99 Yb 1.48 3 2.85 6.03 1.14 -4.29


57

Sr/Sr 1 0.70325 0.70534 0.703134 ~0.70312

AFC MODEL 2

To test if the Woolooga Granodiorite (SC1069) resulted from AFC processes of assimilation of a supra-crustal melt (SC106- composition similar to the foliated S-type granite) in the Mount Mucki Diorite (SC936) Parent (Co) is SC936 (Mount Mucki Diorite) Coef %Cum Mineral 0.081 12.1 936-CPX 0.259 38.7 1000-HB 0.073 10.9 936-MGT 0.257 38.3 936-PLAG 0.323 SC1069 Daughter (CL) (Woolooga Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28 Parent SC936 Obs 47.98 1.20 15.72 12.77 0.24 6.23 12.55 2.14 1.02 0.14 Calc 48.10 0.75 15.84 12.77 0.15 6.33 12.46 1.99 0.84 0.10 Diff* Wt -0.05 0.44 -0.06 0.00 0.09 -0.09 0.09 0.15 0.18 0.04 Sum of squares of residuals R2 = 0.286 AFC MODEL PARAMETERS Fraction of liquid (F): 0.298 Rate of assimilation (R): 0.1

D SC1069(CL) Assim Ca (SC106)

Calc(Co') SC936(Co) Co-Co'/Co

Ba 0.1 336.4 633 73.05 201.70 0.64 La 0.31 22.3 21.04 8.76 4.97 -0.76 Sr 0.79 444.1 244.82 358.09 765.40 0.53 Eu 1.92 1.27 1.36 4.22 0.78 -4.42 Yb 2.01 2.06 2.85 7.52 1.14 -5.60 Sc 4.45 15.1 16.6 1262.99 35.34 -34.74

AFC MODEL 3

To test if the Rush Creek Granodiorite (SC1166) resulted from AFC processes of assimilation of a supra-crustal melt (SC106-composition similar to the foliated S-type granite) in the Mount Mucki Diorite (SC999) Parent (Co) is SC999 (Fractionated Mount Mucki Diorite) Coef %Cum Fractionating phases 0.244 31.4 999-HB 0.060 07.8 936-MGT 0.473 60.9 999-PLAG 0.212 SC1166 Daughter(CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Obs(Co) SC999 53.53 1.07 16.49 10.30 0.17 4.21 9.11 3.23 1.58 0.32 Calc(P) SC999 53.67 0.45 16.59 10.30 0.07 4.54 8.61 3.77 0.77 0.04 Diff* Wt -0.06 0.62 -0.05 0.00 0.10 -0.33 0.50 -0.55 0.81 0.28 Sum of squares of residuals R2 = 1.791


58

AFC MODEL PARAMETERS Fraction of liquid (F): 0.212 Rate of assimilation (R): 0.1

D SC999(Co) Assim Ca (SC106)

Calc(CL ') SC1166(CL) CL- CL '/CL

Ba 0.13 222.6 633 776.54 359.6 -1.16 Nb 0.5 5.91 8.55 11.65 6.7 -0.74 La 0.34 16.3 21.04 38.84 23.6 -0.65 Sr 1.17 907.6 214 655.33 325.9 -1.01 Zr 0.45 83.5 269.3 202.74 137.9 -0.47 Eu 1.84 1.25 1.36 0.46 0.9 0.49 Yb 1.58 2.18 2.85 1.12 2.16 0.48 Sc 3.3 12.1 16.6 1.14 11.7 0.90

AFC MODEL 4

To test if the magmatic differentiation in the Woolooga Granodiorite (SC1069 to SC472) resulted from AFC processes of assimilation of a supra-crustal melt (SC106- composition similar to the foliated S-type granite) Parent (Co) is SC1069 (Woolooga Granodiorite) Coef %Cum Fractionating phases 0.050 18.5 1069-HB (add 382-AB, R2 = 0.183) 0.021 07.9 582-MGT 0.199 73.6 1069-PLAG 0.722 SC472 Daughter (CL) (Woolooga Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 64.20 0.59 15.16 4.65 0.09 3.16 4.73 4.15 3.09 0.18 Obs(Co) SC1069 60.50 0.77 16.56 6.13 0.14 3.37 5.73 4.26 2.26 0.28 Calc(P) SC1069 60.63 0.46 16.26 6.13 0.10 3.23 5.87 4.16 2.31 0.13 Diff* Wt -0.05 0.31 0.15 0.00 0.05 0.14 -0.14 0.10 -0.05 0.15 Sum of squares of residuals R2 = 0.198 AFC MODEL PARAMETERS Fraction of liquid (F): 0.722 Rate of assimilation (R): 0.1


Calc(CL') SC472(CL) CL- CL'/CL

Ba 0.14 336.4 633 469.28 414.2 -0.13 La 0.31 22.9 21.04 29.20 20.8 -0.40 Sr 1.37 444.1 214 381.75 362.3 -0.05 Eu 1.55 1.3 1.36 1.07 1.03 -0.04 Yb 0.95 2.06 2.85 2.13 2.28 0.07 Sc 2.01 15.1 16.6 10.60 13.6 0.22

AFC MODEL 5

To test if the magmatic differentiation in the Rush Creek Granodiorite (SC1166 to SC1185) resulted from AFC processes of assimilation of a supra-crustal melt (SC106 composition similar to the foliated S-type granite) Parent (Co) is SC1166 (Rush Creek Granodiorite) Coef %Cum Fractionating phases 0.004 01.4 1166-BIO 0.103 33.3 1166-HB


59

0.015 04.8 1166-MGT 0.186 60.5 1166-PLAG 0.691 SC1185 Daughter (CL) (Rush Creek Granodiorite)

SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2O K2O P2O5 Daughter 71.17 0.33 14.30 2.56 0.08 1.27 2.35 3.88 3.95 0.10 Obs(Co) SC1166 65.65 0.59 15.01 4.51 0.09 2.78 4.49 3.90 2.82 0.15 Calc(P) SC1166 65.60 0.37 15.02 4.51 0.08 2.83 4.46 3.99 2.87 0.07 Diff* Wt 0.02 0.22 -0.01 0.00 0.01 -0.05 0.03 -0.09 -0.05 0.08 Sum of squares of residuals R2 = 0.069 AFC MODEL PARAMETERS Fraction of liquid (F): 0.691 Rate of assimilation (R): 0.1


Calc(CL') SC1185(CL) CL- CL'/CL

Ba 0.34 359.6 633 481.81 406.4 -0.19 Nb 0.59 6.7 8.55 7.98 7.06 -0.13 La 0.40 23.6 21.04 29.94 24.5 -0.22 Sr 1.80 325.9 214 232.54 226.8 -0.03 Zr 0.14 137.9 269.3 201.40 125.3 -0.61 Eu 2.44 0.9 1.36 0.52 0.66 0.21 Yb 1.69 2.16 2.85 1.66 2.2 0.24 Sc 3.63 11.7 16.6 4.22 5.33 0.21


60

The equilibrium mineralogy of residual phases at different melt fractions (F) used in the partial melting models. The cumulative modal mineralogy are determined experimentally for various degrees of partial melting metabasalt, amphibolite and eclogite. Data for metabasalt from Helz (1973) and the data for amphibolites and eclogite from Rapp et al. (1991), Rapp & Watson (1995) and Gromet & Silver (1987).

Melt % Parent Oli Opx Cpx Gt Amp Plag Mt10 Basalt-MORB 0.0 0.0 0.0 0.0 60.0 35.0 5.020 Basalt-MORB 0.0 0.0 0.0 0.0 70.0 25.0 5.030 Basalt-MORB 0.0 0.0 0.0 0.0 80.0 15.0 5.040 Basalt-MORB 0.0 0.0 0.0 0.0 85.0 10.0 5.050 Basalt-MORB 0.0 0.0 15.0 0.0 80.0 0.0 5.560 Basalt-MORB 3.0 0.0 25.0 0.0 70.0 0.0 2.010 Amphibolite-NMORB 0.0 20.0 0.0 0.0 30.0 50.0 0.020 Amphibolite-NMORB 0.0 15.0 0.0 0.0 45.0 40.0 0.030 Amphibolite-NMORB 15.0 25.0 0.0 0.0 15.0 45.0 0.040 Amphibolite-NMORB 20.0 15.0 0.0 0.0 35.0 30.0 0.050 Amphibolite-NMORB 20.0 10.0 0.0 0.0 55.0 15.0 0.060 Amphibolite-NMORB 25.0 0.0 0.0 0.0 75.0 0.0 0.020 Greenstone-EMORB 0.0 0.0 20.0 0.0 60.0 20.0 0.030 Greenstone-EMORB 5.0 0.0 45.0 0.0 15.0 35.0 0.040 Greenstone-EMORB 5.0 0.0 50.0 0.0 10.0 35.0 0.050 Greenstone-EMORB 10.0 0.0 45.0 0.0 5.0 40.0 0.060 Greenstone-EMORB 15.0 0.0 40.0 0.0 3.0 42.0 0.020 Eclogite-EMORB 0.0 0.0 55.0 25.0 10.0 10.0 0.030 Eclogite-EMORB 0.0 0.0 0.0 40.0 60.0 0.0 0.040 Eclogite-EMORB 0.0 0.0 0.0 40.0 60.0 0.0 0.050 Eclogite-EMORB 0.0 0.0 0.0 40.0 60.0 0.0 0.060 Eclogite-EMORB 0.0 0.0 0.0 40.0 60.0 0.0 0.0

Modes of equilibrium residual mineralogy with melts (%)

PARTIAL MELTING MODELS

A. MetabasaltAccessory minerals Olivine

Amphiboles

0 20 40 60

Plagioclase Pyroxenes

0

20

40

60

80

100

Cum

ulat

ive

wt %

mod

es

(5 kbar, 700-1000 C, water unsaturated)o

0 20 40 600

20

40

60

80

100

Cum

ulat

ive

wt %

mod

es

C. Amphibolite (N-MORB)

(8 kbars, 1000-1100 C, mainly water saturated)o

0

20

40

60

80

100C

umul

ativ

e w

t % m

odes

0 20 40 60Melt fraction (F) %

Amphiboles Plagioclase

Pyroxenes

Olivine

D. Amphibolite (E-MORB)

(8 kbars, 1000-1075 C, water saturated)o

Plagioclase

Amphiboles

Pyroxenes

Garnet

0 20 40 60Melt fraction (F) %

0

20

40

60

80

100

Cum

ulat

ive

wt %

mod

es

B. Eclogite(16-50 kbar, 1030-1100oC, water saturated & unsaturated)

APPENDIX 5 PARTIAL MELTING MODELS

61

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 8.28 6.85 5.85 5.14 4.65 4.36 3 32.29 26.71 22.83 20.04 18.13 17.01 11.7Ce 22.67 17.78 14.68 12.59 11.08 10.21 6.9 77.23 60.57 49.99 42.87 37.74 34.78 23.5Pr 12.5 6.25 4.17 3.13 2.5 2.08 1.25 29 14.5 9.67 7.25 5.8 4.83 2.9Nd 22.37 17.69 14.76 12.93 11.53 10.78 7.8 48.75 38.55 32.18 28.18 25.12 23.5 17Sm 5.76 4.74 4.08 3.7 3.37 3.25 2.6 9.19 7.56 6.52 5.91 5.38 5.19 4.15Eu 2.22 1.94 1.72 1.56 1.4 1.31 1 3 2.62 2.32 2.1 1.9 1.77 1.35Gd 5.22 4.24 3.64 3.31 3.02 2.88 2.4 7.39 6.01 5.16 4.69 4.28 4.09 3.4Tb 0.61 0.54 0.49 0.48 0.48 0.51 0.52 0.83 0.72 0.66 0.64 0.64 0.68 0.7Dy 6.45 5.25 4.5 4.1 3.74 3.58 3 7.52 6.12 5.25 4.79 4.37 4.18 3.5Ho 9 4.5 3 2.25 1.8 1.5 0.9 8.6 4.3 2.87 2.15 1.72 1.43 0.86Er 5.99 4.8 4.07 3.65 3.27 3.08 2.5 5.99 4.8 4.07 3.65 3.27 3.08 2.5Tm 2.34 1.42 1.01 0.79 0.64 0.56 0.34 2.07 1.25 0.9 0.7 0.57 0.49 0.3Yb 5.98 4.87 4.16 3.74 3.35 3.19 2.55 4.36 3.55 3.03 2.73 2.44 2.33 1.86Lu 1.17 0.91 0.75 0.66 0.58 0.53 0.41 1.25 0.97 0.8 0.71 0.62 0.57 0.44Rb 29.7 22.02 17.65 15.02 13.42 12.13 8.3 100.21 74.27 59.55 50.68 45.26 40.91 28Sr 238 267 293 295 319 299 220 469 527 579 583 630 590 434Ba 380 316 272 242 227 211 152 796 660 568 506 474 441 318K 4819 4197 3786 3600 3652 3712 3240 12849 11192 10096 9599 9739 9900 8640Cs 2.3 1.15 0.77 0.58 0.46 0.38 0.23 7.6 3.8 2.53 1.9 1.52 1.27 0.76Pb 29 14.5 9.67 7.25 5.8 4.83 2.9 50 25 16.67 12.5 10 8.33 5Y 37.97 32.3 28.73 27.24 25.69 25.73 25 30.37 25.84 22.98 21.79 20.55 20.58 20Ti 3412 3190 3057 3088 3218 3838 4300 3571 3338 3199 3232 3368 4017 4500Zr 161.7 127.63 107.04 95.33 88.7 83.89 63 284.89 224.88 188.6 167.96 156.28 147.81 111Hf 3.26 2.72 2.37 2.16 2 1.98 1.55 5.1 4.26 3.71 3.38 3.14 3.11 2.43Nb 1.45 1.2 1.05 0.97 0.96 0.97 0.8 9.04 7.51 6.55 6.09 6.01 6.04 5Ta - - - - - - - - - - - - - -Th 0.72 0.56 0.46 0.41 0.38 0.36 0.27 3.24 2.51 2.08 1.85 1.72 1.63 1.21U 2.29 1.41 1.03 0.81 0.68 0.58 0.37 3.84 2.37 1.72 1.36 1.14 0.98 0.62Ni 1.38 1.35 1.37 1.48 1.69 2.37 7 3.54 3.48 3.51 3.8 4.36 6.09 18Co 16.49 15.45 14.88 15.22 16.22 18.54 25 13.19 12.36 11.9 12.18 12.98 14.83 20V 63.36 62.62 63.24 67.59 73.61 103.92 197 54.68 54.04 54.57 58.33 63.52 89.68 170Cr 0.73 0.75 0.79 0.88 0.82 1.15 10 1.67 1.73 1.82 2.02 1.88 2.63 23Sc 22.45 20.48 19.34 19.59 19.84 22.08 31 12.31 11.23 10.6 10.74 10.88 12.11 17

Calculated melt compositions (CL) at various degrees of partial melting (F) of standard sources (CO), using the equilibrium residual assemblage and bulk partition coefficient (D) of a metabasaltic system (Helz, 1973). The

bulk partition coefficient is tabulated in an accompanying table.SOURCE: Island arc basalt (tholeiitic composition) SOURCE: Island arc basalt (calc-alkaline composition)

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 17.39 14.38 12.29 10.79 9.76 9.16 6.3 6.9 5.71 4.88 4.28 3.87 3.64 2.5Ce 49.29 38.66 31.91 27.36 24.09 22.2 15 24.65 19.33 15.95 13.68 12.05 11.1 7.5Pr 20.5 10.25 6.83 5.13 4.1 3.42 2.05 13.2 6.6 4.4 3.3 2.64 2.2 1.32Nd 25.81 20.41 17.04 14.92 13.3 12.44 9 20.93 16.55 13.82 12.1 10.79 10.09 7.3Sm 5.76 4.74 4.08 3.7 3.37 3.25 2.6 5.83 4.79 4.13 3.75 3.41 3.29 2.63Eu 2.02 1.76 1.57 1.42 1.28 1.19 0.91 2.27 1.98 1.76 1.59 1.43 1.33 1.02Gd 6.46 5.25 4.5 4.1 3.74 3.57 2.97 8 6.51 5.58 5.08 4.64 4.42 3.68Tb 0.63 0.55 0.5 0.48 0.49 0.52 0.53 0.79 0.69 0.63 0.61 0.61 0.65 0.67Dy 7.63 6.21 5.33 4.85 4.43 4.24 3.55 9.78 7.96 6.83 6.22 5.68 5.43 4.55Ho 7.9 3.95 2.63 1.98 1.58 1.32 0.79 10.1 5.05 3.37 2.53 2.02 1.68 1.01Er 5.54 4.44 3.76 3.37 3.02 2.84 2.31 7.12 5.7 4.83 4.34 3.89 3.65 2.97Tm 2.46 1.48 1.06 0.83 0.67 0.59 0.36 3.17 1.92 1.37 1.07 0.87 0.76 0.46Yb 5.56 4.52 3.87 3.48 3.11 2.97 2.37 7.16 5.82 4.98 4.48 4.01 3.82 3.05Lu 1.01 0.78 0.65 0.57 0.5 0.46 0.35 1.3 1 0.83 0.73 0.64 0.59 0.46Rb 18.04 13.37 10.72 9.12 8.15 7.36 5.04 2 1.49 1.19 1.01 0.91 0.82 0.56Sr 168 188 207 208 225 211 155 97.27 109.22 119.98 120.85 130.67 122.44 90Ba 143 118 102 91 85 79 57 15.01 12.46 10.72 9.55 8.95 8.33 6K 3123 2720 2454 2333 2367 2406 2100 988 860 776 738 748 761 664Cs 0.63 0.32 0.21 0.16 0.13 0.11 0.06 0.07 0.04 0.02 0.02 0.01 0.01 0.01Pb 6 3 2 1.5 1.2 1 0.6 3 1.5 1 0.75 0.6 0.5 0.3Y 33.41 28.42 25.28 23.97 22.61 22.64 22 42.52 36.18 32.18 30.51 28.78 28.81 28Ti 4762 4451 4265 4309 4490 5356 6000 6031 5638 5403 5458 5688 6784 7600Zr 187.36 147.89 124.04 110.46 102.78 97.21 73 189.93 149.92 125.73 111.97 104.19 98.54 74Hf 4.26 3.56 3.1 2.83 2.62 2.59 2.03 4.31 3.6 3.13 2.85 2.65 2.62 2.05Nb 15 12.46 10.88 10.11 9.98 10.03 8.3 4.21 3.5 3.05 2.84 2.8 2.81 2.33Ta 3.24 1.96 1.4 1.09 0.89 0.77 0.47 0.9 0.54 0.39 0.3 0.25 0.21 0.13Th 1.61 1.24 1.03 0.92 0.85 0.81 0.6 0.32 0.25 0.21 0.18 0.17 0.16 0.12U 1.11 0.69 0.5 0.4 0.33 0.28 0.18 0.31 0.19 0.14 0.11 0.09 0.08 0.05Ni - - - - - - - 42.12 41.39 41.76 45.16 51.82 72.38 214Co - - - - - - - 32.83 30.77 29.63 30.31 32.3 36.92 49.78V - - - - - - - 84.27 83.28 84.11 89.89 97.9 138.21 262Cr - - - - - - - 38.43 39.63 41.72 46.46 43.08 60.46 528Sc - - - - - - - 28.98 26.43 24.96 25.29 25.61 28.5 40.02

SOURCE: E-MORB SOURCE:N-MORB


62

Continued: Melt compositions using the equilibrium residual assemblage of a metabasaltic system

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 1.52 1.26 1.07 0.94 0.85 0.8 0.55 30.36 25.11 21.47 18.84 17.04 16 11Ce 4.73 3.71 3.06 2.63 2.31 2.13 1.44 75.58 59.28 48.93 41.96 36.94 34.04 23Pr 2.1 1.05 0.7 0.53 0.42 0.35 0.21 28 14 9.33 7 5.6 4.67 2.8Nd 4.62 3.65 3.05 2.67 2.38 2.23 1.61 36.42 28.8 24.04 21.06 18.77 17.55 12.7Sm 0.78 0.64 0.55 0.5 0.45 0.44 0.35 7.02 5.78 4.98 4.51 4.11 3.97 3.17Eu 0.29 0.25 0.23 0.2 0.18 0.17 0.13 2.6 2.27 2.01 1.82 1.64 1.53 1.17Gd 1 0.81 0.7 0.63 0.58 0.55 0.46 6.8 5.54 4.75 4.32 3.94 3.76 3.13Tb 0.11 0.09 0.08 0.08 0.08 0.09 0.09 0.7 0.61 0.56 0.54 0.54 0.57 0.59Dy 1.23 1 0.86 0.78 0.71 0.68 0.57 7.74 6.3 5.4 4.92 4.49 4.3 3.6Ho 1.3 0.65 0.43 0.33 0.26 0.22 0.13 7.7 3.85 2.57 1.93 1.54 1.28 0.77Er 0.9 0.72 0.61 0.55 0.49 0.46 0.37 5.27 4.22 3.58 3.21 2.88 2.71 2.2Tm 0.34 0.21 0.15 0.12 0.09 0.08 0.05 2.21 1.33 0.96 0.74 0.61 0.53 0.32Yb 0.87 0.71 0.6 0.54 0.49 0.46 0.37 5.16 4.2 3.59 3.23 2.89 2.75 2.2Lu 0.16 0.13 0.1 0.09 0.08 0.07 0.06 0.83 0.64 0.53 0.47 0.41 0.38 0.29Rb 1.97 1.46 1.17 1 0.89 0.8 0.55 18.97 14.06 11.27 9.59 8.57 7.74 5.3Sr 19.45 21.84 24.00 24.2 26.13 24.49 18.00 248.6 279.1 306.6 308.9 333.9 312.9 230.00Ba 12.51 10.38 8.93 7.96 7.46 6.94 5.00 375.3 311.5 268.0 238.7 223.8 208.2 150.00K 268 233 210 200 203 206 180 3703 3225 2910 2766 2807 2853 2490Cs 0.18 0.09 0.06 0.05 0.04 0.03 0.02 1 0.5 0.33 0.25 0.2 0.17 0.1Pb 1.2 0.6 0.4 0.3 0.24 0.2 0.12 40 20 13.33 10 8 6.67 4Y 5.16 4.39 3.91 3.7 3.49 3.5 3.4 28.86 24.55 21.84 20.7 19.53 19.55 19Ti 762 712 682 689 718 857 960 4758 4447 4262 4306 4486 5352 5995Zr 21.3 16.82 14.1 12.56 11.69 11.05 8.3 179.66 141.82 118.94 105.92 98.56 93.22 70Hf - - - - - - - 4.41 3.68 3.2 2.92 2.71 2.68 2.1Nb 1.01 0.84 0.73 0.68 0.67 0.68 0.56 10.85 9.01 7.86 7.31 7.22 7.25 6Ta - - - - - - - 4.14 2.5 1.79 1.4 1.14 0.98 0.6Th 1.72 1.33 1.1 0.98 0.91 0.86 0.64 2.84 2.2 1.82 1.62 1.51 1.43 1.06U 0.12 0.08 0.06 0.04 0.04 0.03 0.02 1.73 1.07 0.78 0.62 0.51 0.44 0.28Ni 393.69 386.85 390.32 422.07 484.26 676.41 2000 26.57 26.11 26.35 28.49 32.69 45.66 135Co - - - - - - 110* 23.08 21.63 20.83 21.31 22.71 25.96 35V 41.17 40.69 41.09 43.92 47.83 67.52 128 91.66 90.59 91.49 97.78 106.49 150.34 285Cr 218.37 225.19 237.04 263.95 244.75 343.55 3000 17.11 17.64 18.57 20.68 19.17 26.91 235Sc 9.41 8.59 8.11 8.21 8.32 9.26 13 26.07 23.78 22.46 22.75 23.04 25.64 36

SOURCE: Primitive mantle (=depleted mantle) SOURCE: Lower crustal average

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 21.61 17.88 15.28 13.4 12.13 11.39 7.83 102.11 84.47 72.2 63.37 57.32 53.8 37Ce 62.44 48.97 40.42 34.7 30.52 28.12 19 262.9 206.19 170.18 145.93 128.48 118.4 80Pr - - - - - - - 97 48.5 32.33 24.25 19.4 16.17 9.7Nd 37.57 29.71 24.80 21.7 19.36 18.11 13.1 110.41 87.3 72.87 63.83 56.89 53.22 38.5Sm 8.73 7.18 6.19 5.61 5.11 4.93 3.94 22.15 18.23 15.71 14.24 12.96 12.52 10Eu - - - - - - - 6.67 5.81 5.17 4.67 4.21 3.93 3Gd - - - - - - - 16.56 13.48 11.56 10.51 9.6 9.16 7.62Tb - - - - - - - 1.24 1.08 0.99 0.96 0.96 1.02 1.05Dy - - - - - - - 12.03 9.8 8.41 7.66 6.99 6.68 5.6Ho - - - - - - - 10.6 5.3 3.53 2.65 2.12 1.77 1.06Er - - - - - - - 6.28 5.03 4.26 3.83 3.43 3.22 2.62Tm - - - - - - - 2.41 1.46 1.04 0.81 0.66 0.58 0.35Yb - - - - - - - 5.07 4.12 3.52 3.17 2.84 2.7 2.16Lu - - - - - - - 0.85 0.66 0.55 0.48 0.42 0.39 0.3Rb 21.5 15.9 12.8 10.9 9.7 8.8 6 111.0 82.2 65.9 56.1 50.1 45.3 31.0Sr 229 257 283 285 308 288 212 713 801 880 886 958 898 660Ba 193 160 138 123 115 107 77 876 727 625 557 522 486 350K 5308 4623 4170 3965 4023 4089 3569 17847 15544 14022 13332 13527 13749 12000Cs - - - - - - - 3.87 1.94 1.29 0.97 0.77 0.65 0.39Pb - - - - - - - 32 16 10.67 8 6.4 5.33 3.2Y 45.56 38.76 34.48 32.7 30.83 30.87 30 44.04 37.47 33.33 31.6 29.8 29.84 29Ti 6946 6493 6222 6286 6550 7814 8753 13650 12760 12227 12353 12872 15354 17200Zr 333.7 263.4 220.9 197 183.0 173.1 130 718.65 567.26 475.75 423.68 394.23 372.86 280Hf - - - - - - - 16.38 13.68 11.9 10.86 10.07 9.97 7.8Nb 14.46 12.01 10.48 9.75 9.62 9.66 8 86.78 72.07 62.91 58.49 57.74 57.98 48Ta - - - - - - - 18.62 11.25 8.06 6.28 5.11 4.43 2.7Th - - - - - - - 10.72 8.3 6.88 6.1 5.7 5.38 4U - - - - - - - 6.31 3.89 2.83 2.24 1.87 1.61 1.02Ni - - - - - - - - - - - - - -Co - - - - - - - - - - - - - -V - - - - - - - - - - - - - -Cr - - - - - - - - - - - - - -Sc - - - - - - - - - - - - - -

SOURCE: Back-arc basalt SOURCE: OIB (Olivine island basalt)


63

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 11.86 8.55 7.76 6.15 5.14 4.44 3 46.25 33.35 30.25 24 20.05 17.32 11.7Ce 32.61 22.06 19.01 14.8 12.2 10.45 6.9 111.06 75.13 64.75 50.42 41.55 35.57 23.5Pr 12.5 6.25 4.17 3.13 2.5 2.08 1.25 29 14.5 9.67 7.25 5.8 4.83 2.9Nd 33.77 22.39 21.31 16.01 13.02 11.15 7.8 73.61 48.81 46.44 34.89 28.38 24.3 17Sm 9.3 6.27 6.75 4.94 3.99 3.44 2.6 14.85 10.01 10.77 7.88 6.37 5.48 4.15Eu 2.7 2.18 2.18 1.82 1.57 1.39 1 3.65 2.94 2.94 2.45 2.11 1.87 1.35Gd 7.63 5.24 5.96 4.34 3.51 3.04 2.4 10.81 7.43 8.44 6.15 4.97 4.3 3.4Tb 1.15 0.78 1.19 0.77 0.61 0.53 0.52 1.55 1.05 1.6 1.04 0.82 0.71 0.7Dy 9.24 6.44 7.28 5.36 4.35 3.78 3 10.78 7.51 8.49 6.26 5.08 4.41 3.5Ho 9 4.5 3 2.25 1.8 1.5 0.9 8.6 4.3 2.87 2.15 1.72 1.43 0.86Er 7.86 5.61 5.94 4.54 3.73 3.26 2.5 7.86 5.61 5.94 4.54 3.73 3.26 2.5Tm 3.4 1.7 1.13 0.85 0.68 0.57 0.34 3 1.5 1 0.75 0.6 0.5 0.3Yb 7.88 5.81 5.83 4.62 3.85 3.39 2.55 5.75 4.24 4.25 3.37 2.81 2.47 1.86Lu 1.29 0.97 0.93 0.75 0.63 0.56 0.41 1.38 1.04 0.99 0.81 0.68 0.6 0.44Rb 38.75 25.17 23.2 17.41 14.14 12.06 8.3 130.71 84.91 78.28 58.72 47.69 40.7 28Sr 208.55 230.13 235.74 264.7 286.78 298 220 411.41 453.97 465.06 522.09 565.73 586.96 434Ba 476.13 356.51 362.02 285.7 239.6 209 152 996.12 745.85 757.39 597.79 501.27 437.42 318K 7393.6 5384.9 7081.8 5108 4163.8 3646 3240 19716 14360 18885 13622 11104 9722.28 8640Cs 2.3 1.15 0.77 0.58 0.46 0.38 0.23 7.6 3.8 2.53 1.9 1.52 1.27 0.76Pb 29 14.5 9.67 7.25 5.8 4.83 2.9 50 25 16.67 12.5 10 8.33 5Y 60.11 42.29 55.93 39.51 31.76 27.75 25 48.09 33.83 44.74 31.61 25.4 22.2 20Ti 7948.2 5622.4 8780.9 5862 4661.3 4087.5 4300 8317.9 5883.9 9189.3 6134.1 4878.1 4277.57 4500Zr 217.99 151.09 157.35 118.6 96.73 83.87 63 384.08 266.21 277.24 208.93 170.43 147.76 111Hf 6.01 3.91 4.19 3.01 2.41 2.06 1.55 9.42 6.13 6.57 4.71 3.78 3.23 2.43Nb 2.3 1.57 1.93 1.37 1.1 0.95 0.8 14.39 9.82 12.06 8.55 6.86 5.95 5Ta - - - - - - - - - - - - - -Th 1.13 0.7 0.76 0.53 0.42 0.36 0.27 5.05 3.16 3.4 2.39 1.9 1.61 1.21U 2.81 1.55 1.18 0.87 0.7 0.59 0.37 4.71 2.59 1.98 1.47 1.17 0.98 0.62Ni 2.46 2.15 2.79 2.34 2.18 2.17 7 6.34 5.54 7.17 6.02 5.61 5.57 18Co 18.32 17.82 13.12 12.67 13.08 13.44 25 14.66 14.25 10.49 10.13 10.47 10.75 20V 174.26 131.4 255.36 167.4 133.85 121.16 197 150.38 113.39 220.36 144.44 115.51 104.55 170Cr 1.89 1.69 2.91 2.49 2.22 2.26 10 4.36 3.9 6.69 5.73 5.1 5.2 23Sc 33.9 27.21 40.68 31.24 26.21 24.28 31 18.59 14.92 22.31 17.13 14.37 13.31 17

Calculated melt compositions (CL) at various degrees of partial melting (F) of standard sources (CO), using the equilibrium residual assemblage and bulk partition coefficient (D) of an amphibolitic system (Rapp et al., 1991,

Rapp & Watson, 1995). D is tabulated in an accompanying table.SOURCE: Island arc basalt (tholeiitic composition) Island arc basalt (calc-alkaline composition)

F 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 17.53 16.13 13.35 11.31 9.78 6.3 9.88 7.13 6.46 5.13 4.28 3.7 2.5Ce 45.47 39.75 32.26 27.27 23.52 15 35.44 23.98 20.67 16.09 13.26 11.35 7.5Pr 10.25 7.1 5.13 4.1 3.42 2.05 13.2 6.6 4.4 3.3 2.64 2.2 1.32Nd 22.05 20.89 17.79 15.61 13.75 9 31.61 20.96 19.94 14.98 12.19 10.43 7.3Sm 4.89 4.97 4.49 4.15 3.77 2.6 9.41 6.34 6.83 4.99 4.04 3.48 2.63Eu 1.74 1.56 1.43 1.33 1.23 0.91 2.76 2.22 2.22 1.85 1.6 1.42 1.02Gd 4.94 5.17 4.8 4.54 4.2 2.97 11.7 8.04 9.14 6.66 5.38 4.66 3.68Tb 0.58 0.8 0.82 0.8 0.75 0.53 1.49 1 1.53 1 0.78 0.68 0.67Dy 5.83 6.1 5.68 5.39 4.99 3.55 14.02 9.76 11.04 8.13 6.6 5.74 4.55Ho 3.95 2.74 1.98 1.58 1.32 0.79 10.1 5.05 3.37 2.53 2.02 1.68 1.01Er 4.07 4.04 3.71 3.51 3.24 2.31 9.33 6.66 7.06 5.39 4.43 3.87 2.97Tm 1.78 1.23 0.89 0.71 0.59 0.36 4.6 2.3 1.53 1.15 0.92 0.77 0.46Yb 4.45 4.3 3.9 3.65 3.35 2.37 9.42 6.95 6.98 5.53 4.61 4.06 3.05Lu 0.71 0.67 0.6 0.55 0.51 0.35 1.43 1.07 1.03 0.84 0.7 0.62 0.46Rb 14.18 14.01 11.41 9.53 8.12 5.04 2.61 1.7 1.57 1.17 0.95 0.81 0.56Sr 214.33 187.77 186.7 173.83 167.86 155 85.32 94.14 96.44 108.27 117.32 121.72 90Ba 128.8 136.81 118.4 101.27 87.9 57 18.79 14.07 14.29 11.28 9.46 8.25 6K 3025.6 4315.6 4159 3704.4 3247.9 2100 1515.2 1103.6 1451.3 1046.9 853.33 747.18 664Cs 0.32 0.22 0.16 0.13 0.11 0.06 0.07 0.04 0.02 0.02 0.01 0.01 0.01Pb 3 2.08 1.5 1.2 1 0.6 3 1.5 1 0.75 0.6 0.5 0.3Y 26.54 30.14 29.87 29.97 28.89 22 67.32 47.36 62.64 44.25 35.57 31.08 28Ti 6058.2 9227.2 9693 9426.6 8696.7 6000 14048 9937.2 15520 10360 8238.5 7224.33 7600Zr 157.44 179.17 155.2 133.9 115.73 73 256.06 177.48 184.82 139.29 113.62 98.51 74Hf 4.14 4.42 3.9 3.48 3.09 2.03 7.95 5.17 5.54 3.97 3.19 2.73 2.05Nb 14.15 20.09 18.37 15.85 13.55 8.3 6.71 4.58 5.62 3.99 3.2 2.77 2.33Ta 2.33 1.6 1.16 0.93 0.78 0.47 1.3 0.65 0.43 0.33 0.26 0.22 0.13Th 1.34 1.6 1.36 1.15 0.98 0.6 0.5 0.31 0.34 0.24 0.19 0.16 0.12U 0.7 0.56 0.43 0.35 0.3 0.18 0.38 0.21 0.16 0.12 0.09 0.08 0.05Ni - - - - - - 75.34 65.82 85.2 71.62 66.65 66.25 214Co - - - - - - 36.48 35.48 26.12 25.22 26.05 26.76 49.78V - - - - - - 231.76 174.76 339.62 222.6 178.02 161.13 262Cr - - - - - - 100.01 89.44 153.53 131.64 117.12 119.46 528Sc - - - - - - 43.76 35.13 52.52 40.33 33.84 31.34 40.02

SOURCE: E-MORB SOURCE: N-MORB


64

Continued: Melt compositions based on residual assemblage of amphibolitic systems

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 2.17 1.57 1.42 1.13 0.94 0.81 0.55 43.48 31.36 28.44 22.56 18.85 16.28 11Ce 6.81 4.6 3.97 3.09 2.55 2.18 1.44 108.7 73.53 63.37 49.34 40.66 34.82 23Pr 2.1 1.05 0.7 0.53 0.42 0.35 0.21 28 14 9.33 7 5.6 4.67 2.8Nd 6.97 4.62 4.4 3.3 2.69 2.3 1.61 54.99 36.46 34.7 26.06 21.21 18.15 12.7Sm 1.25 0.84 0.91 0.66 0.54 0.46 0.35 11.34 7.65 8.23 6.02 4.87 4.19 3.17Eu 0.35 0.29 0.29 0.24 0.21 0.18 0.13 3.16 2.55 2.55 2.13 1.83 1.62 1.17Gd 1.46 1 1.14 0.83 0.67 0.58 0.46 9.95 6.84 7.77 5.66 4.58 3.96 3.13Tb 0.2 0.13 0.21 0.13 0.1 0.09 0.09 1.31 0.88 1.35 0.88 0.69 0.6 0.59Dy 1.76 1.23 1.39 1.02 0.83 0.72 0.57 11.09 7.73 8.73 6.44 5.23 4.54 3.6Ho 1.3 0.65 0.43 0.33 0.26 0.22 0.13 7.7 3.85 2.57 1.93 1.54 1.28 0.77Er 1.18 0.84 0.89 0.68 0.56 0.49 0.37 6.91 4.94 5.23 4 3.28 2.87 2.2Tm 0.5 0.25 0.17 0.13 0.1 0.08 0.05 3.2 1.6 1.07 0.8 0.64 0.53 0.32Yb 1.14 0.84 0.85 0.67 0.56 0.49 0.37 6.8 5.02 5.03 3.99 3.32 2.93 2.2Lu 0.18 0.13 0.13 0.1 0.09 0.08 0.06 0.91 0.68 0.66 0.53 0.45 0.4 0.29Rb 2.57 1.67 1.54 1.15 0.94 0.8 0.55 24.74 16.07 14.82 11.11 9.03 7.7 5.3Sr 17.06 18.83 19.29 21.65 23.46 24.34 18.00 218.03 240.59 246.46 276.68 299.81 311.06 230.00Ba 15.66 11.73 11.91 9.4 7.88 6.88 5.00 469.87 351.82 357.26 281.98 236.45 206.33 150.00K 410.75 299.16 393.43 283.8 231.32 202.55 180 5682.1 4138.4 5442.5 3925.7 3200 2801.91 2490Cs 0.18 0.09 0.06 0.05 0.04 0.03 0.02 1 0.5 0.33 0.25 0.2 0.17 0.1Pb 1.2 0.6 0.4 0.3 0.24 0.2 0.12 40 20 13.33 10 8 6.67 4Y 8.18 5.75 7.61 5.37 4.32 3.77 3.4 45.68 32.14 42.51 30.03 24.13 21.09 19Ti 1774.5 1255.2 1960.4 1309 1040.7 912.55 960 11081 7838.7 12242 8172 6498.6 5698.67 5995Zr 28.72 19.91 20.73 15.62 12.74 11.05 8.3 242.21 167.88 174.83 131.76 107.48 93.18 70Hf - - - - - - - 8.14 5.3 5.68 4.07 3.27 2.8 2.1Nb 1.61 1.1 1.35 0.96 0.77 0.67 0.56 17.27 11.78 14.48 10.27 8.23 7.13 6Ta - - - - - - - 6 3 2 1.5 1.2 1 0.6Th 2.67 1.67 1.8 1.26 1 0.85 0.64 4.43 2.77 2.98 2.09 1.66 1.41 1.06U 0.15 0.08 0.06 0.05 0.04 0.03 0.02 2.13 1.17 0.89 0.66 0.53 0.44 0.28Ni 704.1 615.16 796.29 669.4 622.91 619.2 2000 47.53 41.52 53.75 45.18 42.05 41.8 135Co - - - - - - 110* 25.65 24.94 18.36 17.73 18.32 18.82 35V 113.22 85.38 165.92 108.8 86.97 78.72 128 252.1 190.1 369.43 242.14 193.65 175.28 285Cr 568.24 508.2 872.31 748 665.45 678.73 3000 44.51 39.81 68.33 58.59 52.13 53.17 235Sc 14.22 11.41 17.06 13.1 10.99 10.18 13 39.37 31.6 47.24 36.28 30.44 28.19 36

SOURCE: Primitive mantle (=depleted mantle) SOURCE: Lower crustal average

F 0.1 0.2 0.3 0.4 0.5 0.6 Co 0.1 0.2 0.3 0.4 0.5 0.6 CoLa 30.949 22.32 20.243 16.06 13.415 11.588 - 102.96 94.71 78.41 66.41 57.43 37Ce 89.792 60.742 52.352 40.76 33.593 28.762 - 242.48 212.01 172.05 145.45 125.46 80Pr - - - - - - - 48.5 33.59 24.25 19.4 16.17 9.7Nd 56.722 37.609 35.789 26.88 21.873 18.725 - 94.33 89.38 76.09 66.78 58.8 38.5Sm 14.094 9.502 10.229 7.482 6.05 5.207 - 18.81 19.1 17.27 15.95 14.51 10Eu - - - - - - - 5.74 5.16 4.7 4.38 4.06 3Gd - - - - - - - 12.67 13.27 12.33 11.65 10.77 7.62Tb - - - - - - - 1.15 1.58 1.62 1.59 1.49 1.05Dy - - - - - - - 9.19 9.62 8.96 8.5 7.88 5.6Ho - - - - - - - 5.3 3.67 2.65 2.12 1.77 1.06Er - - - - - - - 4.62 4.59 4.21 3.98 3.68 2.62Tm - - - - - - - 1.75 1.21 0.88 0.7 0.58 0.35Yb - - - - - - - 4.06 3.92 3.56 3.32 3.06 2.16Lu - - - - - - - 0.6 0.57 0.51 0.47 0.43 0.3Rb 28.01 18.195 16.774 12.58 10.219 8.721 - 87.2 86.17 70.15 58.61 49.92 31Sr 200.97 221.76 227.17 255 276.35 286.72 - 912.61 799.53 794.87 740.16 714.75 660Ba 241.2 180.6 183.39 144.7 121.38 105.92 - 790.85 840.06 726.75 621.84 539.76 350K 8144 5932 7801 5627 4587 4016 - 17289 24661 23767 21168 18560 12000Cs - - - - - - - 1.94 1.34 0.97 0.77 0.65 0.39Pb - - - - - - - 16 11.08 8 6.4 5.33 3.2Y 72.133 50.744 67.114 47.41 38.107 33.296 - 34.99 39.73 39.37 39.51 38.08 29Ti 16179 11445 17874 11932 9488.3 8320.3 - 17367 26451 27787 27023 24930.43 17200Zr 449.83 311.78 324.69 244.7 199.6 173.06 - 603.86 687.23 595.19 513.57 443.89 280Hf - - - - - - - 15.91 16.97 15 13.39 11.86 7.8Nb 23.022 15.711 19.303 13.69 10.97 9.512 - 81.86 116.19 106.22 91.67 78.34 48Ta - - - - - - - 13.36 9.22 6.68 5.37 4.48 2.7Th - - - - - - - 8.96 10.65 9.07 7.67 6.53 4U - - - - - - - 3.98 3.2 2.43 1.99 1.67 1.02Ni - - - - - - - - - - - - -Co - - - - - - - - - - - - -V - - - - - - - - - - - - -Cr - - - - - - - - - - - - -Sc - - - - - - - - - - - - -

SOURCE: Back-arc basalt SOURCE: OIB (Olivine island basalt)


65

Bulk partition coefficient (D) of various elements at different degree of partial melting (F) for the metabasalt and amphibolite systems

METABASALT (<8 kbars, H2O unsat, <1000oC) AMPHIBOLITE N-MORB (8 kbar, H2O sat., >1000oC)

F 0.1 0.2 0.3 0.4 0.5 0.6 F 0.1 0.2 0.30 0.40 0.50 0.60La 0.2915 0.2975 0.3035 0.307 0.2909 0.2192 La 0.17 0.1885 0.12 0.15 0.17 0.19Ce 0.227 0.235 0.243 0.247 0.2453 0.1892 Ce 0.124 0.141 0.09 0.11 0.13 0.15Pr - - - - - - Pr - - - - - -Nd 0.2764 0.3013 0.3262 0.339 0.3535 0.3087 Nd 0.1455 0.1854 0.09 0.15 0.20 0.25Sm 0.3905 0.4358 0.4811 0.504 0.5433 0.4975 Sm 0.1995 0.2683 0.12 0.21 0.30 0.39Eu 0.389 0.395 0.401 0.404 0.4241 0.4107 Eu 0.3 0.3235 0.23 0.25 0.28 0.30Gd 0.4001 0.4568 0.5135 0.542 0.5874 0.5803 Gd 0.2385 0.3222 0.15 0.25 0.37 0.48Tb 0.83 0.96 1.09 1.155 1.1805 1.0725 Tb 0.39 0.585 0.20 0.46 0.72 0.98Dy 0.406 0.4645 0.523 0.552 0.6023 0.595 Dy 0.2495 0.3325 0.16 0.27 0.38 0.48Ho - - - - - - Ho - - - - - -Er 0.3524 0.4011 0.4498 0.474 0.5278 0.5316 Er 0.2425 0.3072 0.17 0.25 0.34 0.42Tm - - - - - - Tm - - - - - -Yb 0.3625 0.4048 0.4471 0.468 0.5228 0.498 Yb 0.2485 0.2983 0.20 0.25 0.32 0.38Lu 0.279 0.316 0.353 0.372 0.4199 0.4289 Lu 0.243 0.2805 0.20 0.24 0.30 0.33Rb 0.1994 0.2213 0.2432 0.254 0.2372 0.2112 Rb 0.1269 0.1622 0.08 0.13 0.17 0.22Sr 0.917 0.78 0.643 0.575 0.3776 0.3376 Sr 1.061 0.945 0.90 0.72 0.53 0.35Ba 0.333 0.352 0.371 0.381 0.3405 0.301 Ba 0.2436 0.283 0.17 0.22 0.27 0.32K 0.636 0.715 0.794 0.834 0.7743 0.6819 K 0.3758 0.5021 0.23 0.39 0.56 0.72Cs - - - - - - Cs - - - - - -Pb - - - - - - Pb - - - - - -Y 0.6205 0.7175 0.8145 0.863 0.946 0.9293 Y 0.351 0.489 0.21 0.39 0.57 0.75Ti 1.289 1.435 1.581 1.654 1.6725 1.3006 Ti 0.49 0.706 0.27 0.56 0.85 1.13Zr 0.3218 0.367 0.4122 0.435 0.4205 0.3774 Zr 0.21 0.2712 0.14 0.22 0.30 0.38Hf 0.4179 0.4628 0.5077 0.53 0.5495 0.4561 Hf 0.1755 0.2454 0.10 0.19 0.29 0.38Nb 0.5035 0.5825 0.6615 0.701 0.6628 0.5696 Nb 0.275 0.3865 0.16 0.31 0.46 0.60Ta 0.05 0.05 0.05 0.05 0.057 0.0233 Ta 0 0 0.00 0.00 0.00 0.00Th 0.3035 0.3525 0.4015 0.426 0.4045 0.3575 Th 0.155 0.229 0.08 0.18 0.28 0.38U 0.0685 0.0775 0.0865 0.091 0.0915 0.0821 U 0.035 0.049 0.02 0.04 0.06 0.08Ni 5.5335 6.2125 6.8915 7.231 7.26 5.892 Ni 3.045 3.814 3.16 4.31 5.42 6.58Co 1.5735 1.7725 1.9715 2.071 2.082 1.871 Co 1.405 1.504 2.29 2.62 2.82 3.15V 3.3435 3.6825 4.0215 4.191 4.3525 3.2393 V 1.145 1.624 0.67 1.30 1.94 2.57Cr 15.154 16.403 17.652 18.28 23.515 20.331 Cr 5.755 7.129 4.48 6.018 8.0165 9.55Sc 1.4235 1.6425 1.8615 1.971 2.125 2.0101 Sc 0.905 1.174 0.66 0.99 1.37 1.69Mn 0 0 0 0 0.045 0.1185 Mn 0.28 0.21 0.57 0.50 0.43 0.36

BULK PARTITION COEFFICIENT (D) BULK PARTITION COEFFICIENT (D)

Mineral F % Rb Sr Ba Co KOlivine 0 10 500 300 50 8000Olivine 1 10.1 504.98 303 48.37 8080.3Olivine 3 10.31 515.24 309.2 45.22 8245.7Olivine 5 10.52 525.94 315.6 42.21 8418.1Olivine 10 11.1 554.74 333 35.32 8882.5Olivine 20 12.47 623.05 374.2 23.94 9984.8Olivine 30 14.23 710.73 427.1 15.41 11401Olivine 50 19.86 990.34 595.9 5.08 15925Olivine 70 32.93 1638.8 988 0.94 26449Olivine 90 97.72 4841.4 2932 0.03 78757Orthopyroxene 0 10 500 300 50 8000Orthopyroxene 1 10.1 504.96 303 48.91 8079.7Orthopyroxene 3 10.3 515.2 309.2 46.76 8243.9Orthopyroxene 5 10.51 525.86 315.6 44.66 8415Orthopyroxene 10 11.09 554.56 332.9 39.66 8875.8Orthopyroxene 20 12.44 622.63 373.9 30.6 9968.8Orthopyroxene 30 14.17 709.97 426.6 22.81 11372Orthopyroxene 50 19.7 988.29 594.6 10.88 15845Orthopyroxene 70 32.46 1632.9 984.5 3.54 26221Orthopyroxene 90 95.06 4808.1 2912 0.32 77462Clinopyroxene 0 10 500 300 50 8000Clinopyroxene 1 10.1 504.68 303 49.75 8077.7Clinopyroxene 3 10.3 514.32 309.2 49.24 8237.9Clinopyroxene 5 10.52 524.34 315.7 48.73 8404.7Clinopyroxene 10 11.09 551.29 333.1 47.43 8853.4Clinopyroxene 20 12.44 614.87 374.4 44.72 9915.6Clinopyroxene 30 14.18 695.88 427.5 41.83 11275

(F %). Mineral KDs are tabulated in the Appendix.

Calculations for mineral vector diagram for Rb, Sr, Ba, Co and K at various degrees of fractional crystallisation (F %). Mineral KDs are tabulated in the Appendix.


66

Calculations for mineral vector diagram (continued)Mineral F % Rb Sr Ba Co KClinopyroxene 50 19.72 950.53 597.1 35.36 15584Clinopyroxene 70 32.54 1526.1 991.6 27.39 25474Clinopyroxene 90 95.5 4224.5 2952 15.81 73298Hornblende 0 10 500 300 50 8000Hornblende 1 10.07 502.72 301.8 47.31 8003.2Hornblende 3 10.22 508.29 305.4 42.29 8009.8Hornblende 5 10.37 514.04 309.1 37.71 8016.4Hornblende 10 10.78 529.27 318.9 28.01 8033.8Hornblende 20 11.72 564.03 341.5 14.65 8071.7Hornblende 30 12.88 606.2 369 7.03 8115Hornblende 50 16.36 726.99 448.5 1.1 8224.9Hornblende 70 23.51 957.91 603.1 0.07 8394.7Hornblende 90 51.29 1733.7 1141 0 8771.8Biotite 0 10 500 300 50 -Biotite 1 9.78 504.64 299.7 - -Biotite 3 9.33 514.19 299.2 - -Biotite 5 8.91 524.13 298.6 - -Biotite 10 7.88 550.83 297.2 - -Biotite 20 6.04 613.8 294 - -Biotite 30 4.47 693.94 290.5 - -Biotite 50 2.09 945.4 281.9 - -Biotite 70 0.66 1511.8 269.2 - -Biotite 90 0.05 4149.3 243.9 - -Plagioclase 0 10 500 300 50 8000Plagioclase 1 10.09 495.85 302.3 50.49 8067Plagioclase 3 10.29 487.52 307.1 51.5 8204.8Plagioclase 5 10.49 479.16 312.1 52.55 8347.9Plagioclase 10 11.03 458.13 325.4 55.38 8731.1Plagioclase 20 12.31 415.47 356.2 62.08 9627.8Plagioclase 30 13.93 371.88 394.8 70.67 10756Plagioclase 50 19.05 281.26 511.6 97.94 14221Plagioclase 70 30.64 184.07 758.1 160.75 21731Plagioclase 90 85.11 73.96 1767 466.63 54087K-feldspars 0 10 500 300 50 8000K-feldspars 1 10.07 485.78 285 - 7598.8K-feldspars 3 10.2 458.15 256.7 - 6844.8K-feldspars 5 10.34 431.56 230.7 - 6152.3K-feldspars 10 10.72 369.53 174.9 - 4664.6K-feldspars 20 11.59 263.53 95.71 - 2552.2K-feldspars 30 12.65 179.64 48.31 - 1288.2K-feldspars 50 15.8 68.39 8.63 - 230.05K-feldspars 70 22.14 15.79 0.63 - 16.825K-feldspars 90 45.71 0.67 0 - 0.0607

APPENDIX 5 PETROGENETIC MODELS REFERENCE DATA

67

AVERAGE GEOCHEMISTRY OF MAJOR SOURCE REGIONS

Mantle N-MORB E-MORB IAB Calc-alkaline

IAB Tholeiite

OIB Lower crust Ocean crust

La 0.55 2.5 6.3 11.7 3 37 11 3.7 Ce 1.44 7.5 15 23.5 6.9 80 23 11.5 Pr 0.21 1.32 2.05 2.9 1.25 9.7 2.8 1.8 Nd 1.61 7.3 9 17 7.8 38.5 12.7 10 Sm 0.35 2.63 2.6 4.15 2.6 10 3.17 3.3 Eu 0.13 1.02 0.91 1.35 1 3 1.17 1.3 Gd 0.46 3.68 2.97 3.4 2.4 7.62 3.13 4.6 Tb 0.09 0.67 0.53 0.7 0.52 1.05 0.59 0.87 Dy 0.57 4.55 3.55 3.5 3 5.6 3.6 5.7 Ho 0.13 1.01 0.79 0.86 0.9 1.06 0.77 1.3 Er 0.37 2.97 2.31 2.5 2.5 2.62 2.2 3.7 Tm 0.05 0.46 0.36 0.3 0.34 0.35 0.32 0.54 Yb 0.37 3.05 2.37 1.86 2.55 2.16 2.2 5.1 Lu 0.06 0.46 0.35 0.44 0.41 0.3 0.29 0.56 Rb 0.55 0.56 5.04 28 8.3 31 5.3 2.2 Sr 18 90 155 434 220 660 230 130 Ba 5 6 57 318 152 350 150 25 K 180 664 2100 8640 3240 12000 2490 - Cs 0.02 0.01 0.06 0.76 0.23 0.39 0.1 0.03 Pb 0.12 0.3 0.6 5 2.9 3.2 4 0.8 Y 3.4 28 22 20 25 29 19 32 Ti 960 7600 6000 4500 4300 17200 5995 - Zr 8.3 74 73 111 63 280 70 80 Hf - 2.05 2.03 2.43 1.55 7.8 2.1 2.5 Nb 0.56 2.33 8.3 5 0.8 48 6 2.2 Ta - 0.13 0.47 - - 2.7 0.6 0.3 Th 0.64 0.12 0.6 1.21 0.27 4 1.06 0.22 U 0.02 0.05 0.18 0.62 0.37 1.02 0.28 0.1 Ni 2000 214 - 18 7 - 135 135 Co 110* 49.78 - 20 25 - 35 47 V 128 262 - 170 197 - 285 250 Cr 3000 528 - 23 10 - 235 270 Sc 13 40.02 - 17 31 - 36 38 Data source Taylor &

McLennan(1985)

Sun & McDonough

(1989)

Sun & McDonough

(1989)

Bailey (1981)

Bailey (1981)

Sun & McDonough

(1989)

Taylor & McLennan

(1985)

Taylor & McLennan

(1985) BAILEY J. C. 1981. Geochemical criteria for a refined tectonic discrimination of orogenic andesites. Chemical Geology

32, 139-154

SUN S. S. & McDONOUGH W. F. 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In Saunders A. D. and Norry M. J. eds. Magmatism in ocean basins. Geological Society of London, Special Publication 42, 313-345

*SUN S. S. 1982. Chemical composition and origin of the earth’s primitive mantle. Geochimica Cosmochimica Acta 46, 179-192

TAYLOR S. R. & McLENNAN S. M. 1985. The continental crust: its composition and evolution. Blackwell, Oxford.


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PARTITION COEFFICIENTS A. Basaltic partition coefficients (for whole rock composition <57 SiO2 wt %) Orthopy Clinopy Hornb. Plag. Biotite Magnetite Ilmenite Olivine Apatite Sphene Zircon La - 0.056 2 0.5442 2 0.1477 2 - 1.5 3 - 0.0004 - 2 4 - Ce 0.02 1 0.092 2 0.843 2 0.0815 2 0.034 1 1.3 3 - 0.0005 - - - Nd 0.03 1 0.230 2 1.3395 2 0.0551 2 0.032 1 1.0 3 - 0.0010 - - - Sm 0.05 1 0.445 2 1.8035 2 0.0394 2 0.031 1 1.1 3 - 0.0013 - 10 4 - Eu 0.05 1 0.474 2 1.5565 2 1.1255 2 0.03 1 0.6 3 - 0.0016 - - - Dy 0.15 1 0.582 2 2.0235 2 0.0228 2 0.03 1 - - 0.0017 - - - Yb 0.34 1 0.542 2 1.642 2 0.0232 2 0.042 1 0.9 3 - 0.0015 - - - Lu 0.42 1 0.506 2 1.5625 2 0.0187 2 0.046 1 - - 0.0015 - 6 4 - Rb 0.022 1 0.056 1 0.29 1 0.071 1 3.06 0.01 - 0.0100 - - - K 0.014 0.0380 0.960 0.170 - - - 0.0068 - - - Sr 0.017 1 0.0732 1 0.46 1 1.83 1 0.081 0.01 - 0.0140 - 0.06 4 - Ba 0.013 1 0.007 1 0.42 1 0.23 1 1.09 0.01 - - - - - Y 0.18 0.9 1 0.03 0.03 0.2 - 0.0015 - - - Nb 0.15 0.005 0.8 0.01 1 0.4 - - - 4.65 - Zr 0.18 0.1 0.5 0.048 0.6 0.1 - 0.400 - - - Th - 0.03 0.5 0.01 - 0.1 - - - - - 12Co 3.2 1.5 6.5 0.0300 - 9.5 5.9 4.3 - - -

B. Andesitic partition coefficients ( for whole rock composition 55-65 SiO2 wt %) Orthopy Clinopy Hornb. Plag. Biotite Magnetite Ilmenite K-feld Apatite Sphene Zircon La 0.031 2 0.047 2 0.5 4 0.302 2 - - 1.223 8 0.08 8 14.5 9 2 4 4.18 9Ce 0.028 2 0.084 2 0.899 1 0.221 2 0.037 1 0.2 6 1.64 8 0.044 1 21.1 9 - 4.31 9Nd 0.028 2 0.183 2 2.89 1 0.149 2 0.044 1 - 2.267 8 0.025 1 32.8 9 - 4.29 9Sm 0.028 2 0.377 2 3.99 1 0.102 2 0.058 1 0.3 6 2.833 8 0.018 1 46 9 10 4 4.94 9Eu 0.028 2 0.8 2 3.44 1 1.214 2 0.145 1 0.25 6 1.013 8 1.13 1 25.5 9 - 3.31 9Dy 0.076 2 0.774 2 6.2 1 0.05 2 0.097 1 - 2.633 8 0.006 1 34.8 9 - - Yb 0.254 2 0.633 2 4.89 1 0.041 2 0.179 1 0.25 6 1.467 8 0.012 1 15.4 9 - 191 9Lu 0.323 2 0.665 2 4.53 1 0.039 2 0.185 1 - 1.203 8 0.006 1 13.8 9 6 4 264.5 9Rb 0.022 5 0.02 6 0.29 1 0.07 6 3.26 1 0.01 6 - 0.34 1 - - - Sr 0.032 5 0.08 6 0.46 1 1.8 6 0.12 1 0.01 6 - 3.87 1 - 0.06 4 - Ba 0.013 5 0.02 6 0.42 1 0.16 6 6.36 1 0.01 6 - 6.12 1 - - - Y 0.45 7 1.5 7 2.5 7 0.06 7 1.233 8 0.5 6 - - 40 1 - - Nb 0.35 7 0.3 7 1.3 7 0.025 7 6.367 8 1 6 - - 0.1 1 6.1 10 - Zr 0.046 7 0.162 7 1.4 7 0.013 7 1.197 8 0.2 6 - 0.03 8 0.64 1 - - Th 0.05 7 0.01 7 0.15 7 0.01 7 0.997 8 0.1 6 0.463 8 0.023 8 - - 76.8 11

C. Dacitic partition coefficients ( for whole rock compositions 65-70 SiO2 wt %) Orthopy Clinopy Hornb. Plag. Biotite Magnetite Ilmenite K-feld Apatite Sphene Zircon La 0.015 2 0.015 2 0.5 4 0.302 2 3.18 11 - 1.223 8 0.08 8 14.5 9 2 4 4.18 9Ce 0.016 2 0.044 2 0.899 1 0.24 1 0.037 1 0.2 6 1.64 8 0.044 1 21.1 9 - 4.31 9Nd 0.016 2 0.166 2 2.89 1 0.17 1 0.044 1 - 2.267 8 0.025 1 32.8 9 - 4.29 9Sm 0.017 2 0.457 2 3.99 1 0.13 1 0.058 1 0.3 6 2.833 8 0.018 1 46 9 10 4 4.94 9Eu 0.028 2 0.411 2 3.44 1 2.11 1 0.145 1 0.25 6 1.013 8 1.13 1 25.5 9 - 3.31 9Dy 0.041 2 0.776 2 6.2 1 0.086 1 0.097 1 - 2.633 8 0.006 1 34.8 9 - 47.4 9Yb 0.115 2 0.64 2 4.89 1 0.077 1 0.179 1 0.25 6 1.467 8 0.012 1 15.4 9 - 191 9Lu 0.154 2 0.683 2 4.53 1 0.062 1 0.185 1 - 1.203 8 0.006 1 13.8 9 6 4 264.5 9Rb 0.022 5 0.02 6 0.014 1 0.048 1 3.26 5 0.01 6 - 0.34 1 - - - Sr 0.032 5 0.08 6 0.23 4 2.84 1 0.12 5 0.01 6 - 3.87 1 - 0.06 4 - Ba 0.013 5 0.02 6 0.044 1 0.36 1 6.36 5 0.01 6 - 6.12 1 - - - Y 0.45 7 1.5 7 2.5 7 0.06 7 1.233 8 0.5 6 - - 40 1 - - Nb 0.35 7 0.3 7 1.3 7 0.025 7 6.367 8 1 6 - - 0.1 1 6.1 10 - Zr 0.033 7 0.184 7 1.4 7 0.013 7 1.197 8 0.2 6 - 0.03 8 0.64 1 - - Th 0.05 6 0.01 6 0.15 7 0.01 6 0.997 8 0.1 6 0.463 8 0.023 8 - - 76.8 11


69

D. Rhyolitic partition coefficients ( for whole rock compositions >70 SiO2 wt %) Orthopy Clinopy Hornb. Plag. Biotite Magnetite Ilmenite K-feld Apatite Sphene Zircon La 0.78 8 1.11 8 0.50 4 0.38 8 3.18 11 - 1.223 8 0.08 8 14.5 9 4 10 4.18 9

Ce 0.15 1 0.50 1 1.52 1 0.27 1 0.32 1 0.2 6 1.64 8 0.044 1 34.7 1 - 4.31 9

Nd 0.22 1 1.11 1 4.26 1 0.21 1 0.29 1 - 2.267 8 0.025 1 57.1 1 - 4.29 9

Sm 0.27 1 1.67 1 7.77 1 0.013 1 0.26 1 0.3 6 2.833 8 0.018 1 62.8 1 21 10 4.94 9

Eu 0.17 1 1.56 1 5.14 1 2.15 1 0.24 1 0.25 6 1.013 8 1.13 1 30.4 1 - 3.31 9

Dy 0.46 1 1.93 1 13.00 1 0.064 1 0.29 1 - 2.633 8 0.006 1 50.7 1 - 47.4 9

Yb 0.86 1 1.58 1 8.38 1 0.049 1 0.44 1 0.25 6 1.467 8 0.012 1 23.9 1 - 191 9

Lu 0.90 1 1.54 1 5.50 1 0.046 1 0.33 1 - 1.203 8 0.006 1 20.2 1 10 10 264.5 9

Rb 0.003 1 0.032 1 0.014 1 0.041 1 2.24 1 0.01 6 - 0.34 1 - - - Sr 0.009 1 0.516 1 0.022 1 4.4 1 0.447 1 0.01 6 - 3.87 1 - 0.06 4 - Ba 0.003 1 0.131 1 0.044 1 0.308 1 9.7 1 0.01 6 - 6.12 1 - - - Y 1 7 4 7 6 7 0.1 7 1.233 8 2 7 - - 40 1 - - Nb 0.8 7 0.8 7 4 7 0.06 7 6.367 8 2.5 7 - - 0.1 1 6.3 10 - Zr 0.2 1 0.6 1 4 1 0.1 1 1.197 8 0.8 1 - 0.03 8 0.1 1 - - Th 0.13 8 0.15 8 - 0.048 8 0.997 8 - 0.463 8 0.023 8 - - 76.8 11

Partition coefficients from: 1 Compilation of Arth (1976); 2 Fujimaki et al. (1984); 3 Schock (1979); 4 Green and Parson (1983); 5 Philpotts and Schnetzler (1970) & Schnetzler and Philpotts (1970); 6 Gill (1981); 7 Pearce and Norry (1979); 8 Nash and Crecraft (1985); 9 Fujimaki et al. (1986); 10 Green et al. (1989); 11 Mahood and Hildreth (1983), 12 Martin (1987). Unnumbered values from Rollinson (1993).

APPENDIX 6 SELECTED PETROGRAPHY OF PLUTONIC UNITS

70

THINSECTION DESCRIPTION 1 SAMPLE NO: SC145 (A1 texture) ROCK TYPE: Hornblende granodiorite LOCALITY: 435066 mE, 7119726 mN UNIT: Woolooga Granodiorite (A1) TEXTURE:Medium-grained, porphyritic, holocrystalline with zoned, euhedral plagioclase cumulates (2-4 mm) and

zoned-actinolitic hornblende phenocrysts (1-2 mm) in granophyric (xenomorphic) groundmass (0.1-1 mm). Plagioclase is rhythmically zoned with inclusions of zircon, apatite, traces of opaque minerals at the core. The composition of plagioclase ranges from An32 to An38, and few crystals have An42-46. Plagioclase demonstrates slight reaction rim with the granophyric groundmass. Hornblende is poikilitic and subhedral, replacing augite (pseudomorphs). Hornblende also forms aggregate incorporating apatite and Fe-Ti oxides. Biotite is a late or secondary mineral associated with the groundmass. Graphic quartz, alkali-feldspar, secondary epidote and actinolite fill the inter-crystal interstices. Orthoclase is a late mineral in interstices that has strong albitic exsolutions.

STRUCTURE:A porphyritic rock comprising plagioclase and actinolitic hornblende phenocrysts in fine grained, perthite and quartz. Late stage micro-cavities (cf. miarolites) of incompletely filled interstices may contain drusy quartz, epidote and calcite.

CRYSTALLISATION SEQUENCE: Zircon> plagioclase>> augite? >> apatite> Fe-Ti oxides> actinolitic hornblende > albite> biotite-epidote-actinolite-perthite-quartz>>> chlorite and uralite.

ALTERATION: Plagioclase core is slightly saussuritised to clay, epidote and calcite; and hornblende rims are partially chloritised and uralitised.

MINERAL COMPOSITION: (Points counted 900) MINERAL GRAIN SHAPE GRAIN-SIZE MODE% Quartz Anhedral restite 0.3-0.5 mm 24.7 Plagioclase An40 Euhedral, cumulates 2-4 mm 46.7 K-feldspar Anhedral 0.5-1 mm 16.0 Hornblende Subhedral 1-2 mm 7.0 Biotite Subhedral 0.1 mm 0.2 Chlorite Secondary, fibrous - 1.7 Opaque minerals Euhedral 0.05-0.1 mm 1.2 Apatite Euhedral, inclusion 0.05 mm 0.2 Epidote Secondary, cluster 0.1 mm 0.2 Augite Remnant core <0.1 mm 2.0

COMMENTS: A granodiorite with earlier pyroxene, plagioclase and hornblende crystals slightly altered by late-stage deuteric alteration.

THINSECTION DESCRIPTION 2 SAMPLE NO: SC215E (A2 texture) ROCK TYPE: Hornblende biotite granodiorite LOCALITY: 433563 mE, 7118725 mN UNIT: Woolooga Granodiorite (A2) TEXTURE:Fine-medium grained, pink, porphyritic rock with euhedral, plagioclase phenocrysts (3-4 mm) hosting traces

of apatite and opaque minerals. The plagioclase has 3 different compositions 1) An32 is unzoned, crystals or clusters, 2) An39-41 is normal zoned crystal with or without mafic mineral inclusions, 3) An42-44 consists of unzoned small crystals. Subhedral, idiomorphic magnesiohornblende has Fe-Ti oxides and apatite inclusions and rimmed by secondary biotite-chlorite-actinolite. Cores of magnesiohornblende contain pyroxene pseudomorphs. Biotite, apatite and micrographic quartz-perthite (microcrystalline to fine-grained) fill the inter-crystal spaces. Myrmekite forms on the edges of some perthite crystals and penetrates the exsolved mineral.

STRUCTURE: A porphyritic rock with cumulates-like texture of plagioclase and magnesiohornblende phenocrysts in fine-grained perthite and quartz. Unit extinction of quartz indicates limited strains although undulose extinction of hornblende is noted.

CRYSTALLISATION SEQUENCE: Zircon> zoned plagioclase> unzoned plagioclase> apatite> Fe-Ti oxides> augite> magnesiohornblende> biotite> apatite> epidote> perthite> quartz> chlorite and uralite (actinolite).

ALTERATION: Plagioclase core is slightly saussuritised to clay, sericite, epidote and calcite while hornblende is partially chloritised and uralitised.

MINERAL COMPOSITION: (Points counted 400) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Anhedral graphic 0.3-0.5 mm 18.2 Plagioclase An20, An38 Euhedral, cumulates 3-4 mm 45.0 K-feldspar Anhedral, perthite 0.5-1 mm 25.5 Hornblendes Subhedral clusters 1-2 mm 6.7 Biotite Bladed, subhedral 0.1 mm Traces Opaque minerals Euhedral 0.05-0.1 mm 0.7 Apatite Euhedral, inclusion 0.1 mm Traces Sericite Secondary - Traces Chlorite Secondary, fibrous - 3.7 Epidote Secondary, cluster 0.2-0.4 mm 0.2 Zircon Subhedral 0.1 mm 0.0


71

COMMENTS: A granodiorite with slightly altered phenocrysts.

THINSECTION DESCRIPTION 3 SAMPLE NO: SC1037 (A3 texture) ROCK TYPE: Hornblende quartz monzodiorite LOCALITY: 437927 mE, 7104747 mN UNIT: Woolooga Granodiorite (A3) TEXTURE: Fine to medium grained, granitic rock comprising plagioclase (2-6 mm), augite (1 mm) and hornblende (1-2

mm) phenocrysts in fine-grained (0.25-1 mm) anhedral quartz, perthite and trace amounts of Fe-Ti oxides, apatite, biotite and epidote. Plagioclase is prismatic, euhedral to subhedral, weakly zoned, fractured and strained, and some crystals are poikilitic (augite inclusions). Most plagioclase crystals have syntaxial albitic overgrowth and kinked twins. Plagioclase has two groups 1) An37-40, zoned with mafic inclusions, and 2) An44-49, zoned and unzoned crystals. Actinolitic hornblende is a late crystallising phase, poikilitic with abundant Fe-Ti oxide inclusions and accessory augite (sieve texture). Bladed actinolite-uralite, chlorite, calcite and epidote are replacement minerals after actinolitic hornblende. The inter-crystal voids are infilled by interlocking, anhedral perthite and quartz (0.25-1 mm) with accessory interpenetrating actinolite, biotite, apatite and Fe-Ti oxides. Quartz exhibits polygonal and granuloblastic textures indicative of recrystallisation and possibly thermal metamorphism.

STRUCTURE: A porphyritic, granitic rock with hiatal size distribution dominated by the plagioclase phenocrysts in perthite and quartz. Plagioclase and actinolitic hornblende are strained (undulose extinction, kinked twins and stylolitic sutures) due to post-crystallisation stresses. Quartz shows evidence of recrystallisation (polygonal or xenomorphic texture) and orthoclase is exsolved.

CRYSTALLISATION SEQUENCE: Zoned plagioclase> augite- apatite- Fe-Ti oxides> poikilitic plagioclase, actinolitic hornblende> actinolite- perthite- quartz- biotite>> epidote>> chlorite, uralite, Fe-oxides> sericite and clay.

ALTERATIONS: Actinolite, chlorite and uralite replace actinolitic hornblende; plagioclase is slightly saussuritised and hornblende is partially chloritised and uralitised.

MINERAL COMPOSITION: (Points counted = 500) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Granophyric, graphic 0.3-0.5 mm 15.0 Plagioclase An28, An35, An44 Euhedral, cumulates 1-7 mm 46.0 K-feldspar Granophyric 0.5 mm 23.2 Amphibole Subhedral 0.5-2 mm 11.0 Biotite Subhedral 0.25-0.5 mm 0.4 Chlorite Secondary, fibrous - 2.0 Opaque minerals Euhedral inclusion 0.05-0.1 mm 2.2 Apatite Euhedral inclusion 0.1 mm Trace Epidote Secondary mineral 0.2-0.4 mm Trace Uralite and iddingsite Secondary mineral 0.1 mm 0.2

COMMENTS: A porphyritic quartz monzodiorite with faint alignment of phenocrysts. Rounded, deformed phenocrysts and mineral alignments indicate pre-crystallisation modification, whereas strains and recrystallisation indicate post-crystallisation deformation and thermal effects. Augite is an early mafic mineral replaced by hornblende, indicating increase water content in the magma.

THINSECTION DESCRIPTION 4 SAMPLE NO: SC792 ROCK TYPE: Monzodiorite LOCALITY: 439370 mE, 7110929 mN UNIT: Gibraltar Quartz Monzodiorite TEXTURE: Fine-grained, anisotropic as defined by alignment of plagioclase crystals (2-3 mm) in fine-grained

feldspathic groundmass (0.5 mm). Two phases of plagioclase are recognised: 1) An74 group (poorly twinned and zoned) and 2) An30 to An44 group (zoned with an albitic rim and may contain inclusions). The latter group has similar composition to plagioclase of the groundmass. Plagioclase crystals are slightly rounded and subhedral. Poikilitic augite has opaque minerals, apatite and sphene inclusions, forming interlocking fabric with plagioclase (An74). There are two optically different pyroxenes, a high birefringence pale-green augite and a light coloured pyroxene. Actinolitic hornblende, actinolite and Fe-Ti oxides crystallise in the interstices of the earlier crystals with quartz-albite-orthoclase and epidote. Most orthoclase has sieved texture, Fe-Ti oxides and pyroxene inclusions. Epidote is a late mineral that occurs as replacement mineral.

STRUCTURE: Flow aligned and porphyritic with plagioclase and augite phenocrysts in fine-grained interlocking actinolite, Fe-Ti oxides, orthoclase, albite and quartz groundmass.

CRYSTALLISATION SEQUENCE: Plagioclase, augite> Fe-Ti oxides, apatite> augite> actinolite, Fe-Ti oxides, orthoclase-albite, quartz > epidote> chlorite, uralite, sericite.

ALTERATION: Intense alterations involve sericitisation of orthoclase, saussuritisation of plagioclase, uralitisation and chloritisation of mafic minerals. The alteration is similar to hydrothermal overprints.

MINERAL COMPOSITION: (Points counted = 1000) MINERAL OCCURRENCE GRAIN-SIZE MODAL % Quartz Interstitial 0.1-0.5 mm 2.8 Plagioclase Phenocryst, rounded 2 - 3 mm 51.3 K-feldspar Phenocryst 2 - 3 mm 17.7


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Augite Corroded 0.5 - 1 mm 1.4 Hornblende Replacement 0.5 mm 16.8 Uralite Secondary - 0.9 Chlorite Secondary Fibrous 3.4 Opaque minerals Euhedral inclusion 0.05-0.1 mm 4.2 Epidote Interstitial, inclusion 0.1-0.2 mm 0.9 Apatite Euhedral 0.1 mm 0.1 Calcite Secondary 0.1 mm Traces

COMMENTS: A monzodiorite with a xenomorphic texture. Rounded plagioclase and mineral alignment indicate pre-crystallisation deformation of phenocrysts, superseded by intense alteration. Sieve-texture in augite indicates chemical disequilibrium with magma, probably evolving towards more silicic composition.

THINSECTION DESCRIPTION 5 SAMPLE NO: SCJT-936 ROCK TYPE: Orthopyroxene-augite-hornblende microgabbro AMG: 440987E, 7112354N UNIT: Rgmm Mount Mucki Diorite TEXTURE AND STRUCTURE: Fine grained, holocrystalline, approximately equigranular rock that displays weak

mineral alignments and subophitic textures. Augite and orthopyroxene form subophitic patches in the interstices between plagioclase, and have Fe-Ti oxides and apatite inclusions. Pyroxenes are subsequently resorbed or being replaced by hornblende. Plagioclase is euhedral, zoned, and some crystals are rounded with syntaxial mantling by labradorite (An54-64). Inclusions of apatite and opaque minerals were noted in plagioclase. Hornblende glomeroporphyroclasts are zoned. The core of the hornblende is greenish, highly birefringence and has Fe-Ti oxides and apatite. The hornblende rim is brown, low birefringence and lacks inclusions noted for its core. Oligoclase (An12) and quartz crystallise in the interstitices between labradorite, pyroxenes and hornblende, and apatite, sphene and calcite fills miarolites.

CRYSTALLISATION SEQUENCE: Plagioclase> augite-orthopyroxene> apatite-sphene-Fe-Ti oxides> hornblende-plagioclase>>albite-quartz> apatite-sphene-calcite

MINERAL COMPOSITION: (Points counted=600) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Interstitial 0.2 mm 4.0 PlagioclaseAn54-64 Subhedral 1 mm 38.3 K-feldspar Interstitial 0.3-0.5 mm 10.5 Hornblende Poikilitic 2-3 mm 30.8 Augite and orthopyroxene Subhedral core 0.2-0.5 mm 8.8 Chlorite Secondary 0.3 Opaque minerals Euhedral 0.05-0.1 mm 4.8 Apatite Euhedral 0.1 mm Traces Sphene Subhedral 0.05-0.1 mm 1.1 Epidote Secondary 1.1 Calcite Interstitial Traces

COMMENTS: A hornblende gabbro sampled from the chilled margin of the Mount Mucki Diorite.

THINSECTION DESCRIPTION 6 SAMPLE NO: SC999 ROCK TYPE: Quartz diorite band LOCALITY: 442100 mE, 7112875 mN UNIT: Mount Muck Diorite TEXTURE: Fine-grained, holocrystalline with poikilitic and mesostasis hornblende clusters incorporating Fe-Ti oxides,

apatite and plagioclase inclusions. Early plagioclase (An53-64) is zoned, subhedral, poorly twinned, has undulose extinction and altered cores; some crystals have apatite and opaque mineral inclusions. The later plagioclase (An36-48) crystallises with hornblende. Poikilitic tschermakitic to actinolitic hornblende envelops the early plagioclase and continues crystallising with An36-48 plagioclase; later actinolitic hornblende has no inclusions and is brown. Interstitial spaces between crystal are filled by plagioclase (An12), orthoclase and quartz with late introduction of albite, apatite and calcite in miarolitic spaces.

STRUCTURE: A homogeneous rock with patches of crescumulate actinolitic hornblende on early tschermakitic hornblende, producing a “trout-like” pattern. Plagioclase and hornblende crystallise in fine-grained interlocking plagioclase and orthoclase feldspars, quartz and calcite.

CRYSTALLISATION SEQUENCE: Plagioclase>hornblende-apatite-sphene-Fe-Ti oxides> hornblende- plagioclase>>albite-orthoclase-quartz-apatite> calcite

ALTERATION: Early plagioclase has been strained and distorted with pressure-solution contacts. The alteration overprints is of deuteric nature, involving argillisation and chloritisation. Plagioclase core is slightly saussuritised to sericite, clay, epidote, zeolites and calcite. Calcite replaces core of plagioclase and infills cracks and late cavities.

MINERAL COMPOSITION: (Points counted = 1000) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Interstitial 0.2 mm 10.3


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Plagioclase An12,44-84 Subhedral 1 mm 39.4 K-feldspar Interstitial 0.3-0.5 mm 9.7 Hornblende Poikilitic 2-3 mm 31.7 Chlorite Secondary 1.4 Opaque minerals Euhedral 0.05-0.1 mm 5.3 Apatite Euhedral 0.1 mm 0.2 Sphene Subhedral 0.05-0.1 mm 0.2 Epidote Secondary 0.1

Calcite Interstitial 1.4

COMMENTS: A hornblende diorite with late replacement by calcite.

THINSECTION DESCRIPTION 7 SAMPLE NO: SC1000 ROCK TYPE: Leucogabbro LOCALITY: 441913 mE, 7112863 mN UNIT: Mount Muck Diorite TEXTURE: Medium grained, holocrystalline, leucocratic rock with clots of intergranular orthopyroxene and

clinopyroxene in a plagioclase rich groundmass. The earliest subhedral plagioclase (An84, 0.5 mm) occurs as inclusions in orthopyroxene oikocrysts and less commonly in clinopyroxene. Sharp contacts between the plagioclase and host pyroxenes indicate no reactions. Tschermakitic hornblende and opaque oxide minerals mantle or replace earlier pyroxenes with intergradational boundary. Some pyroxenes have shown subsequent oxidation with the development of parallel stringers of Fe-oxides along the cleavage planes. Intercrystal spaces are infilled by a later plagioclase (An35), orthoclase, and traces of quartz, apatite and sphene. Epidote, calcite and quartz fill late miarolitic cavities.

STRUCTURE: An anisotropic rock with mafic patches comprising pyroxenes and tschermakitic hornblende in a plagioclase-rich groundmass. The crescumulate growth of hornblende gives a fern-like radiating texture and trout-like appearance. The different mineralogic concentrations appear like schlieren structures.

CRYSTALLISATION SEQUENCE: Plagioclase> poikilitic orthopyroxene> clinopyroxenes> apatite- sphene- Fe-Ti oxides> hornblende> late plagioclase- orthoclase- quartz> epidote-calcite-quartz>> chlorite, uralite, Fe-oxides, sericite & clay.

ALTERATION: Crystals have been strained and faulted indicating post crystallisation strains. The pyroxene is being replaced by hornblende-chlorite whereas plagioclase core is slightly saussuritised to sericite, clay, epidote, and calcite.

MINERAL COMPOSITION: (Points counted = 500)

MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Anhedral 0.2-0.3 mm 5.4 Plagioclase An84,35 Subhedral 0.5 mm 45.4 K-feldspar Subhedral 0.3 mm 11.4 Orthopyroxene Poikilitic 5 mm 7.3 Clinopyroxene Anhedral 2 mm 9.2 Hornblende Subhedral 1-5 mm 12.0 Uralite Secondary 1.0 Chlorite Secondary 1 mm 1.0 Opaque minerals Anhedral 0.05-0.1 mm 6.2 Apatite Euhedral 0.1 mm 0.2 Sphene Anhedral 0.1 mm 0.2

Calcite Interstitial 0.1-0.3 mm 0.2

COMMENTS: A leucogabbro with ferromagnesian clots in a plagioclase-rich groundmass. Pyroxene is being replaced by hornblende from reactions with the crystallising magma; hence, hornblende mantled the pyroxene. Fe-Ti oxides appear to be formed during the clinopyroxene-hornblende transformation.

THINSECTION DESCRIPTION 8 SAMPLE NO: SC1129 ROCK TYPE: Hornblende biotite granodiorite LOCALITY: 447247 mE, 7109122 mN UNIT: Woonga Granodiorite TEXTURE: Medium grained granitoid with zoned and unzoned, euhedral to subhedral plagioclase ranging from 1-2 mm.

The zoned plagioclase forms cluster with syntaxial overgrowth and have core composition of An30-39 whereas unzoned plagioclase has composition of An24. Poikilitic hornblende with sphene, apatite and Fe-Ti oxides co-precipitate with plagioclase. Biotite and chlorite partly replaced hornblende. Anhedral quartz, orthoclase, plagioclase, biotite, apatite and Fe-Ti oxides crystallise with granitic texture. Co-precipitating plagioclase and orthoclase grade into each other along myrmekitic rims. Biotite overprints and replaces earlier hornblende and opaque minerals, forming an apron around hornblende. The rock has been deformed, crystals are fractured with undulose extinctions and quartz is recrystallised to polygonal (granular) texture.

STRUCTURE: A homogeneous, isotropic rock with interlocking plagioclase, hornblende, biotite, orthoclase and quartz.


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Hornblende, plagioclase and Fe-Ti oxides co-precipitate and are subsequently deformed and strained. Fractured quartz shows undulose extinction and recrystallisation.

CRYSTALLISATION SEQUENCE: Zoned plagioclase> plagioclase- apatite- Fe-Ti oxides- sphene- hornblende> orthoclase- quartz- apatite>> chlorite- Fe-oxides> sericite & clay.

ALTERATION: The alteration overprint involves argillisation, chloritisation and recrystallisation associated with deformation. Plagioclase is slightly saussuritised to sericite, clay, epidote and calcite; hornblende is partially replaced by biotite and chlorite.

MINERAL COMPOSITION: (Points counted = 550) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Anhedral 0.5-7 mm 25.5 Plagioclase An28,35,44 Euhedral, cumulates 1-2 mm 43.3 K-feldspar Anhedral 0.5- 2 mm 18.6 Hornblende Subhedral 0.5-1 mm 5.3 Biotite Primary, secondary 0.1-0.5 mm 2.2 Chlorite Secondary, fibrous 0.3 Opaque minerals Euhedral inclusion 0.05-0.1 mm 1.4 Sphene Accessory 0.05 0.2 Apatite Euhedral inclusion 0.1 mm 0.4 Calcite Secondary mineral 0.2-0.4 mm 0.2 Zircon Subhedral 0.1 mm Traces

COMMENTS: A slight porphyritic hornblende-biotite granodiorite that crystallised with two feldspars and with miarolitic cavities. Zoned plagioclase and hornblende are early minerals; biotite and chlorite replace hornblende.

THINSECTION DESCRIPTION 9 SAMPLE NO: SC1148 (T1 texture) ROCK TYPE: Monzogranite LOCALITY: 428275 mE, 7103418 mN UNIT: Rush Creek Granodiorite TEXTURE: Medium grained, porphyritic and granophyric granite comprising zoned euhedral to subhedral plagioclase

phenocrysts (1 to 3 mm). Plagioclase forms clusters with taxial overgrowth; some crystals enclose inclusions of apatite and opaque minerals. Plagioclase composition ranges from with An28 to An36, its adcumulus rim has composition of An20. Poikilitic actinolitic hornblende phenocrysts with apatite and Fe-Ti oxides co-precipitate with early biotite, anhedral quartz and perthite. Late biotite precipitates with the granophyric to granitic (0.5-1 mm) quartz-perthite matrix, some biotite replaces hornblende or envelopes opaque minerals. Miarolitic cavities are partly filled by epidote, quartz and albite.

STRUCTURE: A homogeneous, transitional granophyric to granitic textured rock with hiatal crystal-size distribution. Earlier plagioclase, biotite and hornblende crystallise in finer grained interlocking perthite and quartz.

CRYSTALLISATION SEQUENCE: Zoned plagioclase> apatite- Fe-Ti oxidesbiotite- hornblende> groundmass of biotite, granophyric quartz- perthite- apatite- epidote>> chlorite- uralite- Fe-oxides> sericite and clay.

ALTERATION: Plagioclase phenocrysts are strained, forming undulose extinction and polygonal pressure-solution suture in the crystals. Hornblende is partially replaced by biotite, chlorite and uralite. Plagioclase is slightly saussuritised to sericite, clay, epidote and calcite.

MINERAL COMPOSITION: (Points counted = 500) MINERAL GRAIN SHAPE GRAIN-SIZE MODE% Quartz Granophyric 0.5-1 mm 34.2 Plagioclase An28-36 Euhedral, cumulates 1-3 mm 23.6 K-feldspar Granophyric 0.5 mm 35.3 Hornblende Subhedral 0.5-1 mm 1.4 Biotite Subhedral 0.5 mm 3.6 Chlorite Secondary, fibrous 0.2 Opaque minerals Euhedral inclusion 0.05-0.1 mm 0.3 Spinel? Accessories 0.1 mm Traces Apatite Euhedral inclusion 0.1 mm 0.2 Zircon Euhedral 0.2-0.4 mm Traces

COMMENTS: Hornblende-biotite granite with strongly zoned, slightly rounded plagioclase phenocrysts. The core-to-rim chemical zonation towards more silicic and albitic composition in the phenocryst indicates changing magma chemistry towards less calcic composition. Rounded crystal and deformation of phenocrysts indicate pre-crystallisation modification (strains and reaction after initial crystallisation). Fe-Ti oxides co-precipitate with hornblende and biotite. Late appearance of biotite and orthoclase suggests late concentration of K, and perthitic and miarolite suggests fluid separation at late stages of crystallising.

THINSECTION DESCRIPTION 10 SAMPLE NO: SC1149 (T2 texture) ROCK TYPE: Granodiorite to monzogranite LOCALITY: 430275 mE, 7102575 mN UNIT: Rush Creek Granodiorite


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TEXTURE: Medium grained, porphyritic, granophyriric to granitic textured rock with zoned subhedral plagioclase laths (1 to 2 mm). Individual plagioclase crystal forms clusters by albitic adcumulus growth. There are 2 compositional groups of plagioclase phenocryst 1) An77-80 (zoned and commonly resorbed) and 2) An33-37 (well-twinned population). The adcumulus rim ranges in composition from An16 to An24. The cores of most plagioclase comprise inclusions of Fe-Ti oxides. Poikilitic magnesio hornblende phenocrysts (with apatite and Fe-Ti oxides) crystallise penecontemporaneous with plagioclase and are later replaced by a less birefringence actinolitic hornblende, biotite and chlorite. Biotite is late mineral occurring with perthite in inter-crystal cavities. Quartz crystals show corroded crystal-form. The groundmass comprises interlocking, anhedral quartz and perthite (1 mm), biotite and trace amounts of apatite and Fe-Ti oxides.

STRUCTURE: A homogeneous, isotropic porphyritic granite with hiatal sizes distribution and traces of miarolitic cavities. Strained plagioclase phenocrysts have undulose extinction and pressure-solution sutures.

CRYSTALLISATION SEQUENCE: Zoned plagioclase> plagioclase> apatite- Fe-Ti oxides- hornblende> groundmass of granophyric hornblende- quartz- perthite- biotite>> chlorite- uralite- Fe-oxides> sericite and clay.

POST CRYSTALLISATION CHANGES: The alteration involves argillisation and chloritisation. Plagioclase is slightly saussuritised to clay, epidote and calcite; hornblende is partially replaced by biotite, chloritised and uralitised to fibrous amphiboles, chlorite and Fe-oxides.

MINERAL COMPOSITION: (Points counted: 500) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Granophyric 1 mm 30.0 Plagioclase An33, 77 Euhedral, cumulates 1-2 mm 30.4 K-feldspar Granophyric 0.5-1 mm 30.4 Hornblende Subhedral 0.5-1 mm 5.0 Biotite Subhedral 0.1-0.3 mm 2.5 Uralite Secondary, fibrous 0.2 Opaque minerals Euhedral inclusion 0.05-0.1 mm 0.3 Apatite Euhedral inclusion 0.1 mm 0 Sphene Accessories 0.1 mm 0.4 Calcite Secondary mineral 0.2-0.4 mm 0.2 Zircon Subhedral 0.1 mm Traces

COMMENTS: A hornblende-biotite granite with 2 groups of plagioclase phenocrysts. Strained and fractured crystals indicate modification after crystallisation. Resorbed plagioclase phenocrysts indicate chemical disequilibrium, and zonation towards more albitic rim suggests changing magma chemistry towards more silicic and alkalic composition during the crystallisation.

THINSECTION DESCRIPTION 11 SAMPLE NO: SC1153 (T1 texture) ROCK TYPE: Hornblende augite monzogranite LOCALITY: 432200 mE, 7103475 mN NOTE: Rush Creek Granodiorite TEXTURE: Medium grained, porphyritic, granophyric to granitic texture with zoned subrounded plagioclase laths (1 to 2

mm). Plagioclase core has criss-crossing internal cracks/fractures enclosed in undeformed and unfractured albitic rim. The composition of plagioclase phenocrysts ranges from An40 to An46; adcumulus rims have An16-20. Hornblende clusters with sphene, apatite and Fe-Ti oxides co-precipitate with anhedral quartz and perthite, followed by biotite and apatite. Biotite crystallises around hornblende and replacing it. Sericite and chlorite are late alteration products. Late fractures in the rocks are filled-in by quartz.

STRUCTURE: A homogeneous, porphyritic granite with hiatal grain-size distribution. CRYSTALLISATION SEQUENCE: Zoned plagioclase> apatite- Fe-Ti oxides- hornblende> hornblende- perthite-

quartz> biotite>> chlorite- uralite- Fe-oxides> sericite & clay. POST CRYSTALLISATION CHANGES: The alterations involve intense argillisation and chloritisation typical of epi-

magmatic and hydrothermal overprints. Plagioclase is slightly saussuritised to sericite, clay, epidote and calcite, and hornblende is partly replaced by biotite, chlorite and fibrous amphiboles.

MINERAL COMPOSITION: (Points counted = 500) MINERAL GRAIN SHAPE GRAIN-SIZE MODE% Quartz Granophyric 0.5 mm 33.3 Plagioclase An40-46 Euhedral, cumulates 1-2 mm 19.2 K-feldspar, perthite Granophyric 1 mm 42.6 Hornblende Subhedral 0.3-0.5 mm 1.4 Biotite Subhedral, platy 0.2-0.3 mm 2.5 Chlorite Secondary, fibrous 0.2 Opaque minerals Euhedral inclusion 0.05-0.1 mm 0.2 Iddingsite Secondary mineral Amorphous Traces

COMMENTS: A hornblende-biotite granite. Intense fracturing of plagioclase cores indicates early deformation before final crystallisation. Fe-Ti oxides co-precipitate with hornblende, and biotite and chlorite subsequently replace the assemblage.


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THINSECTION DESCRIPTION 12 SAMPLE NO: SC1166 (T3 texture) ROCK TYPE: Hornblende biotite granodiorite LOCALITY: 429788 m E, 7100100m N NOTE: Rush Creek Granodiorite. TEXTURE: Medium to coarse grained, granitic rock comprising zoned subhedral plagioclase (2-5 mm), hornblende,

augite, biotite, perthite and quartz. Some plagioclase crystals are poilikitic with apatite, plagioclase and augite inclusions. The plagioclase has compositions of An33-39 and An27; rim is oligoclase (An16-24). Poikilitic magnesio hornblende (apatite, Fe-Ti oxides and often augite cores/inclusions) co-precipitates with anhedral quartz-perthite, biotite, apatite and a late actinolitic hornblende. Biotite and chlorite replace hornblende; and biotite crystallises as a late mineral.

STRUCTURE: A homogeneous granitic rock with rounded plagioclase phenocrysts. CRYSTALLISATION SEQUENCE: Zoned plagioclase> plagioclase> clinopyroxene- apatite- Fe-Ti oxides> hornblende>

hornblende- perthite- quartz> biotite>> chlorite, uralite, Fe-oxides> sericite and clay. POST CRYSTALLISATION CHANGES: All minerals including late quartz have been strained forming undulose

extinction and pressure-solution suture, and recrystallised to polygonal texture. Hornblende and biotite replace clinopyroxene. Hornblende is partially replaced by biotite and chlorite, and uralitised to fibrous amphiboles and Fe-oxides. The alteration involves argillisation and chloritisation similar to deuteric and hydrothermal alterations. Plagioclase is saussuritised to sericite, clay, epidote and calcite.

MINERAL COMPOSITION: (Points counted = 500) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Anhedral 1 mm 20.4 Plagioclase An27,35 Subhedral cumulates 2-5 mm 44.6 K-feldspar Anhedral 1 mm 16.0 Hornblende Subhedral 0.5-2 mm 9.4 Biotite Subhedral 0.1 mm 5.5 Chlorite Secondary, fibrous 0.6 Sphene Accessory mineral < 0.1 mm 0.2 Calcite Secondary 0.2 Opaque minerals Euhedral inclusion 0.05-0.1 mm 3.3 Apatite Euhedral inclusion 0.1 mm 0

COMMENTS: A hornblende-augite-biotite granodiorite with sub-rounded plagioclase phenocrysts. Rounded phenocrysts indicated pre-crystallisation modification; recrystallisation, crystal strains and fractures are indicative of post-crystallisation deformation. The presence of two plagioclase compositions suggests magma mixing. Rounded phenocrysts and dissolution imply either reaction of early phenocrysts with the crystallising magma, mixing with higher temperature or high fluid magma, or adiabatic decompression of magma.

THINSECTION DESCRIPTION 13 SAMPLE NO: SC1204 ROCK TYPE: Clinopyroxene monzodiorite (doleritic) LOCALITY: 431650 m E, 7096366 m N NOTE: An intrusion into Rush Creek Granodiorite TEXTURE AND STRUCTURE: A porphyritic, flow aligned, hypabyssal rock comprising phenocrysts of plagioclase,

augite and orthopyroxene in groundmass of orthopyroxene, plagioclase, Fe-Ti oxides and glass traces (?). The zoned, euhedral to subhedral (1-2 mm) plagioclase phenocrysts have An48-60 compositions, and enclose inclusions of rounded/resorbed pyroxenes, glass (?) and opaque minerals. The augite phenocrysts are euhedral and occur as singular crystal or as cluster. The plagioclase crystallites in the groundmass (~1 mm) have composition of An35, and may contain inclusions of pyroxenes and Fe-Ti oxides. Orthopyroxene in the groundmass is anhedral and the crystal boundary is oxidised. Traces of late biotite and quartz are found in late interstitial cavities.

CRYSTALLISATION SEQUENCE: Labradorite plagioclase> augite-orthopyroxene > apatite- Fe-Ti oxides> groundmass of plagioclase- orthopyroxene- Fe-Ti oxides> quartz-biotite- Fe-oxides

MINERAL COMPOSITION: (Points counted = estimation) MINERAL GRAIN SHAPE GRAIN-SIZE MODAL % Quartz Groundmass 0.05-0.1 mm 1 Plagioclase An35, 48-60 Euhedral 1-4 mm 65 K-feldspar Groundmass 0.05 mm Traces Augite Phenocryst 0.5-1 mm 10 Orthopyroxene Phenocryst, gm 0.1-2 mm 10 Biotite Phenocryst 0.1 mm Traces Opaque minerals Euhedral inclusion 0.05-0.1 mm 5-7

Apatite Euhedral inclusion 0.1 mm 0.5 COMMENTS: A porphyritic augite monzodiorite possibly formed as shallow intrusion into the Rush Creek

Granodiorite. The presence of two plagioclase phases may indicate chemical disequilibrium between phenocrysts and the groundmass, or magma mixing. Plagioclase zonation towards an albitic rim suggests evolving magma chemistry from calcic to less calcic composition.

APPENDIX 7 RADIOMETRIC AGES OF UNITS IN SOUTH-EAST QUEENSLAND

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Radiometric ages of lithogic units between 150 Ma and 320 Ma in the Southeast Queensland. Ages with asterix refers to recalculated ages using the Darylmple constants (1979).

Sample Ref. Lithologic unit Analytical method Reported age (Ma)

Error (Ma) Data Source

TL520 (7) Anderson Creek Phyllite Ar/Ar (phengite) 299.0 1.1 Little et al. (1993)KC270 Andesite K/Ar (Wrock) 250* 9 Green (1975)RG50 Avoca Creek Granodiorite K/Ar (amphibole) 255.4 5 Grayson (1995)K89 Black Snake Porphyry K/Ar (biotite) 237.9* 7 Murphy et al. (1976)G4 Boogoramunya Granite K/Ar (hornblende) 214 2 Cranfield & Murray (1989b)G5 Boogoramunya Granite K/Ar (hornblende) 226 2 Cranfield & Murray (1989b)3D1 Booloumba Beds K/Ar (muscovite) 288.0 4 Casley (1993)G6 Boonara Granodiorite K/Ar (hornblende) 233 3 Cranfield & Murray (1989b)G56/10/8 Boondooma K/Ar (hornblende) 244* - Webb & McDougall (1968)GY2 Boondooma K/Ar (biotite) 221.6* 7 Murphy et al. (1976)GY1 Boondooma K/Ar (biotite) 238.9* 7 Murphy et al. (1976)GY4 Boondooma (PRbgg) K/Ar (biotite) 249* 7 Murphy et al. (1976)GY5 Boondooma (PRbgg) Ar/Ar (hornblende) 260.2* 11 Murphy et al. (1976)G56/10/9 Boondooma (PRgb) K/Ar (biotite) 258.2* - Webb & McDougall (1968)LC 636661 Boondooma (PRgbk) Ar/Ar (biotite) 250.1 0.9 Cranfield et al . (in prep.)LC 824444 Boondooma (Rgbo) Ar/Ar (biotite) 272.7 0.9 Cranfield et al . (in prep.)SQRR320 Boondooma (Rgd) Ar/Ar (biotite) 267.9 0.8 Cranfield et al . (in prep.)SQPD407 Boondooma Igneous Complex Ar/Ar (biotite) 229.8 0.5 Vasconcelos and Feng (2000)SQPD407 Boondooma Igneous Complex Ar/Ar (hornblende) 228.7 0.8 Vasconcelos and Feng (2000)GA5324 (L) Brisbane Valley Porphyrites K/Ar (hornblende) 223.6* 5 Webb & McDougall (1967)UQ20402 Brisbane Valley Porphyrites K/Ar (hornblende) 137* - Green & Webb (1974)Broomfield Broomfield Granite Rb/Sr (WRock) 226 16 Cranfield & Murray (1989b)ID5 Buaraba Quartz Diorite K/Ar (hornblende) 187.0 7 Cranfield et al. ( 1976)G3 Calgoa Diorite K/Ar (biotite) 234 2 Cranfield & Murray (1989b)RS345 Capsize Creek Complex K/Ar (amphibole) 318* 4.3 Sliwa (1994)NM156 Capsize Creek Granodiorite K/Ar (biotite) 238.9* 7 McNaughton (1973)Chowey Chowey Granite K/Ar (biotite) 273 3 Cranfield & Murray (1989b)TL116 (2) Claddagh contact (amphibolite) Ar/Ar (hornblende) 306.8 1.3 Little et al. (1993)TL501 (5) Claddagh Granodiorite Ar/Ar (hornblende) 304.9 1.8 Little et al. (1993)G56/14/19 Crows Nest Granite Rb/Sr (biotite) 236.9* - Webb and McDougall (1968)223 Crows Nest Granite K/Ar (biotite) 241.9* 8 Smith (1972)ID7 Dayboro Tonalite K/Ar (biotite) 237.9* 7 Cranfield et al. ( 1976)Degilbo Degilbo Granite Rb/Sr (WRock) 226 16 Webb & McDougall (1967)SQL CDT1 Djuan Tonalite Ar/Ar (biotite) 258.5 0.9 Vasconcelos and Feng, 2000SQL CDT1 Djuan Tonalite Ar/Ar (hornblende) 263.7 0.9 Vasconcelos and Feng, 2000ID2 Djuan Tonalite K/Ar (hornblende) 234.8* 8 Cranfield et al. ( 1976)GA221 (L) Dyke in North Arm Volcanics K/Ar (feldspar) 109.5* - Evernden & Richards (1962)G56/14/0 Enoggera Granite K/Ar (biotite) 223.6* - Evernden & Richards (1962)G56/14/8 Eskdale Granodiorite K/Ar (hornblende) 237.9* - Webb & McDougall (1968)ID4 Eskdale Granodiorite K/Ar (biotite) 248* 7 Cranfield et al. (1976)RS339 Gallangowan Granodiorite K/Ar (biotite) 315.8* 4 Sliwa (1994)NM265 Gallangowan Granodiorite K/Ar (biotite) 319.1* 10 McNaughton (1973)R7844 Glenmaurie Stocks Pg u K/Ar (hornblende) 285 2 Willey (1998)R7833 Glenmaurie Stocks Pg u K/Ar (hornblende) 290 2 Willey (1998)UQ20395 Goomboorian Diorite K/Ar (biotite) 234.8* - Green & Webb (1974)GA3143 (L) Goomboorian Diorite-north K/Ar (hornblende) 239.9* - Green & Webb (1974)UQ20396 Goomboorian Diorite-south K/Ar (hornblende) 233.8* - Green & Webb (1974)SQPD078 Hivesville Granite Ar/Ar (biotite) 260.5 0.8 Cranfield et al . (in prep.)DA 20 Hogback Granite K/Ar (biotite) 228 4 Cranfield & Murray (1989b)SC808 Jurassic stock K/Ar (hornblende) 195 - Tang (this study)GA5386 (L) Kingaham Creek Granodiorite K/Ar (biotite) 220.6* - Webb & McDougall (1967)G10 Kingaham Creek Granodiorite K/Ar (biotite) 241.9* 10 Murphy et al. (1976)RS316 Marumba Beds K/Ar (Wrock) 248.6* 3 Sliwa (1994)V3 Memerambi Granite K/Ar (biotite) 254.0 8 Green (1975)G 1 Mingo Granite K/Ar (biotite) 261 2 Cranfield & Murray (1989b)RS431 Monsildale Granodiorite K/Ar (amphibole) 252.9* 3 Sliwa (1994)QUT245 Monsildale Granodiorite K/Ar (amphibole) 234.1* 3 Kwiecien (1996)QUT294 Monsildale Granodiorite K/Ar (amphibole) 245.3* 3 Kwiecien (1996)SC999 Mount Mucki Diorite K/Ar (hornblende) 210 - Tang (this study)QA213 (L) Mt Byron Volcanics K/Ar (Wrock) 228.2 2.8 Murphy et al.( 1987)QA163 (L) Mt Byron Volcanics K/Ar (Wrock) 227.0 - Murphy et al. (1987)E43 Mt Esk Rhyolite K/Ar (Wrock) 173 4 West (1975)E60 Mt Esk Rhyolite K/Ar (Wrock) 176 2 West (1975)TL245 (13) Mt Mia Serpentinite Ar/Ar (phengite) 293.7 0.8 Little et al. (1993)TL691 (12) Mt Mia Serpentinite Ar/Ar (phengite) 295.2 0.8 Little et al. (1993)TL426 (10) Mt Mia Serpentinite Ar/Ar (phengite) 297.3 0.7 Little et al. (1993)TL430 (11) Mt Mia Serpentinite Ar/Ar (phengite) 297.6 0.8 Little et al. (1993)TL411 (9) Mt Mia Serpentinite Ar/Ar (phengite) 297.9 0.4 Little et al. (1993)TL442 (8) Mt Mia Serpentinite Ar/Ar (phengite) 298.7 0.6 Little et al. (1993)GA5297 (L) Mt Samson Granodiorite K/Ar (biotite) 221.6* 5 Webb & McDougall (1967)G2 Mt Urah Granodiorite K/Ar (biotite) 140 1 Cranfield & Murray (1989b)S060/4 Mungore Granite B K/Ar (plagioclase) 221.2 5.8 Stephens (1991)G3058/1 Mungore Granite G1 K/Ar (biotite) 215.2 2.3 Stephens (1991)B2314/2 Mungore Granite G2 K/Ar (biotite) 230 2.5 Stephens (1991)B2203/2 Mungore Granite G4 K/Ar (biotite) 175.3 2.3 Stephens (1991)G3187/2 Mungore Granite G5 K/Ar (biotite) 228.4 2.5 Stephens (1991)Musket Musket Flat Granodiorite Rb/Sr (WRock) 226 16 Webb & McDougall (1967)J9 Neara Volcanics K/Ar (hornblende) 182.9* 6 Vaughan (1972)I068 Neara Volcanics Ar/Ar (hornblende) 240.9* 11 Irwin (1973)I056 Neara Volcanics K/Ar (Wrock) 241.9* 8 Irwin (1973)AR39-33 Neranleigh-Fernvale Formation K/Ar (whole-rock) 343 4 Lafferty and Golding (1985)G56/10/1 Neurum Tonalite K/Ar (biotite) 227.7* - Webb et al. (1968)DA 19 New Moonta Diorite K/Ar (biotite) 232 4 Cranfield & Murray (1989b)UQ20388 Noosa Quartz Diortte K/Ar (hornblende) 146.2* - Green & Webb (1974)DA18 (GU155) North Arm Volcanics K/Ar (hornblende) 232 4 Unpublished, Goomeri map sheet.RS361 North Arm Volcanics K/Ar (Wrock) 239.9* 3 Sliwa (1994)Bokay North Arm Volcanics? K/Ar (Wrock) 212.4* 7 Green and Webb (1974)DA 16 Nour Nour Granodiorite K/Ar (hornblende) 238 3 Cranfield & Murray (1989b)RHY2 Rhyolite K/Ar (Wrock) 140* 5 Green (1975)RHY1 Rhyolite K/Ar (Wrock) 146* 5 Green (1975)


78

Sample Ref. Lithologic unit Analytical method Reported age (Ma)

Error (Ma) Data Source

1A165 Rocksberg Greenstone Ar/Ar (glaucophane) 229.0 46 Murphy et al.( 1987)26961 Rocksberg Greenstone Ar/Ar (muscovite) 251.0 8 Murphy et al.( 1987)26961 Rocksberg Greenstone Ar/Ar (amphibole) 259.0 12 Murphy et al.( 1987)AA98 (L) Rocksberg Greenstone Ar/Ar (glaucophane) 259.0 46 Murphy et al.( 1987)918361 Rocksberg Greenstone Ar/Ar (muscovite) 260.0 11 Murphy et al.( 1987)4758 Rocksberg Greenstone Ar/Ar (muscovite) 263.0 9 Murphy et al.( 1987)4754 Rocksberg Greenstone Ar/Ar (muscovite) 264.0 11 Murphy et al.( 1987)4756 Rocksberg Greenstone Ar/Ar (muscovite) 265.0 10 Murphy et al.( 1987)PM7 Rocksberg Greenstone Ar/Ar (muscovite) 265.0 10 Murphy et al.( 1987)4A65 Rocksberg Greenstone Ar/Ar (amphibole) 270.0 71 Murphy et al.( 1987)10 Rocksberg Greenstone Ar/Ar (amphibole) 286.0 75 Murphy et al.( 1987)TL266 (14) Rocksberg Greenstone Ar/Ar (phengite) 296.0 0.7 Little et al. (1993)G56/14/19 Rocksberg Greenstone K/Ar (muscovite) 249* - Green & Webb (1974)G56/14/19 Rocksberg Greenstone K/Ar (glaucophane) 254* - Green & Webb (1974)ID8 Samford Granodiorite K/Ar (hornblende) 226.7* 8 Cranfield et al. (1976)GA5323 (L) Somerset Dam Igneous Complex K/Ar (plagioclase) 213* 5 Webb & McDougall (1967)GA5315 (L) Somerset Dam Igneous Complex K/Ar (hornblende) 220* 5 Webb & McDougall (1967)70 average Stanthorpe - 238 - -5 average Stanthorpe - 244 - -22 average Stanthorpe - 245 - -G56/10/4 Station Creek Adamellite K/Ar (biotite) 230.7* - Webb & McDougall (1967)K52 Station Creek Adamellite K/Ar (biotite) 235.8* 7 Brooks et al. (1974)SE158c Station Creek Adamellite K/Ar (amphibole) 226.8* 3 Edgar (1992)NS18-163 Station Creek complex K/Ar (sericite) 223 3 Scott (1983)SC1185 Station Creek Granodiorite Ar/Ar (biotite) 232 - Tang (this study)NS24-371 Station Creek Igneous Complex K/Ar (chlorite) 142 2 Scott (1983)MS139 Station Creek Igneous Complex K/Ar (biotite) 179 2 Scott (1983)SQPD217 Stuart River Granite Ar/Ar (biotite) 250.0 0.8 Cranfield et al. (in prep.)SQPD166 Stuart River Granite Ar/Ar (biotite) 255.5 0.6 Cranfield et al. (in prep.)SQGC387 Sugarloaf Metamorphics Ar/Ar (biotite) 137.4 1.1 Cranfield et al. (in prep.)SQGC250 Sugarloaf Metamorphics Ar/Ar (biotite) 248.8 0.8 Cranfield et al. (in prep.)1 Sugars Basalt K/Ar (Wrock) 232 4 Webb & McNaughton (1978)2 Sugars Basalt K/Ar (Wrock) 229 3 Webb & McNaughton (1978)SQRR130 Taromeo Igneous Complex Ar/Ar (biotite) 233.1 0.7 Cranfield et al. (in prep.)R7626 Taromeo Rg m/gd1 K/Ar (hornblende) 233 2 Willey (1998)G56/10/7 Taromeo Tonalite K/Ar (biotite) 242.9* - Webb & McDougall (1968)GY3 Taromeo Tonalite Ar/Ar (hornblende) 263.3* 21 Murphy et al. (1976)GY1-9 Taromeo Tonalite Rgm/gd2 Ar/Ar (biotite) 229* 11 Green (1975)Tawah Tawah Granite Rb/Sr (WRock) 226 16 Webb & McDougall (1967)DA23 Tenningering Granodiorite K/Ar (muscovite) 256 4 Cranfield & Murray (1989b)CR003 Triassic dyke K/Ar (Wrock) 229.6* 3 Roberts (1992)G7 Tungi Creek Granodiorite K/Ar (biotite) 225.7* 6 Murphy et al. (1976)H133 Undiff. Palaeozoic (amphibolite) K/Ar (biotite) 289.7* 8 Hayden (1971)H2 Undiff. Palaeozoic (amphibolite) K/Ar (hornblende) 294.7* 10 Hayden (1971)UQ33724; V12 Undiff. Palaeozoic (schist) Ar/Ar (amphibole) 250.1 61 Vaughan (1972)QA99 (L) Undiff. Palaeozoic (schist) K/Ar (muscovite) 314* 9 Vaughan (1972)H66 Undiff. Palaeozoic (schist) K/Ar (muscovite) 286.6* 8 Hayden (1971); Green (1973)RS350 Undiff. Triassic Volcanics K/Ar (Wrock) 229.407* 4 Sliwa (1994)TL541 (1) Undiff. Triassic Volcanics Ar/Ar (hornblende) 227.9 0.7 Little et al. (1993)R7899 Unnamed diorite Pg d K/Ar (hornblende) 270 2 Willey (1998)R7769 Unnamed granodiorite Pg u K/Ar (hornblende) 283 2 Willey (1998)SQPD218 Unnamed granodiorite PRg1 Ar/Ar (biotite) 230.6 0.7 Cranfield et al. (in prep.)SQPD218 Unnamed granodiorite PRg1 Ar/Ar (biotite) 230.6 0.7 Cranfield et al. (in prep.)SPG2 Unnamed intrusion K/Ar (hornblende) 245.3 16 Pettigrew (1994)G13 Unnamed intrusion K/Ar (hornblende) 148.3* 3 Murphy et al. (1976)G12 Unnamed intrusion K/Ar (biotite) 241.9* 10 Murphy et al. (1976)SPG1 Unnamed intrusion -Gympie K/Ar (hornblende) 274.5* 4 Pettigrew (1994)?UQ32603; M-2 Intrusion- Mary Creek Ar/Ar (biotite) 221.6* 7 Horton (1972)UQ32618; M-5 Intrusion- Mary Creek Ar/Ar (biotite) 222 7 Horton (1972)UQ32607; M-1 Intrusion- Mary Creek Ar/Ar (hornblende) 244* 8 Horton (1972)UQ32607; M-2 Intrusion- Mary Creek Ar/Ar (biotite) 247* 18 Horton (1972)QA159 (L) Intrusion-Esk Trough K/Ar (biotite) 215* 7 Kerr (1974)8.1B Intrusion-Esk Trough K/Ar (amphibole) 265 10 Johansen (1986)X107 (QA188) Intrusion-Esk Trough K/Ar (biotite) 253* 8 Green (1975)8.4A Intrusion-Esk Trough K/Ar (amphibole) 220 8 Johansen (1986)SR2 Intrusion-Fat Hen Creek K/Ar (plagioclase) 231.1 3 Holcombe et al . (1997)UQ32588; M-4 Unnamed intrusion-Goomeri Ar/Ar (hornblende) 231.8* 8 Horton (1972)G56/10/10 Wigton Adamellite Rb/Sr (WRock) 274.0 28 Webb & McDougall (1968)DA 21 Wolca Granite K/Ar (biotite) 261 4 Cranfield & Murray (1989b)Wonbah Wonbah Granodiorite Rb/Sr (WRock) 226 16 Cranfield & Murray (1989b)SC1129 Wonga Granodiorite Ar/Ar (biotite) 237 - Tang (this study)SC582 Woolooga Granodiorite Ar/Ar (biotite) 234 - Tang (this study)ID1 Woolshed Mountain Granodiorite K/Ar (biotite) 258.2* 8 Cranfield et al. (1976)G56/10/3 Woondum Granite K/Ar (hornblende) 222.6* - Webb & McDougall (1967)G56/10/9 Wooroolin Granite K/Ar (biotite) 258.2* - Webb & McDougall (1968)G56/10/10 Wooroolin Granite Rb/Sr (WRock) 274.0 28 Webb & McDougall (1968)RS374 Yabba Creek Granodiorite K/Ar (amphibole) 317.1* 4 Sliwa (1994)


79

APPENDIX 7B: GEOCHEMISTRY OF PLUTONIC ROCKS IN THE SOUTHEAST QUEENSLAND


80

APPENDIX 7B: GEOCHEMISTRY OF PLUTONIC ROCKS IN THE SOUTHEAST QUEENSLAND (CONTINUED)


81

APPENDIX 7B: GEOCHEMISTRY OF PLUTONIC ROCKS IN THE SOUTHEAST

QUEENSLAND (CONTINUED)


82

APPENDIX 7B: GEOCHEMISTRY OF PLUTONIC ROCKS IN THE SOUTHEAST QUEENSLAND (CONTINUED)

APPENDIX 8 MINERALISATION POTENTIAL

83

THE MINERALISATION POTENTIALS OF THE STATION CREEK IGNEOUS COMPLEX

Introduction

Approximately one hundred and fifty small, polymetallic ore deposits occur around

the Station Creek Igneous Complex (Brooks et al., 1974; Tate, 1989; Randall et al., 1996).

Randall et al. (1996) documented the 149 known mineral occurrences in the Kilkivan

district. The ore associations are Cu-Mo-Au (proximal to porphyritic igneous units), Hg-

Sb-As (veins and stockworks of epithermal deposits), Cu-Pb-Zn (occurring mainly as veins

within volcanic strata), Mn (associated with basalt and chert-mudstone sequences), Co-Ni-

Ag (as veins in schists and serpentine) and native gold (in gold-quartz veins). The diversity

of ore types led to suggestions that the Kilkivan area is a mineralisation corridor (Horton,

1982) or an ore field. Mineralisation in the NNEO is associated with magmatism (Bischoff,

1986; Ridley, 1987; Tate, 1989; Murray, 1997), though Brooks et al. (1974) has

convincingly catergorised mineral associations according to host-rock associations.

Isotopic evidence links the genesis of mineralisation in the NDB to the Triassic plutons

(Golding et al., 1987; Ashley et al., 1996).

Oxygen Isotopic signatures

The Woonga Granodiorite, Rush Creek Granodiorite and Mount Mucki Diorite

have similar and overlapping δ18O (from +7.3 to +8.7‰) that are greater than the mantle

values (+5.5 to +6‰; James, 1981) (Figure 1). The δ18O values of the Rush Creek

Granodiorite increase with corresponding increases in whole-rock SiO2. The δ18O values of

the Woolooga Granodiorite (+2.5 to +4.3‰) and the Gibraltar Quartz Monzodiorite

(+0.4‰) are between the mantle and SMOW range. The low δ18O value of the Gibraltar

Quartz Monzodiorite is associated with subsolidus alteration.

Selected country rocks to the SCIC have relatively low δ18O values below the range

for mantle. The δ18O of the Neara Volcanics is -0.8 to +0.2‰, trachybasalt of the Highbury

Volcanics is +4.6‰ and the Mount Mia Serpentinite is +5.4‰. Previous work by Golding

et al. (1987) reported δ18O values of +6.3 to 12.6‰ in greenstone from the Kilkivan

district. The δ18O of the Palaeozoic country rocks are within the range for metamorphic

waters.

Ore deposits in the Kilkivan region have similar oxygen isotopic ratios to their


84

host-formations. The δ18O of quartz separates from the Mount Victor vein (δ18O= 10.3‰)

and the Shamrock ore deposit (δ18O= 12.9‰) lies within the isotopic range for their

greenstone and serpentine host (5.4-12.9‰). Quartz veins within the Greenrock mine

intruded the silicified and pyritised Neara Volcanics. The δ18O value of quartz from the ore

zone (δ18O= +2.8‰) lies between ratios for the Neara Volcanics (-0.8 to +0.2‰) and

Woolooga Granodiorite (+2.5 to +4.3‰). The Yorkeys stibnite-calcite-quartz vein has

slightly lower δ18O value (δ18O= +4.4‰) than the host diorite rock (δ18O= +5.5‰).

Quartz-cinnabar veins (from Kilkivan Mine) in epiclastic volcanics to the west of Kilkivan

have high δ18O values (+20.3‰) and there is no isotopic information on the host rocks.

The overall δ18O range of the SCIC (+0.4 to +8.7 ‰) falls within the δ18O range for

I-type (mantle-derived or predominantly igneous source) granite (δ18O <9.0) (Chappell &

White, 1992). The Woonga Granodiorite, Rush Creek Granodiorite and Mount Mucki

Diorite have similar δ18O values to the orogenic Cordilleran gabbro to granite range (+6 to

+9‰) (Taylor, 1979).

Hydrogen-oxygen isotopic systems

The δD (biotite and hornblende) and δ18O (whole-rock) of the SCIC and selected

porphyritic bodies plot outside the fields for primary magmatic water and igneous biotites

and hornblende (Figure 2). The stable isotopes data are skewed towards lower δD

compared to the primary magmatic values. Ohmoto (1986) and Taylor (1979) justify the

δD isotopic departures from the primary magmatic-water to post-crystallisation isotopic

exchange between rock and heated meteoric water, and to the possibility that the low δD

are inherent characteristics of the magma themselves. The data for the Woolooga

Granodiorite and Gibraltar Quartz Monzodiorite plot close to the mixing line between

meteoric and hydrothermal waters, which are typical of the results from hydrothermal

alteration (Criss & Taylor, 1986).

Ore bodies (e.g. the Shamrock and Yorkeys deposits) around the SCIC have

different δD and δ18O values to the igneous complex, but have similar isotopic signatures

of the host formation. A quartz separate from the Shamrock mine plots within the isotopic

fields for metasediments, which is similar to the δ18O of the host greenstone. Quartz from

the Yorkeys mine plots within the field for igneous biotite and hornblende, similar to the


85

LEGEND



Woonga Granodiorite

Mount Mucki Diorite

Yorkeys Diorite


MINERALISED ZONE

Yorkeys low quartz

Shamrock low quartz

δ1 8

O

-180

-160

-140

-120

-100

-80

-60

-40

-20

020

Metamorphic waters

Meteor

ic W

ater L

ine

OceanWaters

Primary magmaticwaters

δ DSedimentary waters

Meteoric-hydrothermal alteration

Meteoric-epithermalalteration

SMOW

Fields of igneous biotite and hornblende

Figure 1: The O isotopic values of the Station Creek Igneous Complex, associated volcanic and country rocks and mineralisation. Horizontal bars show the

antle values (Ohmoto, 1986); I- and S-type granite values (Chappell & White, 1992); (1) greenstones of northern NEO (Goldings ., 1987); (2) orogenic gabbro to granite (Taylor, 1979); (3) MORB (Javoy, 1977); (4) shale.

δ1 8

et al

δ1 8

O ranges. Plotted for comparisons are m

Comparison

WORKINGS:

S

TATI

ON

CR

EE

KIG

NE

OU

S C

OM

PLE

X

Mount Mucki Diorite

MA

NTL

E R

AN

GE

Figure 2: Plot of D versus O for plutons of the SCIC and proximal intrusions (the Black Snake Porphyry and Yorkeys Diorite). The

adjacent to the SCIC. Fields of magmatic, sedimentary and metamorphic waters are from Taylor (1978b) and

δ δ1 8

δ δ

δ δ

1 8

1 8

O compositions are whole rock values and D compositions are water of crystallisation from biotite (black) and hornblende (grey). Also plotted are the D and O compositions of quartz veins from mineralised zones

Kerrich (1989); meteoric-hydrothermal and meteoric-epithermal trends from Criss & Taylor (1986).


86

values expected for the host Yorkeys Diorite (δ18O= +5.5 o/oo).

The mineralisation potentials

Granitoids have economic significance, as many poly-metallic mineralisations are

associated directly or indirectly with plutons (e.g. Burnham, 1979; Candela, 1989; Mathez,

1989; Peters & Goldings, 1990; Hedenquist, 1995; Meinert, 1995). The mineralisation

potentials depend on the magmatic source and subsequent evolution, the differentiation

process, the geochemical state of the plutons and source rocks for mineralisation (Whitney,

1989b; Blevin & Chappell, 1992; Candela, 1992; Simmons, 1995). Ore deposits may be

derived from the magmatic system, or concentrated by the hydrothermal cells generated by

the intrusive bodies (e.g. Taylor, 1979; Collins & Williams, 1986; Golding et al., 1987;

Heinrich, 1995; Jiang & Seccombe, 1995; Jiang et al., 1995). Mineralisation of calc-

alkaline granitoids is commonly associated with Mo-skarns and Cu-porphyry style

mineralisation (Naldrett, 1989; Whitney, 1989b). The Mo-Cu mineralisation contrasts from

tin-bearing greisens and tourmalinisation associated with the peraluminous granites, and

REE- and F-bearing mineralisations associated with peralkaline and syenite rich granites.

Gold, silver, copper, lead, zinc, arsenic, mercury, tungsten, antimony,

molybdenum and bismuth mineralisations occurred around Middle-Late Triassic intrusions

in the Kilkivan area (Tang, 2003). The majority (81%) of the 149 ore-bodies are associated

with small (<2 sq km) porphyritic intrusions and only 19% of these deposits are associated

with major plutons such as the SCIC. Ore zones are confined to narrow ENE and NW

trending veins around acid to intermediate intrusives, and form stockworks within some

porphyritic intrusives e.g. the Black Snake Porphyry and Yorkeys Diorite (Tang 2003). The

mineralisation trends match the structural grain of the northern North D’Aguilar Block,

which suggest a strong structural control (Tang, 2003; Little, 1993). The close association

between ore- and intrusive bodies and structural-fabric indicates that mineralisation is

related to the magmatism and their deposition is controlled by the local structures.

The styles of mineralisation differ between the MMD-GQM and the W-RC

groups. In the MMD-GQM group, subhedral chalcopyrite and pyrrhotite (<0.1%) are

disseminated within the mafic layers (monzogabbro and diorite) of the plutons, as well as

in the alteration halos around the plutons. In contrast, mineralisation associated with the

Woolooga and Rush Creek Granodiorites is confined to the alteration halo and along the


87

hornfelsic contacts with the Neara and Highbury Volcanics. Disseminated cubic pyrite,

chalcopyrite, galena and sphalerite are associated with the silicified and argillised

(bleached) zones. The poly-metallic mineralisation may locally crystallise with calcite and

quartz as veins along fracture planes of highly silicified rocks. Examples of such deposits

are the Mount Victor ore (sphalerite-galena-pyrite-chalcopyrite-calcite-quartz) in

serpentine-greenstone host, the Greenrock mine (galena-sphalerite-chalcopyrite-pyrite-

gold-silver-calcite-quartz) in altered Neara Volcanics, and mercury deposits (cinnabar-

calcite-quartz veins) in altered Neara Volcanics. The δ18O values of these ore bodies are

similar to the host rocks (Figure 1), and do not plot along the mixing lines between

magmatic and meteoric waters (Figure 2), suggesting that the mineralisations are not

derived directly from the intrusive bodies.

Blevins & Chappell (1992) remarked significant absence of mineralisation in

restite-fractionated suites in eastern Australia. The Woolooga and Rush Creek

Granodiorites are interpreted as felsic fractionates of dioritic composition derived from

partial melting mantle-derived basaltic precursors, fitting the definition ‘restite-

fractionates’ of Blevins & Chappell (1992). The plutons are high temperature I-type

magmas that possess high liquidus temperatures capable of driving hydrothermal cells. The

W-RG group is pyroxene bearing and perthitic, which implies relatively dry systems with

losses of volatiles before the final crystallisation. Such plutons will contribute little

magmatic water towards mineralisation, except for localised small deposits close to the

intrusive margins.

The MMD-GQM group is regarded as mantle fractionates. These granitoids are

interpreted as relatively hydrous plutons by the presence of magmatic hornblende early in

their crystallisation. The fractionated, high-temperature plutons have better prospects for

mineralisation, whereby incompatible elements have chances to concentrate (Blevins &

Chappell, 1992). Their greater mineralisation potentials compared to the W-RC group are

reflected by the enrichments of most elements except the high temperature orthomagmatic

elements (Ni, Co and Cr).

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