geochemical and petrological constraints on the …

UNIVERSIDADE FEDERAL DE OURO PRETO

ESCOLA DE MINAS

DEPARTAMENTO DE GEOLOGIA

PROGRAMA DE PÓS-GRADUAÇÃO EM EVOLUÇÃO CRUSTAL

E RECURSOS NATURAIS

Tectônica, Petrogênese e Recursos Minerais

DISSERTAÇÃO DE MESTRADO

GEOCHEMICAL AND PETROLOGICAL CONSTRAINTS ON

THE ORIGIN OF THE NEOPROTEROZOIC URUCUM IRON

FORMATION, SANTA CRUZ DEPOSIT, BRAZIL

por

Fernando Ribeiro de Souza

(Pós-graduando)

Orientador:

Hermínio Arias Nalini Jr.

OuroPreto - Fevereiro/2018

i

GEOCHEMICAL AND PETROLOGICALCONSTRAINTS ON THE

ORIGIN OF THE NEOPROTEROZOIC URUCUM IRON

FORMATION, SANTA CRUZ DEPOSIT, BRAZIL

iii

FUNDAÇÃO UNIVERSIDADE FEDERAL DE OURO

PRETO

Reitor

Cláudia Aparecida Marliére de Lima

Vice-Reitor

Hermínio Arias Nalini Júnior

Pró-Reitor de Pesquisa e Pós-Graduação

Sérgio Francisco de Aquino

ESCOLA DE MINAS

Diretor

Issamu Endo

Vice-Diretor

Hernani Mota de Lima

DEPARTAMENTO DE GEOLOGIA

Chefe

Luís Antônio Rosa Seixas

iv

EVOLUÇÃOCRUSTALERECURSOSNATURAIS

v

CONTRIBUIÇÕES ÀS CIÊNCIAS DA TERRA – VOL.

DISSERTAÇÃO DE MESTRADO

Nº 358

GEOCHEMICAL AND PETROLOGICAL CONSTRAINTS

ON THE ORIGIN OF THE NEOPROTEROZOIC URUCUM

IRON FORMATION, SANTA CRUZ DEPOSIT, BRAZIL

Fernando Ribeiro de Souza

Orientador

Dr. Hermínio Arias Nalini Júnior

Dissertação apresentada ao Programa de Pós-Graduação em Evolução Crustal e Recursos

Naturais do Departamento de Geologia da Escola de Minas da Universidade Federal de Ouro

Preto como requisito parcial à obtenção do Título de Mestreem Ciência Naturais, Área de

Concentração: Tectônica, Petrogênese e Recursos Minerais

OURO PRETO

2018

vi

Universidade Federal de Ouro Preto –

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mailto:[email protected]

vii

Acknowledgements

I wish to express my appreciation for this opportunity presented to me by Hermínio Arias NaliniJúnior. I am

gratefully in debt to him for the trust, and for directing and providing all the support necessary for this

research. I am also grateful to Mariângela Garcia PraçaLeite for scientific guidance, discussions, and

feedback on my ideas. Many thanks to the staff of Laboratório de GeoquímicaAmbiental for providing

technical the excellent support during analyses.A special thank you to Adriana Trópia de Abreu Guimarães

for sharing her scientific expertise and to AntônioCelso Torres for his guidance and diligent lab work.

I acknowledge and thank the financial support for the analytic infrastructure provided by the project

FAPEMIG/VALE RDP CRA (grant number: 00063/10). I would also like to thank VetriaMineraçãoS.A. for

allowing the sampling of drill cores. Support from CAPES through my scholarship was also essential in

completing this project. I am also grateful to the Universidade Federal de Ouro Preto and the Programa de

Pós-Graduação em Evolução Crustal e Recursos Naturais of the Departamento de Geologia (DEGEO) for the

funding and logistic support.

Laboratório de Geoquímica Ambiental (DEGEO/UFOP) is thanked for the LA-ICP-MS analyses.Laboratorio

de Microssonda e Microscopia Eletrônica (DEGEO/UFOP) – RMIc, Rede de Microscopia e Microanálises de

Minas Gerais – FAPEMIG, is thanked for EMP and SEM-EDS analyses. Laboratório de Microscopia

Eletrônica, Microanálises e Caracterização de Materiais (DEMET/UFOP) is thanked for SEM-EDS-EBSD

analyses. Laboratório de Microestrutural (DEGEO/UFOP) is thanked for SEM-EBSD analysis. I am grateful

to all staff of all these laboratories, as well as those of LAMIN and LOPAG, for their assistance during

preparation and analysis of the samples.

ix

Summary

ACKNOWLEDGEMENTS ...................................................................................................... vii

LIST OF FIGURES ................................................................................................................. xiii

LISTOF TABLES ................................................................................................................... xvii

ABSTRACT .............................................................................................................................. xix

RESUMO .................................................................................................................................. xxi

CHAPTER 1. INRODUCTION ................................................................................................. 1

1.1. General Introduction .............................................................................................................. 1

1.2. StatementofPurpose ................................................................................................................ 3

1.3. Objective ................................................................................................................................ 4

1.4. Location .................................................................................................................................. 5

1.5. Methods of Study ................................................................................................................... 6

1.5.1. Sample Selection and Preparation ............................................................................. 6

1.5.2. Petrographic Investigations ....................................................................................... 7

1.5.3. In SituElement Analyses ........................................................................................... 7

1.5.4. Statistical Treatment ................................................................................................. 9

CHAPTER 2.NEOPROTEROZOIC IRON FORMATIONS ............................................... 11

2.1. Definition of Iron Formation ................................................................................................ 11

2.2. Depositional Constrains ....................................................................................................... 13

2.2.1. Modern Fe Sources and FeCycle ............................................................................ 13

2.2.2. Basin Water Redox ................................................................................................. 14

2.2.3. Oxidation Mechanisms ........................................................................................... 14

2.3. Neoproterozoic Iron Formations .......................................................................................... 17

3.3.1. Types of Neoproterozoic Iron Formations .............................................................. 20

3.3.2. Geochemistry .......................................................................................................... 22

3.3.2.1. Rare Earth Elements (REE) ....................................................................... 23

3.3.2.2. Isotopes ...................................................................................................... 25

3.3.3. Genetic Models ....................................................................................................... 27

x

CHAPTER 3.GEOLOGICAL BACKGROUND ................................................................... 31

3.1. Structural Geology ............................................................................................................... 32

3.2. Geochronology ..................................................................................................................... 34

3.3. Lithostratigraphy .................................................................................................................. 34

3.3.1. Urucum Formation .................................................................................................. 36

3.3.2. Córrego das Pedras Formation ................................................................................ 36

3.3.3. Banda Alta Formation ............................................................................................. 36

3.4. Basin Tectonic-Depositional Evolution ............................................................................... 37

3.5. Geochemistry and Genetic Models ...................................................................................... 41

CHAPTER 4.IN-SITU LA-ICP-MS AND EMP TRACE ELEMENT ANALYSES OF

HEMATITE: INSIGHT INTO THE GEOCHEMICAL SIGNATURE OF THE

NEOPROTEROZOIC URUCUM IRON AND MANGANESE FORMATION, BRAZIL 49

Abstract ....................................................................................................................................... 49

4.1. Introduction .......................................................................................................................... 50

4.2. Geological Setting ................................................................................................................ 51

4.3. Analytical Methods .............................................................................................................. 54

4.3.1. Sample Preparation and Petrography ...................................................................... 54

4.3.2. AnalyticalTechniques ............................................................................................. 55

4.3.3. Factor Analysis ....................................................................................................... 56

4.4. Results .................................................................................................................................. 57

4.4.1. Petrography ............................................................................................................. 57

4.4.2. Mineral Chemistry .................................................................................................. 61

4.4.3. Factor Analysis ....................................................................................................... 68

4.5. Discussion ............................................................................................................................ 71

4.5.1. Paragenetic Model .................................................................................................. 71

4.5.2. Precursor Sediments ................................................................................................ 73

4.5.3. Basin Stratification .................................................................................................. 75

4.5.4. Influx of Freshwater ................................................................................................ 77

4.6. Concluding Remarks ............................................................................................................ 79

xi

CHAPTER 5.CONCLUSIONS ................................................................................................ 81

4.6. Recommendation for Future Studies .................................................................................... 82

REFERENCES .......................................................................................................................... 83

APPENDICES ......................................................................................................................... 107

xiii

List of Figures

Figure 1.1- Timeline showing the major events during the Neoproterozoic.Fragmentation of the

supercontinent Rodinia and assembly of the supercontinent Gondwana; Large Igneous

Provinces (LIP) emplacement; main Neoproterozoic iron (IF) and manganese formations (MnF)

ocurrences; predominant deep and shallow seawater conditions (oxic, sulfidic, and ferruginous);

biological evolution; evolution of atmospheric and oceanic oxygen levels; Neoproterozoic

global glaciations (Gaskiers, Marinoan, Sturtian). Modified after Narbonne (2005),

Love et al. (2009), Canfield et al. (2008), Och& Shields-Zhou (2012), Bekkeret al. (2014),

Cox et al. (2016b) ......................................................................................................................... 2

Figure 1.2- SRTM image of the Urucum massif with the main hills and access routes. The

Santa Cruz mine is located about 30 Km from Corumbá. Modified after Freitas (2010) ............. 5

Figure 2.1-Major occurrences worldwide: (1) MalyKhinghan Fm.; (2) Yerbal Fm.; (3) Jacadigo

Gr. (Urucum IF); (4) Bisokpabe Gr.; (5) Chestnut Hill Fm.; (6) Holowilena Ironstone;

(7) Braemar IF; (8) Vil’va Fm. and Koyva Fm.; (9) Bakeevo (Tolparovo) Fm.; (10) Dzhetymtau

Suite; (11) Uk Fm.; (12) Yamata Fm.; (13) Lake Khanka Fm.; (14) Rapitan Fm.; (15) Chuos

Fm.; (16) Tindir Gr.; (17) Fulu Fm.; (18) Medvezhevo Fm.; (19) Kingston Peak Fm.; (20)

Numees Fm.; (21) Mugur Fm.; (22) Nizhne-Angara Fm.; (23) Aok Fm.; (24)Xiamaling Fm.;

(25) Roper Gr.; (26) South Nicholson Gr.; (27) Shoshong Fm.; (28) Chuanlinggou IF; (29)

Pike’s Peak IF; (30) Frere Fm.; (31) Alwar Gr.; (32) Lake Superior region (Gunflint IF,

Negaunee IF, Biwabik IF, Ironwood IF, Riverton IF); (33) Sokoman IF; (34) Rochford Fm.;

(35) Liaohe Gr.; (36) Estes Fm.; (37) Päkäkö IF; (38) Glen Township Fm.; (39) Lomagundi Gr.;

(40) Caldeião belt; (41) Ijil Gr.; (42) NimbaItabirite; (43) Hotazel IF; (44) Timeball Hill Fm.;

(45) Kursk Supergroup; (46) KrivoyRogSupergroup; (47) Transvaal Province (Griquatown IF,

Kuruman IF, Penge IF); (48) Hamersley basin IFs (BoolgeedaIron Fm., Weeli Wolli Fm.,

Brockman IF, Mt. Sylvia Fm., Marra Mamba IF); (49) Cauê Fm.; (50) Indian Creek

Metamorphic Suite; (51) Ruker Series; (52) Benchmark IF; (53) Hutchison Gr.; (54) Nemo IF;

(55) Chitradurga Gr.; (56) Beardmore-Geraldton assemblage; (57) AnshanIron Fm.; (58)

Manjeri IF; (59) Bababudan Gr.; (60) Central Slave Gr.; (61) Carajá Fm.; (62) West Rand Gr.;

(63) Pongola Supergroup; (64) Jack Hills belt; (65) Moodies Gr. Modified after

Bekker et al. (2010) ..................................................................................................................... 12

Figure 2.2-Proposed oxidation mechanismsfor Precambrian IFs. Dissolved Fe2+

, sourced

primarily fromhydrothermal vents, ismixed into seawater saturated with dissolved continental

silica. (1) Abiotic oxidation of dissolved Fe2+

with oxygen produced by cyanobacteria; (2)

deposition of cell-Fe3+

-mineral aggregates by microaerophilic Fe2+

-oxidizing bacteria in

presence of some oxygen; (3) UV light photo-oxidation of Fe2+

precipitating abiogenic

Fe3+

(oxyhydr)oxides in anoxic conditions; (4)direct microbial oxidation byanoxygenic Fe2+

-

oxidizing phototrophs, forming cell-Fe3+

-mineral aggregates. Modified after Posthet al. (2014)

..................................................................................................................................................... 17

xiv

Figure 2.3-Approximate paleogeographic distribution of Neoproterozoic IFs-MnFs, based on

the reconstruction of Rodiniaby Torsvik (2003) and Li et al. (2013). The Neoproterozoic IFs-

MnFsoccur in mostly in rift-basins developed on the margins of Rodinia. Modified after

Cox et al. (2013) ......................................................................................................................... 18

Figure 2.4-Depositional settings for the three types of Neoproterozoic IFs classification: (a)

Rapitan-type; (b) Algoma-type; and (c) Superior-type. Modified after Gaucheret al. (2015) .... 21

Figure 2.5-Plot of major elements (expressed as oxides in weight %), recalculated to 100% on

an H2O-CO2-free basis, in IFs. The shaded area represents the range of average values of ~215

pristine whole-rock analyses. Modified after Klein (2005)......................................................... 22

Figure 2.6-Shale-normalized (MUQ – Mud from Queensland; Kamber et al. 2005, updated by

Marx &Kamber 2010)REE diagram. The shaded areas bracket the range of profiles reported by

previously published studies of Neoproterozoic IFs: (a) Lake Superior-type; (b) Algoma-type;

and (c) Rapitan-type .................................................................................................................... 25

Figure 3.1-Lithostratigraphic correlations of sequences on the Amazon craton-Rio Apa block.

The transgression is glacio-esutatic. Modified after Trompette et al. (1998) and

Freitas et al. (2011) ..................................................................................................................... 31

Figure 3.2-Geotectonic context of the Urucum Massif. (a) Simplified geotectonic framework of

South America showing the position of the inferred R-R-R triple junction (modified after

Del’Reyet al. 2016) (b) Simplified geotectonic context of the Urucum massif, Chiquitos-

Tucavacaaulacogen and Paraguay fold and thrust belt (according to Trompetteet al. 1998). (c)

Geological context of the area shown in (b) (according to Trompetteet al. 1998)...................... 33

Figure 3.3-Geological map and schematic cross section (AB) of the Santa Cruz deposit

(modified after Haralyi&Walde 1986, Trompetteet al. 1998, Freitaset al. 2011,

Angerer et al. 2016). (b) Composite stratigraphic profile of the “Santa Cruz deposit (modified

after Freitaset al. 2011, Angereret al. 2016, Kroeninger 2016) .................................................. 35

Figure 3.4-Sequence stratigraphic framework. The Jacadigo-Boqui Gr. is comprised by a single

depositional sequence (S1). The overlying Corumbá Gr. is comprised by two depositional

sequences. Modified after Freitaset al. (2011) ............................................................................ 38

Figure 3.5-Tectonic-stratigraphic evolution of the Jacadigo-Boqui Gr. (a) Rift initiation tract.

(b) Initial rift climax systems. (c) Rift climax tract. (d) Post-rift tectonic tract (Corumbá Gr.). (e)

Basin inversion. (f) Present day topography. Modified from Freitaset al. (2011) ...................... 38

Figure 3.6- Shale-normalized (MUQ – Mud from Queensland; Kamber et al. 2005, updated by

Marx &Kamber 2010)REE diagram. Complete REE profiles reported in previous studies of the

Urucum IF: (a) Angerer et al. (2016); (b) Viehmannet al. (2016); Freiet al. (2017) .................. 42

Figure 3.7-Climatic genetic models for the Urucum IF-MnF:(a) formation of MnF and IF was

controlled by deposition along a dynamic redoxcline, respectively in shallower and deeper

zones (Viehmannet al. 2016); (b) likewise, the formation of the main IF facies was related to

variation of the depth of the redoxclinedue to transgression juxtaposed with glaciogenic

processes (Angerer et al. 2016). Metals were sourcedeither from low-temperature hydrothermal

fluids or pore water (Angerer et al. 2016) ................................................................................... 48

xv

Figure 4.1-(a) Simplified geotectonic framework of South America showing the position of the

inferred R-R-R triple junction (modified after D’el-Rey et al. 2016) (b) Geological map of the

Urucum Massif (modified after Freitaset al. 2011),and schematic cross section (AB) of the

Santa Cruz deposit (modified after Angerer et al. 2016). (c) Composite stratigraphic profile of

the Santa Cruz deposit (modified after Freitaset al. 2011, Angerer et al. 2016, Kroeninger 2016)

..................................................................................................................................................... 54

Figure 4.2-Transmitted and reflected light photomicrographs showing (a) banded and podded

chert-hematite IF, and (b) banded and nodular chert-dolomite-hematite IF, with a peloidal layer

(bottom). SEM back scattered electron images of a (c) nodular hematite-rich band (top) with a

carbonate-rich peloidal layer (bottom), and (d) hematite inclusions in gangue minerals. SEM-

EBSD mineral maps of (e) a chert-dolomite-hematite IF and (f) a chert-hematite IF sample.

Note the occurrence of magnetite and siderite. Mineral abbreviations: chert (Cht); hematite

(Hm); Fe-dolomite (Fe-dol) - ankerite (Ank); apatite (Ap); quartz (Qtz). .................................. 58

Figure 4.3-Back scattered (BEC) and secondary electron (SEI) images of the hematite stages.

(a) Anhedral hematite (Hm1) (bottom right) (EMP BEC); (b) Texturally heterogeneous

aggregate where Hm1 is predominant (SEM SEI); (c) Peloid composed of reticulated Hm2

aggregates (SEM BEC); (d) Hm2 aggregates with minor Hm3 platelets (center) (SEM SEI); (e)

Enriched sample with Hm3 composes nodules and laminations (SEM SEI); (f) Cluster of Hm3

crystals (SEM SEI). Mineral abbreviations: Fe-dolomite (Fe-dol); apatite (Ap); quartz (Qtz) .. 60

Figure 4.4-MUQ-normalized diagrams of rare earth (REE) and trace (TE) elements measured

by LA-ICP-MS. Complete data is presented in appendix E. The light and dark grey shaded areas

bracket the range of whole-rock profiles in chert-carbonate-hematite IF and chert-

hematite IF, respectively (unpublished manuscript). .................................................................. 66

Figure 4.5-Diagram of (Ce/Ce*)MUQ vs. (Pr/Pr*)MUQ used to discriminate between real Ce

anomalies and those induced by positive La anomalies (Bau&Dulski 1996). Real negative Ce

anomalies are defined by (Ce/Ce*)MUQ and (Pr/Pr*)MUQ below and above the unit, respectively.

Representative anomalies for modern oxidized seawater (De Baaret al. 1985, German et al.

1995, Zhang & Nozaki 1996, Alibo& Nozaki 1999); high- and low-T hydrothermal fluids

(Michardet al. 1993, Bau&Dulski 1999, Douville et al. 1999); and CFB - continental flood

basalt (Franklin Large Igneous Province data compiled from the GEOROC repository) are

plotted for comparison ................................................................................................................ 67

Figure 4.6-Rotated component plots for the FA of the (a) EMP and (b) LA-ICP-MS data sets.

The plots are composed by the first 3 factors, which account for most of the variability in the

corresponding data sets. The dashed line delineates clusters of variables most pronounced in

each factor. See text for further details ....................................................................................... 69

xvii

List of Tables

Table 2.1-Distribution and age of the Neoproterozoic IFs. Modified after Bekker et al. (2014) 19

Table 3.1-Depositional environment of the Jacadigo-Boqui Gr proposed in sedimentological

studies. Modified after Del’Arcoet al. (1982) ............................................................................. 40

Table 3.2-Arguments in favor and against the genetic models proposed for the Fe and Mn

deposits of the Urucum district. Modified after Walde&Hagemann (2007) ............................... 47

Table 4.1-Summary of the EMP data: mean values (in wt. %) standard deviationof different

hematite stages from the Urucum IF. See appendix B for complete analytical results ............... 62

Table 4.2-Summary of the LA-ICP-MS data: mean element abundances (in ppm) and standard

deviations of different hematite stages (Hm1; Hm2; Hm3) from the Urucum IF. See appendix C

for complete analytical results, including quantitation limits, standard deviations, and detection

limits ............................................................................................................................................ 63

Table 4.3-Rotated component matrices for the EMP (Fa) and LA-ICP-MS (Fb) data sets.

Complete analytical results are presented in appendix F. The corresponding rotated component

plots are presented in Fig. 4.6 for visualization .......................................................................... 68

xix

Abstract

The Jacadigo-Boqui Group, SW Brazil and SE Bolivia, hosts the so-called Urucum Iron and Manganese

Formation (IF-MnF); one of the most well-known and archetypaloccurrence of Neoproterozoic ageand the

last large expression of coupled Fe and Mn deposition of the Precambrian. This sedimentary sequence was

developed in rifts within the Amazon-Rio Apapaleocontinent,coeval witha Neoproterozoic glaciation event

and the early BrasilianoOrogeny. The Urucum IF hosts a very low-grade metamorphic assemblage,

generally composed of hematite, chert and carbonates of the Fe-dolimite-ankerite series. EMP and LA-ICP-

MS were used to determine the chemical composition of hematites from the carbonaceous and siliceous

facies IF found in the Santa Cruz hill, Brazil. Three mineralization stages wererecognized based on the

texture and morphology of the hematites: (i) anhedral microcrystalline, (ii) subhedral to

euhedralmicrospecular and (ii) microplaty.EMP resultsshow nearly pure Fe2O3 compositions, with

predominantly trace amounts of impurities. Both EMPand LA-ICP-MSresultsshow similar trace element

concentrations for all hematite stages, which vary within a relatively narrow range suggesting limited post-

depositional redistribution. Statistical Factor Analysis discriminated four groups of trace elements: (i)

incorporated in the crystalline structure of hematite (Ti, Al, V, Mn, Mg), (ii) associated with carbonate

contamination (Mg, Ca, Mn, P, Sr), (iii) associated with chertcontamination (Si), (iv) and hydrogenous

adsorbed on the precursor particles(REE, Ba, U, Th,Zr, Hf, Cu). Seawater-like shale-normalized REE

patterns and fractionated Zr/Hf and Th/U ratios indicate a recrystallization from precursor hydrogenous

sediments composed offerrihydrite.Microcrystalline hematite was formed earlyduring diagenesisthrough

solid-state dehydration of amorphous ferrihydrite; while the microspecular and microplaty varieties were

formed predominantly via diffusions processes during diagenesis-low grade metamorphismassociated with

the early BrasilianoOrogeny. These transformations were coeval and likely involved the participation of

hypogenemineralizingfluids (basin brines), which led to chert leaching. Supergene fluids further leached the

gangue minerals, but led to small modifications in the texture and trace element composition of primary

hematites. Real negative Ce anomalies and fractionated Th/U ratiosindicate that theprecursor

sedimentswere deposited in a stratified basin, above a redox chemocline, under well-oxygenated conditions.

The presence of hematite peloids corroborates a shallow marine setting, near the fair-weather wave base.

This surface oxic layer was likely connected with the open ocean, based on the typical marine REE

signature of the hematites, particularly the pronounced LREE depletion, but also received influx of

freshwater, indicated by varied by predominantly CHARAC (charge-and-radius-controlled behavior) Zr/Hf

ratios.

xxi

Resumo

O Grupo Jacadigo-Boqui, situado no SW do Brasil e SE da Bolivia, hospeda a Formação Ferrífera e

Manganesífera (FF-FMn) do Urucum; um das ocorrências mais conhecidas e arquetípica do

Neoproterozoico e a ultima grande expressão de deposição conjunta de Fe e Mn do Pré-cambriano. A

sequência sedimentar do GrupoJacadigo-Boqui foi depositada em rifts desenvolvidos no paleocontinente

Amazonas-Rio Apa, paralelamente a um evento de glaciação e o começo do ciclo Brasiliano. A FF do

Urucum é caracterizada por uma assembléia metamórfica de baixo a muito baixo grau, geralmente

composta por hematita, cherte e carbonatos da série Fe-dolomite-ankerita. EMP e LA-ICP-MS foram

usados para determinar a composição química de hematitas dos facies carbonático e silicoso encontrados no

morro Santa Cruz, Brasil. Três estágios de mineralização foram reconhecidos com base na textura e

morfologia: (i) hematita anédricamicrocristalina, (ii) hematita subédrica a euédrica microespecular e (iii)

microplacóide. Os resultados da EMP mostram composições químicas quase puras em Fe2O3 com

quantidades traço de impurezas. Os resultados das analises de EMP e LA-ICP-MS mostram concentrações

similares de elementos traço para todos os estágios, com pequena margem de variação, indicando uma

redistribuição pós-deposicional relativamente limitada dos elementos traço. A análise fatorial das

composições discriminou quatro grupos de elementos traço: (i) elementos incorporados na estrutura

cristalina das hematitas (Ti, Al, V, Mn, Mg), (ii) associados com contaminação por carbonatos (Mg, Ca,

Mn, P, Sr), associados com contaminação por cherte (Si), e hidrógenos adsorvidos em partículas

precursoras (ETR, Ba, U, Th, Zr, Hf, Cu). Padrões de elementos terras raras (ETR), normalizados com

folhelho, com características marinhas e razões de Zr/Hf e Th/U fracionadas sugerem uma recristalização a

partir de sedimentos hidrógenos compostos por ferrihidrita. A hematita microcristalina foi formada

precocemente durante a diagênese, através de desidratação, no estado sólido,de partículas amorfas de

ferrihidrita; equanto que as variedades microespecular e microplacóide se formaram por processos de

difusão durante estágios posteriores de diagênese-metamorfismo de baixo grau relacionado com o inicio da

Orogenia Brasiliana.Essas transformações ocorreram concomitantemente e, possivelmente, envolveram a

participação de fluidos hipogenéticos basinais, os quais promoveram o enriquecimento da FF através da

lixiviação de chert. Fluidos supergênicos promoveram a lixiviação de minerais de ganga, porémnão

modificaram significativamente a textura e composição química de hematitas primárias. Anomalias

negativas reais de Ce e razões fracionadas de Th/U indicam que o os sedimentos precursores foram

depositados em uma bacia estratificada, acima da fronteira redox, em condições óxicas. A presença de

pelóides de hematita corrobora um ambiente marinho raso; próximo ao nível de base das ondas em tempo

normal. Esta camada óxica superficial apresentava uma conexão com o oceano aberto, baseado nas

assinaturas de ETR caracteristicamente marinhas, particularmente a pronunciada depleção em ETR leves,

mas também recebeu um influxo de água doce, indicado por razões de Zr/Hf dentro do campo CHARAC

(charge-and-radius-controlled behavior).

CHAPTER 1

INTRODUCTION

1.1- GENERAL INTRODUCTION

Iron and manganese formations (IFs, MnFs) are controversial sedimentary rocks, whose

existence is intimately connected to the geological evolution of the Earth during the Precambrian

(Trendall 2002, Bekker et al. 2010, Maynard et al. 2010). Investigating their origin and relationship

with the evolving composition of the hydrosphere-atmosphere system is a key subject within the field

of geosciences (Pufahl & Hiatt 2012, Evans et al. 2013). Given the lack of unequivocal modern

analogues, the mineralogy and geochemistry of these rocks are often used to indirectly study their

origin (Planavsky et al. 2010b, Akin et al. 2014, Bekker et al. 2014, Maynard et al. 2014).

Neoproterozoic IFs and MnFs are particularly important because they represent the last

manifestation of these rocks in the geological record, after a prolonged hiatus during the

Mesoproterozoic (Bekker et al. 2010, Gaucher et al. 2015). The recurrence of Fe-Mn deposition

occurred during a period characterized by paleogeographic reconfiguration, tectonic disturbances, and

plume-related magmatism after the fragmentation of the supercontinent Rodinia, which triggered

extreme changes in the oceans-atmosphere system (Fig. 1.1) (Bekker et al. 2010, Maynard et al. 2010,

Och et al. 2012, Li et al. 2013, Cox et al.2016a). Among the most significant changes, the increase in

Fe and Mn supply and development of ferruginous reservoirs, concurrent with global glaciations

events conjectured in the “Snowball Earth” hypothesis (Hoffman et al. 1998, Higgins & Schrag 2003,

Kasemann et al. 2010), and the subsequent increase in oxygen availability during the Neoproterozoic

oxygenation event (NOE), led to the resume of this particular type of sedimentation

(Bekker et al. 2004, Kump & Seyfried 2005, Canfield et al. 2008, Johnston et al. 2010,

Halverson et al. 2010, Poulton & Canfield 2011, Cox et al. 2016a,b). These chemical and climatic

perturbations led to the eukaryotic diversification (Canfield et al. 2007, McFadden et al. 2008), and

ultimately the development of the modern environment.

Souza, F.R. de, 2017. Geochemical and Petrologic Constraints on the Origin of the Neoproterozoic…

2

The Urucum IF-MnF, hosted in the Jacadigo-Boqui Gr., SW Brazil and SE Bolivia, was

deposited during the late Neoproterozoic and represents the last large expression of coupled Fe and

Mn deposition (Bühn & Stanistreet 1997, Bekker et al. 2010, Maynard et al. 2010), and one of the

most well-preserved and archetypal examples of Neoproterozoic age (Cox et al. 2013,

Gauher et al. 2015). The intra-continental rift setting (Trompette et al. 1998, D’el-Rey et al. 2016),

and associated with glaciogenic deposits (Walde et al. 1981, Almeida 1984), tentatively associated

with a glaciation event (Halverson et al. 2011), are both emblematic characteristics of these

Neoproterozoic occurrences (Cox et al. 2013). Besides, these rocks record a peculiar habitat

(Morais et al. 2017), which preceded the biological evolution of the Ediacaran-Cambrian, preserved in

fossils found in the overlying Corumbá Group (Walde et al. 2015). Therefore, in many ways, the

Urucum IF-MnF epitomizes the convoluted changes of the Neoproterozoic and offers a window into

this decisive period in Earth’s evolution.

Figure 1.1- Timeline showing the major events during the Neoproterozoic. Fragmentation of the

supercontinent Rodinia and assembly of the supercontinent Gondwana; Large Igneous Provinces (LIP)

emplacement; main Neoproterozoic iron (IF) and manganese formations (MnF) ocurrences;

predominant deep and shallow seawater conditions (oxic, sulfidic, and ferruginous); biological

evolution; evolution of atmospheric and oceanic oxygen levels; Neoproterozoic global glaciations

(Gaskiers, Marinoan, Sturtian). Modified after Narbonne (2005), Love et al. (2009),

Canfield et al. (2008), Och & Shields-Zhou (2012), Bekker et al. (2014), Cox et al. (2016b).

Contribuições às Ciências da Terra, Série M (77), vol. 358, 155p.

3

1.2- STATEMENT OF PURPOSE

In recent years, a number of studies have contributed to pending temporal (e.g.

Piacentini et al. 2013, Viehmann et al. 2016, Frei et al. 2016), stratigraphic (e.g. Freitas et al. 2011,

Kroeninger 2016), tectonic and structural (e.g. D’el-Rey et al. 2016) questions concerning the

Jacadigo-Boqui Gr. However, to date, the particular conditions (e.g. Buhn & Stanistreet 1997,

Klein 2005, Bekker et al 2014, Maynard et al. 2014) necessary for the origin of the Urucum IF-MnF

and are not yet completely understood (e.g. Hagemann & Walde 2007); which include, among other

things, the role of hydrothermalism and glaciation in the development of the large Fe-Mn reservoir and

the mechanisms responsible for the deposition.

Hematites present in IFs are widely regarded as products of diagenetic transformation of

precursor phases, (bio)chemically precipitated from water columns or formed authigenically in pore

waters (Klein 2005, Pufahl & Hiatt 2012, Posth et al. 2013). If these precursor phases were formed

under thermodynamic equilibrium, the geochemical signatures of these hematites can be used as a

proxy for the environmental conditions of the coeval water (e.g. Derry & Jacobsen 1990,

Bau & Dulski 1996, Bolhar et al 2004, 2005, Kato et al. 2006, Alexander et al. 2008,

Planavsky et al. 2010b). Additionally, cyclic interbedding between IF-MnF and clastic lithologies

offer a favorable framework to study the paleodepositional environment (e.g. Krapez et al. 2003,

Pickard et al. 2004, Bontognali et al. 2013). A previous study on the petrography and geochemistry of

the Urucum IF, undertaken by this author in 2014 as a monograph at Universidade Federal de Ouro

Preto (UFOP), demonstrated that primary sedimentary and chemical traits are ostensibly preserved in

this occurrence; which was subsequently corroborated by other studies (e.g. Angerer et al. 2016,

Kroeninger 2016, Viehmann et al. 2016, Frei et al. 2017).

In such circumstances, the geochemistry of the hematites present in the Urucum IF-MnF can

provide important clues to the depositional controls of these rocks and their connection with the

convoluted changes in the Neoproterozoic environment. However, their value as a proxy for the

depositional environment rests on the accurate characterization of their primary geochemical signature

(e.g. Bau & Dulski 1996, Webb & Kamber 2000, Bolhar et al. 2004, 2005, Nothdurft et al. 2004,

Bolhar & Kranendonk 2007Alexander et al.2008, Zhao et al. 2010, Planavsky et al. 2010b,

Johnson et al. 2013). This represents a challenge because the chemical composition of these minerals

results from a complex interplay between multiple geological processes.


4

Micro-chemical techniques offer direct mineral compositions within textural contexts, which

avoids the contamination and heterogeneity of conventional whole-rock analyses and allow an

evaluation of post-deposition redistributions (e.g. Pecoits et al. 2009, Thurston et al. 2012,

Oliveira et al. 2015, Gourcerol et al. 2015, Hensler et al. 2015, Albert 2016). Additionally,

multivariate statistical techniques such as factor analysis (FA) can be used to identify hidden patterns

in large and complex geochemical data sets, which can be interpreted in terms of geological processes

(Ragno et al. 2007, Zhao et al. 2011). In Chapter 4, the geochemistry of hematites from the

Urucum IF, Santa Cruz deposit, is explored using in laser ablation-inductively coupled plasma mass

spectrometry (LA-ICP-MS) and electron microprobe (EMP), assisted by statistical FA, to identify

their primary trace element signature and the effects of post-depositional alterations.

1.3- OBJECTIVE

The goal of this study is to contribute to the knowledge of the origin and post-depositional

history of the Urucum IF-MnF and its overall connotation in the Neoproterozoic context. It is also the

intention of this study to establish a practical reference for future researches on the Jacadigo-Boqui Gr.

and similar successions worldwide.

This study seeks to address the following objectives:

Report high-resolution petrographic information and in situ element compositions of hematites

from the Urucum IF, Santa Cruz deposit;

Use factor analysis to refine the geochemical signature of the hematites;

Articulate new and previously published data to better constrain the paleodepositional

conditions and develop an appreciation of the genetic model for the formation of the hematites

in the Urucum IF;


5

1.4- LOCATION

The main outcrop of the Jacadigo-Boqui Group occurs in the area known as Urucum massif

(Fig. 1.2) – a region of approximately 200 km2, located between Brazil and Bolivia (Urban et al. 1992,

Klein & Ladeira 2004). The samples were collected from the Santa Cruz iron ore deposit, located in

the southeastern portion of the Urucum massif. The Santa Cruz deposit (operated by Vetria

Mineração S.A. until 2014) lies in the southeastern flank of the homonym hill, located about 30 km

from Corumbá. The main access route to the deposit is first via the highway BR-262, which runs from

Corumbá to Campo Grande (Fig. 1.2), and then via adjacent dirt roads. Alternatively, the deposit can

be accessed via highway MS 432, connecting BR-262 to MS 228.

Figure 1.2- SRTM image of the Urucum massif with the main hills and access routes. The Santa Cruz

mine is located about 30 Km from Corumbá. Modified after Freitas (2010).


6

1.5- METHODS OF STUDY

Sample preparation and microanalyses were undertaken at the department of

geology (DEGEO) of the Federal University of Ouro Preto (UFOP), Brazil. The petrography was

examined using a combination of conventional optical microscopy, using optical and electron

microscopy, consisting of scanning electron microscopy (SEM) coupled to energy-dispersive x-ray

spectroscopy (EDS) and electron backscattered diffraction (SEM-EBSD). The chemical composition

of the hematites was analyzed in situ via laser-ablation inductively coupled plasma-mass

spectrometry (LA-ICP-MS) and via electron-microprobe (EMP).

1.5.1- Sample Selection and Preparation

A total of sixteen representative drill core samples, , with a length of ~10-15 cm, were

collected from different depths along two stratigraphic holes: STCR-DD-24-36 (samples: LS-02, -08, -

09, -11, -12, -13, -14, -15, -19, -20,-21) and DD-40-40A (samples: DE-L-02, -04, -06, -08, -11),

located in the southeastern flank of the Santa Cruz deposit. The stratigraphic drill holes, cross-cutting

most of the Banda Alta Fm., provide a comprehensive geologic context for the interpretation of

geochemical data. The relative scarcity of cross-formational faulting, apart from a few minor inferred

faults to the west and south of the site, also facilitates the effort in this area. The selection was

lithofacies specific with focus on pristine IF lithologies with low crustal contamination and lacking

major veins, suitable for investigating conditions close to the time of deposition (Pufahl & Hiatt 2012,

Pufahl et al. 2014). The sample set is composed of ten chert-hematite IF samples and six chert-

dolomite-hematite IF samples.

Polished thin sections and rock slabs were prepared for every sample at Laboratório de

Laminação (LAMIN). Upon inspection, seventeen sections were selected for in situ chemical analyses

and supplementary petrographic investigations. The selected areas were cut into small blocks from the

rock slabs using a diamond blade saw, assembled into discs (appendix A, Fig. A.1) using a cold epoxy

compound, then polished with colloidal alumina and diamond suspension, and finally ultrasonically

rinsed to clean residues. A few paired sections were broken to expose surfaces for secondary electron

imaging. Two sections were selected for complementary SEM-EBSD analyses. The sections were cut

perpendicular to the xy-xz plane, resized into cubes using a slow speed, oil-cooled Buhler Isomet 1000

diamond saw. The small cubes were then mounted on an AROTEC PRE 30Mi hot mounting press

using a conductive resin. The mount with the samples underwent a systematic grinding and polishing

process in steps of decreasing granulometry with silicon carbide paper (240, 400 and 600 grit) and

diamond paste (9, 3, and 1µ), respectively. As a final step, the mount underwent a chemo-mechanical

lapping with colloidal silica (20 nm Buheler solution) on a Buhler Minimet 1000 polishing machine.

Polished thin sections, mounts and broken fragments were sputter-coated with carbon for the electron

microscopy using an evaporation coater model JEOL JEE-4C.


7

1.5.2- Petrographic Investigations

Textural investigations were performed at different scales using petrographic microscopes,

SEM and EMP. Mineralogical identification was based on optical properties, chemical compositions

(SEM-EDS) and crystal structures (SEM-EBSD). Transmitted and reflected light microscopy was

performed on polished thin section and mounts using binocular and petrographic microscopes at

Laboratório de Microscopia. Mineral-chemical characterization and imaging via SEM-EDS were

performed at Laboratorio de Microssonda e Microscopia Eletrônica (LMME) using a JEOL

JSM-6010-LA SEM and a JEOL JSM-6510 SEM, operated with acceleration voltage between 15 and

20 kV, equipped with Oxford EDS detectors. Mineral characterization via SEM-EBSD was performed

at Laboratório de Microestrutural (MICROLAB) on a JEOL JSM-5510 equipped with a Nordlys

Oxford EBSD and a high-resolution CCD camera. The acquired data was processed with the software

suite Channel 5 (Oxford) and the MATLAB MTEX toolbox.

1.5.3- In Situ Analyses

The electron microprobe analyses were performed on a JEOL JXA 8230 superprobe equipped

with 5 wave length-dispersive spectrometers (WDS). The analytical conditions were: beam diameter

of 5 µm, 20-nAlow-beam current and a 15-kV accelerating voltage. The values and measurement

conditions, including crystals and standards, are listed in Appendix B. Laser ablation analyses were

performed on a New Wave Research UP-213 Nd:YAG 213 nm coupled to an Agilent 7700x

Q-ICP-MS. The ablation was conducted in He atmosphere within a customized ablation cell

(Stellenbosch University) attached to a gas mixer with Ar injection for transport to the ICP-MS. The

total acquisition time for each analytical site was of 70 s, including 20 s for background acquisition

and 40 s for chamber washout. The laser was operated with continuous 10 Hz pulses with energy

density varying between ~8.6 and 9.35 J/cm2. A small, 30-μm beam diameter was chosen due to the

fine graining of the matrix. Although a larger spot size would improve signal intensity and stability,

the incorporation of contaminants would be significantly increased.


8

The analytes were split into two batches based on the atomic mass of the elements improve

counts and minimize mass bias. The lower- and higher-mass sets (respectively termed Group I and

Group II in appendix C) were measured in adjacent spots. The ICP-MS instrument parameters were

calibrated separately for each batch with the NIST SRM 610 and 612 standards, and adjusted using

matrix-matching standards (Jochum et al. 2007). The analytical signals were calibrated against an

external standard bracketed at intervals of 6-10 sample analyses. At present there is no commercially

available standard for IF to decrease matrix effects (Jarvis & Williams 1993, Jochum et al. 2016). We

investigated two macro-crystals of hematite using laser and solution-based ICP-MS. However, these

crystals were deemed inappropriate due to low trace element abundances and heterogeneous element

distributions. A seemingly suitable alternative was found in the basalt glass USGS BHVO-2G (11.15

wt. % FeO). Although not a perfect matrix match for hematite, the range of trace element

concentrations and chemical composition of this standard is somewhat similar to those observed in the

samples. Plasma conditions were tuned to reduce interferences. The formation of oxides and double

charge, monitored respectively with ThO/Th and Ca+/Ca

2+, were kept under 1%. The analytical

conditions and accuracy of the analyses were verified with the USGS BCR-2G as secondary standard.

The GEOREM preferred values were used for the standards (Jochum et al. 2016). The data was

processed using the software GLITTER® (Access Macquarie LTD). Raw intensities were corrected

for background and normalized to 57

Fe to correct time-dependent signal drift and fractionation

(Nadoll & Koenig, 2011), using an average value of 85.90 wt. % FeO determined by EMP was. Only

values above the quantitation limit, defined as three times the local minimum detection limit, were

reported in the results (appendix C). The spots were filtered for noticeable contamination because of

the frequent incorporation of inclusion and underlying phases (appendix A, Fig. A.2) in the ablation

pits. Coefficients of variation (Horwitz 1982) for most elements are within 75-125% of the secondary

standard’s published values (appendix C).


9

1.5.4- Statistical Treatment

Factor Analysis (FA) was used to explore the underlying constructs in the dataset. Multivariate

FA transforms large data sets composed of inter-correlated variables (elements) into smaller subsets of

linearly uncorrelated factors, which account for the maximum variation in the original data set

(Yongming et al. 2006, Astel et al. 2007, Ragno et al. 2007, Moura et al. 2010). This transformation is

based on a model that assumes the existence of common factors, which allow the existence of factors

with different behaviors (Reimann 2002).

In practice, FA detects all processes determining element behavior (Reimann 2002). In

contrast to conventional descriptive graphics, all variables are examined simultaneously, providing a

summarized data that facilitates the recognition of processes governing element behavior, and

decreases subjective assessment of data. Also, the contribution of individual observations (samples) to

the variables and of each variable (elements) to the factors can be assessed (Cheng et al. 2011,

Cox et al. 2013). This offers a better understanding of the influence of the geological processes in

every sample and element, and vice-versa.

Factor analysis was performed separately for the data sets generated by the EMP and

LA-ICP-MS analyses. Elements and spots with over >25% of the data below the quantitation limit

were excluded from the factor analysis. The remaining values below the quantitation limits were set to

half the respective local quantitation limit. Additionally, Pb and W were excluded from the FA of the

LA-ICP-MS data set to reduce dimensionality. The variables were first tested and standardized

applying a two-step normalization using the software IBM SPSS Statistics V. 23.0 (Templeton 2011).

The statistical software XLSTAT 2014.5.03 was used with principal component extraction method and

Kaiser Varimax rotation (Kaiser 1958). Only factor scores outside the -0.5 to 0.5 range were

interpreted, following the suggestion of Nadoll et al. (2012).


10

CHAPTER 2

NEOPROTEROZOIC IRON FORMATIONS

2.1- DEFINITION OF IRON FORMATION

The terminology iron formation (IF) has been broadly used to designate stratigraphic units

composed of iron-rich minerals, commonly interlayered with quartz or carbonate (Gross 1980,

James 1954). For the purposes of this study, the term iron formation is defined as a sedimentary rock

containing over 15 % in weight of Fe2O3 (James 1954, Trendall 2002, Simonson 2003, Klein 2005).

everal attempts to classify the IFs have been made over the years. One of the first attempts was made

by James (1954), who assigned the IFs into four chemical facies based on their mineralogy: silicate,

carbonate, oxide, and sulfide. Hematite and magnetite are the predominant Fe-rich mineral phase in

the oxide facies, while siderite and ankerite dominate the carbonate facies, and pyrite dominates the

sulfide facies. The silicate-facies has a more complex mineralogy that depends upon the degree of

metamorphism. However, this model has since become obsolete because depth relations and position

within sedimentary basin weren’t demonstrated worldwide (Beukers & Gutzmer 2008).

While other classifications exists (e.g. Dimroth 1975, Kimberley 1978, Beukes 1980,

Young 1989, Trendall 1983), the most widely used seems to be that defined by Gross in 1980.

Gross (1980) proposed the subdivision of IFs into the Lake Superior and Algoma categories, based on

the tectonic and depositional settings. Algoma-type IFs are hosted in volcano-sedimentary sequences,

deposited mostly in arc or rift settings (Isley & Abbott 1999), whereas Lake Superior-type IFs are

associated with minor amounts of volcanic rocks, and were deposited in continental-shelf settings

(Gross 1980). Algoma-type IFs are more abundant and widespread compared to Superior-type IFs

(Fig. 2.1), but the latter are generally more laterally extensive, thicker, and voluminous (Klein 2005,

Beukes & Gutzmer 2008, Beukes et al. 2010). In practice, a gradation usually occurs between these

types, reflecting distal or proximal precipitation associated with submarine volcanism and

hydrothermal activity. The Algoma-type records a greater volcanic and/or hydrothermal influence;

whereas Superior-type reflects large scale seawater compositions, with higher crustal influences

(Klein 2005, Beukes & Gutzmer 2008, Bekker et al. 2010).


12

The Rapitan-type IF defined by Beukes & Klein (1992) is commonly used along with the

Algoma- and Lake Superior-type defined by Gross (1980). According to Beukes & Klein (1992), the

Rapitan-type IF is characterized by glacially influenced basins, and occurs exclusively in the

Neoproterozoic. In general, Rapitan-type IFs are less voluminous, and have more variable thicknesses

compared to the other two categories. Also, the typical banding observed in other Precambrian IFs is

less ubiquitous, and the mineralogy of pristine Rapitan-type IFs is considerably more monotonous

(Cox et al. 2013, Bekker et al. 2014). Even though these categories present several deterrents under

closer inspection, they are well-established in literature and still widely used, and showcase the often

overlooked link between volcanism/hydrothermal and Neoproterozoic IFs-MnFs (Bekker et al. 2014,

Gaucher et al. 2015).

Figure 2.1- Major occurrences worldwide: (1) Maly Khinghan Fm.; (2) Yerbal Fm.; (3) Jacadigo Gr.

(Urucum IF); (4) Bisokpabe Gr.; (5) Chestnut Hill Fm.; (6) Holowilena Ironstone; (7) Braemar IF; (8)

Vil’va Fm. and Koyva Fm.; (9) Bakeevo (Tolparovo) Fm.; (10) Dzhetymtau Suite; (11) Uk Fm.; (12)

Yamata Fm.; (13) Lake Khanka Fm.; (14) Rapitan Fm.; (15) Chuos Fm.; (16) Tindir Gr.; (17)

Fulu Fm.; (18) Medvezhevo Fm.; (19) Kingston Peak Fm.; (20) Numees Fm.; (21) Mugur Fm.; (22)

Nizhne-Angara Fm.; (23) Aok Fm.; (24)Xiamaling Fm.; (25) Roper Gr.; (26) South Nicholson Gr.;

(27) Shoshong Fm.; (28) Chuanlinggou IF; (29) Pike’s Peak IF; (30) Frere Fm.; (31) Alwar Gr.; (32)

Lake Superior region (Gunflint IF, Negaunee IF, Biwabik IF, Ironwood IF, Riverton IF); (33)

Sokoman IF; (34) Rochford Fm.; (35) Liaohe Gr.; (36) Estes Fm.; (37) Päkäkö IF; (38)

Glen Township Fm.; (39) Lomagundi Gr.; (40) Caldeião belt; (41) Ijil Gr.; (42) Nimba Itabirite; (43)

Hotazel IF; (44) Timeball Hill Fm.; (45) Kursk Supergroup; (46) Krivoy Rog Supergroup; (47)

Transvaal Province (Griquatown IF, Kuruman IF, Penge IF); (48) Hamersley basin IFs

(BoolgeedaIron Fm., Weeli Wolli Fm., Brockman IF, Mt. Sylvia Fm., Marra Mamba IF); (49)

Cauê Fm.; (50) Indian Creek Metamorphic Suite; (51) Ruker Series; (52) Benchmark IF; (53)

Hutchison Gr.; (54) Nemo IF; (55) Chitradurga Gr.; (56) Beardmore-Geraldton assemblage; (57)

AnshanIron Fm.; (58) Manjeri IF; (59) Bababudan Gr.; (60) Central Slave Gr.; (61) Carajá Fm.; (62)

West Rand Gr.; (63) Pongola Supergroup; (64) Jack Hills belt; (65) Moodies Gr. Modified after

Bekker et al. (2010).


13

2.2- DEPOSITIONAL CONSTRAINS

As a result of the secular changes in Earth’s systems, clear-cut modern analogues to

Precambrian IFs are unknown (Bekker et al. 2014). Consequently, the various sources and processes

involved in the deposition of Fe are still unclear, but some basic constraints are generally agreed upon

(Holland 1973, Drever 1974, Kump & Holland 1992).

2.2.1. Modern Fe Sources and Fe Cycle

In Earth’s surface and near surface systems Fe occurs in the Fe2+

and Fe3+

states. The latter is

dominant in both seawater and rivers as consequence of their oxidizing conditions. The limited

solubility of Fe3+

results in small amounts of dissolved iron in ocean (ca. 0.5 nM), bound mainly by

ligands, and small residence time (ca. 100-200 years) (Cox et al. 2013, Bekker et al. 2014).

Leaching of continental margin sediments is a dominant source of Fe to the ocean, especially

in glacially influenced oceans (Tagliabue et al. 2010). Fe remobilized from continental margins

sediments is derived from the diffusion of reduced Fe2+

from pore waters (Aller et al. 2010), mainly by

bacterial dissimilatory iron reduction (DIR) of detrital Fe oxides (Lovley 1991, Elrod et al. 2004).

Another significant Fe influx is provided by outwashes from continental glaciers, which carry

particulate matter and dissolved Fe from DIR in sub-glacial brines (Mikucki et al. 2009) and

photo-reduction (Kim et al. 2010) of Fe2+

-bearing minerals trapped in ice (Rainswell et al. 2006).

Dissolved Fe from wind-blown dust and re-suspended sediments corresponds to a significant share of

the Fe influx associated with upwelling deep waters (Bekker et al. 2014). Continentally derived Fe,

sourced by weathering and transported in rivers and groundwater as complexes, colloids, and

particulate matter, is mostly deposited in estuaries due to oxidative precipitation or salinity-induced

flocculation (Schroth et al. 2011, Bekker et al. 2014).

Hydrothermal input, although not as well constrained, accounts for a large portion of deep-

ocean Fe reservoir (Poulton & Raiswell 2002, Boyd & Ellwood 2010). Although, most of the Fe and

Mn derived from hydrothermalism are precipitated close to the source, upon mixing of hot reducing

fluids with cold oxidized seawater, hydrothermal plumes can carry Fe and other metals for long

distances (Yucel et al. 2011, Cox et al. 2013). The concentration of metals in hydrothermal fluids

depends mostly on the temperature and salinity, but can also be affected by the composition of the host

rocks, magma degassing and subsurface sulfide dissolution/precipitation (e.g. Edmond et al. 1979;

Mottl et al. 1979). Elevated temperatures and salinities, as well as alteration of Fe2+

-bearing mafic and

ultramafic rocks, especially seafloor basalt, result in higher concentrations of Fe (Cox et al. 2013,

Cox et al. 2016a).


14

Modern metalliferous sediments are possibly the best available reference for the interpretation

of IF (Bekker et al. 2010). Hydrothermal deposits enriched in Fe form in exhalative vent systems in

mid-ocean ridges, off-axis seamounts, and arc/back-arc submarine volcanoes (e.g.

De Carlo et al. 1983, Alt 1988, Mills 1995). Shallow-water, Fe-rich sediments are restricted to areas

strongly affected by hydrothermal circulation, associated with active volcanism and some degree of

biological influence (e.g. Heikoop et al. 1996, Hanert 2002). Arguably, the most interesting example is

that of the Red Sea, where metalliferous sediments are precipitated from hot stratified brine pools,

formed by rift-hosted hydrothermal systems (e.g. Dekov et al. 2007). The brine deposits are

characterized by strong hydrothermal geochemical signatures, whereas shallower-water deposits

formed above have signatures dominated by seawater due to the removal of proxies (mostly REE)

adsorbed onto the precipitating particles (Cocherie et al. 1994).

2.2.2. Basin Water Redox

One of the prerequisites for the occurrence of IFs is the build-up and transport of an ample Fe

reservoir (Bekker et al. 2010). The concentration of this element in contemporary oceans is extremely

low because it occurs predominantly as the Fe3+

species, which is essentially insoluble unless

supported by complexation with ligands (Cox et al. 2013). The solubility of Fe2+

under the conditions

of most oceans is also extremely low, but Fe2+

is the dominant stable species at lower Eh and pH

values (Cox et al. 2013). It is generally agreed that in the Precambrian this dissolved Fe reservoir must

have been made up of Fe2+

(Bekker et al. 2014). A second condition for the accumulation and

transport of Fe in solution is the low concentrations of sulfate and sulfides (Habicht et al. 2002), or

alternatively the lack of organic substrate for bacterial sulfate reduction (BSR) (Mikucki et al. 2009).

Essentially, in presence of H2S, dissolved Fe2+

is titrated, forming a precursor to pyrite

(Wilkin & Barnes 1996). A broad threshold of H2S/Fe2+

< 2 is required for the development of anoxic

ferruginous conditions; otherwise, euxinic conditions are prevalent (Canfield 2004).

2.2.3. Oxidation Mechanisms

The general consensus is that IFs were formed by precipitation of precursor sediments from

seawater containing soluble Fe2+

(0.05–0.5 mM) and silica (~2mM) (Holland1973, Siever 1992,

Morris 1993, Posth et al. 2014). Nonetheless, the exact mechanism for primary oxidation of Fe2+

is

still not entirely resolved (Fig. 2.2). In any case, the precursor precipitates were likely constituted by

Fe oxy-hydroxides, which were later dehydrated and converted to hematite during early diagenesis

(Klein 2005, Posth et al. 2013).


15

The classic deposition model proposes an abiotic chemical oxidation of dissolved Fe2+

(Cloud 1965, Cloud 1973), as shown in reaction (1). The source of mobile O2 in Precambrian oceans is

believed to be derived from oxygenic photosynthesis by plankton, generally cyanobacteria

(Posth et al. 2014). Hence, this hypothesis involves the metabolic activity of microorganisms in the

photic zone, either in microenvironments rich in O2 (i.e. oxygen oases) or in a mildly oxic water

column. Bacterial blooms may have flourished during episodic supply of nutrients, including Fe2+

,

leading to indirect precipitation of IFs (Bekker et al. 2014). During the Neoproterozoic, although

cyanobacteria were possibly the primary producers, eukaryotic autotrophs also contributed to the O2

production (Gould 2012). Furthermore, surface water was oxygenated, following the presumed first

stage of the great oxidation event, while ferruginous conditions prevailed in the deep Neoproterozoic

oceans (Canfield et al. 2008).

2Fe2+

+ 0.5O2+ 5H2O ⇋ 2Fe(OH)3 + 4H+ (1)

Photochemical oxidation, catalyzed by ultraviolet (UV) radiation, has been previously

suggested as an alternative abiotic model for Fe precipitation. According to Cairns-Smith (1978),

dissolved Fe species could be photo-oxidized, as shown in the reaction below (2), by the high levels of

UV flux reaching Earth's surface prior to the development of a protective ozone layer. The

dissolved Fe would absorb UV radiation in the 200–400 nm range, releasing H2 gas, and forming

aqueous Fe3+

(Cairns-Smith 1978, Braterman et al. 1983). However, Konhauser et al. (2007)

demonstrated that under more complex solutions, postulated for the Precambrian oceans, photo-

oxidation of Fe is negligible compared to the precipitation of Fe-silicates or Fe-carbonate phases due

to kinetic inhibition. Besides, after the first stage of the Great Oxidation Event (GOE), partial

pressures of oxygen sufficient for the establishment of the ozone layer were attained

(Farquhar et al. 2000, Farquhar & Wing 2003, Och & Shields-Zhou 2012). Therefore, UV photo-

oxidation can be ruled out as primary pathway during the Neoproterozoic.

2Fe2+

(aq) + 2H++ hv→ 2Fe

3+(aq) + H2 ↑ (2)

Recent developments have led to various metabolic Fe2+

oxidation models becoming more

prominent (Konhauser et al. 2005). Biologically mediated Fe2+

oxidation can occur in presence or

absence of oxygen, and result in precipitation of insoluble Fe3+

oxy-hydroxides. Microaerophilic

Fe2+

-oxidizing bacteria (e.g. Gallionella ferruginea, Leptothrix ochracea, and Mariprofundus

ferrooxydans), present in several marine systems, can be used as modern analogous. Aerobic

chemolithoautotrophic processes occurs under circum-neutral pH at modern hydrothermal vents (3)

(Emerson & Moyer 2002), and under low pH in acid mine drainage sites (4) (Templeton 2011).

Microaerophilic chemolithoautotrophic organisms use Fe2+

as electron donor, and transform CO2 in

organic C.


16

6Fe2+

+ 0.5O2 + CO2 + 16H2O → CH2O + 6Fe(OH)3 + 12H+ (3)

2Fe2+

+ 0.5O2 + 2H+→ 2Fe

3+ + H2O (4)

In anaerobic settings, anoxygenic photoferrotrophs can use Fe2+

as electron donor for CO2

fixation, producing Fe oxy-hydroxide as a byproduct (5) (Baur 1979, Hartman 1984,

Widdel et al. 1993). A number of sulfur and non-sulfur bacteria strains are known to use

photoferrotrophy (Widdel et al. 1993, Ehrenreich & Widdel 1994, Heising & Schink 1998,

Heising etal. 1999, Straub et al. 1999). Other electron acceptors such as nitrate (6) (Straub et al. 1996)

can also be used. Denitrifying bacteria occurs in sediments and uses different organic substrates for

phototrophic growth. Only a consortium of chemoheterotrophic and chemolithoautotrphic

Fe2+

-oxidizing bacteria has been shown to be capable of auto-photoferrotrophy

(Blothe & Roden 2009).

4Fe2+

+ CO2 + 11H2O + hv→ CH2O + 4Fe(OH)3 + 8H+ (5)

10Fe2+

+ 2NO3- + 24H2O → 10Fe(OH)3 + N2 + 18H

+ (6)

Bacteria can also passively support bio-mineralization, as templates for mineral nucleation or

changing micro-environmental conditions, which can promote precipitation. The rates of microbial Fe

oxidation are up to 50 times more favorable than direct abiotic reactions, under low oxygen conditions

(Søgaard et al. 2000, Emerson & Moyer 2002) and even modest populations (Konhauser et al. 2002,).

Besides, metabolic Fe oxidation appears to be common in modern ferruginous aquatic systems, where

Fe3+

-rich sediments are deposited (Lehours et al. 2007). On the other hand, the general lack of reduced

Fe phases in Neoproterozoic IFs, imply that very little organic C was delivered to the sediment

(Cox et al. 2013), speaking against an appreciable production of biomass and consequently metabolic

Fe2+

oxidation (Haverson et al. 2011).

Another Fe-deposition mechanism has been proposed for volcanic-hosted IFs, associated with

VMS deposits. According to Foustoukos & Bekker (2008), during eruptions, magmatic chambers can

expel brine solutions enriched in Cl-complexed transition metals. These solutions can undergo phase

separation, removing HCl into the vapor phase and forming oxidizing and alkaline Fe3+

-rich brine

fluids from which Fe oxy-hydroxides might form. However, this hypothesis has not been supported by

empirical data nor detailed modeling, and can only be applied to Algoma-type IFs.


17

Figure 2.2- Proposed oxidation mechanisms for Precambrian IFs. Dissolved Fe2+

, sourced primarily

from hydrothermal vents, is mixed into seawater saturated with dissolved continental silica. (1)

Abiotic oxidation of dissolved Fe2+

with oxygen produced by cyanobacteria; (2) deposition of

cell-Fe3+

-mineral aggregates by microaerophilic Fe2+

-oxidizing bacteria in presence of some oxygen;

(3) UV light photo-oxidation of Fe2+

precipitating abiogenic Fe3+

oxy-hydroxides in anoxic conditions;

(4) direct microbial oxidation by anoxygenic Fe2+

-oxidizing phototrophs, forming cell-Fe3+

-mineral

aggregates. Modified after Posth et al. (2014).

2.3- NEOPROTEROZOIC IRON FORMATIONS

IFs are considered characteristic geological feature of the Neoproterozoic. The reappearance

of these rocks in the Neoproterozoic stratigraphic record is extremely relevant to understand the

tectonic, biogeochemical and climatic conditions that prevailed during this interval (Klein &

Beukes 1993, Cox et al. 2013). The Neoproterozoic mark last occurrence of Precambrian IFs, after

this interval the distinct and less abundant Phanerozoic Minette-Clinton-type ironstones appear in the

geological record (Young 1989).

Neoproterozoic IFs differ from their older Archean and Paleoproterozoic counterparts in

several ways. In these IFs, the Fe resides almost exclusively in hematite (Klein 2005, Cox et al. 2013),

indicating that it transformed after precursor forms of Fe3+

oxy-hydroxide, such as ferrihydrite

(Bekker et al. 2014, Posth et al. 2013, 2014). Magnetite, and Fe-bearing silicates and sulfides are

generally secondary phases or alteration products (Cox et al. 2013). Hematite occurs in laminations

and nodules alternated with chert (usually jasper), but also as in granular beds and as matrix/cement to

siliciclastic rocks (Cox et al. 2013, Bekker et al. 2014).


18

Neoproterozoic IFs are commonly associated with presumed low latitude glacial deposits

(Fig. 2.3) (Macdonald et al. 2010b, Cox et al. 2013), linked to the conjectured global glaciation events

of the snowball Earth hypothesis (Kirschivink 1992, Hoffman et al. 1998, Hoffman & Schrag 2002),

primarily the Cryogenian Sturtian and Marinoan events, but also the less defined Ediacaran Gaskiers

event (Table 2.1.) (Cox et al. 2013, Gaucher et al. 2015). This is the case of the well-known Rapitan

IF, the Namibian (Chuos and Numees IFs) and Australian (Braemar and Holowilena IFs) occurrences,

and the Brazilian Urucum IF-MnF, to name a few (Klein & Beukes 1993, Baldwin 2014,

Frimmel 2008, Hoffman & Halverson 2008, Angerer et al. 2016). Nevertheless, recent researches

demonstrate that others bear no clear stratigraphic or temporal relationship with glaciations

(Ilyin 2009, Cox et al. 2013, Bekker et al. 2014, Gaucher et al. 2015), and resemble more closely IFs

of the Algoma- and Lake Superior-types (e.g. Basta et al. 2011, Cox et al. 2013, Frei et al. 2013,

Xu et al. 2013, Gaucher et al. 2015, Sial et al. 2015). Additionally, the occurrence of Neoproterozoic

IFs in rift-basins within and on the margins of the Rodinia (Fig. 2.3) implies that their deposition can

be accounted for by local anoxia, and not necessarily a global ferrous ocean predicted in the snowball

Earth hypothesis (Ilyin 2009, Cox et al. 2013).

Figure 2.3- Approximate paleogeographic distribution of Neoproterozoic IFs-MnFs, based on the

reconstruction of Rodinia by Torsvik (2003) and Li et al. (2013). The Neoproterozoic IFs-MnFs occur

in mostly in rift-basins developed on the margins of Rodinia. Modified after Cox et al. (2013).


19

Table 2.1- Distribution and age of the Neoproterozoic IFs. Modified after Bekker et al. (2014).

Formation/Group/Deposit Location Age (Ma)

Maly Khinghan Fm. Far East, Russia ~ 560

Yerbal and Cerro Espuelitas Fm.,

Arroyo del Soldado Gr.

Southeastern Uruguay ~ 560

550-566(±8)

Urucum IF, Jacadigo-Boqui Gr.;

Puga Fm.

Brazil ~ 600

587(±7)-709(±6)

Bisokpabe Gr. Togo, West Africa ~ 600

Chestnut Hill Fm. New Jersey, USA ~ 600

Jucurutu Fm. Seridó Belt, northeastern Brazil ~ 600(?)-634(±13)

Holowilena and Oparinna IFs,

Uberatana Gr.

Flinders Ranges, South Australia,

Australia

~ 650

600(±5)-?

Braemar IF South Australia, Australia ~ 650

Vil’va and Koyva Fm. Middle Ural Mts., Russia ~ 650

Bakeevo (Tolparovo) Fm. Southern Ural Mts, Russia ~ 650

Dzhetymtau Suite Middle Tian-Shan, Kyrgyzstan ~ 650

UK Fm. Ural Mountains, Russia ~ 700(?)

Yamata Fm. East Siberia, Russia ~ 700(?)

Lake Khanka Fm. Far East, Russia ~ 700(?)

Sayunei Fm., Rapitan Gr. Yukon Territory and Northwest

Territories, Canada

716.5(±0.24)

Chuos Fm., Otavi Gr. Northwestern Namibia 715 (?)

636(±1)-746(±2)

Tatonduk IF, Tindir Gr. Alaska, USA 715

Fulu Fm., Jiangkou Gr. Jiangxi Province, China 725(±10)-741

Medvezhevo Fm. Patom uplift, Siberia, Russia ~ 700-750

Kingston Peak Fm. California, USA ~ 700-750

Numees Fm. Gariep Belt, Southern Namibia ~ 600(?)-750

WadiKarim, Wadi El Dabbah, Um

Anab, and Sarawin IFs

Arabian-Nubian Shield (Egypt and

Saudi Arabia)

710(±5)-759(±17)

Erzin IF, Mugur Fm. Tuva, Russian Federation, and

Mongolia

~ 767(±15)

Nizhne-Angara Fm. Angara-Pit area, Enisey Ridge,

Siberia, Russia

~ 800

Aok Fm. Northwest Territories, Canada ~ 840

Shilu IF, Shilu Gr. Southern China ~ 830-960

References :(1)James (1983);(2)Ilyin(2009);(3) Aubet et al. (2012); (4) Pecoits et al.(2008); (5)

Blanco et al.(2009);(6) Gaucher et al. (2009); (5) Urban et al. (1992);(8) Trompette et al. (1998); (9)

Klein & Ladeira (2004); (10) Babinski et al. (2013); (11) Døssing et al.(2010); (12) Piacentini et al.

(2013); (13) Beukes (1973); (14)Simpara et al. (1985); (15) Volkert (2001); (16) Volkert et al. (2010);

(17) Sial et al. (2015); (18) Van Schmus et al. (2003); (19) Dalgarno & Johnson (1965); (20) Preiss

(2006); (21) Kendall et al. (2009); (22) Fanning & Link (2008); (23) Le Heron et al. (2011); (24)

Whitten (1970); (25) Lottermoser& Ashley (2000); (26) Ablizin et al.(1982); (27) Bekker (1988); (28)

Chumakov (1992); (29) Chumakov (2011); (30) Zubtsov (1972); (31) Korolev & Maksumova (1984);

(32) Sagandykov&Sudorgin(1984); (33) Chumakov(2009); (34) Young(1976); (35) Yeo (1986);

(36) Klein & Beukes (1993); (37) Macdonald et al. (2010); (38) Roesener & Schreuder (1992); (39)

Hoffmann et al. (2004); (40) Hoffman et al. (1996); (41) Fölling & Frimmel (2002); (42) Macdonald

et al. (2010b); (43)Gaucher et al. (2005); (44) Young (1982); (45) Kaufman et al. (1992); (46) Tang et

al.(1987); (47) Ivanov et al. (1995); (48) Chumakov (2011); (49) Miller (1985); (50) Condon et al.

(2002); (51) Van Staden et al. (2006); (52) Basta et al.(2011); (53) Stern et al. (2013); (54) Yudin

(1968); (55) Rainbird et al. (1996); (56)Rainbird et al. (1994); (57) Xu et al. (2013b).


20

2.3.1- Types of Neoproterozoic Iron Formation

Neoproterozoic IFs that hold persuasive evidences for glaciomarine settings are assigned to

the archetypal Neoproterozoic Rapitan-type (Fig. 2.4 – a) (Klein & Beukes 1993). Outsized clasts

within IF beds, interbedded diamictites, sometimes including faceted and striated clasts, and sharply

overlying post-glacial “cap carbonates”, with negative δ13

C signatures (Hoffman & Schrag 2002), are

recurrently interpreted as testimonies of glacial settings (e.g. Young 2002, Frimmel 2008,

Hoffman & Halverson 2008, Miller 2008, Halverson et al. 2011). The Urucum IF-MnF exhibits many

of these features, but its correlation with a glacial event is somewhat contentious (a more

comprehensive discussion is presented in Chapter 3).

In recent years, some Neoproterozoic occurrences have been correlated with the classic

Algoma-type IF (Gross 1980), particularly because of their geotectonic setting and lithostratigraphic

association, but also their distinctive geochemistry signature. The most emblematic occurrences are

the correlative Arabian-Nubian shield IFs, found in Egypt and Saudi Arabia (Ali et al. 2009,

Basta et al. 2011, Stern et al. 2013), the Brazilian Jucurutu IF (Sial et al. 2015), and the Chinese Fulu

IF (Goldbaum 2014). Neoproterozoic Algoma-type IFs (Fig. 2.4 – b), for the most part

(e.g. Ali et al. 2010a), lack evidences indicating a glacially influenced deposition. Like their older

counterparts, these IFs are associated with volcanic/volcanoclastic rocks, and usually occur in

compressional arc or back arc settings (Van Schmus et al. 2003, Ali et al. 2009, Basta et al. 2011,

Stern et al. 2013, Gaucher et al. 2015, Sial et al. 2015).

Other Neoproterozoic IFs have been tentatively assigned to the Lake Superior-type (Fig. 2.4 –

c). These IFs are hosted in thick and laterally persistent passive margin successions, without glacial

deposits and volcanic rocks (Gaucher et al. 2015). The Ediacaran IFs of the Uruguayan Arroyo del

Soldado Gr. (Yerbal Fm. and Cerro Espuelitas Fm.) are the best documented examples

(Gaucher et al. 2003, Frei et al. 2011). A stable platform tectonic setting was proposed for these IFs on

the basis of facies association and provenance of detrital zircons (Gaucher et al. 2008). Similarly, a

shelf setting was proposed for the Tonian Shilu IF (Shilu Gr., South China) (Xu et al. 2013).


21

Figure 2.4- Depositional settings for the three types of Neoproterozoic IFs classification: (a) Rapitan-

type; (b) Algoma-type; and (c) Superior-type. Modified after Gaucher et al. (2015).


22

2.3.2- Geochemistry

The major element composition of the Neoproterozoic IFs is similar to other pre-Cambrian

IFs, with predominance of Fe and Si, and lesser amounts of Ca, Mg, Mn, Al, K, Na and P (Fig.2.5).

Conversely, the elemental contents of these rocks are remarkably different. This enrichment in Fe is

offset by depletion in most elements compared to older IFs. The average redox state of these IFs with

respect to Fe is noticeably more oxidizing (Klein 2005), reflecting the predominance of hematite

relative to other Fe-minerals (James 1992, Beukes & Klein 1993, Lottermoser & Ashley 2000,

Pelleter et al. 2006, Mukherjee 2008, Pecoits 2010). Another distinctive feature is the high P

enrichment. Planavsky et al. (2010a) suggested that the Neoproterozoic seawater was characterized by

a high concentration of dissolved phosphate, which was possibly enhanced by post-glacial resurfacing

of continental crusts (Swanson-Hysell et al. 2010). Mn distribution is also a peculiar. It is generally

only recognized chemically, in concentrations of less than 1% wt. (Klein 2005). Nevertheless, a few

occurrences, including the Urucum IF-MnF, can be enriched by up to ~40% compared to average

shale (Cox et al. 2013).

Figure 2.5- Plot of major elements (expressed as oxides in weight %), recalculated to 100% on an

H2O-CO2-free basis, in IFs. The shaded area represents the range of average values of ~215 pristine

whole-rock analyses. Modified after Klein (2005).


23

Major element concentrations provide clues to distinguish the prevalence of hydrothermal or

hydrogenous sources (Neale 1993, Beukes & Klein 1993, Lottermoser Ashley 2000, Stern et al. 2013,

Xu et al. 2013b, Khalil et al. 2015, Mohseni et al. 2015). Although there’s no consensus on the

prevalent source, a mixed-source model, similar to modern near-ridge metalliferous sediments, is

currently more commonly proposed: combining a hydrothermal component (enrichments in Si, Fe and

Mn), and a detrital component, possibly from basalt/volcanogenic material (enrichments in Ti, Mg,

Ca, Na and K) (Halverson et al. 2011, Cox et al. 2013, Cox et al. 2016).

2.3.2.1- Rare Earth Elements (REE)

Rare earth elements (REEs) are often used as a proxy for the depositional conditions and to

trace the source of Fe (Derry & Jacobsen 1990). Neoproterozoic IFs show (Fig. 2.6), with few

exceptions (e.g. Khalil & El-Shazly 2002, Mohseni et al. 2015) superchrondritic Y/Ho ratios (Y/Ho ≥

27.7) and shale-normalized LREE-depleted patterns (e.g. Neale 1993, Klein & Beukes 1993,

Lottermoser & Ashley 2000, Pecoits 2010, Halverson et al. 2011, Basta et al. 2011, Cox et al. 2013,

Stern et al. 2013, Baldwin et al. 2013, Xu et al. 2013, Goldbaum 2014, Khalil et al. 2015,

Angerer et al. 2016, Cox et al. 2016). On the other hand, other diagnostic REE features, particularly

Ce and Eu anomalies, exhibit more variation.

The Algoma-type Neoproterozoic IFs show shale-normalized small to strong positive Eu

anomalies and variable Ce anomalies (Fig. 2.6. – a). The Arabian Nubian Shield (ANS) IFs are

characterized by absent to negative Ce anomalies (0.71-0.92; Basta et al. 2011, Stern et al. 2013);

whereas the Brazilian Jucurutu IF shows positive Ce anomalies (0.6-1.7; Sial et al. 2015). The

Jucurutu IF also shows stronger Eu anomaly (up to 3.1; Sial et al. 2015) compared to the Moroccan

Menhouhou inlier IF (1.52-1.66; Pelleter et al. 2006) and the ANS IFs (0.99-2.79; Basta et al. 2011,

Khalil & El-Shazly 2012, Stern et al. 2013, Khalil et al. 2015), but it is smaller than that reported for

the Chinese Fulu IF (2.52-4.17; Goldbaum 2014). The varied nature of the Ce anomaly in these IFs

indicates depositions in suboxic to anoxic conditions. The presence of positive Eu anomaly is usually

considered an evidence for the participation of hydrothermal fluids as a source for the REE, and

indirectly the Fe (Basta et al. 2011, Khalil & El-Shazly 2012, Stern et al. 2013, Goldbaum 2014,

Khalil et al. 2015, Sial et al. 2015).


24

The shale-normalized REE signatures of Rapitan-type Neoproterozoic IFs are generally more

variable, but characterized by absent Eu anomalies and slight negative Ce anomalies (Fig. 2.6. – b).

The Rapitan IF shows overall absent to subtle positive Eu anomalies (0.93-1.51) and negative Ce

anomalies (0.8-1.07) (Klein & Beukes 1993, Halverson et al. 2011, Baldwin et al. 2012), consistent

with those anomalies found in the Braemar IF in Australia (Neale 1993, Lottermoser & Ashley 2000).

The American Chestnut Hill IF shows larger negative Ce anomalies (0.17-1) but negative Eu anomaly

(Volkert et al. 2010). On the other hand, the Holowilena IF and Tatonduk IF show significant positive

Eu anomalies (av. 1.57) and Ce anomalies (up to 2.1) (Cox et al. 2016). The Iranian Bafq IF shows

negative Eu anomaly (0.02- 0.85) and positive Ce anomaly (1.08-1.78) (Mohseni et al. 2015).

Interpretation of the source of Fe based on these signatures vary from: a strictly continental source

from glacially derived nanoparticles (Baldwin et al. 2012); distal low-temperature hydrothermal

source with minor continental input (Klein & Beukes 1993, Halverson et al. 2011); and low-

temperature hydrothermal source mixed with a preponderant basalt-derived sediment component

(Cox et al. 2016a).

The geochemical signature of the Neoproterozoic Superior-type IF is intermediate between the

other two types (Fig. 2.6. – a). Both Yerbal and Shilu IFs are characterized by positive Eu anomalies

(respectively 1.15-1.21 and 1-11) (Pecoits 2010, Frei et al. 2013, Xu et al. 2013, Gaucher et al. 2015).

The Chinese occurrence displays positive shale-normalized Ce anomaly (1-2.4; Pecoits et al. 2010),

while the Uruguayan occurrence shows negative Ce shale-normalized anomaly (0.61-0.8; Xu et al.

2013). The positive Ce anomaly in the Yerbal IF indicates a deposition under anoxic conditions

(Pecoits et al. 2010, Frei et al. 2013), corroborated by other proxies (FeHR/FeTot = 05-0.7;

Frei et al. 2013).


25


Marx & Kamber 2010) REE diagram. The shaded areas bracket the range of profiles reported by

previously published studies of Neoproterozoic IFs (NIFs): (a) Lake Superior-type; (b) Algoma-type;

and (c) Rapitan-type.

2.3.2.2- Isotopes

There is a growing interest in the use of Fe isotopes (δ57

Fe) to track the degree of oxygenation

of the water column, as well as provenance and biogeochemical cycle of Fe (Bekker et al. 2014).

However, the δ57

Fe data reported for Neoproterozoic IFs is currently limited to the glacially influenced

occurrences. Systematic progressions from light to heavier isotopic compositions (δ57

FeIRMM-14) up

section have been reported in the Holowilena IF (min. -0.52 to max. 3.1 ‰; Halverson et al. 2007,

Cox et al. 2016a), Rapitan IF (-0.7 to 1.2 ‰; Halverson et al. 2011), and Tatonduk IF (-0.45 to 1.95

‰; Cox et al. 2016a). In the Rapitan IF, an accompanying positive excursion of δ98

Mo (up to +0.7 ‰)

near the top of the unit, in line with enrichment in other trace elements (Re, U, W and Mo

(Baldwin et al. 2012, 2013), has been used to suggest low sulfate availability and oxic to reducing

conditions during its deposition (Baldwin et al. 2013). These trends, together with trace element data

and sedimentological evidences, indicate that the precursor Fe sediments precipitated along weak and

dynamic redoxclines during marine transgression (Halverson et al. 2011, Cox et al. 2016a). The δ56

Fe

data in these IFs has also been used to suggest a partially hydrothermal provenance for the Fe

(Halverson et al. 2011, Goldbaum 2014, Cox et al. 2016a).


26

Algoma-type IFs exhibit distinct non-fractionated, mantle-like δ53

Cr values (as well as high Cr

contents), possibly reflecting hydrothermal venting (Frei et al. 2009, Frei et al. 2013, Sial et al. 2015).

For instance, the Jucurutu IF displays unfractionated δ53

CrSRM979 values (-0.30 to -0.12 ‰;

Sial et al. 2015) consistent with the magmatic field and values reported in Archean IFs

b(Frei et al. 2009). However, the synglacial Rapitan IF and the Superior-type Yerbal IF are

characterized by positive δ53

CrSRM979 values (0.90-0.96 ‰ and 0.7-5 ‰, respectively), derived from

land-derived, oxidized Cr4+

(Frei et al. 2009, Frei et al. 2013). This is interpreted to represent a larger

oxygenation of the surface environments, but also the proximity with deeply weathered old cratons

(Gaucher et al. 2015).

The εNd(t) and Sm-Nd ΤDM ages of the Lake Superior-type Yerbal and Shilu IFs, together

with distinctive facies associations has been used to suggest shallow stable platform setting for these

occurrences (Gaucher et al. 2004, Frei et al. 2009, Gaucher et al. 2009, Frei et al. 2011, Frei et l. 2013,

Xu et al. 2013b), or a restricted or sheltered marine basin setting is not excluded (Aubet et al. 2012,

Xu et al. 2013). Negative εNd(t) values in the Yerbal IF (-24 to -5; Frei et al. 2013) Shilu IF (-8.5

to -4.8; Xu et al. 2013b) are thought to reflect a mixing between continentally-derived sediments from

cratonic hinterlands and subaqueous low temperature hydrothermal solutions (Pecoits 2010,

Frei et al. 2013, Xu et al. 2013). On the other hand, negative εNd(t) compositions reported in the

glaciogenic Holowilena (av. -6.0) and Tatonduk (av. -2.0) IFs have been interpreted as reflecting a

predominant source from leaching of basalt-dominated margin sediments (Cox et al. 2016). In the

Algoma-type ANS IFs, strongly positive εNd(t) values (min. +1.2 to max. +9) are regarded as

demonstrating sedimentary sources from the juvenile crust and hydrothermal input (Ali et al. 2009,

Stern et al. 2013).


27

Consistently negative δ13

C values, reported in carbonates within the Rapitan IF (-3.37 to

+0.83; Beukes & Klein 1993), Chestnut Hill IF (-4.35±0.85 ‰; Volkert et al. 2010), and Shilu IF

(-5.40 to +2.5 ‰; Xu et al. 2013b) are generally considered primary, but their interpretation vary

wildly. Although the δ18

O compositions found in these carbonates are usually comparable with the

values inferred for the Neoproterozoic seawater, few authors suggest a primary origin (e.g. Mohseni

et al. 2015, Beukes & Klein 1993, Xu et al. 2013). Postglacial cap carbonate-like δ13

C stratigraphic

excursions, from negative δ13

C values at the contact with the IF to positive values up section, are

observed in carbonates overlying the Braemar IF (-5.5 to +0.9 ‰; Lottermoser & Ashley 2000), Bafq

IF (-0.43-6.6‰ to 2.9 ‰; Mohseni et al. 2015), Numess IF (as low as -9 up and to +6 ‰,

MacDonald et al. 2010a), Yerbal IF (-4.5 ‰; Frei et al. 2011), and Jucurutu IF (-12 to +10 ‰;

Sial et al. 2015). These trends are predominantly regarded as evidences for glaciations, but have also

been interpreted as bioproductivity bursts associated with upwelling nutrient-rich waters

(Gaucher et al. 2004, Sial et al. 2015). 87

Sr/86

Sr data in supposed cap carbonates overlying the

Jucurutu IF (0.7074-0.7075; Sial et al. 2015), Numees IF (0.7071-0.7072; MacDonald et al. 2010b),

and Yerbal IF (0.7070-0.7073; Frei et al. 2011), have indicated correlations with postglacial periods

during the Neoproterozoic.

2.3.3- Genetic Models

The close association between Neoproterozoic IFs-MnFs and low latitude glacial deposits is

one of the central evidences in support of the Snowball Earth model (Kirschivink 1992,

Hoffman et al. 1998, Hoffman & Schrag 2002). In the classic model, global glaciations would have

induced widespread anoxia as a result of the protracted isolation of the oceans from atmospheric

exchange and waning in oxygenic photosynthetic productivity (Kirschivink 1992,

Klein & Beukes 1993, Hoffman et al. 1998). In such scenario, during the global glaciation events,

dissolved Fe2+

and Mn2+

would build up in an anoxic ocean, supplied by hydrothermal vent fluids or

volcanic discharges (Yeo 1981, Klein & Beukes 1993, Halverson et al. 2011), similarly to the older

counterparts (Bau et al. 1996, Bau & Dulski 1999, Bekker et al. 2010), or conversely from glacially

sourced continental material (Urban et al. 1992). Conceivably, Fe and Mn deposition would have

occurred upon mixing with oxygenated waters, either from glacial outwash (Urban et al. 1992,

Halverson et al. 2011), reinvigorated circulation following glacial meltdown (Kirschivink 1992,

Klein & Beukes 1993), or alternatively near photosynthetic oases (Hoffman & Schrag 2002).


28

However, it has been demonstrated by Canfield et al. (2008) that anoxic and ferruginous

conditions prevailed throughout the Neoproterozoic. These authors claimed that the shift from

conditions during the Mesoproterozoic to ferruginous conditions during the Neoproterozoic could

have been triggered by low S and high Fe delivery into the oceans. During the glacial episodes,

alluvial sulfate delivery – a dominant source of sulfur during this period (Bao et al. 2008) – would

have been significantly limited, either by decreased alluvial activity or lower continental sulfur

reservoir (Canfield 2004, Canfield et al. 2008). Moreover, the ice cover may have limited bacterial

sulfate reduction (BSR), further limiting euxinia (MacDonald et al. 2010a). This shift to ferruginous

deep oceans could also have been achieved through the scouring of continental crusts by extensive

continental ice sheets over the Rodinia, exposing fresh bed rock to physical and chemical weathering

(Swanson-Hysell et al. 2010). Consequently, the Fe flux and Fe2+

/H2S ratio of subaqueous exhalations

(hydrothermal vents and volcanic plumes) should have been significantly increased due to sulfate-

controlled changes in redox conditions (fluids become fayalite–pyrrohotite–magnetite buffered rather

than anhydrite–magnetite buffered), and hydrostatic depressurization during glacio-eustatic sea-level

draw-down, which also increases Fe solubility (Kump & Seyfried 2005).

The Blood Falls sub-glacial outwash system in Antarctica has been suggested as a possible

analogue for Neoproterozoic IFs (Mikucki et al. 2009, Hoffman et al. 2011). Beneath the ice cover, a

sulfate-rich brine concentrates Fe, derived from glacial scouring and dissolution of bedrock, under

relatively low pH conditions and active dissimilatory iron reduction (DIR); the Fe is precipitated as

goethite when melt water mixes with oxygenated waters (Mikucki et al. 2009). A similar model based

on local glacial basin anoxia has been proposed by Baldwin et al. (2012). Baldwin et al. (2012)

suggested that partially restricted basins (or sub-basins) would have allowed the development of local

anoxia during glacial advance, when sea level would have fallen below basin-bounding sills. Reactive

Fe would have been delivered as glacially-sourced Fe oxy-hydroxides nanoparticulate

(Poulton & Raiswell 2002, Raiswell et al. 2006), then biogenically reduced, and subsequently

oxidized during interglacial periods (Baldwin et al. 2012).


29

The only existing model not to establish a direct link with glacial events is the sedimentary

exhalative-rifting model (e.g. Breitkopf 1988, Eyles & Januszczak 2004). The apparent association

between IFs-MnFs and rift basins has led many authors to suggest a link between the restricted nature

of continental rift basins and hydrothermal fluids migrating along basin-forming faults, driven by

underlying mafic volcanism (e.g. Volkert et al. 2010, Freitas et al. 2011, Sial et al. 2015). The mixing

between the anoxic hydrothermal fluids and oxygenated waters would cause precipitation of Fe oxy-

hydroxides. Cox et al. (2016a) proposed a mixed model, combining glaciation and mafic volcanism,

with associated hydrothermal activity and preponderance of mafic substrates to weathering. Like in

other glacial models, the IFs-MnFs of Cryogenian age would be linked to ice-capped basins

(Klein & Beukes 1993, Cox et al. 2013), creating or enhancing deep ocean anoxia. Fe and Mn influx

would have been enhanced by contemporary emplacement of large igneous provinces and rift related

hydrothermal activity associated with the breakup of Rodinia (Cox et al. 2013, Cox et al. 2016a). In

this model, sediments derived from continental flood basalts (CFB) weathering would be the primary

source for the Fe and Mn, while hydrothermal alteration of oceanic crust would be a secondary

component. The weathering of CFBs, with higher Fe:S ratios, would also assist in the development of

ferruginous conditions (Cox et al. 2016a). The precipitation of Fe and Mn oxy-hydroxides would have

ensued the oxygenation of the waters, driven either by ice shelf collapse and opening of the basins

(Halverson et al. 2004) or inflow of oxygenated melt water plumes (Hoffman 2005).


30

CHAPTER 3

GEOLOGICAL BACKGROUND

In the broadest sense, the Jacadigo-Boqui Gr. is constituted by a transgressive continental-

marine sequence, with suspected glacial influence, capped by carbonate platform deposits

(Litherland et al. 1986, Trompette et al. 1998, Alvarenga et al. 2011, Freitas et al. 2011). This cover

sequence overlies unconformably the meta-igneous basement of the southern Amazon craton and

northern Rio Apa block. In the Urucum massif, two lithostratigraphic units are recognized

(Almeida 1945, Dorr II 1945): the lower Jacadigo Gr., constituted by clasto-chemical deposits, and the

upper Corumbá Gr., constituted by carbonate deposits. This lithostratigraphic succession is correlated,

in the Chiquitos-Tucavaca aulacogen (Litherland et al. 1986), by the lower Boqui Gr. and the upper

superior Pororó Fm, lower part of the Tucavaca-Murciélago Gr. (Fig. 3.1) (Graf et al. 1994,

Trompette et al. 1998). In the southern and northern Paraguay belts (Alvarenga & Trompette 1994,

Alvarenga et al. 2000, 2007, 2011), the Puga Fm., overlain by the Corumbá Gr., is thought to be

coeval with the Jacadigo-Boqui Gr. (Fig. 3.1) (Trompette et al. 1998, Freitas et al. 2011); however this

correlation is still unclear. The Jacadigo Gr., and to a lesser extent its counterparts Boquí Gr. (herein

referred as Jacadigo-Boqui Gr.) and Puga Fm., hosts IFs and MnFs, more commonly referred as

Urucum IF-MnF.

Figure 3.1- Lithostratigraphic correlations of the supra-crustal sequences found on the margins of the

Amazon craton and Rio Apa block. The transgression is of glacio-esutatic nature. Modified after

Trompette et al. (1998) and Freitas et al. (2011).


32

3.1- STRUCTURAL GEOLOGY

The Jacadigo-Boqui Gr. is constituted by a Neoproterozoic-Cambrian clasto-chemical

succession, deposited in rift settings on the Amazon craton and Rio Apa block paleocontinent

(Trompette et al. 1998, D’el-Rey et al. 2016). Extensional tectonics during the late Neoproterozoic,

possibly linked to the collisions of the early Brasiliano Cycle orogeny, were responsible for the

opening of an intra-continental axial rift system with three branches, centered nearby the Urucum

massif area (Jones 1985, Litherland et al. 1986, Trompette et al. 1998, Angerer et al. 2016, D’el-

Rey et al. 2016). However, there is still no consensus regarding the geodynamic significance of these

structures (Trompette et al. 1998, Freitas et al. 2011, Angerer et al. 2016, D’el-Rey et al. 2016).

In the Urucum massif, a (half-) graben system (Trompette et al. 1998, Fretias et al. 2011) was

formed, presumably associated with the R-R-R type (Fig. 3.2 – a) intersection between the precursor

basins of the WNW-trending Chiquitos-Tucavaca aulacogen, which stretches 500 km along the

western boundary of the Amazon craton, the NNE-trending northern Paraguay belt and the

SSE-trending southern Paraguay belt, which follow along the eastern boundaries of the Amazon craton

and Rio Apa block (Fig. 3.2 – b, c) (Jones 1985, Litherland et al. 1986, Trompette et al. 1998,

Cordani et al. 2009, 2010, Walde et al. 2015, Angerer et al. 2016, D’el-Rey et al. 2016).

The Jacadigo-Boqui Gr. underwent deformation and metamorphism during the Brasiliano

orogeny (Trompette et al. 1998, D’el-Rey et al. 2016). The collision between the Paraná block and the

southern margin of the Amazon craton-Rio Apa block (Godoy et al. 2010, D’el-Rey et al. 2016) led to

high strain in the eastern portion of the northern and southern Paraguay belts. This event is temporally

poorly constrained, but older than ca. 518±4 Ma (zircon U-Pb; McGee et al. 2012); age of

emplacement of the post-tectonic São Vicente granite in the southern Paraguay belt. High-angle

reverse faults define the contact with the metasedimentary sequences, characterized by higher

metamorphic recrystallization and folds and thrusts (Trompette et al. 1998).

The Urucum massif has undergone metamorphism of sub-green schist facies

(Trompette et al. 1998, D’el-Rey et al. 2016), bracketed in the ca. 547-513 Ma interval, based on

40Ar/

39Ar dating of metamorphic braunite and muscovite (Piacentini et al. 2013). Calculated quartz-

hematite δ18

O temperatures indicate a re-equilibration at 250-280 ºC, marking the inferred diagenesis-

burial metamorphism peak temperature (Hoefs et al. 1987). Overprinting of the diagenetic-burial

metamorphism paragenesis is very limited (Urban et al. 1992, Piacentini et al. 2013, D’el-

Rey et al. 2016), but hydrothermal and metasomatic assemblages occur in veins and county rocks

(Urban et al. 1992, Klein & Ladeira 2004, Johnson et al. 2016).


33

Deformation during the Brasiliano orogeny is marked by ductile and brittle tectonic structures

grouped in three superimposed deformation phases (D1-D2-D3) (D’el-Rey et al. 2016). Crustal

shortenings caused by compressional stresses in the SW-NE and SE-NW directions, reflected

respectively in the D3T structures (Chiquitos-Tucavaca basin closure) and the D1-D2 (ductile flow) and

D3P structures (Paraguay basin closure), led to gentle dipping, chiefly to SSE and NNW, associated

with open-style folds (D’el-Rey et al. 2016). According to Freitas et al. (2011), this deformation cycle,

in two orthogonal directions, was responsible for the tectonic inversion of the basin in a dome-like

structure, controlled by reactivation of the basement faults. Exhumation and erosion, at least ca. 60 Ma

according to 40

Ar/39

Ar dating of supergene cryptomelane (Piacentini et al. 2013), and uplift of fault

blocks ca. 3 Ma with the subsidence of the Pantanal basin (Shiraiwa 1994), formed the current

inselberg topography (Fig. 3.3 – c, cross-section) (Trompette et al. 1998, Piacentini et al. 2013).

Figure 3.2- Geotectonic context of the Urucum Massif. (a) Simplified geotectonic framework of

South America showing the position of the inferred R-R-R triple junction (modified after D’el-

Rey et al. 2016) (b) Simplified geotectonic context of the Urucum massif, Chiquitos-Tucavaca

aulacogen and Paraguay fold and thrust belt (according to Trompette et al. 1998). (c) Geological

context of the area shown in (b) (according to Trompette et al. 1998).


34

3.2- GEOCHRONOLOGY

In the Urucum massif, the crystalline basement is composed of gneisses of the Rio Apa block,

dated at 1950±23-1721±25 Ma (zircon U-Pb; Cordani et al. 2010), and cross-cutting granitoids, dated

at 1826.3±4.2 (zircon U-Pb; Viehmann et al. 2016), 1730±22 (biotite K-Ar), and 889±44 Ma

(K-feldspar K-Ar) (Hasui & Almeida 1970). The plutonic-volcanoclastic La Pimienta Fm., tentatively

included in the lower part of the Jacadigo-Boqui Gr. in the Chiquitos-Tucavaca aulacogen

(O'Connor & Walde 1985, Litherland et al. 1986), has an uncertain age K/Ar of 623±15 Ma

(Walde 1988). Detrital zircons found in glaciomarine diamictites interlayered with IF beds of the

correlative Puga Formation (Trompette et al. 1998, Freitas et al. 2011), have a U-Pb age of

706±09 Ma (Babinski et al. 2013). This age is consistent with a maximum depositional age of

695±17 Ma, measured by U-Pb dating of detrital zircons from shaly-sandy horizons within the IF beds

(Døssing et al. 2010, Frei et al. 2017). A Sm-Nd dating of the IF beds also provided a consistent

dating at 566±110 Ma (Viehmann et al. 2016).

The overlying Corbumba Gr. as an apparent minimum depositional age of 549-543 Ma, based

on the presence of diagnostic Ediacaran fossils (Cloudina lucianoi and Corumella werneri)

(Amthor et al. 2003, Warren et al. 2012), and 543±3 Ma, based on U-Pb dating of zircons found in ash

layers of the Tamengo Fm. (Babinski et al. 2008) (lowermost unit of the Corbumba Gr.)

(Gaucher et al. 2003, Boggiani et al. 2003, Boggiani et al. 2010). Minimum depositional ages are

constrained at 587±7 Ma, interpreted as the age of diagenesis-burial metamorphism, based on

40Ar/

39Ar dating of cryptomelane in the lowermost MnF bed (Mn 1) (Piacentini et al. 2013). Because

of the poor temporal constraint (Piacentini et al. 2013) and disputed glacial evidences

(Trompette et al. 1998, Freitas et al. 2011), the correlation of the Jacadigo-Boqui Gr. with a

Neoproterozoic glaciation event remains unresolved. Nonetheless, the depositional age presented

above is compatible with the Sturtian (ca. 715 Ma) Marinoan (ca. 635 Ma) and Gaskiers (ca. 583 Ma)

glaciations (Hoffmann et al. 2004, Hebert et al. 2010).

3.3- LITHOSTRATIGRAPHY

In the Urucum massif, the Jacadigo-Boqui Gr. consists of two (Almeida 1945) or three

(Dorr II 1945) partially transitional and partially superimposed units (Freitas et al. 2011). According to

Dorr II (1945), this group consists of, from the base to the top: Urucum Fm., Córrego das Pedras Fm.,

and Banda Alta Fm. (Fig. 3.3 – a, b). Almeida (1945) proposed an alternative subdivision: Urucum

Fm., equivalent to the Urucum Fm. and Córrego das Pedras Fm., and Santa Cruz Fm., corresponding

to the Banda Alta Fm. This lithostratigraphic division has been modified by other authors

(e.g. Urban et al. 1992, Piacentini et al. 2013), who subdivide the Santa Cruz Fm. in two members:

Córrego das Pedras or Inferior Member, and Banda Alta or Superior Member. The divisions of Dorr II

(1945) are followed in this dissertation (Fig. 3.3), in accordance with the most recent researches.


35

In the Urucum massif, the Jacadigo-Boqui Gr. outcrops as a series of flat topped hills divided

by high declivity faults, where the Corumbá Gr. is absent due to erosive removal (Fig. 3.3 – a, cross

section AB) (Trompette et al. 1998). The plains adjacent to the hills are covered by Cenozoic

sediments of the Pantanal Formation. Cangas and eluvial-coluvial covers are also present in the

vicinities of the hills (Piacentini et al. 2013). The basement is constituted by the gneisses of the Rio

Apa block, crosscut by granitoids of the Urucum granite and local mafic dykes of the Taquaral suite

(Dorr II 1945, Almeida 1946, Hasui & Almeida 1970, Cordani et al. 2010). The overlying

Corumbá Gr. is comprised by post-rift carbonate platform deposits of the Bocaina and Tamengo

formations (Boggiani et al. 2003, Boggiani et al. 2010, Walde et al. 2015). The Tamengo Fm. is

composed of limestones, margas, rhythmites, oolitic limestones, while the Bocaina Fm. is composed

of limestones, dolomites, phosphates, carbonatic breccias, silexites and oolitic limestones

(Bartorelli 2012).

Figure 3.3- Geological map and schematic cross section (AB) of the Santa Cruz deposit (modified

after Haralyi & Walde 1986, Trompette et al. 1998, Freitas et al. 2011, Angerer et al. 2016). (b)

Composite stratigraphic profile of the Santa Cruz deposit (modified after Freitas et al. 2011,

Angerer et al. 2016, Kroeninger 2016). For information on the parasequences see Kroeninger (2016).


36

3.3.1- Urucum Formation

The Urucum Fm. unconformably overlies the basement. This formation comprises siliciclastic

deposits of rift initiation to early climax system tract, constituted by bedload-dominated river, alluvial

fan, fan-delta and lacustrine facies (Freitas et al. 2011). The rocks of the Urucum Fm. are typically

characterized by large amount of feldspar clasts and carbonatic cementation and/or matrix

(Freitas et al. 2011, Bartorelli 2012). Arkoses with medium granulation and coarse siliciclastic rocks

(conglomerates, diamictites and conglomeratic arkoses) are the main lithologies, but sandstones,

siltites, graywacks, black shales, limestones and dolomites are also found (Urban et al. 1992,

Trompette et al. 1998, Klein & Ladeira 2004, Freitas et al. 2011, Bartorelli 2012). Primary structures

are generally small to medium size plane-parallel stratifications and cross-stratifications

(Bartorelli 2012).

3.3.2- Córrego das Pedras Formation

The Córrego das Pedras Fm. overlies the Urucum Fm. through a transitional contact. This

formation is constituted of shallow marine deposits of mid to late rift system tract, composed of shore

facies, including mixed siliciclastic and allochemical rocks (Freitas et al. 2011). The transition

between the Urucum and Córrego das Pedras formations is characterized by the occurrence of

arkosean sandstones with fine to medium granulation, plane-parallel and cross stratifications, and Fe

and Mn cementation (Urban et al. 1992, Bartorelli 2012). Intercalations with hematitic layers and

granular iron formation (GIF) occur in more abundance towards the top (Freitas et al. 2011,

Bartorelli2012). Diamictites, conglomerates, manganic arkoses, criptomelane levels occur throughout

this unit (Freitas et al. 2011, Bartorelli 2012). A massif, nodular and clastic MnF bed (i.e. the basal

Mn 1) marks the top of this unit (Urban et al. 1992, Freitas et al. 2011).

3.3.3- Banda Alta Formation

The Banda Alta Fm. comprises chemogenic shallow-deep marine deposits of mid to late rift

system tract (Freitas et al. 2011). It is composed predominantly of by IF beds, intercalated with three

MnF beds (i.e. Mn 2-4), Fe-rich sandstones, arkoses and diamictites (Freitas et al. 2011,

Bartorelli 2012, Piacentini et al. 2013, Kroeninger et al. 2016). Diamictites and punctual outsized

clasts, composed of limestones and granites from the basement, in the IF are thought to represent

glacial deposits (Klein & Ladeira 2004, Urban et al. 1992, Piacentini et al. 2013), or alternatively

mass flow deposits (Trompette et al. 1998, Freitas et al. 2011) and gravitationally reworked till

(Angerer et al. 2016, Kroeninger 2016). The outsized clasts are more common towards the top of the

sequence, and sometimes occur associated with fine arkose and sandstone horizons

(Klein & Ladeira 2004, Urban et al. 1992, Rosière & Chemale 2000, Freitas et al. 2011,

Bartorelli 2012).


37

The MnFs are composed of criptomelane, braunite and pirolusite as anastomosing, nodular or

continuous tabular beds, and cement in siliciclastic rocks (Urban et al. 1992). These MnFs decrease in

thickness and width towards the top of the column and margins of the basin (Urban et al. 1992). The

IF has two main faciological subdivisions: a stratigraphically inferior, and possibly superior, banded

and nodular carbonaceous facies, composed of chert-dolomite-hematite IF (Klein & Landeira 2004,

Angerer et al. 2016); and an intermediate, banded and nodular, siliceous facies, constituted of chert-

hematite IF (Graf et al. 1994, Klein & Landeira 2004, Angerer et al. 2016, Kroeninger 2016,

Viehmann et al. 2016, Frei et al. 2017). The chert-hematite IF is commonly texturally podded from

hypogene leaching of chert, and more rarely banded and nodular (Angerer et al. 2016). Comparatively

less common facies are also present, including (Graf et al. 1994, Freitas et al. 2011, Angerer et al.

2016, Kroeninger 2016, Frei et al. 2017): laminar magnetite and hematite mudstones; laminar to

nodular (jaspilitic) chert; GIF; and goethitic IF. The nodules are usually concentric and ellipsoidal, or

spheroids, with varied composition (Urban et al. 1992, Angerer et al. 2016). These features are more

commonly interpreted as diagenetic and microbial nodules (Angerer et al. 2016), but also as oolites

(Haralyi & Walde 1986, Freitas et al. 2011), or coated grains (i.e. diagenetic nodules with or without

reworking) (Kroeninger 2016).

3.4- BASIN TECTONIC-DEPOSITIONAL EVOLUTION

Several sedimentary models (summarized in Table 3.1) have been proposed to explain the

tectono-depositional evolution of the Jacadigo-Boqui Gr. Most publications advocate a lacustrine-

marine environment; although a glacial influence more commonly suggested it is rather contentious.

The most recent sedimentological and stratigraphic study recognized a sedimentary sequence

(Fig. 3.4), deposited during marine transgression associated with active rift tectonics, with six

depositional systems (Freitas et al. 2011): (i) aluvial fan, comprising sheet flood- and debris-flow-

dominated fan facies association (Fig. 3.5 – a, b); (ii) clastic lacustrine, comprising shore and offshore

facies association (Fig. 3.5 – b); (iii) fan delta, comprising fan-delta facies association (Fig. 3.5 – b);

(iv) bedload-dominated fluvial, comprising channel belt facies association (Fig. 3.5 – b); (v) shore-

offshore lacustrine/gulf system, including subaquatic gravitational flows facies association (Fig. 3.5 –

c). The first four systems refer to the rift initiation to early rift climax system tracts; the mid- to late

rift climax system tract includes the marine systems (Freitas et al. 2011). The overlying Corumbá Gr.

is constituted by carbonate shelf deposits of immediate to late post-rift system tract. Subsequent

studies by Angerer et al. (2016) and Kroeninger (2016), combining chemical and sedimentological

investigations, corroborated the basin evolution model of Freitas et al. (2011). However, a central

difference in these models refers to the climatic influence. Angerer et al. (2016) and Kroeninger

(2016) favor a more accepted glacial setting (Table 3.1), whereas Freitas et al. (2011) inferred an arid

environment (Dorr II 1970) without glacial influence (Dardenne 1998, Trompette et al. 1998).


38

Figure 3.4- Sequence stratigraphic framework. The Jacadigo-Boqui Gr. is comprised by a single

depositional sequence (S1). The overlying Corumbá Gr. is comprised by two depositional sequences.

Modified after Freitas et al. (2011).

Figure 3.5- Tectonic-stratigraphic evolution of the Jacadigo-Boqui Gr. (a) Rift initiation tract. (b)

Initial rift climax systems. (c) Rift climax tract. (d) Post-rift tectonic tract (Corumbá Gr.). (e) Basin

inversion. (f) Present day topography. Modified from Freitas et al. (2011).


39

According to Angerer et al. (2016), the Banda Alta Fm. was deposited during a major marine

transgression-regression cycle, controlled by first- and second-order periodic variations, resulting from

the juxtaposition of active rift tectonics, glacial advance/retraction cycles, and isostatic adjustment or

eustatic sea-level changes. The deposition of shallow-water facies would have concurrent during

glacial retreat, while deep-water facies would be deposited during glacial advance

(Angerer et al. 2016). According to Kroeninger (2016), the Banda Alta Fm. was deposited in a

glaciomarine environment, transitioning from middle shelf to distal shelf. These sediments record

deposition in lowstand (LST) and transgressive systems tracts (TST), during a first-order marine

transgression punctuated by second-order fluctuations, controlled by glacial retreat and advance, as

well as rifting rate, glacial isostasy and fluctuations in sediment (e.g. outwash and eolian) input

(Kroeninger 2016).

Besides chemical data (section 3.5), a marine environment is supported by sedimentological

and stratigraphic evidences (e.g. Almeida 1945, Almeida 1946, Dorr II 1945, Dorr II 1973,

Corrêa et al. 1979, Freitas et al. 2011). The presence of diamictites and erratic metric clasts

(“dropstones”), within the finely laminated MnF and IF beds, are pointed out as an evidence for a

glaciomarine environment (e.g. Dorr II 1945, Barbosa & Oliveira 1978, Almeida 1984,

Urban et al. 1992, Graf et al. 1994, Klein & Ladeira 2004, Kroeninger 2016). Melting of sediment-

rich icebergs, produced by retreating glacial cover, would release dropstones and siliciclastic levels

from glacial drift, into the chemical sediments (Urban et al. 1992, Bartorelli 2012,

Piacentini et al. 2013, Gaucher et al. 2015, Angerer et al. 2016, Viehmann et al. 2016,

Kroeninger 2016). Diamictites, as previously mentioned, are interpreted as tills in this model

(Barbosa & Oliveira, Walde et al. 1981, Almeida 1984, Urban et al. 1992).

Other authors have argued against a glacial influence (Dardenne 1998, Trompette et al. 1998,

Freitas 2010), suggesting that the metric erratic lonestones and associated clastic lenses, as well as the

diamictites, were produced by mass flows (e.g. turbidite currents, debris flows), transporting

sediments from slopes and escarpments of the graben. According to Gaucher et al. (2015), bullet clasts

– elongated casts with major axis perpendicular to the bedding – cannot be formed by mass flows.

Angerer et al. (2016) suggested that detritus settling from glacial drifts (e.g. Bartorelli 2012,

Gaucher et al. 2015) and direct deposition of tills (e.g. Urban et al. 1992) are no compatible with the

inferred deep basin setting and high energy involved the deposition of some diamictites (e.g. middle

diamictite). Reworking and transport of till by gravitation flow was proposed as an alternative origin

for these diamictites (Angerer et al. 2016, Kroeninger 2016).


40

Tabele 3.1- Depositional environment of the Jacadigo-Boqui Gr proposed in sedimentological studies. Modified after Del’Arco et al. (1982).

Depositional environment

Jacadigo

Group

Dorr II

(1945)

Almeida

(1945, 1946)

Dorr II

(1970)

Corrêa et al.

(1976)

Barbosa &

Oliveira

(1978)

Walde et al.

(1981)

Almeida

(1984)

Litherland&

Bloomfield

(1981)

Trompette

et al.

(1998)

Freitas et al.

(2011)

Santa Cruz

/ Banda

Alta and

Córrego

das Pedras

formations

Marine,

estuarine or

lacustrine

Shallow

marine

epicontinental

Estuarine

or

lacustrine

(arid

climate)

Marine or

epicontinental

Continental

basin

with

chemical

deposition

and glacial

influence

Epicontinental

with glacial

influence

Shallow

marine

epicontinental

with glacial

influence

Lacustrine

or marine

with

turbidites

Lacustrine or

marine gulf

Urucum

Fm.

Continental

fluvial and

lacustrine,

glacial (?)

Fanglomerates

and mud flows

Continental

Continental Continental

tectonically

instable

Continental

with

subordinate

periglacial

influence

Continental

with

possible

glacial

influence

Fanglomerates

Alluvial fans,

lagoons and

submarine

mud flows

Alluvial

fans

Alluvial fan,

deltaic,

lacustrine

and bedload

fluvial


41

3.5- GEOCHEMISTRY AND GENETIC MODELS

The uncertainties in the paleodepositional environment, together with the still poorly

understood origin of IFs and MnFs (Bekker et al. 2014, Maynard et al. 2014), are reflected in the

larger number of genetic models (summarized in Table 3.2) proposed for the Urucum IF-MnF. In this

context, geochemical data plays a crucial role in constraining the possible sources of metal,

paleoenvironmental conditions, and depositional controls.

Overall, the chemistry of the Urucum IF is remarkably similar to that of other Neoproterozoic

IFs, in terms of major and minor elements, but closer to the glaciogenic Rapitan-type IFs (Fig. 2.6)

with respect to trace element and isotope compositions (e.g. Klein & Ladeira 2004,

Angerer et al. 2016, Viehmann et al. 2016, Frei et al. 2017). The Urucum IF shows shale-normalized

REE patterns similar to most Rapitan-type IFs. The REE systematic of pure (i.e. uncontaminated by

continental detritus) IF lithologies (Fig. 3.6) indicate signatures compatible with modern oxygenated

oceans, characterized by depletion of light (LREE) relative to heavy REE (Pr/Yb < 1), super-

chondritic Y/Ho ratios (positive Y anomalies), moderate positive Gd and La anomalies, absent Eu

anomalies, and negative or absent Ce anomalies, possibly reflecting a marine gulf or coastal

environment (Derry & Jacobsen 1990, Graf et al. 1994, Klein & Ladeira 2004, Angerer et al. 2016,

Viehmann et al. 2016, Frei et al. 2017). More attenuated LREE depletions and anomalies, and sub-

chondritic Y/Ho ratios, close to shale-like patterns, are observed in IF lithologies contaminated by

detrital input (Fig. 3.6 – b, c) (Graf et al. 1994, Viehmann et al. 2016, Frei et al. 2017) and altered by

post-depositional processes (Graf et al. 1994).


42


Marx & Kamber 2010) REE diagram. Complete REE profiles reported in previous studies of the

Urucum IF: (a) Angerer et al. (2016); (b) Viehmann et al. (2016); Frei et al. (2017).


43

The REE patterns suggest an overall cycling and precipitation across an active redoxcline

(Fig. 3.6). Deposition of the carbonate-rich facies, characterized by shale-normalized negative Ce

anomalies, larger LREE-depletion, and well developed Y anomalies (higher Y/Ho values), occurred

above the redoxcline of Fe in an oxic surface layer, likely associated with microbial activity, based on

δ13

C and δ57

Fe signatures and sedimentological evidence (Angerer et al. 2016). The most pervasive

chert-rich IF facies, and to some extent chemical hematite chert and hematite mud, are characterized

by more variable Pr/Yb and Y/Ho ratios and decreased, shale-normalized, negative Ce anomalies,

indicating less oxygenated conditions, consistent with a deposition closer within and below the

redoxcline (Graf et al. 1994, Klein & Ladeira 2004, Angerer et al. 2016, Viehmann et al. 2016,

Frei et al. 2017). Chemical hematite mud, in particular, displays no to slight negative Ce anomalies,

shifts towards flatter or hump-shaped higher REE patterns and sub-chondritic Y/Ho ratios; compatible

with a deposition in anoxic deeper seawater (Angerer et al. 2016, Frei et al. 2017).

There is some degree of agreement between the geochemical signature of the IF and MnF

lithologies (Graf et al. 1994, Klein & Ladeira 2005, Viehmann et al. 2016), but the latter display a

wider range of geochemical characteristics. The REE patterns of chemical MnF (Mn1 and Mn2) beds

show distinct distributions. Mn2 and Mn3 show patters similar to those of the Urucum IF and modern

oxic seawater, with more developed, shale-normalized, negative Ce anomalies (Graf et al. 1994,

Viehmann et al. 2016). Mn1 shows two types of patters: one controlled by growth/sedimentation rate,

present in Fe-poor portions, characterized by LREE-depleted to flat REE patters with negative Ce

anomalies (Graf et al. 1994, Klein & Ladeira 2004, Viehmann et al. 2016); and another controlled by

the mineralogical composition, present in Fe-rich portions, characterized by absent to positive Ce

anomalies, Pr/Yb > 1 and sub-chondritic Y/Ho (Viehmann et al. 2016).

The higher detrital influence in Mn1 is also corroborated by 87

Sr/86

Sr ratios reported by

Urban et al. (1992) and εNd(T) values reported by Viehmann et al. (2016). Mn1 displays higher

87Sr/

86Sr ratios (0.71125±0.00280) and radiogenic

87Sr (0.235±0.198), contrasting with the relatively

homogeneous ratios in the other beds (Mn2: 0.70884±0.00011; Mn3: 0.70711±0.00013;

Mn4: 0.70831±0.00041), which do not correlate with 87

Rb/86

Sr ratios (Urban et al. 1992).

Additionally, Mn1 and Mn2 show similar εNd(TCHUR) values (-5.57 to -4.80 and -5.38 to -4.66,

respectively), more negative compared with pure IF, reflecting a higher contribution of clastic

sediments (-8.35 to -7.69) originated from the basement (-13.7 to -14.4) (Viehmann et al. 2016). These

signatures, along with sedimentary and stratigraphic evidence (Freitas et al. 2011), indicate a

precipitation of the MnF in a more oxygenated, shallow-water environment, with influx from fresh

water and sediments (Fig. 3.6 – a) (Urban et al. 1992, Graf et al. 1994, Klein & Ladeira 2004,

Viehmann et al. 2016).


44

Variations in the REE parameters, as well as other redox-sensitive trace elements, are linked to

changes in redox stratification of the water column in response to changing sea-level or freshwater

input (Fig. 3.6 – b) (Urban et al. 1992, Graf et al. 1994, Angerer et al. 2016, Viehmann et al. 2016,

Frei et al. 2017). The redox-sensitive systematics also supports deposition in a restricted marine

environment (e.g. gulf), during a transgression event, with subordinate fluvial influx or glacial

outwash (Urban et al. 1992, Graf et al. 1994, Klein & Ladeira 2004, Angerer et al. 2016,

Viehmann et al. 2016, Frei et al. 2017), in accordance with sedimentological models (Table 3.1).

The consistent negative δ13

CV-PDB values in IF carbonates, reported at the Urucum hill

(-5.2 to -7.0 ‰; Klein & Ladeira 2004) and Santa Cruz hill (-3.4 to -4.3 ‰; Angerer et al. 2016), are

consistent with values typically observed in Neoproterozoic glaciogenic carbonates

(Halverson et al. 2011, Och & Shields 2012). These values were used by Klein & Ladeira (2004) to

suggest a glacial setting. However, Angerer et al. (2016) pointed out that this signature can potentially

reflect diagenesis, including microbial dissimilatory iron reduction (DIR); supported by the

fractionated δ57

Fe values (-2.6 to -1.2 ‰) observed in the carbonate-rich IF facies

(Angerer et al. 2016). The overlying carbonate rocks of the Corumbá Gr. are also commonly

suggested as cap carbonates due to negative δ13

CV-PDB excursions (e.g. Tamengo Fm.: rising from -3.5

to 5.8 ‰), and 87

Sr/86

Sr ratio (e.g. Tamengo Fm.: 0.7084-0.7085) consistent with post-Varanger

sediments worldwide (Boggiani et al. 2003, Gaucher et al. 2003, Misi et al. 2007,

Babinski et al. 2008).

Fresh water inputs are indicated by the constant supply of alluvial, continentally-derived Cr,

characterized by strongly positively fractionated, authigenic chromium isotope signatures (av. δ53

Craut

= 1.10±0.4 ‰ at Urucum hill; δ53

Craut = 0.29±0.34 ‰ at Fazenda São Manuel) (Freit et al. 2017).

These values increase up-section in both localities; a trend replicated by authigenic enrichments of

redox-sensitive trace element, compatible with an increasing oxygenation of the surface environment,

possibly accompanying glacier meltdown (Døssing et al. 2010, Freit et al. 2017). The authigenic

enrichments in U, and Mo at the base of the Urucum IF (Døssing et al. 2010) can also be linked with

ferruginous bottom waters and low sulfate availability (Gaucher et al. 2015); which would be

consistent with a more developed ice cover at the beginning of the deposition, in analogy with findings

at the Rapitan IF (Baldwin et al. 2013).


45

Current glaciogenic models propose a proglacial environment associated with glacier

meltdown and ice shelf retreat (Graf et al. 1994, Viehmann et al. 2016, Frei et al. 2017), or

alternatively glacial advance and retraction cycles (Urban et al. 1992, Angerer et al. 2016,

Kroeninger 2016). The development of an anoxic Fe-Mn reservoir is generally explained by long-term

ice cover, lowering atmospheric exchange and impairing photosynthesis (Urban et al. 1992,

Gaucher et al. 2015); while oxidation and deposition of Fe and Mn is interpreted to result from

deglaciation intervals with oxygenated outwash influx and ice-free conditions (Urban et al. 1992,

Graf et al. 1994, Angerer et al 2016, Viehmann et al. 2016, Frei et al. 2017) or in coastal polynyas

opened by katabatic winds (Kroeninger 2016).

Metal-fertilization of seawater by sin-tectonic hydrothermal fluids, moving through the active

extensional fault system, has been proposed in several publications (Dardenne 1998,

Trompette et al. 1998, Walde & Hagemann 2007, Freitas et al. 2011, Graf et al. 1994,

Klein & Ladeira 2004, Angerer et al. 2016, Viehmann et al. 2016, Frei et al. 2017). The geotectonic

setting of the Jacadigo (half-) graben basin suits well this source, which can originate from the

leaching of underlying plutonic mafic rocks (Walde et al. 1981, Leonardos & Walde 1982).

Contributions from glaciogenic continental detritus, outwash discharge and aeolian dust

(Urban et al. 1992, Kroeninger 2016), benthic pore water flux, leaching of seafloor sediments

(Angerer et al. 2016) have also been envisaged.

The pure IF reported by Viehmann et al. (2016) yielded εNd(T) values between -4.56 to -4.08,

consistent with older measurements -2.9 ± 2.1 (Derry & Jacobsen 1990), and more positive than those

of ambient clastic sediments, locally derived from the Amazon craton. These values are compatible

with those observed in the MnF beds, indicating no contribution from mantle sources to the dissolved

REE budget (Viehmann et al. 2016). The εNd(T) compositions, along with the lack of positive Eu

anomalies, rule out the contribution of anoxic, high-temperature, hydrothermal fluids to the dissolved

REE budget and, indirectly, as significant sources of Fe and Mn (Graf et al. 1994,

Klein & Ladeira 2004, Angerer et al. 2016, Viehmann et al. 2016, Frei et al. 2017). However, the REE

patterns of high-temperature hydrothermal fluids can be modified by interaction with rocks with

negative Eu anomaly (e.g. mafic or volcanic glass), dilution with seawater (Graf et al. 1994,

Klein & Ladeira 2004), and discharges with very high Fe/REE ration in suboxic conditions

(Viehmann et al. 2016).


46

More specifically, diluted anoxic low-temperature discharges from submarine vents are

compatible with the REE patterns observed in chemical hematite mud (Angerer et al. 2016,

Frei et al. 2017); although these patterns can also be produced by fresh water input, including glacial

outwash and bethic pore water flux (Angerer et al. 2016, Frei et al. 2017). A fertilization by low-

temperature hydrothermal fluids is also likely because of the almost non-fractionated δ57

Fe values (-

0.7 to 0.0 ‰) reported in the siliceous IF facies, also associated with metal enrichment (e.g. elevated

Zn/Co) (Angerer et al. 2016). The εNd(TCHUR) signature of the IF and MnF does not support a source

from either local clastic sediments nor crystalline basement (Viehmann et al. 2016). For this reason, as

well as the seawater-like fractionation of the REE (Viehmann et al. 2016) and low metal content of

proximal facies (Angerer et al. 2016), a weathered continental hinterland (Urban et al. 1992,

Frei et al. 2017) is an unlikely sources for the Fe and Mn; unless these elements were completely

decoupled from the other rock-forming elements. Leaching of authigenic basin sediments (e.g. black

shale) constitutes another possible source (Angerer et al. 2016).

The IF was enriched in two stages: (i) a hypogene ore upgrade was probably caused by

circulation of diagenetic/low-temperature hydrothermal warm Si-undersaturated, alkaline fluids

(Wlade & Hagemann 2007, Angerer et al. 2014a), leading to dissolution-mobilization of silica and

volume reduction (Hagemann et al. 2016); (ii) subsequent exhumation led to supergene leaching and

further enrichment (Urban et al. 1992, Angerer et al. 2014a, Hagemann et al. 2016).


47

Table 3.2- Arguments in favor and against the genetic models proposed for the Fe and Mn deposits of

the Urucum district. Modified after Walde & Hagemann (2007).

Model Author(s) In favor Against

Epicontinental-

marine

Syn-sedimentary

basin

Model

Dorr II (1945)

Field relationships,

chemical (marine)

sedimentary

rocks

Graben model and

associated fault

system,

Hydrothermal minerals

not explained,

Source of Fe and Mn is

vague

Volcanic-

hydrothermal

epigenetic model

Walde (1981)

Walde et al. (1981)

Leonardos & Walde

(1982)

Hydrothermal quartz,

tourmaline

Limited information on

distribution of

volcanic rocks and

hydrothermal

minerals

Climate-controlled

syn-sedimentary,

supergene model

Walde et al. (1981)

Schneider (1984)

Schreck (1984)

Urban et al. (1992)

Leeuwen & Graf (1987)

Graf et al. (1994)

Tillites with drop-stones,

Concretionary and detritus

rich ores,

Supergene enrichment


not explained,

Graben model and

associated fault

System,

High Fe content of the

manganese ore

Hydrothermal

volcanism/ seawater

circulation and

halmyrolysis

(SEDEX) epigenetic

model

Trompette et al. (1998)

Dardenne (1998)

Walde & Hagemann

(2007)

Graben model with fault

zones,

High P-T Mn minerals,

Quartz-tourmaline veins

and hydrothermal

magnetite

Lack of data on

distribution of

hydrothermal minerals,

Lack of fluid data

Ocean water with

deep seated

hydrothermal

fluids,

Hybrid syn-epigenetic

model?

Graf et al. (1994)

Klein & Ladeira (2004)

Costa et al. (2005)

REE analyses, Eu depleted

Deep seated fluids not

defined,

Graben model and

associated fault

system,


not explained

Hydrothermal model

with syn-sedimentary

control

Freitas et al. (2011) Stratigraphic and tectono-

sedimentary relations

Hydrothermal fluids not

defined

Climate-controlled

syn-sedimentary,

with hydrothermal

fluids

Angerer et al. (2016)

Viehmann et al. (2016)

Kroeninger (2016)

Frei et al. (2017)

REE analyses, redox-

sensitive trace elements,

δ57

Fe, δ13

C, δ53

Cr

Glaciation uncertain

Sources not well defined


48

Figure 3.7. Climatic genetic models for the Urucum IF-MnF: (a) formation of MnF and IF was

controlled by deposition along a dynamic redoxcline, respectively in shallower and deeper zones

(Viehmann et al. 2016); (b) likewise, the formation of the main IF facies was related to variation of the

depth of the redoxcline due to transgression juxtaposed with glaciogenic processes

(Angerer et al. 2016). Metals were sourced either from low-temperature hydrothermal fluids or pore

water (Angerer et al. 2016).

CHAPTER 4

IN-SITU LA-ICP-MS AND EMP TRACE ELEMENT ANALYSES

OF HEMATITE: INSIGHT INTO THE GEOCHEMICAL SIGNATURE

OF THE NEOPROTEROZOIC URUCUM IRON AND MANGANESE

FORMATION, BRAZIL

ABSTRACT

Authigenic iron oxide minerals hosted in iron formations (IFs) offer insights into the genesis of these

enigmatic rocks for their intrinsic potential to register the conditions and mechanisms controlling its

much debated deposition. The widely held view of hematites in IFs as synsedimentary (bio)chemical

precipitates makes them attractive targets to mineral-specific geochemical investigations aiming at

distinguishing its primary signature from ore-related transformations. This study reports in situ

Electron Microprobe (EMP) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

(LA-ICP-MS) analyses of hematites from the Neopreoterozoic Urucum IF, Jacadigo Group, SW Brazil

and SE Bolivia. The hematites were divided into three mineralization stages, defined on the basis of

their morpho-texture: (i) anhedral microcrystalline hematite (Hm1); (ii) subhedral to euhedral,

elongated bladed hematite (microspecular; Hm2) and (iii) subhedral to euhedral microplaty hematite

(Hm3). Factor analysis (FA) was used to trace underlying relationships among the elements

incorporated in the hematites. FA discriminates four groups of trace elements: (i) incorporated in the

hematite structure; (ii) associated with carbonate contamination; (iii) associated with chert inclusions;

(iv) hydrogenous, including the REEs and the geochemical pairs U-Th and Zr-Hf. The trace element

compositions reveal small ranges of abundances in all stages and broadly consistent behaviors, in

particular for the REEs. This trend suggests limited post-depositional overprinting, during

mineralization associated with diagenetic basin brines and supergene solutions, and extensive

preservation of the primary element compositions. Microcrystalline hematite was formed earlier in

diagenesis, whereas microspecular and microplaty hematite are coeval; and were formed later during

hypogene enrichment of the IF. The distinctively seawater-like REEs profiles prevalent all stages of

hematites indicate a recrystallization from common precursor hydrogenous sediments composed of

ferrihydrite. Real negative Ce anomalies and generally low Th/U ratios indicate that the precursor

sediments were deposited above a redox chemocline, in oxic conditions, in a stratified basin. The

presence of strong LREE depletion in the hematites, as well as other features of the marine REE

signature, supports a connection of the surface oxic layer with the open ocean. The variation observed

in the Zr/Hf ratios suggests that the local basin waters also received inputs from a freshwater source.

Souza F.R. de*,1, Nalini H.A.Jr.2, Abreu A.T. de3

1Departamento de Geologia, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000, Ouro Preto, MG, Brazil 2Departamento de Geologia, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000, Ouro Preto, MG, Brazil 3Departamento de Geologia, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400-000, Ouro Preto, MG, Brazil *Corresponding author: Fernando R. de Souza. E-mail: [email protected]

Article submitted to Journal of South American Earth Science

Keywords: Neoproterozoic; Iron Formation; Hematite; Geochemistry; Laser Ablation Inductively Coupled Plasma Mass Spectrometry; Electron Microprobe; Factor Analysis; Brazil

mailto:[email protected]


50

4.1- INTRODUCTION

Iron formations (IFs) are Fe-rich chemical sedimentary rocks, whose origin is intimately

connected to the geological evolution of the Earth during the Precambrian. Although subject of

extensive research, the genesis of these rocks remains one of the most contentious topics in the field of

geosciences (Bekker et al. 2010). The late Neoproterozoic Urucum iron and manganese formation (IF-

MnF), hosted in the Jacadigo-Boqui Gr., SW Brazil and SE Bolivia, is one of the largest and best

preserved examples of this Era (e.g. Cox et al. 2013, Gaucher et al. 2015). This IF-MnF bears features

related to the convoluted tectonic, chemical and climatic changes of the Neoproterozoic (e.g.

Halverson et al. 2010, Och et al. 2012, Bekker et al. 2010, Cox et al. 2016a). Above all, it records the

development of anoxic conditions, concurrent with increased Fe and Mn supply, and subsequent

oxidation of this reservoir (Kump & Seyfried 2005, Poulton & Canfield 2011, Gaucher et al. 2015,

Cox et al. 2016b). These processes were fundamentally associated with the tectonic and magmatic

events following the break-up of the supercontinent Rodinia (Bekker et al. 2010, Cox et al. 2016a) and

associated global glaciation events conjectured in the “snowball Earth” hypothesis

(Hoffman et al. 1998, Halverson et al. 2010); presumably reflected in the geotectonic setting and

glacial deposits of the Urucum IF-MnF (e.g. Urban et al. 1992, Trompette et al. 1998).

Fe-oxide minerals hosted in IFs are regarded as diagenetic products of precursor sedimentary

phases, precipitated from basin and pore waters (e.g. Klein 2005, Pufahl & Hiatt 2012,

Posth et al. 2013). If these precursor phases were formed in thermodynamic equilibrium with the

ambient water, the preserved geochemical signatures can be used as proxy for paleo-environmental

conditions and element sources (e.g. Bekker et al. 2010). In situ techniques, such as Laser Ablation

Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and Electron Microprobe (EMP), have

the advantage of providing mineral-specific chemical signatures. In doing so, the contamination and

mineralogical heterogeneity of the conventional whole-rock analyses are avoided (Baldwin et al. 2011,

Thurston et al. 2012). Over the past decade, a growing number of studies have applied these

techniques to Fe-oxide minerals to constrain primary genetic aspects and ore-related mineralization

processes of Ifs (e.g. Pecoits et al. 2009, Baldwin et al. 2011, Thurston et al. 2012,

Mloszewska et al. 2012, Angerer et al. 2012, Hensler et al. 2015, Oliveira et al. 2015,

Chung et al. 2015, Gourcerol et al. 2015, Alibert 2016).


51

This is particularly relevant for the Urucum IF-MnF since it host a low-grade metamorphic

assemblage, where hematite constitutes overwhelmingly the main Fe-oxide mineral, which has been

demonstrated by pervious whole rock studies (e.g. Angerer et al. 2016, Viehmann et al. 2016,

Frei et al. 2017) to ostensibly preserve primary chemical traits. This provides a fitting framework for

micro-chemical investigations of these minerals, aimed at exploring the origin of these enigmatic

rocks and their overall significance in the Neoproterozoic context. This study explores the use of EMP

and LA-ICP-MS to investigate the trace element compositions of different hematite stages from the

Santa Cruz hill, Urucum IF-MnF, Brazil. Furthermore, statistical Factor Analysis (FA) is used to

identify natural relationships among elements and refine the trace element signatures. The results offer

insights into the mineral element inheritance of the hematites, and constraints in the paleo-

environmental conditions governing the formation of this IF.

4.2- GEOLOGICAL SETTING The geology of the Jacadigo-Boqui Gr. was recently summarized in several publications

(Walde et al. 2015, Angerer et al. 2016, D’el-Rey et al. 2016, Viehmann et al. 2016, Frei et al. 2017).

The main outcrop of this group occurs in the Urucum massif (Fig. 1). Extensional tectonics during the

late Neoproterozoic opened a rift system on the boundary between the Amazon and Rio Apa cratons,

where the precursor basins of the Chiquitos-Tucavaca aulacogen and the North and South Paraguay

belts intersected in an R-R-R junction (Fig. 4.1 – a, b) (Trompette et al. 1998, Walde & Hagemann

2007, Walde et al. 2015, Angerer et al. 2016, D’el-Rey et al. 2016). The geodynamic significance of

this rift basin (herein referred to as Urucum basin) is still under debate; but its opening is thought to be

correlated with the collisions of the early Brasiliano Cycle Orogeny (Trompette et al. 1998,

Angerer et al. 2016, D’el-Rey et al. 2016). The Jacadigo-Boqui sedimentary succession was deposited

overlying the Rio Apa block basement, composed of gneisses and intrusive granitoids and mafic dykes

(Dorr II 1945, Almeida 1946, Haralyi & Walde 1986), and underlying the Corumbá Gr., composed of

carbonate platform deposits of a post-rift transgression (Freitas et al. 2011, Walde et al. 2015).


52

The geochronological framework is constrained by maximum depositional ages of: (i) 1730±22

Ma and 889±44 Ma, based on K-Ar dating of the granitic basement (Hasui & Almeida 1970); (ii) 706±09

Ma, based on U-Pb dating of detrital zircons of the correlative Puga Fm. (Babinski et al. 2013); (iii)

695±17 Ma, based on U-Pb dating of detrital zircons in sandstones of the Urucum IF-MnF

(Frei et al. 2017); (iv) a dubious K/Ar age of 623±15 Ma, yielded by plutonic rocks cross-cutting the

basement in the Chiquitos-Tucavaca aulacogen (Litherland et al. 1986). Minimum depositional ages are

defined at: (i) 543±3 Ma, based on U-Pb dating of zircons in ash layers of the Tamengo Fm. – lowermost

unit of the Corumbá Gr. (Babinski et al. 2008); (ii) 549-543 Ma, imposed by diagnostic Ediacaran fossils

(Cloudina lucianoi and Corumella werneri) in the Corumbá Gr. (Amthor et al. 2003, Warren et al. 2012);

(ii) 587±7 Ma, yielded by 40

Ar/39

Ar dating of diagenetic-metamorphic cryptomelane from the basal MnF

bed (Piacentini et al. 2013).

The Jacadigo-Boqui Gr. represents a continental-marine sequence deposited in an evolving rift

(Freitas et al. 2011), possibly in a periglacial environment (Urban et al. 1992). Much of the current

literature divides the Jacadigo Group into three lithostratigraphic units, partially transitional and

superimposed, following the division proposed by Dorr II (1945) (Fig. 4.1 – c). The basal unit is

constituted by the Urucum Fm., comprising a continental siliciclastic succession formed by alluvial and

lacustrine facies of rift initiation to early climax (Freitas et al. 2011). The overlying Córrego das Pedras

and Banda Alta formations comprises shore and offshore facies of mid to late rift climax

(Freitas et al. 2011), deposited during an overall marine transgression (Kroeninger 2016). The Córrego das

Pedras Fm. is composed of shore facies granular IF, MnF (Mn 1), and siliciclastic rocks with Fe-Mn

cementation (Urban et al. 1992, Freitas et al. 2011). The Banda Alta Fm. constitutes the main chemogenic

unit dominated by IF, with intercalated MnF beds (Mn 2-4), ferruginous sandstones, arkoses and

diamictites (Freitas et al. 2011, Piacentini et al. 2013). Diamictites and outsized clasts within the IF are

usually regarded as glacial deposits (e.g. Klein & Ladeira 2004, Urban et al. 1992, Piacentini et al. 2013),

or alternatively mass flow deposits (e.g. Trompette et al. 1998, Freitas et al. 2011). Because of the poor

temporal constraint (e.g. Piacentini et al. 2013), and disputed glacial evidences (e.g. Trompette et al. 1998,

Freitas et al. 2011), it’s still unresolved whether this group is correlated with a Neoproterozoic glaciation

event.


53

Low grade metamorphism correlated with deformation in the Paraguay belt is bracketed in the

547-513 Ma interval (Piacentini et al. 2013), matching the emplacement of the post-tectonic São Vicente

granite, dated at 518±4 Ma (zircon U-Pb; McGee et al. 2012). The metamorphic paragensis indicates a

sub-green schist facies (Piacentini et al. 2013, D’el-Rey et al. 2016), consistent with peak temperatures of

250-280 ºC (quartz-hematite δ18

O; Hoefs et al. 1987). Evidences of ductile and brittle deformation during

the Brasiliano Cycle are registered in three sets of tectonic structures from superimposed deformation

phases (D’el-Rey et al. 2016). Two nearly orthogonal crustal shortenings, with stresses in the SE-NW (D1-

D2 ductile flows and D3P) and SW-NE (D3T) directions, created gentle dipping, mostly to SSE or NNW,

correlated with open-style folds (D’el-Rey et al. 2016). According to Freitas et al. (2011), this

deformation event was responsible for the reactivation of the basement faults and tectonic inversion of the

basin in a dome-like structure. Exhumation during the Mesozoic-Cenozoic, after ca. 60 Ma (Piacentini et

al. 2013), and uplift of the fault blocks linked to the subsidence the surrounding Pantanal basin, at ca. 3

Ma (Shiraiwa 1994) formed the present inselberg topography (Trompette et al. 1998,

Piacentini et al. 2013).

This study focuses on the Santa Cruz deposit, located in south-eastern portion of the homonym

hill (Fig. 4.1 – c, AB cross-section). Broader descriptions of the Santa Cruz deposit have been provided by

Angerer et al. (2016) and Kroeninger (2016). In the Santa Cruz deposit, the IF is subdivided in two main

lithofacies (Angerer et al. 2016): (i) the stratigraphically inferior, and possibly superior, “shallow” water

carbonaceous facies, composed of banded and nodular chert-dolomite-hematite IF; (ii) and an intermediate

“deep” water siliceous facies, constituted of texturally podded (from hypogene leaching), and more rarely

banded and nodular, chert-hematite IF.


54

Figure 4.1- (a) Simplified geotectonic framework of South America showing the position of the inferred

R-R-R triple junction (modified after D’el-Rey et al. 2016) (b) Geological map of the Urucum Massif

(modified after Freitas et al. 2011), and schematic cross section (AB) of the Santa Cruz deposit (modified

after Angerer et al. 2016). (c) Composite stratigraphic profile of the Santa Cruz deposit (modified after

Freitas et al. 2011, Angerer et al. 2016, Kroeninger 2016).

4.3- ANALYTICAL METHODS

4.3.1- Sample Preparation and Petrography

A complete description of the methods can be found in appendix A. Sixteen IF core samples were

collected from different depths along two stratigraphic drillcores (STCR-DD-24-36 and DD-40-40A) from

the Santa Cruz deposit. Eight samples come from the stratigraphically superior siliceous facies, composed

of nodular and podded chert-hematite IF (Fig. 4.2 – a), and nine com from the inferior carbonaceous

facies, composed of banded and nodular chert-dolomite-hematite IF (Fig. 4.2 – b). Sample preparation and

microanalyses were undertaken at facilities of the school of mines of the Federal University of Ouro Preto,

Brazil. The different textural stages of hematite were analyzed by LA-ICP-MS at Laboratório de

Geoquímica Analítica, and by EMP at Laboratório de Microscopia e Microssonda Eletrônica.


55

The petrography was examined using a combination of conventional optical microscopy and

electron microscopy, including EMP and Scanning Electron Microscopy (SEM) coupled to Energy-

Dispersive x-ray Spectroscopy (EDS) and Electron Backscattered Diffraction (EBSD). Upon screening of

polished thin sections, seventeen areas were selected and prepared for EMP and LA-ICP-MS. These areas

were cut into small sections from the corresponding rock slabs, assembled into epoxy mounts (Fig. A.1),

polished and rinsed ultrasonically. Two sections underwent a special preparation for complementary

SEM-EBSD analyses. Polished thin sections and mounts were sputter-coated with an ultra-thin film of

carbon, using an evaporation coater model JEOL JEE-4C, for electron microscope analyses. SEM-EDS

imaging and mineral-chemical characterization were performed using a JEOL JSM-6010-LA and a JEOL

JSM-6510, equipped with Oxford Instruments EDS sensors, operated under acceleration voltage of 15-

20 kV. Complementary SEM-EBSD analyses were performed on a JEOL JSM-5510 SEM equipped with a

Nordlys Oxford EBSD. The acquired EBSD data was processed with the software suite Channel 5

(Oxford) and MATLAB MTEX toolbox.

4.3.2- Analytical Techniques

EMP element analyses were acquired on a JEOL JXA 8230 equipped with 5 wavelenght

dispersive spectrometers (WDS). The analytical conditions were: 5 µm beam diameter, 15kV acceleration

voltage, 20nA low-beam current. The measurement conditions, crystals and standards are listed in

appendix B (Table B.2 and Table B.3). LA-ICP-MS analyses were performed on a New Wave Research

UP-213 Nd:YAG 213 nm laser ablation system coupled to an Agilent 7700x Quadrupole ICP-MS. The

ablation was carried out in He atmosphere using a customized ablation cell attached to a gas mixer with

Ar carrier gas injection. Samples were ablated using: 30 μm beam diameter, pulse frequency of 10 Hz,

and energy density varying between ~8.6 and 9.35 J/cm2. A small beam size was chosen to decrease the

incorporation of non-hematite phases. The total acquisition time was of 70 s, including 20 s for

background acquisition and 40 s for chamber washout after each analysis. To improve signal intensity and

minimize mass bias, the analytes were split into two sets based on their atomic mass (heavy and light

elements), ablated in adjacent sites.


56

The ICP-MS instrument parameters were tuned for each set ablating the international standards

NIST SRM 610 and 612. Plasma conditions were tuned to reduce interferences. Double charge and oxides

formation were monitored respectively with Ca+/Ca

2+ and ThO/Th, and kept under 1%. Analytical signals

were calibrated against an external standard, bracketed at regular intervals for instrumental drift

correction. In the absence of a widely-available external standard for hematite, the basalt glass

USGS BHVO-2G was considered a practical alternative given its high Fe content (Fe = 8.63±14 wt. %).

Analytical conditions and accuracy were verified using the international standard glass USGS BCR-2G for

quality control. Raw intensities were corrected for background and normalized to 57

Fe to correct time-

dependent signal drift and fractionation (Nadoll & Koenig, 2011). An average value of 87.3 wt. % FeO

determined by EMP was used for the internal standard normalization. Data reduction and processing were

performed using the software GLITTER® (Access Macquarie LTD). The dataset was filtered to exclude

values suspected of contamination using foreign peaks in the element spectra (Nadoll & Koenig 2011),

and fingerprint elements in the processed data (Baldwin et al. 2011, Thurston et al. 2012,

Hensler et al. 2015). The reported data considers only concentrations exceeding quantitation limits

corresponding to 3.33 times the respective local detection limits (appendix C – Table C.2). Coefficients of

variation for most elements are within 75-125% of the secondary standard’s published values (appendix C

– Table C.3), except for: Cu (137%); W (131%); Pb (64%); Na (129%); Ge (262%); Cd (62%).

4.3.2- Factor Analysis

Factor analysis was performed in the EMP and LA-ICP-MS data sets. Elements and spots with

over >25% of the data below the detection limit were excluded from analysis. The remaining values below

detection limit were set to half the respective local detection limit. Additionally, Pb and W were excluded

to reduce dimensionality. FA was performed on the statistical software XLSTAT 2014.5.03 using a

principal component extraction method with Pearson matrix and Kaiser Varimax rotation (Kaiser 1958).

The variables were first tested and standardized applying a two-step normalization using the software IBM

SPSS Statistics V. 23.0 (Templeton 2011). Only factor scores outside the -0.5 to 0.5 range were

interpreted, following the suggestion of Nadoll et al. (2012).


57

4.4- RESULTS

4.4.1- Petrography All samples preserve fine-grained, low-grade metamorphic assemblages. Hematite occurs as

grains typically not exceeding <50 µm. It is the predominant constituent in Fe-rich meso- and microbands

(0.5-5 cm and 0.5-5 mm thick, respectively), in both chert-hematite IF (Fig. 4.2 – a, b) and chert-dolomite-

hematite IF, but also occurs in nodules and intraclasts (Fig. 4.2 – b, c), and as submicrometric to

micrometric inclusions, and finely intergrown crystals, in gangue minerals (Fig. 4.2 – d). Quartz, either as

cryptocrystalline chert (<1 µm) or larger recrystallized micrometric crystals, is the dominant gangue

mineral in the siliceous facies, while carbonates and apatite are only minor components. Members of the

Fe-dolomite-ankerite series dominate the carbonaceous facies IF assemblage, with subordinate amounts of

quartz and other minerals (apatite, siderite, calcite, dolomite, and barite). Clastic minerals are rare, but

millimetric quartz and feldspar clasts are present in peloidal layers. Although hematite is the predominant

Fe-oxide mineral, sparse anhedral magnetite grains (<10 µm grain size) occur scattered throughout Fe-rich

bands (Fig. 4.2 – e), predominantly in chert-hematite IF samples (1-5 % of the rock) and more rarely in

chert-dolomite-hematite IF samples (<1 %), where siderite is more common (Fig. 4.2 – f).


58

Figure 4.2- Transmitted and reflected light photomicrographs showing (a) banded and podded chert-

hematite IF, and (b) banded and nodular chert-dolomite-hematite IF, with a peloidal layer (bottom). SEM

back scattered electron images of a (c) nodular hematite-rich band (top) with a carbonate-rich peloidal

layer (bottom), and (d) hematite inclusions in gangue minerals (Hm0). SEM-EBSD mineral maps of (e) a

chert-dolomite-hematite IF and (f) a chert-hematite IF sample. Note the occurrence of magnetite and

siderite. Mineral abbreviations: chert (Cht); hematite (Hm); Fe-dolomite (Fe-dol) - ankerite (Ank); apatite

(Ap); quartz (Qtz).


59

The hematites were divided in four textural stages. The first stage is composed of submicrometric

(<1 µm), dusty hematite (Hm0). Hm0 occurs as anhedral crystals disseminated in interstices or as

inclusions in gangue minerals (Fig. 4.2 – d, detail), primarily chert (jasper), Fe-dolomite-ankerite, and

apatite. The presence of Hm0 impairs the distinctive macroscopic red-stained coloration of bands and

nodules composed by the gangue minerals. This stage was not analyzed because of its small grain size.

The second stage consists of microcrystalline, anhedral to subhedral hematite (Hm1), typically not

exceeding 10 µm in size (Fig. 4.3 – a, b). Hm1 occurs in massive inequigranular aggregates, frequently

intergrown with gangue minerals. The third and fourth stages are composed of coarser, subhedral to

euhedral, bladed hematite (termed microspecular, Hm2), and microplaty hematite (Hm3). Individual Hm2

crystals are thin, elongated laths, reaching up to 40 µm in length. This stage appears more commonly in

reticulated aggregates within intraclasts (Fig. 4.3 – c, d), and more rarely in nodules and in nodular

mesobands. The Hm3 platelets are roughly equant, 10-30 µm across and constitute massive, clustered

(Fig. 4.3 – e, f), or lepdoblastic aggregates. This stage is commonly observed in higher grade matrices, on

the contact between compositional laminae (Fig. D.1 – a), in diagenetic nodules, and surrounding

diagenetic veinlets (Fig. D.1 – b). It also occurs in foliation-defining laminae (<2 mm) and oblate nodules

(<3 mm) within the hematite matrix (Fig. D.1 – c), and in weathered samples associated with secondary

porosity and cryptocrystalline goethite aggregates (observed only in sample DE-06) (Fig. D.1 – d). Very

small hematite (<5 µm) can also be observed in rare micrometric (<10 µm) veinlets.


60

Figure 4.3- Back scattered (BSE) and secondary electron (SE) images of the hematite stages. (a) Anhedral

hematite (Hm1) (bottom right) (BSE); (b) Texturally heterogeneous aggregate where Hm1 is predominant

(SE); (c) Peloid composed of reticulated Hm2 aggregates (BSE); (d) Hm2 aggregates with minor Hm3

platelets (center) (SE); (e) Enriched sample with Hm3 composes nodules and laminations (BSE); (f)

Cluster of Hm3 crystals (SE). Mineral abbreviations: Fe-dolomite (Fe-dol); apatite (Ap); quartz (Qtz).


61

4.4.2- Mineral Chemistry Tables 4.1 and 4.2 present a summary of the mean trace element compositions in the different

hematite stages, measured respectively by EMP and LA-ICP-MS. Complete analytical results are

available in appendices B and C. The hematites show the expected near-pure composition

(EMP: 97.0±1.73 wt. % Fe2O3, n = 95), with minor impurity from other elements. Unsurprisingly, the

results indicate that the LA-ICP-MS data is on average more contaminated by incorporation of non-

hematite minerals because of the comparatively larger beam size. Nonetheless, it is important to bear in

mind that the LA-ICP-MS data only includes values above the established quantitation limits.

The main chemical contaminant is constituted by Si (EMP: 0.64±0.84 wt. %, n = 95; LA-ICP-MS:

4.14±3.17 wt. %, n = 116). Elevated abundance in this element is thought to reflect contamination by

micro- and nanometric chert crystals. In the EMP data, Si decreases in concentration from Hm1 and Hm2

to Hm3. In the LA-ICP-MS data, Si concentrations in Hm2 spots are generally similar to those of Hm1

and Hm3, with the exception of sample DE-L-06, where Hm2 hematites show the highest concentrations.

Elevated concentrations of Ca (EMP: 0.11±0.14 wt. %, n = 95; LA-ICP-MS: 3.27±2.87 wt. %, n = 40) Mg

(EMP: 0.004±0.02 wt. %, n = 95; LA-ICP-MS: 0.36±0.63 wt. %, n = 116) and, lesser significantly, Mn

(EMP: 0.01±0.01 wt. %, n = 95; LA-ICP-MS: 0.195±0.598 wt. %, n = 116) are thought to reflect

contamination Fe-dolomite-ankerite crystals observed petrographically. In the LA-ICP-MS data set, a

decreasing trend is observed from Hm1 to Hm3. Otherwise, variations in the abundance of these elements

are primarily controlled by faciological patterns, with hematites from chert-hematite IF samples showing

on average slightly higher Si concentrations, while hematites from chert-dolomite-hematite IF samples

show higher Ca, Mg (and sporadically Mn, P, and Sr) concentrations.


62

The remaining elements are often present in trace amounts. The most abundant are: P, Al, Ti, K,

Na, Ba and Sr, which range from a few hundred up to a few thousand ppm. The hematites (Hm2) in

sample DE-L-06 show unusually high concentrations of Al, K, P, and Ti, in addition to Zr and Si, as

previously mentioned. These values are interpreted to result from contamination by other phases. Two

LA-ICP-MS spots show anomalous concentrations of Na (1.73 wt. %) and P (2.99 wt. %), possibly caused

by silicate and apatite inclusions. Atypical Sr and Ba abundances in a number of LA-ICP-MS spots is also

indicative of some degree of mineral contamination. The trace elements V, Zr, Pb, Co, Cu and Zn are

present in concentrations of several ppm, rarely exceeding 100 ppm; while Mo, Hf, W, Th, U, Ga, Cd, Nb

are less abundant, with concentrations typically below 1 ppm. The trace elements Sc, Ga, Cd, Cr and Ni

occur in values below quantitation limit in all but a few spots. With regards to the rare earth elements

(REEs), higher-abundance REEs (La, Ce, Pr, Nd and Y) were detected in about three quarters of the spots,

with concentrations in the order of several ppm. Lower-abundance REE were detected in between half

(Sm, Dy, Er, Yb, Tb, Ho) and a quarter (Eu, Tm, Lu) of the spots, with concentrations typically below 1

ppm. The REE Gd was measured above the quantitation limit in only one spot.

Table 4.1. Summary of the EMP data: mean values (in wt. %) standard deviation of different hematite

stages from the Urucum IF. See appendix B for complete analytical results.

FeO* SiO2 Al2O3 CaO P2O5 TiO2 MnO MgO K2O Na2O

Hm

1 87.0

±1.03

(8)

1.47

±1.14

(8)

0.205

±0.112

(8)

0.093

±0.063

(8)

0.096

±0.072

(8)

0.062

±0.052

(8)

0.025

±0.020

(8)

0.005

±0.007

(8)

0.007

±0.006

(8)

0.003

±0.006

(8)

Hm

2 86.9

±1.67

(47)

1.60

±2.08

(47)

0.120

±0.057

(47)

0.125

±0.076

(47)

0.120

±0.060

(47)

0.033

±0.026

(47)

0.016

±0.018

(47)

0.003

±0.056

(47)

0.006

±0.006

(47)

0.002

±0.007

(47)

Hm

3 86.5

±1.53

(40)

1.07

±1.47

(40)

0.255

±0.162

(40)

0.210

±0.282

(40)

0.120

±0.049

(40)

0.058

±0.082

(40)

0.020

±0.022

(40)

0.01

±0.011

(40)

0.011

±0.008

(40)

0.005

±0.012

(40)

Notes: *total Fe; values in parentheses indicate the number of spots.


63

Table 4.2. Summary of the LA-ICP-MS data: mean element abundances (in ppm) and standard deviations

of different hematite stages (Hm1; Hm2; Hm3) from the Urucum IF. See appendix C for complete

analytical results, including the quantitation limits.

Hm1 Hm2 Hm3

V 55.7 ±9.74 (24) 49.0 ±13.7 (28) 56.6 ±7.67 (40)

Mn 1561 ±3626 (17) 4869 ±16467 (17) 153 ±226 (24)

Sr 877 ±2637 (41) 165 ±405 (26) 83.8 ±98.4 (43)

Y 32.1 ±51.9 (40) 37.7 ±43.5 (30) 16.3 ±34.0 (45)

Zr 11.0 ±6.78 (35) 42.5 ±73.4 (27) 9.42 ±2.33 (37)

Mo 0.732 ±0.261 (9) 0.998 ±0.354 (13) 1.10 ±0.606 (9)

Ba 487 ±1313 (32) 131 ±271 (23) 95.1 ±194 (35)

La 13.9 ±29.9 (38) 12.2 ±16.7 (26) 3.51 ±4.58 (40)

Ce 16.8 ±25.3 (40) 17.4 ±22.6 (28) 5.00 ±7.20 (45)

Pr 3.90 ±7.05 (30) 3.63 ±4.28 (22) 1.45 ±1.60 (26)

Nd 15.9 ±25.5 (27) 16.7 ±19.2 (22) 6.65 ±7.75 (27)

Sm 2.25 ±3.41 (12) 3.79 ±5.22 (16) 2.00 ±1.63 (17)

Eu 0.307 ±0.184 (9) 0.458 ±0.437 (13) 0.599 ±0.519 (9)

Gd <Q.L. <Q.L. 7.42 (1)

Tb 0.497 ±0.419 (22) 0.586 ±0.589 (27) 0.521 ±0.595 (20)

Dy 2.37 ±2.25 (16) 4.84 ±5.73 (20) 3.27 ±4.58 (22)

Ho 0.606 ±0.546 (15) 1.21 ±1.57 (19) 0.704 ±1.02 (19)

Er 2.19 ±2.11 (15) 3.72 ±4.99 (20) 2.49 ±3.32 (21)

Tm 0.271 ±0.220 (9) 0.373 ±0.355 (14) 0.557 ±0.603 (10)

Yb 2.16 ±1.89 (13) 2.63 ±2.91 (17) 2.40 ±3.43 (20)

Lu 0.323 ±0.307 (9) 0.334 ±0.290 (15) 0.667 ±0.866 (10)

Hf 0.393 ±0.296 (12) 0.433 ±0.629 (16) 0.537 ±0.246 (16)

W 0.267 ±0.189 (12) 0.295 ±0.173 (14) 0.253 ±0.120 (16

Pb 1.60 ±0.481 (13) 2.01 ±0.381 (13) 6.59 ±21.4 (20)

Th 0.442 ±0.475 (13) 0.656 ±0.961 (17) 0.405 ±0.402 (19)

U 0.157 ±0.097 (13) 0.183 ±0.099 (16) 0.201 ±0.119 (16)

Na 1142 ±3662 (22) 293 ±241 (10) 197 ±82.2 (26)

Mg 8667 ±12941 (40) 1215 ±3212 (30) 879 ±2615 (46)

Al 1330 ±1805 (40) 1265 ±1855 (30) 962 ±589 (46)

Si 35573 ±22087 (40) 69541 ±42070 (30) 28019 ±33309 (46)

P 2044 ±1354 (8) 5107 ±8898 (10) 1371 ±1004 (25)

K 428 ±25.4 (2) 1625 ±1041 (5) <Q.L.

Ca 45111 ±38519 (22) 22815 ±20154 (8) 13369 ±13096 (10)

Sc 6.26 ±1.74 (8) 5.35 ±0.318 (2) <Q.L.

Ti 276 ±149 (40) 361 ±548 (30 233 ±136 (46)

Ga 0.803 ±0.273 (4) <Q.L. 0.760 ±0.156 (2)

Cd 0.470 (1) <Q.L. 0.303 ±0.156 (3)

Nb 0.930 ±0.397 (14) 0.589 ±0.088 (3) 2.16 ±1.74 (5)

Cr 12.4 (1) <Q.L. 3.15 (1)

Co 5.13 ±3.43 (17) 3.01 ±1.59 (4) 0.760 ±0.481 (2)

Ni <Q.L. 13.5 ±4.35 (4) <Q.L.

Cu 74.9 ±145 (21) 45.4 ±69.1 (26) 55.4 ±46.2 (34)

Zn 15.5 ±10.1 (13) 8.00 ±6.53 (30) 12.7 ±7.13 (4)

Notes: <Q.L. data points below quantitation limit; values in parentheses indicate the number of spots.


64

Trace elements abundances in chemical sediments are commonly normalized to upper continental

crust composites to assess syn- or post-depositional modifications to primary hydrogenous signals

(Bolhar et al. 2005, Pecoits et al. 2009, Thruston et al. 2012). The alluvial sediment average MUQ (Mud

from Queensland; Kamber et al. 2005, updated by Marx & Kamber 2010) was chosen for normalization

(subscript MUQ) because of the influence of weathered basalt in the catchment, reflecting a possible

contribution from continental flood basalt to the Neoproterozoic ocean (Cox et al. 2016a, 2016b).

Consistent, sub parallel REEMUQ profiles (Fig. 4.4) are observed irrespective of the hematite stage and

texture; implying an overall iso-chemical recrystallization. Similar patterns are obtained using PAAS

(Post-Archaean Australian shale; Taylor & McLennan 1985) for normalization (Fig. D.2); which attests a

small role of normalization on the patterns (e.g. Kamber et al. 2004, Bolhar et al. 2005).

Individual REEMUQ profiles are in general uniform within individual samples and similar to the

range observed in whole-rock analyses. Hence, post-depositional mobilization of REEs and incorporation

of heterogeneities had a small impact of the general distribution of these elements. Irregular, serrated and

stepped profiles are observed when the absolute REE concentrations approach the respective detection

limits. This results from the extrapolation of few detected counts yielded by short dwell times on low

abundance isotopes, as well as an increased influence of isobaric interferences (Baldwin et al 2011).

Profiles with higher absolute concentrations are generally smoother and possibly less affected by artificial

peaks. However, it is possible that profiles above the range defined by the whole-rock analyses may be

overestimated due to inadequate correction for contamination in the internal normalization, since whole-

rock analyzes yield abundances nearly an order of magnitude larger than laser analyzes

(Thurston et al. 2012).

The normalized data displays patterns broadly consistent with those of modern marine

hydrogenous sediments, characterized by: (i) variable but typically negative CeMUQ anomalies; (ii)

depletion of light REEMUQ (LREE) relative to heavy REEMUQ (HREE); (iii) super-chondritic Y/Ho ratios

(i.e. >26.2; Pack et al. 2007) (positive YMUQ anomalies); (iv) positive LaMUQ and GdMUQ anomalies. Two

diagnostic features are systematically observed in the data (Supplementary Material S6) for all stages and

textures: strong LREEMUQ depletion, indicated by (Pr/Yb)MUQ ratios below the unit (mean = 0.3, n = 38);

and real negative CeMUQ anomalies (mean = 0.63, n = 54) (Fig. 4.5). Only two data points display real

positive CeMUQ anomalies. The single spot where Gd was detected above the local quantitation limit shows

positive (Gd/Gd*)MUQ (1.2).


65

Both (La/La*)MUQ (mean = 1.2, n = 32) and Y/Ho (mean = 30.4, n = 41) are very inconsistent,

often showing negative and sub-chondritic values, respectively. Although negative (La/La*)MUQ could

result from normalization to a composite that does not reflect the basin catchment

(e.g. Baldwin et al. 2012), the spots displaying these anomalies are also characterized by peaks in Pr and

Nd, which are not produced in seawater (Bau & Dulski 1996). Therefore, it is probable that these values

reflect the imprecision associated with analyses of low concentration REEs, particularly the monoisotopic

(i.e. Pr, Tb, Ho, and Tm) (Baldwin et al. 2011). Accordingly, sub-chondritic Y/Ho values are generally

correlated with jagged patterns, indicating that they might be caused by artificial enrichments of Ho.

Nevertheless, the average Y/Ho ratio is relatively close that documented by Angerer et al. (2016) (mean =

37.7, n = 9) for whole-rock analyses of chert-hematite IF, chert-dolomite-hematite IF, and hematite mud

from the Santa Cruz deposit. It is also interesting to note that sub-chondritic ratios were reported for

reworked hematite mud and hematite chert (mean = 25.3, n = 2) in the same study.

The presence of high field strength elements (HFSE) in chemical rocks is usually regarded as

representing detrial contamination, even in micro-chemical investigations (e.g. Baldwin et al. 2011,

Thurston et al. 2012). Nonetheless, the geochemical pairs Th-U and Zr-Hf show low absolute

concentration and ratios that differ from the field of ionic charge and radius (CHARAC: 26 < Zr/Hf < 46)

controlled behavior defined by Bau (1996), consistent with a hydrogenous signal for these elements. The

hematites show a wide range of Zr/Hf ratios (8.41-81.54; Supplementary material S6). The majority is

fractionated relative to chondrite (38; Anders & Grevesse 1989) and the average upper continental crust

(36; Rudnick & Gao 2003), but fall within the CHARAC field (26 < Zr/Hf < 46). The Th/U ratios also

vary (0.633-9.13; Supplementary material S6), but are generally smaller than the average upper

continental crust value of 3.9 (Condi 1993). Data points with ratios above 3-5 might reflect contamination

by sedimentary detritus and phosphates (Condie 1993).


66

Figure 4.4- MUQ-normalized diagrams of rare earth (REE) and trace (TE) elements measured by LA-ICP-MS. Complete data is presented in

appendix E. The light and dark grey shaded areas bracket the range of whole-rock profiles in chert-carbonate-hematite IF and chert-

hematite IF, respectively (unpublished manuscript).


67

Figure 4.5- Diagram of (Ce/Ce*)MUQ vs. (Pr/Pr*)MUQ used to discriminate between real Ce anomalies

and those induced by positive La anomalies (Bau & Dulski 1996). Real negative Ce anomalies are

defined by (Ce/Ce*)MUQ and (Pr/Pr*)MUQ below and above the unit, respectively. Representative

anomalies for modern oxidized seawater (De Baar et al. 1985, German et al. 1995,

Zhang & Nozaki 1996, Alibo & Nozaki 1999); high- and low-T hydrothermal fluids

(Michard et al. 1993, Bau & Dulski 1999, Douville et al. 1999); and CFB - continental flood basalt

(Franklin Large Igneous Province data compiled from the GEOROC repository) are plotted for

comparison.


68

4.4.3- Factor Analysis

The rotations converged in four iterations, establishing four rotated factors (respectively F1a-

F4a and F1b-F4b) accounting together for over 65% of the variability in both data sets. Table 3 presents

the rotated component matrices for the EMP (Fa) and LA-ICP-MS (Fb) data sets. The corresponding

rotated component plots displayed in Fig. 4.6 provide an intuitive reading of the element groupings.

Table 4.3- Rotated component matrices for the EMP (Fa) and LA-ICP-MS (Fb) data sets. Complete

analytical results are presented in appendix F. The corresponding rotated component plots are

presented in Fig. 4.6 for visualization.

EMP F1a (18.2%) F2a (19.5%) F3a (17.7%) F4a (12.7%)

SiO2 0.912 -0.065 -0.127 -0.078

FeO -0.873 -0.145 -0.142 -0.080

CaO 0.076 0.922 0.045 0.021

P2O5 -0.058 0.775 -0.225 0.234

Al2O3 -0.086 -0.144 0.794 0.077

TiO2 0.296 -0.114 0.592 -0.156

MgO 0.129 0.542 0.547 -0.427

MnO -0.103 0.131 0.533 0.268

Na2O -0.093 0.300 -0.014 0.803

K2O 0.299 -0.213 0.339 0.518

LA-ICP-MS F1b (17.6%) F2b (15.8%) F3b (19.3%) F4b (12.7%)

Al 0.835 0.199 -0.102 -0.001

Ti 0.813 0.108 0.136 -0.081

V 0.741 0.091 -0.030 -0.118

Sr 0.106 0.775 0.329 0.021

Mn 0.158 0.770 0.042 0.143

Mg 0.358 0.601 -0.333 -0.133

REE -0.214 0.419 0.750 0.268

Ba -0.365 0.154 0.728 0.117

Th 0.163 0.167 0.692 0.124

Zr 0.142 -0.380 0.676 0.188

Cu 0.066 -0.125 0.586 -0.478

U -0.106 0.078 0.097 0.763

Si -0.329 -0.257 0.176 0.703

Hf 0.213 0.370 0.189 0.533

Notes: values in parentheses display the variance described by each factor; values in bold correspond

to variables significantly correlated to each factor (outside the interval -0.5 to 0.5).


69

Figure 4.6- Rotated component plots for the FA of the (a) EMP and (b) LA-ICP-MS data sets. The plots are composed by the first 3 factors, which account for

most of the variability in the corresponding data sets. The dashed line delineates clusters of variables most pronounced in each factor. See text for further

details.


70

The element grouping in factor F2a (P2O5-CaO-MgO), is presumed to reflect apatite and Fe-

dolomite-ankerite contamination. This relationship is somewhat replicated in factor F2b, controlled by

Mg-Mn-Sr, since Mg, Mn and Sr are readily incorporated into the structure of carbonates

(Morgan et al. 2013). The strong antithetic relationship between FeO and SiO2 observed in factor F1a

is thought to represent contamination by chert inclusions. On the other hand, the element association

in factor F4b, controlled by Si-U-Hf, may also be inherited from the sorption of these elements onto

the precursor particles (e.g. Schmidt et al. 2014), in addition to chert inclusions. The interpretation of

factor F4a warrants caution because of the Na2O and K2O showed concentrations close the detection

limit of the EMP; however, these elements may be inherited from adsorbed cations (e.g.

Pochard et al. 2002, Chen et al. 2007).

The element grouping in factor F3a (MgO-MnO-Al2O3-TiO2) possibly reflects replacements in

the crystalline structure of the hematites. Both Al and Ti cations (Al3+

= 0.5 Å; Ti3+

= 0.75 Å and more

rarely Ti4+

= 0.68 Å) are common substitutes for Fe3+

because of the shared isostructural lattice of

hematite, ilmenite (FeTiO3), and corundum (Al2O3) (Kessler & Müller 1988). This relationship is also

seen in factor F1b, controlled by Al-Ti-V. The latter also forms cations (V4+

= 0.61 Å and

V3+

= 0.74 Å) with charge density similar to those of Ti (e.g. Oliveira et al. 2015). Although cation

exchange in hematite is primarily restricted to trivalent cations, Mn (Mn3+

= 0.64 Å; Mn2+

= 0.80 Å)

and Mg (Mg2+

= 0.65 Å) are occasionally incorporated in limited amounts (Kessler & Müller 1988).

Hence, Mg likely figures in two factors (F3a and F2a) because of structural replacements and

incorporation of contaminant phases. It is conceivable that the elements in factor F2b (Mg-Mn-Sr)

account for some Fe replacement (e.g. Hensler et al. 2015, Oliveria et al. 2015) in addition to

contamination by carbonate minerals, even though Sr is less fitting in the Fe3+

octahedron because of

its larger ionic radius (Sr2+

= 1.13 Å).

Two element clusters are recognized in factor F3b: (i) Th-Zr-Cu and (ii) Ba-REE (Fig. 4.6).

The first cluster may reflect contamination by clays, volcanic ash or phosphate minerals (e.g.

Bolhar 2007, Baldwin et al. 2011, Thurston et al. 2012), or alternatively a hydrogenous component

(e.g. Bau 1996, Bau & Alexander 2009). The second element cluster is interpreted to be primarily

hydrogenous because of the seawater-like REE patterns. The correlation between REE and Ba could

result from an incorporation of barite (Paytan et al. 2002). However, contamination by barite is likely

trivial since this is only as an accessory diagenetic phase. Adsorption of Ba (Dymond et al. 1992,

Chen et al.2007) and REEs ions (Alibert 2016) onto precursor Fe (hydro)oxide particles or negatively

charged hematites (Pochard et al. 2002) are plausible explanations for this relationship. The former is

more likely considering that REEs are generally unaffected by diagenetic and metamorphic

remobilizations (e.g. Bau 1993, Bau & Dulski 1996), and the primary REE patterns were preserved.

Additionally, part of the REE budget may be hosted in carbonates (Zhong & Mucci 1995) because the

REEs are somewhat associated with F2b (loading factor 0.419).


71

4.5- DISCUSSION

4.5.1- Paragenetic Model

The different hematite stages reflect fluid-mediated recrystallization during syn-tectonic

diagenesis-low grade metamorphism. Hematite dust (Hm0) is generally regarded as the earliest

transformation of the precursor ferrihydrite particles (Bekker et al. 2010, 2014). However, it appears

that submicrometric to micrometric hematite was also precipitated from fluids carrying remobilized

Fe, as attested by rare micrometric hematite veinlets. The earliest unambiguous stage is constituted by

Hm1 due to its widespread occurrence in least-altered matrices, anhedral habit, and smaller size. The

inheritance of primary signatures by subsequent stages suggest that recrystallization was for the most

part isochemical, implying the prevalence of diffusion processes such as Ostwald ripening (e.g.

Li et al. 2013b, Li 2014, Sun et al. 2015), in which larger and more euhedral crystals are formed by

competitive growth, drawing material from smaller, energetically unfavorable crystals. The ionic

diffusion of mobile elements (e.g. Pecoits et al. 2009), resulting in progressive segregation of gangue

minerals with recrystallization, explains the decrease in elements associated with contamination (i.e.

Ba and elements in factor F2a and F2b) from Hm1 to Hm2 and Hm3.

In addition to solid-state growth, replacement and solution precipitation processes may also

have been involved in the hematite recrystallization, albeit to a lesser extent. Hematite partially

replaces round Fe-dolomite-ankerite pseudonodules (Angerer et al. 2016), situated on the contact with

hematite-rich matrices, with smaller and oblate hematite-rich nodules. The oblate nodules in the

hematite-rich matrices may result from progressive replacement and compaction of pseudonodules and

peloids/intraclasts. Although an inheritance of REEs from carbonates could explain their moderate

connection with factor F2b, the negative correlation with F1b indicates that REEs were not

significantly incorporated into the hematite structure, and the relatively unfractionated signatures

between nodules and corresponding host matrices (Fig. 4.6) suggests an overall primary origin.

We interpret Hm2 and Hm3 to reflect different textural configurations rather than distinct

epigenetic stages (e.g. Dimroth & Chauvel 1973) due to their similar trace element signatures. The

prevalence of Hm2 in peloids/intraclasts may be linked with smaller cementation, leading to higher

permeability and dissolution, increasing the space available for growth. The differential growth of

Hm3 around diagenetic nodules, particularly in pressure shadows, implies that differential stress from

compaction seems to have been a driving factor. Additionally, the observation that Hm3 develops

preferentially on the contact between compositional bands indicates that internal boundaries may also

have played a role by focusing fluid flow along specific surfaces. In this context, the pervasive

lepdoblastic foliation within the Fe-rich mesobands may have originated from higher hydraulic

conductivity and/or increased replacement and compaction of some laminae.


72

The general lack of mobility of trace elements, particularly the redox-sensitive (e.g.

Angerer et al. 2012, 2014b, Hensler et al. 2015, Oliveira et al. 2015), indicates that hematite

dissolution was not significant (Frierdich et al. 2011); which is consistent with the small solubility of

Fe for hematite assemblages in saline alkaline solutions under 300 °C (Zheng et al 1989, Panias et al.

1996, Taxiarchou et al. 1997). The observation of micrometric hematite veinlets, primarily associated

with carbonate-rich matrices with scarce cryptocrystalline hematite, can be explained by an increased

solubility in the presence of bicarbonate (Bruno et al. 1992), in addition to remobilization of Fe2+

from

Fe-rich carbonates.

Hyper-saline brines probably facilitated the recrystallization of hematite because of the low

recrystallization temperature (e.g. Hagemann et al. 2016), inferred at 250-280 ºC (quartz-hematite

δ18

O; Hoefs et al. 1987). Crenulated quartz veinlets and elliptical dissolution pods, formed by silica

mobilization from originally continuous chert bands (Angerer et al. 2014, 2016, D’el-Rey et al. 2016),

indicate that hematite recrystallization and desilicification, accompanied by volume reduction, were

cogenetic processes. The leaching of silica implies the participation of warm/hot, high-pH, hypersaline

fluids (Evans et al. 2013, Hagemann et al. 2016). The participation of basin brines and/or ancient

“warm” seawater, involving alkaline, Si-understaurated fluids, during diagenesis-low grade

metamorphism has been proposed by Angerer et al. (2014, 2016) for the Santa Cruz deposit. In

addition to burial compaction with an open fluid-system, ductile flow during the early Brasiliano

orogeny (D’el-Rey et al. 2016) may have provided the fluid pressure and enhanced permeability

necessary for the circulation of large volumes of fluids for silica leaching and Fe upgrade (Hagemann

et al. 2016).

Angerer et al. (2016) observed an increasing partition of V and Cr into the hematite lattice

with increasing hypogene enrichment based on whole-rock analyses of IF samples from the Santa

Cruz deposit. However, excluding a minor depletion of Al in Hm3, the elements incorporated in the

hematite structure (F1b) show no sign of fractionation with recrystallization. Therefore, it is likely that

recrystallization occurred with an oxygen fugacity above the hematite-magnetite buffer, due to the

prevalence of hematite, but not high enough to drive out incompatible oxidized V5+

from the hematite

lattice (Nadoll et al. 2014). This is supported by the diagenetic cryptomelante dated at 587±7 Ma

(40

Ar/39

Ar) documented by Picantini et al. (2013); which was likely formed by the oxidation of early

diagenetic rhodochrosite/kutnohorite and braunite (Johnson et al. 2016).


73

Cenozoic exhumation and uplift after ca. 60 Ma (40

Ar/39

Ar age of supergene cryptomelane;

Piacentini et al. 2013), in conjunction with increased structural conductivity created by the

reactivation of pre-existing fault systems during the Brasiliano orogeny, led to intensive weathering

near exposed surfaces, forming lateritic crusts on exposed plateaus (Urban et al. 1992), and infiltration

of descending oxic meteoric waters to permeable layers, forming porous-goethitic ores

(Angerer et al. 2014, 2016, Hagemann et al. 2016, Johnson et al. 2016). The ubiquitous secondary

porosity in the samples corroborates the deep percolation of weathering solutions (e.g.

Urban et al. 1992); even so, evidences of intensive alteration are found only in sample DE-L-06. In

this sample, supergene goethite and Al-phosphates (crandalite group?) are present infilling cavities in

chert-rich nodules. Consequently, the anomalous contents of P and Al in these hematites appear to

reflect contamination by Al-phosphates and goethite with P in its lattice (Graham 1973). Since

hematites can be nucleated from goethite during supergene enrichment (e.g. Dimroth & Chauvel 1973,

Morris 1985, 2012), the uncharacteristic element enrichments in these hematites may be inherited

from goethites.

4.5.2- Precursor Sediments

The preciptiate sediments of Fe-rich bands were probably constituted by ferric oxyhydroxides

such as ferrihydrite (Bekker et al. 2010, Posth et al. 2013, 2014). Hematite was likely formed by

structural ordering and dehydration of amorphous, colloidal ferrihydrite particles during early

diagenesis (Ahn & Buseck 1990). Desiccation and compaction of precursor hydrous sediments is

attested by quartz- and carbonate-infilled shrinkage septarias (e.g. Hoefs et al. 1987) and ptigmatic

veinlets (e.g. Angerer et al. 2016), representing thixotropic fluid-escape of colloidal sediments

(Lascelles 2006a, b). Minute hematite inclusions in Fe-dolomite-ankerite and quartz crystals

suggesting that these phases postdate hematite (Hoashi et al. 2009). Although similar textures are also

formed by fluid-mediated oxidation and replacement of ferrous silicates (e.g. Rasmussen et al. 2013,

2014, 2016, Sun et al. 2015), no evidence for precursor silicate phases were found. Rare ferrous

silicates (identified by SEM-EDS) in carbonate-rich bands were probably formed during

metamorphism by reaction between quartz and Fe-rich carbonates (Klein 2005). This supports the role

of Fe-dolomite-ankerite and quartz as diagenetic cements in the Fe-rich bands, seeing as interstitial

waters enriched in dissolved Si, Mg and Ca would likely form early authigenic Fe-silicates such as

greenalite and stilpnomelane (Klein 2005, Pecoits et al. 2009).


74

The inheritance of primary, seawater-like REE patterns indicates that these compositions were

not significantly re-equilibrated during diagenesis, suggesting that topotactic solid-state dehydration

was likely the predominant transformation mechanism. Hematite formed by reductive dissolution tend

to incorporated REE differentially due to inner sphere complexation at the surface of hematites

(Estes et al. 2013, Alibert 2016) and remineralization of organic coatings and reductive dissolution of

reactive particles (Haley et al. 2004, Fazio et al. 2013). The limited presence of magnetite/siderite

(Fig. 4.2) also rules out an extensively reductive transformation of hematite. Magnetite and siderite

crystals, respectively in the siliceous and carbonaceous facies, were likely formed through diagenetic

reactions of ferrihydrite with reductants possibly with microbial mediation (Bazylinski et al. 2007,

Köhler et al. 2012, Posth et al. 2013, 2014). It is interesting to note that the relative abundance of

hematite entails a limited export of reductants to the sediments, since the amount of aqueous Fe2+

released in anoxic pore waters was insufficient to extensively catalyze the transformation to siderite

and/or magnetite (Pedersen et al. 2005).

The precursor ferrihydrite particles were possibly precipitated and accumulated in a shallow

water environment, below the storm wave base, because of the lack of sedimentary structures (e.g.

Fralick & Pufahl 2006, Pufahl et al. 2014) and recurrent hematite intraclasts- and peloid-rich beds,

derived from hardground fragments and unconsolidated sediments (e.g. Gross 1972,

Dimroth & Chauvel 1973). The presence of reworked fragments is more common in chert-dolomite-

hematite IF samples in comparison with chert-hematite IF samples supporting a shallower

environment for the former. It is, thus, likely that a connection exists between the depositional depth

and these lithofacies. Hence, it could conceivably be hypothesized that the precipitation of precursor

carbonates like aragonite/Mg-calcite, recrystallized to Fe-dolomite-ankerite during diagenesis, was

induced by higher bioproductivity in shallower, marginal settings (Veizer et al.1990,

Planavsky et al. 2009, Czaja et al. 2010, Craddock & Dauphas 2011); whereas cyclic deposition

and/or cementation amorphous silica (Posth et al. 2008, Stefurak et al. 2014), later transformed to

chert (jasper) (Klein 2005), was predominant in comparatively deeper depositional settings. Drawing

on stable isotope and trace element systematics, a recent research by Angerer et al. (2016) on the Santa

Cruz deposit also recognized a lateral transition, controlled by the water depth, between these two

lithofacies. The higher pCO2 in shallower waters proposed by these authors also explains the absolute

concentration and relative proportion of siderite relative to magnetite in the carbonaceous facies.


75

4.5.3- Basin Stratification

The seawater-like REE patterns observed are compatible with an oceanographic processing of

REE, akin to modern oxygenated seawater. In oxygenated water bodies, Ce is depleted relative to its

redox-insensitive neighbors due to oxidative scavenging (German & Elderfield 1990,

German et al. 1991). The sorption of Ce3+

onto scavenging particles, particular Fe-Mn

(oxyhydr)oxides (Byrne & Sholkovitz 1996), is followed by its oxidation to Ce4+

, which is much less

soluble, decreasing the abundance of Ce in solution (Bau & Koschinsky 2009). Adsorbed Ce is

released by reductive dissolution of the scavenging particles, cycled across redox boundaries in the

water column or at and below the sediment-water interface (Tribovillard et al. 2006,

Planavsky et al. 2010). Only two spots display Ce enrichments, which probably reflect early

diagenetic redistribution of Ce in suboxic pore fluids (e.g. Haley et al. 2004) since other REEMUQ

features remain unchanged. Thus, the real negative CeMUQ anomalies observed in all the other spots

attests to oxidized conditions in the shallow environments of the Urucum basin during the deposition

of the Urucum IF. Similar negative CeMUQ anomalies are observed in most whole-rock data of pure

(i.e. uncontaminated by continental detritus) IF lithologies throughout the Urucum massif (e.g.

Angerer et al. 2016, Viehmann et al. 2016, Frei et al. 2017), implying conditions that the oxidation

and deposition occurred above Ce4+

/Ce3+

redox equilibria.

The Th/U ratios offer further evidence in support of oxic shallow waters in the Urucum basin.

In seawater, the fractionation of the geochemical pair Th-U, characterized by similar ionic charges and

radius, generally occurs due to the oxidation of the immobile U4+

species to the mobile U6+

during

weathering and/or diagenesis (Bau & Alexander 2009). Frei et al. (2017) documented substantial

authigenic enrichments of U in samples from the Urucum hill. The correlated enrichments of U, Cr,

and Mo, and the strongly fractionated Cr isotope signatures reported by these authors were interpreted

as evidences for a prevalent oxidative weathering of continental hinterland and influx to oxic surface

waters. Provided that Th and U had a similar continental source in the Santa Cruz hill, the low Th/U

ratios (<3; Condie 1993) confirms the elevated influx and accumulation of U, reflecting oxic

conditions in both source and ambient water, much like the study of Frei et al. (2017). However,

distinct non-detrital sources (e.g. from the seafloor; Angerer et al. 2016) and/or mixing with water

masses (external to the basin) may also modify this ratio and cannot be excluded. Additionally, U is

sensitive to post-depositional oxygenations (e.g. Tribovillard et al. 2006), which probably occurred

during diagenesis-low grade metamorphism (previous section). Local migrations of U, in addition to

phosphate and detrital contamination (values >3-5; Condie 1993), may explain the variability observed

in the Th/U ratio.


76

Collectively, these evidences outline a stratification of the basin waters, with a pronounced

redox chemocline separating shallow waters, above the Ce4+

/Ce3+

and U6+

/U4+

equilibria, from

presumed anoxic conditions in the deep basin, which must have existed to support the large dissolved

ferrous and manganous reservoir that gave rise to the Urucum IF-MnF (e.g. Bekker et al. 2010,

Cox et al. 2013). The transgressive nature of this sequence (e.g. Freitas et al. 2011, Kroeninger 2016)

suggests that ferrihydrite was formed during periodic upwelling of the deeper waters with dissolved

Fe2+

and mixing with oxic surface waters, and ensuing oxidation by abiotically or mediated by

bacteria. A potential role of bacteria in the deposition of the Urucum IF, either through metabolic Fe2+

oxidation and/or passive bio-mineralization (e.g. Konhauser et al. 2005, Posth et al. 2014), has been

evoked by several authors (e.g. Angerer et al 2016, Viehmann et al.2016); however, no evidence was

found supporting a role of bacteria based on the REE profiles (e.g. Takahashi et al. 2005, 2007).

This scenario conforms to the typical rift system architecture of the Urucum IF basin. The

Urucum IF is thought to have been accumulated in dynamic half-graben (Freitas et al. 2011), possibly

segmented in sub-basins due to stratigraphic and geochemical difference in different hills

(Viehmann et al. 2016, Frei et al. 2017). The present-day subvertical faults dividing these hills have

been hypothesized as reactivated graben system faults (Trompette et al. 1992), which may have

controlled the configuration of these sub-basins. Rifting and differential subsidence along the fault

blocks during deposition (Freitas et al. 2011) could have formed physical barriers, like subaqueous

sills, limiting exchange of bottom waters with the open ocean (Baldwin et al. 2012, 2016). This

restricted circulation and/or isolation, coupled with a low availability of H2S, seem like a feasible

explanation for the development of ferruginous conditions. Although an elevated burial flux of organic

carbon from enhanced primary productivity, associated with the upwelling of nutrient-rich waters, can

lead to anoxia (e.g. Maynard 2010), it is unlikely that this occurred, at least in the Santa Cruz sub-

basin, given the minor δ57

Fe fractionation of the deeper facies and lack of evidence of bacterial

sulphate reduction discussed by Angerer et al. (2016). On the other hand, the presence of diamictite

layers and outsized clasts within the Urucum IF speaks in favor of a potential influence of glaciers,

coupled with the basin restriction provided by the sills, on the establishment and preservation of the

water-column redox stratification. Subglacial redox stratification and stagnation can be promoted by

prolonged ice cover, resulting in isolation from the atmosphere, or formation of hydrological barriers

from glacier outwash influx (Baldwin et al. 2012, and references therein).


77

The marine REEMUQ patterns, in particular the LREE depletion, supports a partial hydrological

connection of the shallower waters to the open ocean, in agreement with whole-rock data of most pure

(i.e. uncontaminated by continental detritus) IF lithologies throughout the Urucum massif (e.g. Derry

& Jacobsen 1990, Graf et al. 1994, Klein & Ladeira 2004, Angerer et al. 2016, Viehmann et al. 2016),

with a few notable exceptions (i.e. Angerer et al. 2016, Frei et al. 2017). The LREE depletion is

initially formed in seawater upon the mixing of fluvial waters, characterized by smooth shale-

normalized patterns, with saline waters in estuaries, resulting in modifications induced by coagulation

and settling of colloidal REE and suspended particles (Elderfield et al. 1990, Sholkovitz 1994,

Lawrence & Kamber 2006). Fractionations in trivalent REE are further induced in seawater by

competing solution and surface complexation processes arising from differences in their orbital

configuration and ionic radii (Lee & Byrne 1992, Sholkovitz et al. 1994). The lanthanide contraction

from LREE to HREE, characterized by progressive ionic radii decreased due to filling of f-electron

shell (Bolhar et al. 2004), leads to preferential solution complexation of the former with ligands

(especially carbonate ions) (Lee & Byrne 1992, Sholkovitz et al. 1994). Consequently, LREE are more

available to sorption onto particle-reactive surfaces, like Fe-Mn (oxyhydr)oxides

(Byrne & Sholkovitz 1996). This produces a relative depletion of these elements in seawater, which

increases with depth as suspended scavenging particles settle through the water column

(Alibo & Nozaki 1999). Consequently, the REE load possibly reflects superficial waters with a higher

degree of connection to the open ocean.

4.5.4- Influx of Freshwater

Similarly to the speciation of trivalent REE, in seawater and estuaries, the behavior of the

geochemical pair Zr-Hf is dependent on electron configurations of the hydrolyzed cations, resulting in

different complexation to ligands and sorption reactivity (Bau 1996, Bau & Koschinsky 2009,

Schmidt et al. 2014, Censi et al. 2015). There is an increase in the Zr/Hf ratio depth and age of water

bodies due to stronger surface-complexation of Hf relative to Zr with reactive particle surfaces,

including Fe-Mn (oxyhydr)oxides (Bau & Koschinsky 2006, Schmidt et al. 2014). Consequently,

seawater is characterized by highly fractionated, super-chondritic ratios (56-300;

Bau & Alexander 2009, Schmidt et al. 2014, and references therein); whereas hydrogenetic Fe-Mn

crusts (40-90; Bau 1996, Schmidt et al. 2014) and IF (39-55; Bau & Alexander 2009) lie between the

ratios of ambient seawater and crustal sources. The variations in the Zr/Hf ratios is interpreted to

reflect a dilution of the ambient seawater signal, registered by super-chondritic ratios (49.2-81.5), by

fresh water influx, carrying larger dissolved concentrations of continentally-derived HFSE recorded by

the predominant CHARAC ratios. Although the variable Y/Ho ratios including CHARAC ratios could

indicate a strong influence of continentally-derived REE fluxes into the basin, the imprecision

indentified in low abundance REE with low absolute concentrations preclude any conclusion.


78

The super-chondritic Zr/Hf ratios are in agreement with Viehmann’s (2016) findings showing

a primary continental source for immobile elements in detritus-contraminated IF and MnF samples

from the Rabicho and Urucum hills; while uncontaminated samples showed fractionated Zr-Th-Ti

ratios, compatible with a hydrogenous source. Although no direct evidence of fresh water input was

documented in the studies of Graf et al. (1994) and Viehmann et al. (2016), Angerer et al. (2016)

alluded to a possible influence of fluvial or melt water in the Santa Cruz hill on the basis of negative

Ce anomalies in shallow water facies, and Frei et al. (2017) observed continentally-derived

fractionated Cr isotopes in the Urucum hill, as well as REE patterns compatible with a mixing between

fresh water or hydrothermal solutions and seawater. Collectively, these distinct evidences point out

differences in the topographic configuration of the Urucum basin as noted by authors

(e.g. Viehmann et al. 2016, Frei al. 2017). Moreover, a freshwater input is consistent with the

occurrence of alluvial fans on the basin margins (e.g. Freitas et al. 2011) and speculated glacial

outwash systems associated with glacier meltdown (e.g. Urban et al. 1992, Kroeninger 2016).

Alternatively, the CHARAC ratios observed in the hematites could be produced by mixing with

hydrothermal solutions; a hypothesis not supported by the REE signature (previous section).

The expression of Hf and U in factor F4b, together with Si, might reflect an authigenic

component. The accumulation of authigenic U occurs mainly via diffusion of uranyl carbonate ions

across the sediment-water interface and reduction reactions, partly mediated by bacterial reduction and

organic matter, forming U-oxides (Tribovillard et al. 2006, Algeo & Tribovillard 2009). In such

circumstances, the uptake of U by the hematites might have resulted from reductive incorporation of

uranyl carbonate ions (Partin et al. 2013) adsorbed onto the precursor ferrihydrite particles

(Tribovillard et al. 2006, Bau & Alexander 2009). Correspondingly, Hf may have been captured by

ferrihydrite accumulated on the seafloor (e.g. Schmidt et al. 2014). It is, however, unlikely that

ferrihydrite was co-precipitate and/or settled with adsorbed Si. As a consequence of the increased

stability of the Si-ferrihydrite phase, a rupture of its structural bonds is required to form hematite

(Vempati & Loepper 1989, Vempati et al. 1990). This has been shown by Alibert (2016) to result in

trace element compositions re-equilibrated with pore waters. No evidence was found in this study to

support substantial dissolution-reprecipitation (previous section). In general, therefore, it seems that Si

associated with the hematites was precipitated during diagenesis as cement. Interestingly, a number of

spots show sub-chondritic Zr/Hf ratios, consistent with values documented in Archean cherts (17-48)

of the Temagami IF by by Bau & Alexander (2009). This is coherent with the strong surface-reactivity

of Hf towards amorphous silica Takahashi et al. 1999, Rickli et al. 2009, Frank 2011), which might

explain the correlation of Si with factor F4b.


79

4.6- CONCLUDING REMARKS

The results offer insights into the mineral element inheritance of the hematites in the Santa

Cruz deposit, Urucum IF-MnF, Brazil-Bolivia, and paleo-environmental conditions governing its

formation. The trace element compositions were preserved through diagenesis and subsequent

alterations, without significant modifications. The lack of evidences for re-equilibration with pore

waters suggests that the transformation of amorphous ferrihydrite to hematite occurred predominantly

through solid-state dehydration. Likewise, hematite recrystallization during diagenesis-low grade

metamorphism, from anhedral hematite to the microplaty and microspecular varieties, was nearly

isochemical, indicating a predominance of diffusions processes. Hematite recrystallization occurred

associated with the early stages of the Brasiliano Orogeny, involving the participation of basin brines

which led to hypogene silica leaching. Supergene weathering led to further gangue leaching but had a

negligible impact on the trace element composition of hematites in pristine IF.

The findings confirm that Neoproterozoic Urucum basin water had REE and HFSE

systematics akin to modern oxic seawater, as previously proposed based on whole-rock studies

(Angerer et al. 2016, Viehmann et al. 2016). The precursor ferrihydrite particles were deposited and

accumulated, near the water-sediment interface, in a well-oxygenated shallow water setting, based on

the systematic negative (Ce/Ce*)MUQ, low U/Th ratios, and presence of hematite peloids, which

implies the existence of a discrete redoxcline separating the deep ferruginous waters. Additionally, the

varied Zr/Hf results indicate that the basin received varying inputs of freshwater and continental

solutes as previously suggested (Angerer et al. 2016).

We thank VETRIA S.A. for the core samples. We acknowledge and thank the financial support provided by CNPq; CAPES; and the project

FAPEMIG/VALE RDP CRA 00063/10. We thank the Laboratorio de Microscopia e Microanálises (DEGEO/UFOP) – RMIc, Rede de Microscopia e Microanálises de Minas Gerais – FAPEMIG, for EMP and SEM analyses; the Laboratório de Microscopia Eletrônica,

Microanálises e Caracterização de Materiais (DEMET/UFOP) for SEM analyses; and the Laboratório de Microscopia Eletrônica de

Varredura (DEGEO/UFOP) for SEM-EBSD analyses. The staff of the LAMIN, LGqA, Nanolab and Microlab are thanked for their assistance during sample preparation and analysis. Thomas Angerer is thanked for providing information of the drill core for this study.


80

CHAPTER 5

CONCLUSIONS

Hematites in iron formations are direct transformations of precipitates from the basin waters,

but also the final products of complex epigenetic processes responsible for the transformation of iron

formation protoliths into iron ores. The study of these minerals is, therefore, particularly important to

unravel early environmental conditions of the ancient waters and geochemical modifications

associated with the enrichment processes. Herein, hematites from the late Neoproterozoic Urucum IF,

Brazil, were studied using petrographic and in situ LA-ICP-MS and EMP techniques. The results

provide a broad framework for textures and geochemical signatures of these hematites, and a

perspective in understanding the origin and post-depositional history of this IF. The main results and

findings of this research are summarized as follows:

Three morpho-textural stages of hematite (anhedral microcrystalline; subhedral to euhedral

microspecular; and subhedral to euhedral microplaty) were identified and related to epigenetic

processes. Microcrystalline hematite was formed through solid-state dehydration of the

precursor amorphous ferrihydrite. Microspecular and microplaty hematite were formed

predominantly via diffusions processes during diagenesis-low grade metamorphism associated

with the early Brasiliano Orogeny.

Mineralizing hypogene and supergene fluids led to considerable gangue leaching but played a

minor role in the modification of the trace element content of primary hematites, resulting in a

relatively narrow range of trace element concentrations for all stages.

Statistical factor analysis was used to refine the signatures of these hematites. Four groups

trace element were recognized: (i) incorporated in the crystalline structure (Ti, Al, V, Mn,

Mg); (ii) associated with carbonate contamination (Mg, Ca, Mn, P, Sr); (iii) associated with

chert contamination (Si); (iv) and hydrogenous/authigenic, adsorbed onto the precursor

particles (REE, Ba, U, Th, Zr, Hf, Cu).

A marine origin for the hematites is supported by characteristic seawater-like MUQ-

normalized REE patters, including features such as: strong LREE depletion, real negative Ce

anomalies, as well as predominantly positive La anomalies and superchondritic Y/Ho ratios.

The presence of hematite peloids corroborates a shallow marine setting, near the normal

weather wave base. Negative Ce anomalies and mostly low Th/U reflect an oxic shallow

environment. This implies a redox-stratification of the basin waters and the existence of a

discrete redox chemocline separating deep ferruginous waters.

A subordinate contribution of freshwater in the shallow basin waters is recognized on the basis

of predominantly CHARAC (charge-and-radius-controlled behavior) Zr/Hf ratios.


82

5.1- RECOMMENDATION FOR FUTURE STUDIES

Although the results presented in this research demonstrated that it is possible to apply in situ

LA-ICP-MS to the study hematites in the Urucum IF, incomplete and apparently irregular REEMUQ

patterns reveal a disadvantage of this technique for concentrations close to the detection limit of the

instrument. Hence, a few modified approaches are necessary to produce more accurate data and

increase the confidence of the geological interpretations. The discrimination of element associations in

this research paved the way for studies aimed at specific elements (e.g. REE, HFSE), allowing a

decrease in the number of analytes. Consequently, analytical signals can be better calibrated and dwell

time of each analyte increased. Consequently, this leads to improved counts and less extrapolation and

isobaric iterferences. Additionally, different dwell times can be used for low abundance isotopes (e.g.

Knipping et al. 2015) to measure above the detection limit.

Another issue concerns the fine graining of the matrix. If by one hand this indicates a large

degree of preservation of original textures and compositions, it also complicates phase separation for

in situ analyses. Even though completely avoiding contamination seems impracticable for the matrix

in question, as exposed by EMP results, smaller spot sizes could significantly decrease contamination.

Previous studies have used spot sizes of up to 10µ (e.g. Cabral & Rosière 2013, Hu et al. 2015,

Alibert 2016). Nonetheless, this further decreases detectable concentrations. Another possibility would

be the use of more precise analytical techniques, such as Secondary Ion-Mass Spectroscopy (SIMS);

which allows a much smaller spot size, but is more susceptible to matrix effects and mass interference

(M ller et al. 2003).

A combination of methods (e.g. Pecoits et al. 2009) may be more appropriate since the in situ

LA-ICP-MS technique allows a selection of samples and areas of interest (e.g. detritus-free for HFSE

studies) for the more precise dilution ICP-MS (e.g. Baldwin et al. 2011). Moreover, detailed in situ

isotopic analyses on the hematites, such Fe (e.g. Czaja et al. 2013) and O (e.g. Hensler et al. 2013),

may be useful to further develop a genetic model of these minerals and, consequently, help to explain

the sources, oxidation mechanisms, and depositional environment of the Urucum IF. In situ Fe

isotopes can be used as proxies for variations in the redox conditions and biological participation in

the oxidation of Fe, while O isotopes can provide equilibrium conditions and isotopic exchange during

deposition, and the nature of the hematite-fluid interactions during the enrichment of the IF.

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109

Appendices

Appendix A- Methodology................................................................................................................. 109

Appendix B- EMP data ...................................................................................................................... 114

Appendix C- LA-ICP-MS data ......................................................................................................... 116

Appendix D- Supplementary figures ................................................................................................ 133

Appendix E- MUQ-normalized data and diagnostic features ........................................................ 135

Appendix A- Factor analysis ............................................................................................................. 143

110

Appendix A– Methodology

Sample preparation and microanalyses were undertaken at the department of

geology (DEGEO) of the Federal University of Ouro Preto (UFOP), Brazil. The chemical composition

of the hematites was analyzed via laser-ablation inductively coupled plasma-mass

spectrometry (LA-ICP-MS) at Laboratório de Geoquímica Analítica (LGqA) and via electron-

microprobe (EMP) at Laboratorio de Microssonda e Microscopia Eletrônica (LMME). The

petrography was examined using a combination of conventional optical microscopy, using transmitted

and reflected light petrographic microscopes at Laboratório de Microscopia, and electron microscopy,

consisting of scanning electron microscopy (SEM) coupled to energy-dispersive x-ray

spectroscopy (EDS) and electron backscattered diffraction (SEM-EBSD). Mineral-chemical

characterization and imaging via SEM-EDS were performed at Laboratório de Microssonda e

Microscopia Eletrônica (LMME) using a JEOL JSM-6010-LA SEM and a JEOL JSM-6510 SEM,

operated with acceleration voltage between 15 and 20 kV, equipped with Oxford EDS detectors.

Mineral-chemical characterization via SEM-EBSD was performed at Laboratório de Microestrutural

(MICROLAB) on a JEOL JSM-5510 equipped with a Nordlys Oxford EBSD and a high-resolution

CCD camera. The acquired data was processed with the software suite Channel 5 (Oxford) and the

MATLAB MTEX toolbox.

Sixteen representative drill core samples were collected from different depths along two

stratigraphic holes: STCR-DD-24-36 (samples: LS-02, -08, -09, -11, -12, -13, -14, -15, -19, -20,-21)

and DD-40-40A (samples: DE-L-02, -04, -06, -08, -11). Polished thin sections and rock slabs were

prepared for each sample at Laboratório de Laminação (LAMIN). Seventeen sections were selected

upon screening for in situ chemical analyses. These sections were cut from the corresponding rock

slabs using a diamond blade saw, assembled into discs (Fig. A.1) using a cold epoxy compound, thin

thoroughly polished with colloidal alumina and diamond suspensions, and at last rinsed ultrasonically.

A few sections were broken for SEM-EDS secondary imaging. Two sections were selected for

complementary SEM-EBSD analyses. These sections were cut perpendicular to the xy-xz plane,

resized into cubes using a slow speed, oil-cooled Buhler Isomet 1000 diamond saw. The small blocks

were then mounted on an AROTEC PRE 30Mi hot mounting press using conductive resin. The mount

with the samples underwent a systematic grinding and polishing process in steps of decreasing

granulometry with silicon carbide paper (240, 400 and 600 grit) and diamond paste (9, 3, and 1µ),

respectively. As a final step, the mount underwent a chemo-mechanical lapping with colloidal silica

(20 nm Buheler solution) on a Buhler Minimet 1000 polishing machine. Polished thin sections, mounts

and broken fragments were sputter-coated with carbon for the electron microscopy using an

evaporation coater model JEOL JEE-4C at LMME.

111

The electron microprobe analyses were performed on a JEOL JXA 8230 superprobe equipped

with 5 wave length-dispersive spectrometers (WDS). The analytical conditions were: beam diameter

of 5 µm, 20-nAlow-beam current and a 15-kV accelerating voltage. The values and measurement

conditions, including crystals and standards, are listed in Appendix B. Laser ablation analyses were

performed on a New Wave Research UP-213 Nd:YAG 213 nm coupled to an Agilent 7700x Q-

ICP-MS. The ablation was conducted in He atmosphere within a customized ablation cell

(Stellenbosch University) attached to a gas mixer with Ar injection for transport to the ICP-MS. The

total acquisition time for each analytical site was of 70 s, including 20 s for background acquisition

and 40 s for chamber washout. The laser was operated with continuous 10 Hz pulses with energy

density varying between ~8.6 and 9.35 J/cm2. A small, 30-μm beam diameter was chosen due to the

fine graining of the matrix. Although a larger spot size would improve signal intensity and stability,

the incorporation of contaminants would be significantly increased.

The analytes were split into two sets based on the atomic mass of the elements improve counts

and minimize mass bias. The lower- and higher-mass sets (respectively termed Group I and Group II

in appendix C) were measured in adjacent spots. The ICP-MS instrument parameters were calibrated

for each set with the NIST SRM 610 and 612 standards, and adjusted using matrix-matching standards

(Jochum et al. 2007). The analytical signals were calibrated against an external standard bracketed at

intervals of 6-10 sample analyses. At present there is no commercially available standard for IF to

decrease matrix effects (Jarvis & Williams 1993, Jochum et al. 2016). We investigated two macro-

crystals of hematite using laser and solution-based ICP-MS. However, these crystals were deemed

inappropriate due to low trace element abundances and heterogeneous element distributions. A

seemingly suitable alternative was found in the basalt glass USGS BHVO-2G (11.15 wt. % FeO).

Although not a perfect matrix match for hematite, the range of trace element concentrations and

chemical composition of this standard is somewhat similar to those observed in the samples. The

analytical conditions and accuracy of the analyses were verified with the USGS BCR-2G as secondary

standard. The GEOREM preferred values were used for the standards (Jochum et al. 2016). The data

was processed using the software GLITTER® (Access Macquarie LTD). Raw intensities were

corrected for background and normalized to 57

Fe to correct time-dependent signal drift and

fractionation (Nadoll & Koenig, 2011), using an average value of 85.90 wt. % FeO determined by

EMP was. The formation of oxides and double charge, monitored respectively with ThO/Th and

Ca+/Ca

2+, were kept under 1%. Only values above the quantitation limit, defined as three times the

local minimum detection limit, were reported in the results (appendix C). The spots were filtered for

noticeable contamination because of the frequent incorporation of inclusion and underlying phases

(Fig. A.2) in the ablation pits.

112

Figure A.1- Epoxy mounts containing the sections selected from the samples samples (series LS- and

DE-). Carbonate and chert data are unpublished.

113

Figure A.2- Ablation pit within an hematite aggregate (white) showing an incorporation of underlying

carbonates (dark).

Supplementary References

Jarvis K.E., Williams J.G. 1993. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS): a

rapid technique for the direct, quantitative determination of major, trace and rare-earth elements in

geological samples. Chem. Geol., 106:251-262.

Jochum K.P., Stoll B., Herwig K., Willbold M. 2007. Validation of LA-ICP-MS trace element analysis of

geological glasses using a new solid-state 193 nm Nd:YAG laser and matrix-matched calibration. J. Anal.

At. Spectrom., 22:112-121.

Jochum K.P., Wilson S.A., Becker H., Garbe-Schönberg D., Groschopf N., Kadlag Y., Macholdt D.S., Mertz-

Kraus R., Otter L.M., Stoll B., Stracke A., Weis U., Haug G.H., Andrea M.O. 2016. FeMnOx-1: A new

microanalytical reference material for the investigation of Mn–Fe rich geological samples. Geochemical

Geology, 432:34-40.

Nadoll P., Koenig A.E. 2011. LA-ICP-MS of magnetite: methods and reference materials. J. Anal. At. Spectrom.,

26:1872–1877.

http://www.sciencedirect.com/science/article/pii/S0009254116301486






114

Appendix B– EMP data

Table B.1- Trace element data (in weight %) of EMP analyses of hemetaites from the Santa Cruz

deposit, Urucum IF, Brazil. BDL = below detection limit. Sample - (m) Field ID Stage Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO Total

LS-02 - 12.9

C3_Hem-14 14 Hm2 BDL 5.814 0.11 0.033 84.2 0.051 0.035 0.055 0.013 0.024 90.3

C3_Hem-15 15 Hm2 BDL 4.232 0.169 0.014 84.5 0.09 0.015 0.083 0.023 BDL 89.1

C4_Hem-16 16 Hm1 BDL 1.888 0.042 BDL 86.5 0.125 0.036 0.161 0.004 BDL 88.7 C4_Hem-17 17 Hm1 BDL 1.511 0.147 BDL 87.1 0.017 0.022 0.037 0.014 0.034 88.9

LS-09 - 121.2

C6_Hem-32 32 Hm2 BDL 0.627 0.127 BDL 87.2 0.219 0.053 0.182 0.008 BDL 88.4

C6_Hem-33 33 Hm2 BDL 0.475 0.086 0.011 87.9 0.215 0.038 0.217 0.002 0.031 89.0

C6_Hem-34 34 Hm2 BDL 2.90 0.127 0.008 85.8 0.251 0.101 0.156 0.005 0.023 89.4 C6_Hem-35 35 Hm2 0.001 0.563 0.057 0.005 87.3 0.23 0.033 0.152 0.009 BDL 88.3

C6_Hem-36 36 Hm2 BDL 0.817 0.186 0.033 87.3 0.117 0.077 0.184 0.003 0.029 88.7 C6_Hem-37 37 Hm2 BDL 5.70 0.222 BDL 83.3 0.067 0.066 0.018 0.016 0.038 89.4

LS-11 - 147

C1_Hem-1 1 Hm2 BDL 0.622 0.074 BDL 87.4 0.073 BDL 0.084 0.014 0.056 88.4


C1_Hem-3 3 Hm2 BDL 8.94 0.022 BDL 81.2 0.081 0.028 0.059 BDL 0.009 90.3 C1_Hem-4 4 Hm2 BDL 0.914 0.059 BDL 88.2 0.07 0.04 0.096 0.006 BDL 89.4

C1_Hem-5 5 Hm2 BDL 6.58 0.052 0.005 82.5 0.101 BDL 0.071 0.002 BDL 89.4



C2_Hem-9 9 Hm2 BDL 0.317 0.13 BDL 87.7 0.036 0.029 0.041 0.002 BDL 88.3 C2_Hem-10 10 Hm2 BDL 0.241 0.117 BDL 88.2 0.037 BDL 0.012 0.01 BDL 88.7

C2_Hem-11 11 Hm2 BDL 0.303 0.149 BDL 87.9 0.01 BDL 0.04 0.002 0.008 88.4

C2_Hem-12 12 Hm2 BDL 0.322 0.115 BDL 88.3 0.055 0.009 0.043 0.005 0.026 88.9 C2_Hem-13 13 Hm2 BDL 0.269 0.079 BDL 87.9 0.059 0.04 0.099 BDL 0.001 88.5

LS-12 - 147

C4_Hem-18 18 Hm2 BDL 0.577 0.115 0.014 87.8 0.161 0.037 0.116 0.004 0.042 88.9

C4_Hem-19 19 Hm1 BDL 0.361 0.191 BDL 88.3 0.053 0.062 0.021 0.012 0.04 89.0 C4_Hem-20 20 Hm2 BDL 0.667 0.061 BDL 87.5 0.205 0.015 0.208 0.005 0.04 88.7

C4_Hem-21 21 Hm2 0.022 0.691 0.108 0.001 87.6 0.169 0.029 0.168 0.003 0.02 88.8

C4_Hem-22 22 Hm1 0.007 0.902 0.18 0.009 87.0 0.211 0.012 0.173 0.011 BDL 88.5 C4_Hem-23 23 Hm1 0.016 0.527 0.098 BDL 87.6 0.188 0.001 0.085 0.009 0.053 88.6

C4_Hem-24 24 Hm2 BDL 0.633 0.052 0.002 87.9 0.175 0.02 0.136 BDL 0.049 88.9

LS-13 - 154.65

C1_Hem-1 1 Hm3 BDL 0.396 0.218 0.016 87.0 0.145 0.026 0.096 0.003 BDL 87.9

C1_Hem-2 2 Hm3 0.041 0.519 0.415 BDL 87.0 0.143 0.063 0.084 0.011 BDL 88.3 C1_Hem-3 3 Hm3 BDL 0.395 0.757 0.013 86.4 0.176 0.071 0.109 0.002 0.031 87.9

C1_Hem-4 1 Hm3 BDL 0.378 0.35 0.01 86.9 0.109 0.151 0.102 0.007 BDL 88.0 C1_Hem-5 2 Hm3 BDL 0.42 0.324 0.011 87.2 0.104 0.028 0.131 0.004 BDL 88.2

C1_Hem-6 3 Hm3 BDL 0.325 0.281 0.029 86.6 0.149 0.049 0.192 0.017 0.037 87.6

C2_Hem-7 4 Hm3 BDL 6.17 0.254 0.006 82.1 0.097 0.009 0.2 0.018 BDL 88.9 C2_Hem-8 5 Hm3 BDL 5.94 0.231 0.01 82.7 0.147 0.065 0.202 0.012 BDL 89.3

C2_Hem-9 6 Hm3 0.003 0.487 0.292 0.006 86.4 0.18 0.073 0.236 0.017 0.002 87.7

C2_Hem-10 7 Hm3 BDL 1.81 0.366 0.031 86.0 0.124 0.029 0.273 0.013 0.046 88.7 C2_Hem-11 8 Hm3 BDL 0.434 0.402 0.025 86.8 0.109 BDL 0.163 0.003 0.028 88.0

C2_Hem-13 10 Hm3 0.014 0.493 0.667 0.001 86.2 0.086 0.098 0.131 0.02 0.049 87.8

C2_Hem-14 11 Hm3 BDL 1.50 0.29 0.018 85.5 0.098 0.059 0.235 0.007 0.037 87.8 C3_Hem-15 12 Hm3 BDL 0.782 0.302 0.01 86.8 0.101 0.028 0.08 0.005 BDL 88.1


C3_Hem-17 14 Hm3 BDL 0.245 0.385 0.007 87.7 0.08 BDL 0.093 0.017 0.032 88.6 C3_Hem-18 15 Hm3 BDL 0.273 0.422 0.017 88.0 0.104 0.033 0.067 0.024 0.01 88.9

LS-15 - 168.25

C4_Hem-19 16 Hm2 0.023 0.371 0.216 BDL 86.1 0.166 BDL 0.383 0.018 0.054 87.3

C4_Hem-20 17 Hm2 0.003 0.346 0.455 0.013 85.3 0.159 0.007 0.589 0.017 0.054 87.0

C4_Hem-21 18 Hm2 BDL 0.294 0.126 0.173 85.7 0.166 0.04 0.938 0.008 BDL 87.4

C5_Hem-22 19 Hm2 BDL 0.273 0.158 0.002 88.8 0.051 BDL 0.058 BDL BDL 89.3

C5_Hem-23 20 Hm2 BDL 1.53 0.24 0.019 87.2 0.046 0.057 0.025 0.014 0.02 89.1

C5_Hem-24 21 Hm2 BDL 0.519 0.173 0.029 87.6 0.116 0.04 0.075 0.004 0.011 88.6 C5_Hem-25 22 Hm2 BDL 1.95 0.064 BDL 87.4 0.105 0.039 0.155 0.007 0.04 89.8

C5_Hem-26 23 Hm2 0.006 0.385 0.103 0.022 87.6 0.159 0.014 0.264 0.011 BDL 88.6

C5_Hem-27 24 Hm2 BDL 0.82 0.075 0.41 83.9 0.157 0.058 1.62 0.004 0.039 87.1 C5_Hem-28 25 Hm2 BDL 0.46 0.147 0.016 87.8 0.135 0.046 0.28 0.014 BDL 88.9

C6_Hem-29 26 Hm2 0.049 0.393 0.211 BDL 87.0 0.137 BDL 0.096 0.006 BDL 87.9

C6_Hem-30 27 Hm2 BDL 0.357 0.106 0.007 87.8 0.147 0.02 0.265 0.003 BDL 88.7 C6_Hem-31 28 Hm2 BDL 0.321 0.035 BDL 88.6 0.164 0.031 0.181 0.005 BDL 89.3

C6_Hem-34 31 Hm2 BDL 1.28 0.068 BDL 87.4 0.189 0.016 0.174 0.007 BDL 89.1 C6_Hem-35 32 Hm2 BDL 0.417 0.085 0.01 88.2 0.132 0.051 0.123 0.004 0.03 89.0

LS-20 - 203.2 C7_Hem-36 33 Hm3 BDL 0.311 0.213 0.041 87.4 0.127 BDL 0.228 BDL 0.059 88.4

C7_Hem-37 34 Hm3 BDL 0.581 0.089 0.016 87.5 0.176 0.028 0.12 0.006 BDL 88.6

C7_Hem-38 35 Hm3 0.037 0.429 0.056 BDL 86.9 0.161 0.009 0.118 BDL 0.026 87.8 C7_Hem-39 36 Hm3 0.017 0.372 0.1 BDL 88.0 0.165 0.011 0.119 0.019 0.044 88.8

C7_Hem-40 37 Hm2 0.003 0.669 0.147 0.028 87.7 0.186 0.076 0.311 0.005 0.045 89.2

115

Continuation Sample - (m) Field ID Stage Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO Total

LS-20 - 203.2

C7_Hem-41 38 Hm2 BDL 0.379 0.137 0.014 87.0 0.134 0.053 0.235 BDL 0.047 88.0

C7_Hem-42 43 Hm2 0.04 0.339 0.105 0.034 86.8 0.154 0.026 0.385 0.001 0.041 87.9

C7_Hem-43 44 Hm2 BDL 0.396 0.167 0.01 87.1 0.134 0.076 0.208 0.013 0.04 88.1 C7_Hem-44 45 Hm2 0.012 0.375 0.093 0.027 87.5 0.176 0.103 0.282 0.001 0.047 88.7

DE-02 - 28.65


C1_Hem-2 2 Hm2 BDL 0.6 0.155 BDL 88.2 0.167 0.043 0.077 0.01 0.008 89.2

C1_Hem-3 3 Hm2 BDL 0.516 0.126 0.008 87.9 0.14 0.042 0.102 BDL BDL 88.9 C1_Hem-4 4 Hm2 BDL 0.406 0.164 0.025 87.4 0.181 0.007 0.19 0.006 BDL 88.4

C1_Hem-5 5 Hm2 BDL 0.434 0.125 BDL 87.9 0.166 0.018 0.136 0.006 0.004 88.8

C1_Hem-6 6 Hm2 BDL 0.38 0.263 BDL 87.5 0.065 0.044 0.092 BDL 0.005 88.4 C1_Hem-7 7 Hm2 BDL 0.445 0.315 0.009 88.0 0.134 BDL 0.11 BDL 0.015 89.1

C2_Hem-8 8 Hm2 BDL 0.658 0.219 0.016 88.2 0.124 0.026 0.135 0.009 0.003 89.4

C2_Hem-9 9 Hm2 BDL 0.3 0.103 BDL 88.8 0.119 0.032 0.11 0.006 0.03 89.5 C2_Hem-10 10 Hm1 BDL 3.582 0.31 0.018 85.3 0.068 0.113 0.161 0.001 0.038 89.6

C2_Hem-11 11 Hm2 BDL 0.34 0.105 0.011 87.6 0.16 0.01 0.099 0.009 BDL 88.3

C2_Hem-12 12 Hm1 BDL 0.514 0.336 0.01 88.2 0.068 0.115 0.063 BDL 0.025 89.3

C2_Hem-13 13 Hm1 BDL 2.487 0.339 BDL 86.1 0.035 0.135 0.04 0.002 0.009 89.2

DE-06 - 28.65

C3_Hem-14 14 Hm3 BDL 5.21 0.226 0.031 82.7 0.005 0.156 0.041 0.025 BDL 88.4

C3_Hem-15 15 Hm3 BDL 2.9 0.28 0.006 85.3 0.023 0.19 0.051 0.029 0.038 88.8 C3_Hem-16 16 Hm3 BDL 1.09 0.364 0.003 86.5 0.017 0.351 0.026 0.023 0.031 88.4

C3_Hem-17 17 Hm3 BDL 1.29 0.478 0.02 86.4 0.009 0.367 0.033 0.026 0.069 88.6

DE-11 - 113.9

C5_Hem-25 25 Hm2 BDL 4.58 0.128 0.007 84.7 0.093 BDL 0.14 BDL BDL 89.6


C5_Hem-28 28 Hm2 BDL 0.683 0.149 0.034 88.3 0.094 0.034 0.121 0.014 0.008 89.4 C5_Hem-29 29 Hm2 BDL 3.86 0.071 0.01 85.7 0.092 0.01 0.125 0.015 0.002 89.9

C5_Hem-30 30 Hm2 BDL 1.09 0.114 BDL 87.5 0.1 0.052 0.083 BDL 0.025 89.0

C5_Hem-31 31 Hm2 BDL 3.33 0.116 0.013 86.5 0.105 0.038 0.098 BDL 0.012 90.2

Table B.2- Measurement conditions, WDS elements, and measurement channels used in the EMP

analyses. Element X-ray Crystal CH Acc.v Peak Pos. (nm) BG_L BG_U Peak Back Pksk Gain High.V Base.L Window. M.

1 Na Ka TAPH 1 15 129.182 1.19 3.217 2.087 10 5.0 (s) 2 16 1622 0.7 0 (V) Int

2 Si Ka TAP 2 15 77.46 0.712 4.764 1.609 10 5.0 (s) 2 8 1668 0.5 9.4 (V) Dif 3 Al Ka TAP 2 15 90.65 0.834 2.7 1.5 10 5.0 (s) 2 8 1668 0.5 9.4 (V) Dif

4 Mg Ka TAP 2 15 107.484 0.989 2.826 3.261 10 5.0 (s) 2 8 1668 0.5 9.4 (V) Dif

5 Fe Ka LIFH 3 15 134.814 0.194 1.157 1.062 10 5.0 (s) 2 8 1772 1 9.0 (V) Dif 6 P Ka PETH 3 15 197.153 0.616 2.304 1.392 20 5.0 (s) 2 32 1686 1 0 (V) Int

7 Ti Ka PETJ 4 15 88.06 0.275 1.739 1.174 10 5.0 (s) 1 64 1620 0.7 0 (V) Int

8 Ca Ka PETJ 4 15 107.568 0.336 1.2 0.6 10 5.0 (s) 2 64 1620 0.7 0 (V) Int 9 K Ka PETL 5 15 119.764 0.374 1.434 0.87 10 5.0 (s) 2 16 1754 0.4 9.3 (V) Dif

10 Mn Ka LIFL 5 15 146.047 0.210 1.356 1.345 10 15.0 (s) 2 8 1754 0.4 9.6 (V) Dif

Table B.3- Standards and analytical conditions used in the EMP analyses. Element Standard Mass(%) ZAF Fac. Z A F Curr.(A) Net(cps) Bg-(cps) Bg+(cps) S.D.(%)

1 Na2O Anorthoclase 9.31 5.3131 10.7359 0.493 1.0038 2.03E-08 1729.8 49.5 34.7 0.95

2 SiO2 Quartz 99.99 3.5148 4.3603 0.8061 1 2.03E-08 18403.7 130.3 106.7 0.29 3 Al2O3 Gahnite 55.32 3.2839 6.1449 0.5344 1 2.03E-08 8080.6 93.8 60.7 0.43

4 MgO Diopside 17.14 4.6481 7.8766 0.5873 1.0048 2.03E-08 2764.9 37.1 17.3 0.74

5 FeO Magnetite 91.1215 0.2147 0.2175 0.987 1 2.00E-08 10131.8 82 115.9 0.39 6 P2O5 Fluor-Apatite 40.78 2.7803 3.4076 0.8119 1.005 2.03E-08 4380.2 15.6 24.4 0.42

7 TiO2 Rutile 100 0.5913 0.606 0.9757 1 2.03E-08 10963.1 49.6 65.2 0.37

8 CaO Fluor-Apatite 54.02 0.8863 0.9521 0.9308 1 2.03E-08 7679.1 52.6 79 0.45 9 K2O MIcrocline 15.14 1.0691 1.202 0.8894 1 2.03E-08 6944.7 42.4 48.6 0.47

10 MnO Ilmenite 4.77 0.2718 0.2844 0.9555 1 2.03E-08 305 15.8 14.1 2.29

116

Appendix C– LA-ICP-MS data

Table C.1- Trace element data (in ppm) of LA-ICP-MS analyses of hematites from the Santa Cruz

deposit, Urucum IF, Brazil. Concentrations reported in ppm. BQL = below quantitation limit.

Sample - (m) Stage ID Group I

51V 55Mn 88Sr 89Y 90Zr 95Mo 137Ba 139La 140Ce 141Pr 146Nd

LS-02 - 12.9

Hm1 21 29.3 BQL 14.7 BQL 12.4 BQL BQL BQL BQL BQL BQL

Hm2 24 49.3 103 16.0 7.3 8.8 BQL 18.5 2.4 4.1 BQL BQL Hm1 28 45.2 78 23.8 16.9 BQL BQL 36.3 3.8 7.1 BQL BQL

Hm2 29 42.0 70 19.7 5.9 8.4 BQL 17.1 2.4 4.0 BQL BQL

Hm2 31 30.1 480 78.4 74.0 16.5 BQL 320 27.1 38.0 6.1 31.4 Hm2 32 27.8 90 172 74.4 9.4 BQL 680 55.1 87.8 15.3 48.9

LS-08 - 94.5

Hm1 10 54.5 2554 34.3 55.0 6.0 0.85 120 9.7 123 1.9 5.7

Hm3 11 61.2 411 45.8 189 13.1 1.62 46.7 6.8 14.1 2.4 10.4 Hm3 14 56.8 142 23.2 5.4 8.9 0.68 12.5 1.6 3.4 0.5 2.6

Hm1 38 53.8 52 36.8 10.2 7.0 0.59 24.7 3.0 5.0 0.9 5.9

Hm1 43 51.3 87 22.6 4.5 6.5 0.56 7.4 1.2 1.7 0.4 1.7

LS-09 - 121.2 Hm3 106 43.0 259 38.8 4.4 6.5 BQL BQL BQL 2.2 BQL BQL Hm3 119 52.2 435 46.5 97.5 BQL BQL BQL 19.1 31.8 6.4 33.8

LS-11 - 147

Hm3 47 54.7 BQL 27.0 3.3 7.1 0.61 10.9 0.9 1.7 0.3 1.0

Hm3 53 38.7 BQL BQL 7.0 BQL 2.27 23.8 6.1 5.2 1.5 7.4 Hm3 60 32.9 BQL 60.8 91.5 BQL 1.21 214 33.5 29.5 6.6 32.5

Hm3 15 41.5 BQL 14.1 5.8 6.2 1.19 5.8 2.2 3.0 0.7 2.9

Hm3 16 40.5 BQL 24.4 59.2 6.0 0.70 105 10.7 18.8 3.4 16.8 Hm3 17 37.5 BQL 20.8 5.1 4.0 0.90 16.0 3.2 3.2 0.6 3.1

Hm3 18 33.6 BQL 21.1 8.7 4.9 0.78 16.1 2.0 2.6 0.6 2.9

Hm3 23 45.8 BQL 57.4 56.2 6.7 1.13 268 39.4 35.4 8.2 36.6 Hm3 26 42.2 BQL 16.2 5.8 6.8 0.34 5.7 2.4 2.6 0.8 4.8

LS-12 - 147

Hm3 64 56.9 366 29.1 6.0 11.3 0.94 26.0 1.5 2.3 0.5 2.2

Hm3 69 51.3 780 28.6 4.8 11.3 0.74 8.3 1.2 2.0 0.5 2.2

Hm3 72 59.3 130 31.3 16.8 11.8 1.58 9.6 2.4 4.6 1.2 4.7 Hm3 71 63.1 111 21.4 6.7 11.8 0.70 14.9 2.0 3.9 0.5 2.6

Hm3 80 59.8 158 21.6 4.1 11.6 1.27 14.5 1.5 2.6 0.5 4.1

Hm3 81 55.5 BQL 31.2 4.8 11.8 1.50 12.7 1.1 2.2 0.4 3.5

LS-13 - 154.65

Hm3 27 BQL BQL 31.8 1.5 9.6 BQL 7.1 0.5 0.5 BQL BQL

Hm3 35 BQL BQL 464 2.4 5.9 BQL 1022 0.6 0.9 BQL BQL

Hm3 24 BQL BQL 15.9 BQL 5.0 BQL BQL BQL 0.5 BQL BQL

Hm3 28 BQL BQL 35.2 1.0 10.8 BQL 169 BQL 0.3 BQL BQL

Hm3 32 BQL BQL 22.2 0.9 11.7 BQL 5.9 BQL 0.4 BQL BQL

Hm3 33 BQL BQL 15.2 0.8 5.1 BQL BQL BQL BQL BQL BQL

LS-14 - 167.5

Hm1 10 BQL BQL 13747 267 BQL BQL 228 151 88.8 29.7 105

Hm1 12 BQL BQL 8039 132 BQL BQL BQL 80.0 41.9 24.4 50.2

Hm1 13 BQL BQL 7231 177 25.6 BQL 121 92.9 48.4 15.2 80.1 Hm1 14 BQL BQL 1086 20.1 3.7 BQL 6403 9.1 5.4 2.2 9.4

LS-15 - 168.25

Hm3 14 42.3 239 66.7 2.0 BQL BQL BQL 0.8 0.7 0.3 1.3

Hm3 16 64.5 BQL 14.8 0.7 BQL BQL BQL 0.4 0.3 0.2 1.2 Hm3 28 50.7 648 264 10.6 BQL BQL BQL 6.2 4.1 1.6 7.9

Hm3 29 73.3 BQL 30.3 2.9 BQL BQL BQL 0.7 0.7 0.3 2.1

Hm3 31 54.7 886 215 4.2 BQL BQL BQL 1.9 1.2 0.6 1.6 Hm3 33 60.4 BQL BQL 0.8 BQL BQL BQL 0.4 0.5 0.2 1.7

Hm3 47 50.1 BQL BQL 0.9 BQL BQL BQL 0.3 0.2 0.3 1.1

LS-19 - 200.35

Hm1 50 57.2 747 59.8 3.4 6.3 BQL BQL 0.9 1.5 0.3 1.6

Hm2 61 54.5 14884 988 85.9 BQL BQL BQL 29.4 56.0 7.6 39.2 Hm2 62 BQL 68611 1934 196 BQL BQL BQL 57.8 80.5 13.3 73.4

Hm2 64 75.3 819 287 113 10.3 BQL 19.8 20.2 40.1 7.8 38.8

Hm2 66 45.1 1529 187 5.5 BQL BQL 43.4 1.4 2.2 0.4 1.7 Hm1 68 59.3 4235 326 18.5 BQL BQL BQL 6.8 10.8 1.7 7.9

LS-20 - 203.2

Hm1 46 BQL BQL 35.3 14.3 8.5 BQL 11.3 3.6 6.0 1.2 4.0

Hm1 47 BQL BQL 109 12.4 7.0 BQL 11.0 3.6 6.4 0.7 2.9 Hm1 48 BQL BQL 137 10.7 7.9 BQL 8.6 2.9 4.9 0.7 3.0

Hm1 58 BQL BQL 221 7.1 5.4 BQL 3923 2.0 3.9 0.6 3.4

Hm2 59 BQL BQL 934 34.9 3.3 BQL 1147 9.9 18.2 2.9 15.8 Hm1 64 BQL BQL 166 15.8 8.0 BQL 8.6 5.5 8.2 1.0 4.6

Hm1 67 BQL BQL 212 8.4 4.5 BQL 57.2 3.2 6.8 0.7 3.9

Hm1 71 BQL BQL 342 17.5 2.1 BQL 620 3.0 5.7 BQL BQL

117

Continuation



LS-20 - 203.2

Hm1 49 BQL BQL 52.4 6.0 4.6 BQL 73.9 1.8 2.2 BQL BQL

Hm1 50 BQL BQL 187 7.9 5.4 BQL 10.7 2.5 5.4 0.7 3.2 Hm1 51 BQL BQL 152 6.5 5.4 BQL 163 3.2 4.3 0.6 BQL

Hm1 60 BQL BQL 57.7 5.6 8.2 BQL 194 1.7 3.1 0.7 BQL

Hm1 66 BQL BQL 150 6.5 4.9 BQL 24.0 1.8 2.5 BQL BQL Hm1 72 BQL BQL 234 10.4 BQL BQL 111.9 BQL 5.4 BQL BQL

LS-21 - 210.3 Hm1 23 76.8 2071 187 8.9 12.3 BQL 11.3 3.0 7.2 0.8 3.5

DE-02 - 28.65

Hm3 25 52.8 23 63.8 33.0 8.7 BQL 66.9 8.3 16.8 2.4 9.6

Hm3 26 64.3 42 50.1 4.3 10.2 BQL 18.3 1.2 2.3 BQL BQL Hm3 32 54.8 35 66.8 7.4 9.0 BQL 29.4 2.4 4.7 0.7 3.0

Hm3 34 55.8 25 37.6 4.5 7.2 BQL 14.4 1.0 1.3 BQL BQL

Hm3 40 67.4 45 57.2 4.8 8.5 1.45 27.9 1.4 2.7 BQL 2.4 Hm3 41 61.4 BQL 32.3 3.2 7.4 BQL 18.4 0.8 1.0 BQL BQL

Hm3 43 59.3 15 90.8 5.1 8.8 BQL 116 2.1 4.2 BQL 2.7

Hm3 44 72.0 73 46.7 3.8 12.0 BQL 24.0 1.0 2.0 BQL BQL

Hm3 48 51.7 BQL 107 33.0 7.6 BQL 168 4.7 7.4 1.7 4.4

Hm3 50 68.8 79 47.5 4.4 11.7 BQL 27.2 BQL 3.1 0.4 BQL

Hm3 52 60.3 37 284 21.0 11.1 BQL 466 15.6 19.4 3.4 14.7 Hm3 59 60.0 25 368 76.1 8.4 BQL 373 7.8 8.2 2.4 12.3

Hm3 60 63.6 BQL 42.4 4.1 8.2 BQL 19.1 0.7 1.4 BQL BQL

Hm3 61 63.8 30 74.2 6.3 9.1 BQL 54.7 2.0 3.5 0.7 2.7 Hm3 62 46.7 BQL 40.2 3.1 7.9 BQL 35.0 1.3 1.6 BQL BQL

Hm3 63 61.5 BQL 50.7 10.8 9.4 BQL 22.9 1.7 2.4 BQL BQL

Hm3 24 54.1 59 251 12.6 9.1 BQL 327 5.8 6.4 1.5 6.7 Hm3 30 57.8 16 52.4 9.9 8.6 BQL 22.2 1.2 2.7 0.4 BQL

Hm3 31 53.3 BQL 51.6 6.0 9.5 BQL 18.3 1.3 2.6 BQL BQL

Hm3 33 63.4 54 72.8 6.1 10.5 BQL 29.3 1.9 4.2 0.5 2.8 Hm1 91 61.0 84 335 24.8 12.6 BQL 857 16.5 23.8 3.2 11.8

Hm3 92 61.3 101 954 45.6 14.5 BQL 1796 26.0 48.4 7.2 29.0

Hm3 93 66.6 89 281 20.7 13.2 BQL 431.7 10.7 19.7 3.0 BQL Hm3 94 63.5 80 78.9 30.3 11.8 BQL 87.2 BQL 6.8 BQL BQL

DE-04 - 54.45

Hm3 68 45.7 31 64.8 4.9 10.8 BQL 23.2 1.1 2.6 BQL BQL

Hm2 70 34.9 BQL 19.8 2.9 9.8 BQL 21.3 1.0 1.8 BQL BQL Hm2 77 25.8 42 34.9 36.3 10.0 BQL 21.3 10.9 18.5 2.5 7.8

Hm3 75 59.9 33 65.5 5.8 11.9 BQL 21.3 1.7 3.1 BQL BQL

Hm3 76 51.0 20 67.9 5.3 9.1 BQL 23.7 1.5 2.6 BQL BQL Hm3 79 51.1 36 65.1 5.7 7.7 BQL 23.1 1.2 2.4 BQL 3.0

DE-06 - 28.65

Hm2 130 50.8 BQL BQL 57.8 201 BQL BQL BQL BQL BQL BQL

Hm2 132 57.7 BQL BQL 86.4 314 BQL BQL BQL 7.7 BQL BQL

Hm2 128 71.3 2013 BQL 22.1 62.5 BQL BQL BQL 8.3 BQL BQL Hm2 129 74.7 348 21.5 35.7 145 BQL BQL 4.1 11.4 BQL BQL

Hm2 131 55.5 BQL BQL 29.3 115 BQL BQL BQL BQL BQL BQL

DE-08 - 86.27

Hm2 58 54.2 3029 95.4 19.1 92.7 BQL 23.1 7.3 17.2 2.5 11.2 Hm2 60 58.7 4100 123 54.1 37.8 BQL BQL 15.2 34.1 4.5 20.5

Hm1 74 60.5 128 27.0 54.9 24.7 BQL BQL 4.2 9.8 BQL BQL

Hm1 85 68.0 194 83.3 59.8 25.4 BQL BQL 16.1 36.1 5.8 26.5 Hm1 76 60.4 965 65.0 25.5 23.6 BQL BQL 5.5 16.2 BQL BQL

Hm1 84 67.6 155 30.7 20.8 24.8 BQL BQL 4.5 10.1 BQL BQL

Hm1 84 67.6 155 30.7 20.8 24.8 BQL BQL 4.5 10.1 BQL BQL

DE-11 - 113.9

Hm1 31 50.4 BQL 41.8 39.0 11.8 0.66 179 9.0 16.2 3.0 13.0

Hm1 32 50.2 BQL 27.9 6.7 12.4 0.62 7.4 2.0 3.8 0.6 2.0

Hm3 49 53.7 BQL 55.8 86.8 13.3 0.59 33.8 17.5 32.4 5.7 26.3 Hm3 50 52.8 BQL 27.0 15.2 13.4 1.36 10.6 2.2 4.8 0.7 4.9

Hm3 52 50.4 BQL 37.0 10.3 12.3 0.52 20.7 4.9 8.4 1.8 8.1

Hm1 62 51.5 BQL 27.4 5.0 10.5 0.77 15.3 1.8 3.2 0.4 3.0 Hm1 35 50.6 BQL 25.9 5.6 11.6 0.38 8.2 2.0 4.6 0.6 2.9

Hm1 43 46.2 BQL 30.0 8.0 14.3 0.86 9.8 2.3 4.1 0.6 3.4

Hm3 48 51.5 BQL 44.3 8.0 14.6 0.79 20.7 2.7 4.6 1.0 3.9 Hm1 61 51.0 BQL 29.4 6.7 11.4 1.30 18.5 2.1 4.1 0.8 3.0

118

Continuation


147Sm 153Eu 157Gd 159Tb 163Dy 165Ho 166Er 169Tm 172Yb 175Lu 178Hf

LS-02 - 12.9

Hm1 21 BQL BQL BQL 0.4 BQL BQL BQL BQL BQL BQL BQL

Hm2 24 BQL BQL BQL 0.2 BQL BQL BQL BQL BQL BQL BQL Hm1 28 BQL BQL BQL 0.5 BQL BQL BQL BQL BQL BQL BQL


Hm2 31 BQL BQL BQL 0.8 7.3 2.1 6.5 BQL BQL BQL BQL Hm2 32 BQL BQL BQL 0.9 9.3 2.3 6.0 BQL BQL BQL BQL

LS-08 - 94.5

Hm1 10 1.8 0.6 BQL 0.7 4.5 1.2 5.1 0.7 6.4 1.1 0.5

Hm3 11 4.2 1.4 BQL 2.0 13.6 4.1 12.3 2.1 15.5 3.0 0.8

Hm3 14 1.2 0.2 BQL 0.2 0.8 0.2 0.6 0.1 1.2 0.2 0.3 Hm1 38 0.9 0.4 BQL 0.3 1.7 0.5 1.3 0.2 1.1 0.2 0.3

Hm1 43 1.0 0.1 BQL 0.1 0.9 0.2 0.5 0.1 1.1 0.2 0.2

LS-09 - 121.2 Hm3 106 BQL BQL BQL 0.1 BQL BQL BQL BQL BQL BQL BQL Hm3 119 BQL BQL BQL 1.9 16.3 BQL 9.4 BQL BQL BQL BQL

LS-11 - 147

Hm3 47 0.5 0.2 BQL 0.2 0.5 0.1 0.5 0.1 0.7 0.1 0.1

Hm3 53 2.2 0.4 BQL 0.3 1.3 0.4 1.3 0.2 1.1 0.1 0.9

Hm3 60 6.8 1.3 BQL 1.5 9.9 2.6 7.6 1.1 4.1 0.8 0.4 Hm3 15 2.2 0.3 BQL 0.3 0.8 0.2 0.6 0.2 0.9 0.1 0.6

Hm3 16 5.3 1.0 BQL 0.8 5.7 1.0 3.2 0.7 2.8 0.5 0.2

Hm3 17 1.2 0.2 BQL 0.1 0.9 0.2 0.8 0.1 0.7 0.1 0.2 Hm3 18 1.5 0.2 BQL 0.2 1.3 0.2 0.6 0.2 1.1 0.2 0.1

Hm3 23 5.6 1.3 BQL 0.8 6.5 1.5 3.8 0.6 3.9 0.4 0.4

Hm3 26 1.5 0.3 BQL 0.1 1.3 0.2 0.6 0.1 1.6 0.1 0.2

LS-12 - 147

Hm3 64 0.7 0.2 BQL 0.2 0.9 0.2 1.0 0.2 1.1 0.1 0.3

Hm3 69 0.9 0.3 BQL 0.1 1.2 0.3 0.5 0.2 0.9 0.2 0.1

Hm3 72 2.4 0.4 BQL 0.4 2.7 0.4 1.7 0.4 1.6 0.3 0.2 Hm3 71 0.9 0.2 BQL 0.2 1.2 0.2 0.8 0.2 1.3 0.2 0.4

Hm3 80 0.5 0.1 BQL 0.2 0.8 0.3 1.0 0.2 0.9 0.1 0.2

Hm3 81 0.8 0.2 BQL 0.1 0.8 0.2 0.9 0.1 1.0 0.2 0.4

LS-13 - 154.65

Hm3 27 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL


Hm3 24 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Hm3 28 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL



LS-14 - 167.5



Hm1 14 BQL BQL BQL BQL 2.1 0.4 BQL BQL BQL BQL BQL

LS-15 - 168.25

Hm3 14 0.9 BQL BQL 0.2 0.8 0.2 0.5 BQL 0.9 BQL 0.4

Hm3 16 1.1 BQL BQL 0.1 0.4 0.1 0.4 BQL 0.8 BQL 0.6

Hm3 28 2.5 BQL BQL 0.5 1.7 0.5 1.4 BQL 1.1 BQL 0.6 Hm3 29 1.3 BQL BQL 0.1 0.6 0.1 0.3 BQL 0.9 BQL 0.7

Hm3 31 1.2 BQL BQL 0.2 1.1 0.1 0.2 BQL 0.7 BQL 0.4


LS-19 - 200.35

Hm1 50 0.5 BQL BQL 0.1 0.6 0.1 0.4 BQL 0.5 BQL 0.2

Hm2 61 12.9 BQL BQL 1.9 9.0 2.1 7.1 BQL 5.8 BQL 1.2

Hm2 62 20.8 BQL BQL 2.3 22.2 6.4 21.5 BQL 12.2 BQL 2.7 Hm2 64 8.9 BQL BQL 2.2 15.3 3.0 9.6 1.0 5.1 0.8 0.4


LS-20 - 203.2

Hm1 46 BQL BQL BQL BQL BQL BQL 1.7 BQL BQL BQL BQL

Hm1 47 BQL BQL BQL BQL 1.7 BQL 1.2 BQL 1.8 BQL BQL



Hm2 59 BQL BQL BQL BQL 2.9 BQL 2.9 BQL 5.0 BQL BQL

Hm1 64 BQL BQL BQL BQL BQL 0.5 BQL BQL BQL BQL BQL Hm1 67 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL


119

Continuation



LS-20 -

203.2


Hm1 50 BQL BQL BQL BQL 1.7 BQL BQL BQL BQL BQL BQL Hm1 51 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL



LS-21 -

210.3 Hm1 23 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

DE-02 -

28.65

Hm3 25 2.8 BQL BQL 0.4 4.3 0.8 3.5 BQL 2.8 BQL 1.0 Hm3 26 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL



Hm3 41 BQL BQL BQL BQL 1.0 BQL BQL BQL BQL BQL BQL



Hm3 48 BQL BQL BQL BQL 2.2 BQL 2.7 0.6 2.6 0.8 BQL

Hm3 50 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Hm3 52 BQL BQL BQL BQL 2.5 0.8 BQL BQL BQL BQL BQL

Hm3 59 3.9 BQL 7.4 1.1 8.4 2.1 6.3 0.9 6.5 0.8 BQL



Hm3 63 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Hm3 24 BQL 0.7 BQL 0.6 BQL BQL BQL BQL 1.9 BQL BQL

Hm3 30 BQL BQL BQL BQL BQL BQL 1.0 BQL BQL BQL BQL

Hm3 31 BQL BQL BQL BQL BQL BQL BQL BQL 1.5 BQL BQL Hm3 33 BQL BQL BQL BQL BQL BQL 0.8 BQL BQL BQL BQL




DE-04 -

54.45


Hm2 77 BQL BQL BQL BQL 5.4 1.3 4.6 BQL BQL 0.9 BQL



DE-06 -

28.65





DE-08 - 86.27



Hm1 74 BQL BQL BQL 0.9 BQL BQL 5.6 BQL BQL BQL BQL Hm1 85 BQL BQL BQL 1.1 BQL BQL BQL BQL BQL BQL BQL



DE-11 -

113.9

Hm1 31 3.0 0.6 BQL 0.8 5.7 1.4 3.5 0.6 3.5 0.5 0.6

Hm1 32 1.0 0.2 BQL 0.1 0.8 0.3 0.9 0.2 1.3 0.2 0.3

Hm3 49 6.7 1.6 BQL 1.3 10.6 2.2 6.5 0.9 4.8 0.9 0.7 Hm3 50 1.2 0.4 BQL 0.3 1.7 0.4 1.6 0.3 2.0 0.2 0.3

Hm3 52 1.7 0.4 BQL 0.3 1.7 0.4 1.0 0.3 1.2 0.3 0.5

Hm1 62 0.8 0.2 BQL 0.2 1.5 0.2 1.0 0.2 1.1 0.3 0.4 Hm1 35 0.7 0.3 BQL 0.2 0.8 0.2 0.5 0.2 0.6 0.2 0.2

Hm1 43 1.3 0.2 BQL 0.2 0.8 0.4 0.8 0.2 1.8 0.2 0.2

Hm3 48 0.8 0.3 BQL 0.2 1.3 0.2 1.2 0.1 0.8 0.3 0.3 Hm1 61 1.4 0.2 BQL 0.2 1.2 0.3 1.3 0.1 1.3 0.2 0.4

120

Continuation

Sample - (m) Stage ID Group I Group II

182W 208Pb 232Th 238U 23Na 24Mg 27Al 28Si 31P 66Zn 39K

LS-02 - 12.9

Hm1 21 BQL BQL BQL BQL BQL 92.7 282 93892 BQL BQL BQL

Hm2 24 BQL BQL BQL BQL 144 41.0 273 59129 1418 BQL BQL Hm1 28 BQL BQL BQL BQL BQL 19.4 377 19497 BQL BQL BQL


Hm2 31 BQL BQL BQL BQL BQL 95.1 1475 138379 BQL BQL BQL Hm2 32 BQL BQL BQL BQL BQL 301 104 41703 BQL BQL BQL

LS-08 - 94.5

Hm1 10 0.1 2.3 1.3 0.2 BQL 76.8 730 52036 BQL BQL BQL

Hm3 11 0.3 1.6 1.0 0.3 BQL 23.6 1249 30315 BQL BQL BQL

Hm3 14 0.2 0.8 0.2 0.4 BQL 18.5 792 16507 1280 BQL BQL Hm1 38 0.2 1.1 0.2 0.1 120 33.0 490 10516 952 0.3 BQL

Hm1 43 0.2 1.5 0.2 0.2 BQL 16.0 775 29108 BQL BQL BQL

LS-09 - 121.2 Hm3 106 BQL BQL BQL BQL 94.0 24.9 587 3821 910 BQL BQL Hm3 119 BQL BQL BQL BQL BQL 12.7 820 3594 BQL BQL BQL

LS-11 - 147

Hm3 47 0.2 1.2 0.2 0.1 BQL 17.1 770 9731 BQL BQL BQL

Hm3 53 0.5 2.1 0.4 0.3 BQL 21.5 374 100564 BQL BQL BQL

Hm3 60 0.3 1.8 0.7 0.3 BQL 124 268 123639 BQL BQL BQL Hm3 15 0.1 1.8 0.2 0.1 BQL 11.4 354 74700 BQL BQL BQL

Hm3 16 0.1 1.7 0.4 0.2 BQL 9.4 311 61248 BQL BQL BQL

Hm3 17 0.3 1.6 0.1 0.1 BQL 19.1 279 39729 BQL BQL BQL Hm3 18 0.3 1.8 0.2 0.2 BQL 13.9 337 69338 BQL BQL BQL

Hm3 23 0.2 1.7 0.5 0.3 BQL 12.1 503 113328 BQL BQL BQL

Hm3 26 0.2 1.6 0.1 0.2 BQL 17.6 360 95059 BQL BQL BQL

LS-12 - 147

Hm3 64 0.3 2.2 0.5 0.2 136 244 466 85547 1734 BQL BQL

Hm3 69 0.1 2.6 0.4 0.2 BQL 111 518 53779 1068 BQL BQL

Hm3 72 0.5 2.2 0.6 0.2 801 210 553 35404 29867 0.5 BQL Hm3 71 0.4 2.0 0.5 0.1 BQL 182 907 55822 BQL BQL BQL

Hm3 80 0.5 2.5 0.5 0.2 BQL 32.6 1069 42520 BQL BQL BQL

Hm3 81 0.3 2.6 0.5 0.1 115 112 552 39941 1138 BQL BQL

LS-13 - 154.65

Hm3 27 BQL 97.6 BQL BQL 293 4944 2994 52151 979 BQL BQL

Hm3 35 BQL 1.7 BQL BQL 298 32.0 1323 23303 BQL BQL BQL

Hm3 24 BQL 1.6 0.3 BQL 283 2209 1640 143757 1061 10.8 BQL

Hm3 28 BQL 2.3 BQL BQL 314 6870 2223 87971 BQL 17.1 BQL

Hm3 32 BQL 2.3 BQL BQL 355 56.1 1679 10030 817 19.4 BQL

Hm3 33 BQL 1.6 BQL BQL 280 7877 2404 87890 BQL BQL BQL

LS-14 - 167.5

Hm1 10 BQL BQL BQL BQL 600 3784 2231 3248 BQL 11.4 BQL

Hm1 12 BQL BQL BQL BQL 2791 33324 950 4873 BQL BQL BQL

Hm1 13 BQL BQL BQL BQL 402 425 908 15502 1401 BQL BQL Hm1 14 BQL 1.5 0.6 BQL BQL BQL BQL BQL BQL BQL BQL

LS-15 - 168.25

Hm3 14 0.2 BQL 0.1 0.2 118 773 665 33059 5831 BQL BQL

Hm3 16 0.3 BQL 0.2 0.2 167 378 504 29808 2729 BQL BQL

Hm3 28 0.4 BQL 0.4 0.2 116 964 514 36288 828 BQL BQL Hm3 29 0.2 BQL 0.1 0.2 BQL 34.6 897 16356 BQL BQL BQL

Hm3 31 0.2 BQL 0.2 0.1 BQL 36.1 749 40807 BQL BQL BQL

Hm3 33 0.2 BQL 0.1 0.1 211 581 336 6475 1217 BQL BQL Hm3 47 0.2 BQL 0.1 0.1 192 14237 2150 27320 BQL BQL BQL

LS-19 - 200.35

Hm1 50 0.3 BQL 0.1 0.1 127 9485 1783 28722 1733 BQL BQL

Hm2 61 0.8 BQL 1.3 0.3 165 258 1026 13314 BQL 8.3 BQL Hm2 62 0.7 BQL 1.5 0.5 378 15619 477 5338 BQL 10.9 BQL

Hm2 64 0.2 BQL 0.4 0.2 71.3 2336 1707 20809 BQL 12.6 BQL

Hm2 66 0.4 BQL 0.1 0.1 529 7739 695 3809 1187 BQL BQL Hm1 68 0.2 BQL 0.2 0.1 694 39040 1432 13638 BQL 31.6 BQL

LS-20 - 203.2

Hm1 46 BQL BQL BQL BQL BQL 1367 1368 6536 BQL BQL BQL




Hm2 59 BQL BQL BQL BQL 463 5107 500 7382 988 BQL BQL Hm1 64 BQL BQL BQL BQL 280 31651 612 54347 BQL 13.9 BQL

Hm1 67 BQL BQL BQL BQL 374 34085 411 45412 1232 BQL BQL


121

Continuation



LS-20 - 203.2

Hm1 49 BQL 1.8 BQL 0.4 66 3130 3373 55628 BQL 14.2 BQL

Hm1 50 BQL BQL BQL BQL 144 3066 1177 15217 BQL BQL BQL Hm1 51 BQL 1.9 BQL BQL 328 38847 518 55724 BQL 9.1 BQL


Hm1 66 BQL BQL BQL BQL 252 11362 11634 37670 BQL 38.8 BQL Hm1 72 BQL BQL BQL BQL 235 31567 561 38754 BQL 17.3 BQL

LS-21 - 210.3 Hm1 23 BQL 2.7 BQL BQL 168 20552 484 46466 BQL BQL BQL

DE-02 - 28.65

Hm3 25 BQL 1.9 0.7 BQL BQL 65.2 943 4878 1089 BQL BQL

Hm3 26 0.5 BQL BQL BQL 173 51.9 694 3515 1326 BQL BQL Hm3 32 BQL BQL BQL BQL BQL 15.8 579 2198 BQL BQL BQL

Hm3 34 BQL BQL BQL BQL 123 48.4 1243 10463 1730 BQL BQL

Hm3 40 BQL BQL BQL BQL 107 50.8 1174 4843 BQL BQL BQL Hm3 41 BQL 1.7 BQL BQL 112 62.1 808 2542 1155 BQL BQL

Hm3 43 BQL 1.7 BQL BQL 312 78.2 701 4507 1231 BQL BQL


Hm3 48 BQL BQL 0.4 BQL 112 70.9 839 2129 1078 BQL BQL

Hm3 50 BQL BQL BQL BQL BQL 25.7 1195 4645 963 BQL BQL

Hm3 52 BQL 1.9 0.9 BQL 124 47.8 672 3118 890 BQL BQL Hm3 59 BQL 4.2 BQL 0.5 278 57.1 707 4302 1100 BQL BQL


Hm3 61 BQL BQL BQL BQL BQL 30.8 678 15923 BQL BQL BQL Hm3 62 BQL BQL BQL BQL 139 76.9 595 5379 1005 BQL BQL


Hm3 24 BQL BQL BQL BQL 174 64.5 725 3383 1225 BQL BQL Hm3 30 BQL BQL BQL BQL 105 37.0 723 3128 1002 BQL BQL


Hm3 33 BQL 1.2 BQL BQL BQL 93.9 917 5667 BQL BQL BQL Hm1 91 BQL BQL BQL BQL BQL 112 2708 28040 2318 BQL BQL


Hm3 93 BQL BQL BQL BQL BQL 60.9 1518 13461 BQL BQL BQL Hm3 94 BQL BQL BQL BQL BQL 39.3 1632 18094 BQL BQL BQL

DE-04 - 54.45


Hm2 70 BQL BQL BQL BQL BQL 13.8 291 108930 BQL BQL BQL Hm2 77 BQL BQL BQL BQL BQL 62.1 347 48072 BQL BQL BQL


Hm3 76 BQL BQL BQL BQL BQL 29.6 363 49443 1166 3.5 BQL Hm3 79 BQL BQL BQL BQL BQL 33.2 2053 63469 BQL BQL BQL

DE-06 - 28.65


Hm2 132 BQL BQL BQL BQL BQL 560 7537 92424 4315 BQL BQL

Hm2 128 BQL BQL BQL BQL BQL 182 5549 135460 BQL BQL BQL Hm2 129 BQL BQL BQL BQL BQL 54.5 1519 142022 BQL BQL BQL


DE-08 - 86.27

Hm2 58 BQL BQL BQL BQL BQL 2721 1300 42698 2546 BQL 10730 Hm2 60 BQL BQL 4.2 BQL 149 220 1184 45211 6811 BQL 12131

Hm1 74 BQL BQL BQL BQL BQL 589 1624 65886 2728 BQL 5371

Hm1 85 BQL BQL BQL BQL 115 1673 1963 32957 5010 BQL 11204 Hm1 76 BQL BQL BQL BQL BQL 4335 1714 21812 BQL BQL 15371

Hm1 84 BQL BQL BQL BQL BQL 156 1474 46563 BQL BQL BQL

DE-11 - 113.9


Hm3 49 0.3 1.8 1.7 0.1 BQL 18.0 537 60396 BQL BQL BQL


Hm1 62 0.3 1.4 0.2 0.2 BQL 12.5 587 32194 BQL BQL BQL


Hm3 48 0.2 1.7 0.2 0.1 BQL 14.6 495 103210 BQL BQL BQL

Hm1 61 0.3 1.7 0.2 0.2 BQL 21.5 453 34566 BQL BQL BQL

122

Continuation

Sample - (m) Stage ID Group II

44Ca 45Sc 47Ti 71Ga 111Cd 93Nb 51V 52Cr 59Co 60Ni 63Cu

LS-02 - 12.9

Hm1 21 BQL BQL 179 BQL BQL BQL BQL BQL BQL BQL 8.3

Hm2 24 BQL BQL 67 BQL BQL BQL BQL BQL BQL BQL 18.9 Hm1 28 BQL BQL 161 BQL BQL BQL BQL BQL BQL BQL 17.4



LS-08 - 94.5





LS-09 - 121.2 Hm3 106 BQL BQL 203 BQL BQL BQL BQL BQL BQL BQL 34.4 Hm3 119 BQL BQL 413 BQL BQL BQL BQL BQL BQL BQL 24.0

LS-11 - 147








LS-12 - 147

Hm3 64 2878 BQL 126 BQL BQL BQL BQL BQL BQL BQL 33.0


Hm3 72 50691 BQL 125 BQL BQL BQL BQL BQL BQL BQL 153.4 Hm3 71 BQL BQL 228 BQL BQL BQL BQL BQL BQL BQL 21.1



LS-13 - 154.65

Hm3 27 13963 BQL 670 0.9 0.3 4.7 64.2 BQL BQL BQL BQL

Hm3 35 BQL BQL 104 BQL BQL 0.6 24.0 BQL BQL BQL BQL

Hm3 24 5800 BQL 180 BQL 0.2 1.0 31.0 BQL BQL BQL BQL Hm3 28 19487 BQL 642 BQL 0.5 3.3 56.3 BQL 1.1 BQL BQL

Hm3 32 655 BQL 206 0.7 BQL 1.2 31.8 3.2 0.4 BQL 1.7

Hm3 33 19319 BQL 115 BQL BQL BQL 33.2 BQL BQL BQL BQL

LS-14 - 167.5

Hm1 10 10226 BQL 91 0.9 BQL 0.5 29.0 BQL BQL BQL BQL Hm1 12 80674 BQL 100 0.6 BQL BQL 34.4 BQL 2.9 BQL BQL

Hm1 13 BQL BQL 82 BQL BQL BQL 34.2 BQL 0.6 BQL BQL


LS-15 - 168.25

Hm3 14 11983 BQL 107 BQL BQL BQL BQL BQL BQL BQL BQL

Hm3 16 9424 BQL 640 BQL BQL BQL BQL BQL BQL BQL BQL

Hm3 28 4764 BQL 168 BQL BQL BQL BQL BQL BQL BQL BQL Hm3 29 BQL BQL 114 BQL BQL BQL BQL BQL BQL BQL BQL

Hm3 31 BQL BQL 273 BQL BQL BQL BQL BQL BQL BQL BQL

Hm3 33 2613 BQL 106 BQL BQL BQL BQL BQL BQL BQL BQL Hm3 47 45683 BQL 230 BQL BQL BQL BQL BQL BQL BQL BQL

LS-19 - 200.35

Hm1 50 35358 BQL 382 1.2 BQL BQL BQL BQL BQL BQL BQL

Hm2 61 10371 BQL 168 0.6 BQL 0.7 71.7 BQL 0.9 BQL BQL

Hm2 62 55922 BQL 77 BQL BQL BQL 49.0 BQL 4.8 19.3 BQL Hm2 64 8299 BQL 211 BQL BQL 0.7 46.1 BQL 1.5 BQL BQL

Hm2 66 27821 BQL 98 BQL BQL 0.5 54.4 BQL 1.9 BQL BQL Hm1 68 117629 6.1 412 BQL BQL 1.8 73.1 BQL 8.2 BQL BQL

LS-20 - 203.2 Hm1 46 4370 BQL 565 BQL 0.5 1.6 67.9 BQL 1.7 BQL BQL

Hm1 47 25680 BQL 309 BQL BQL 0.9 53.6 BQL 3.2 BQL BQL


Hm1 58 43025 BQL 518 BQL BQL 1.1 66.1 12.5 4.9 BQL BQL


Hm1 64 75851 8.3 184 BQL BQL 0.7 58.7 BQL 8.6 BQL BQL

Hm1 67 86624 BQL 136 BQL BQL BQL 53.8 BQL 8.9 BQL BQL

Hm1 71 79310 6.3 178 BQL BQL 0.5 37.3 BQL 9.0 BQL BQL

123

Continuation




LS-20 - 203.2

Hm1 50 10179 BQL 425 BQL BQL 1.0 70.2 BQL 1.5 BQL BQL Hm1 51 121248 9.2 306 BQL BQL BQL 56.6 BQL 11.7 BQL BQL


Hm1 66 32196 BQL 152 BQL BQL 0.8 56.3 BQL 4.8 BQL BQL Hm1 72 101477 6.5 158 BQL BQL 0.6 43.7 BQL 9.0 BQL BQL

LS-21 - 210.3 Hm1 23 57437 BQL 283 BQL BQL BQL BQL BQL BQL BQL 195

DE-02 - 28.65



Hm3 34 BQL BQL 174 BQL BQL BQL BQL BQL BQL BQL 256












Hm3 33 BQL BQL 239 BQL BQL BQL BQL BQL BQL BQL 65.0 Hm1 91 BQL 4.9 556 BQL BQL BQL BQL BQL BQL BQL 680


Hm1 93 BQL 4.4 521 BQL BQL BQL BQL BQL BQL BQL 91.3 Hm1 94 BQL 4.4 506 BQL BQL BQL BQL BQL BQL BQL 57.1

DE-04 - 54.45


Hm2 70 BQL BQL 63 BQL BQL BQL BQL BQL BQL BQL 38.7 Hm2 77 BQL 5.1 76 BQL BQL BQL BQL BQL BQL BQL 42.1


Hm3 76 BQL BQL 141 BQL BQL BQL BQL BQL BQL BQL 73.7 Hm3 79 BQL BQL 172 BQL BQL BQL BQL BQL BQL BQL 138

DE-06 - 28.65


Hm2 132 BQL BQL 1644 BQL BQL BQL BQL BQL BQL 14.4 278

Hm2 128 BQL BQL 2269 BQL BQL BQL BQL BQL BQL 10.2 22.3 Hm2 129 BQL BQL 917 BQL BQL BQL BQL BQL BQL BQL 11.3

Hm2 131 BQL BQL 1623 BQL BQL BQL BQL BQL BQL 10.0 241

DE-08 - 86.27

Hm2 60 10730 5.6 194 BQL BQL BQL BQL BQL BQL BQL 39.2 Hm2 74 12131 BQL 414 BQL BQL BQL BQL BQL BQL BQL 47.6

Hm1 85 5371 BQL 285 BQL BQL BQL BQL BQL BQL BQL 26.4

Hm1 76 11204 BQL 338 BQL BQL BQL BQL BQL BQL BQL 48.5 Hm1 84 15371 BQL 287 BQL BQL BQL BQL BQL BQL BQL 44.3


DE-11 - 113.9 Hm1 31 BQL BQL 191 BQL BQL BQL BQL BQL BQL BQL 26.5

DE-11 - 113.9







124

Table C.2- Quantitation limitis (in ppm) defined as three times the detection limit. BQL = below

quantitation limit.



LS-02 - 12.9

Hm1 21 16 83 14 4 9 15 25 3 3 3 15 Hm2 24 10 52 9 2 6 9 16 2 2 2 9

Hm1 28 11 56 9 2 6 10 17 2 2 2 10

Hm2 29 8 42 7 2 5 8 13 2 2 1 8 Hm2 31 9 50 8 2 6 9 15 2 2 2 9

Hm2 32 12 61 10 3 7 12 19 2 2 2 11

LS-08 - 94.5

Hm1 10 8 46 7 BQL 5 BQL BQL BQL BQL BQL BQL Hm3 11 13 75 11 BQL 8 BQL BQL BQL BQL BQL BQL

Hm3 14 6 34 5 BQL 4 BQL BQL BQL BQL BQL BQL

Hm1 38 9 51 8 BQL 5 BQL BQL BQL BQL BQL BQL Hm1 43 10 58 9 BQL 6 BQL BQL BQL BQL BQL BQL

LS-09 - 121.2 Hm3 106 11 57 9 2 6 17 18 2 2 2 11

Hm3 119 18 96 15 4 11 31 32 4 3 3 18

LS-11 - 147




Hm3 15 BQL 76 7 BQL 5 BQL BQL BQL BQL BQL BQL Hm3 16 BQL 76 7 BQL 5 BQL BQL BQL BQL BQL BQL

Hm3 17 BQL 59 6 BQL 4 BQL BQL BQL BQL BQL BQL



LS-12 - 147





LS-13 - 154.65

Hm3 27 BQL BQL 2 1 2 BQL 5 0 0 0 2

Hm3 35 BQL BQL 2 1 2 BQL 5 0 1 0 3

Hm3 24 BQL BQL 3 1 1 BQL 8 1 0 0 3

Hm3 28 BQL BQL 2 1 1 BQL 4 0 0 0 2

Hm3 32 BQL BQL 2 0 1 BQL 4 1 0 1 3

Hm3 33 BQL BQL 2 0 1 BQL 6 1 1 0 2

LS-14 - 167.5

Hm1 10 BQL BQL 63 20 46 BQL 93 19 10 15 91 Hm1 12 BQL BQL 50 17 42 BQL 103 11 14 7 50

Hm1 13 BQL BQL 38 11 20 BQL 69 9 10 8 45

Hm1 14 BQL BQL 2 1 2 BQL 6 0 0 0 2

LS-15 - 168.25

Hm3 14 9 54 10 BQL 6 9 19 BQL BQL BQL BQL Hm3 16 8 49 9 BQL 5 7 16 BQL BQL BQL BQL

Hm3 28 15 97 19 BQL 11 5 25 BQL BQL BQL BQL




LS-19 - 200.35






LS-20 - 203.2

Hm1 46 BQL BQL 2 1 2 BQL 6 0 1 1 4

Hm1 47 BQL BQL 2 1 1 BQL 5 1 0 0 3

Hm1 48 BQL BQL 3 1 2 BQL 6 1 1 1 3


Hm1 64 BQL BQL 3 1 2 BQL 8 1 1 1 3


125

Continuation



LS-20 - 203.2

Hm1 49 BQL BQL 3 1 2 BQL 9 0 1 1 5


Hm1 60 BQL BQL 3 1 2 BQL 7 1 1 0 3


LS-21 - 210.3 Hm1 23 4 21 3 1 2 6 9 1 1 1 2

DE-02 - 28.65

Hm3 25 4 20 3 1 2 3 8 1 1 1 3

Hm3 26 2 13 2 1 1 3 6 0 0 0 4 Hm3 32 3 15 2 0 1 5 5 0 0 0 2

Hm3 34 3 20 3 1 1 4 7 0 1 0 4

Hm3 40 3 17 3 1 2 4 6 1 1 1 BQL Hm3 41 2 15 2 1 1 3 4 0 1 0 3

Hm3 43 3 14 2 1 2 4 5 0 0 0 2

Hm3 44 3 15 2 1 1 3 4 1 1 0 3

Hm3 48 4 16 3 1 2 3 8 1 0 1 3

Hm3 50 2 16 2 1 1 3 6 1 1 0 2

Hm3 52 3 18 3 1 2 5 6 1 1 0 3 Hm3 59 2 13 2 1 2 3 6 0 1 0 3

Hm3 60 2 14 2 0 1 4 4 1 1 0 4

Hm3 61 3 15 2 0 2 4 6 BQL 0 0 2 Hm3 62 3 17 2 1 2 3 5 1 1 0 3

Hm3 63 3 14 2 1 1 4 5 1 0 0 3

Hm3 24 3 15 3 1 2 3 6 0 1 0 2 Hm3 30 3 15 2 0 1 3 7 1 1 0 2

Hm3 31 3 15 2 0 1 2 4 1 0 1 2

Hm3 33 3 16 2 1 1 4 7 1 1 0 1 Hm1 91 11 60 10 3 7 16 19 2 2 2 11

Hm3 92 13 68 11 3 8 18 22 3 2 2 13

Hm3 93 12 63 10 3 7 17 20 3 2 2 12 Hm3 94 12 64 10 3 7 17 21 3 2 2 12

DE-04 - 54.45

Hm3 68 3 17 3 1 2 9 4 0 1 0 3

Hm2 70 4 22 3 1 2 4 8 1 0 0 6 Hm2 77 4 23 4 1 2 5 7 1 0 1 6

Hm3 75 3 19 2 1 2 5 7 1 1 0 5

Hm3 76 3 18 3 1 2 5 7 1 1 1 4 Hm3 79 3 21 3 1 2 5 7 1 1 0 2

DE-06 - 28.65

Hm2 130 29 154 24 7 17 55 51 6 6 5 29

Hm2 132 28 148 23 7 16 54 49 6 5 5 28

Hm2 128 37 193 31 9 21 68 64 8 7 6 37 Hm2 129 18 94 15 4 10 33 31 4 3 3 18

Hm2 131 41 216 34 10 24 77 72 9 8 7 41

DE-08 - 86.27

Hm2 58 10 53 9 2 6 12 17 2 2 2 10 Hm2 60 17 89 15 4 10 19 28 4 3 3 16

Hm1 74 13 68 11 3 7 16 21 3 2 2 13

Hm1 85 19 102 17 4 11 26 33 4 4 3 19 Hm1 76 16 87 14 4 10 21 28 3 3 3 16

Hm1 84 21 109 18 5 12 27 35 4 4 4 20


DE-11 - 113.9







Hm3 61 BQL 91 8 BQL 6 BQL BQL BQL BQL BQL BQL Hm1 58 10 53 9 2 6 12 17 2 2 2 10

126

Continuation



LS-02 - 12.9

Hm1 21 15 5 31 BQL 10 2 6 3 11 2 9

Hm2 24 9 3 20 BQL 6 1 4 2 7 1 6 Hm1 28 10 3 21 BQL 7 1 4 2 7 2 6

Hm2 29 8 3 16 BQL 5 1 3 1 5 1 4

Hm2 31 5 2 19 BQL 6 1 4 2 6 1 5 Hm2 32 6 2 23 BQL 8 2 5 2 8 2 6

LS-08 - 94.5



Hm3 14 BQL BQL 10 BQL BQL BQL BQL BQL BQL BQL BQL Hm1 38 BQL BQL 16 BQL BQL BQL BQL BQL BQL BQL BQL


LS-09 - 121.2 Hm3 106 10 3 22 BQL 7 2 5 2 8 2 6 Hm3 119 18 5 38 BQL 12 3 9 4 13 3 9

LS-11 - 147








LS-12 - 147






LS-13 - 154.65

Hm3 27 2 1 6 0 2 0 1 0 1 0 1

Hm3 35 3 1 6 1 1 0 1 0 2 0 2

Hm3 24 3 1 6 0 2 0 1 0 3 0 2 Hm3 28 3 1 3 0 1 0 1 0 1 0 1

Hm3 32 2 1 4 0 1 0 1 0 2 0 1

Hm3 33 2 1 5 0 2 0 1 0 1 0 1

LS-14 - 167.5

Hm1 10 107 20 167 16 67 15 39 14 53 11 47 Hm1 12 83 21 119 13 34 10 36 10 47 11 27

Hm1 13 60 11 102 6 26 9 29 8 30 7 26

Hm1 14 5 1 8 1 1 0 2 1 3 0 2

LS-15 - 168.25

Hm3 14 BQL 2 19 BQL BQL BQL BQL 1 BQL 1 BQL


Hm3 28 BQL 4 34 BQL BQL BQL BQL 2 BQL 2 BQL Hm3 29 BQL 3 21 BQL BQL BQL BQL 1 BQL 1 BQL



LS-19 - 200.35





LS-20 - 203.2

Hm1 46 3 1 5 0 3 1 1 0 2 1 2

Hm1 47 5 1 7 0 1 0 1 0 1 1 1

Hm1 48 4 1 5 0 2 1 1 1 3 1 2

Hm1 58 5 1 10 1 2 0 2 1 3 0 2

Hm2 59 3 1 7 0 3 1 2 1 4 1 2

Hm1 64 5 1 7 1 2 0 2 1 2 1 2 Hm1 67 5 2 7 1 3 1 2 1 2 1 2

Hm1 71 3 1 6 1 1 0 2 1 3 1 3

127

Continuation



LS-20 -

203.2

Hm1 49 3 1 5 0 3 1 2 0 3 1 2

Hm1 50 3 1 4 0 1 0 2 0 2 0 2 Hm1 51 4 1 6 0 2 0 1 0 1 0 2

Hm1 60 5 1 5 0 2 1 2 0 2 1 2

Hm1 66 23 6 35 3 2 0 2 1 2 1 2 Hm1 72 3 1 7 1 15 2 11 4 15 4 12

LS-21 -

210.3 Hm1 23 1 2 8 0 2 1 2 0 2 1 2

DE-02 -

28.65

Hm3 25 3 1 6 0 2 1 2 1 3 0 Hm3 26 2 1 7 1 2 0 1 0 2 0 1

Hm3 32 2 1 7 1 1 0 1 0 2 0 2

Hm3 34 3 1 7 0 2 1 1 1 3 0 1 Hm3 40 2 1 5 0 2 1 1 0 2 0 2

Hm3 41 3 1 6 0 1 0 1 0 1 0 2

Hm3 43 2 1 5 1 2 0 1 0 2 0 1

Hm3 44 3 1 7 1 2 1 1 0 1 0 1

Hm3 48 2 1 6 1 1 1 1 0 2 0 1

Hm3 50 3 1 7 1 1 1 1 1 2 0 2 Hm3 52 2 1 4 0 1 0 2 1 3 0 2

Hm3 59 2 1 6 1 2 0 2 0 2 0 1

Hm3 60 3 1 5 0 1 0 1 1 3 0 1 Hm3 61 2 1 6 1 2 0 1 1 3 0 1

Hm3 62 3 1 6 0 2 1 1 1 3 1 1

Hm3 63 3 5 0 2 0 1 0 2 0 1 Hm3 24 2 1 6 0 2 0 1 0 1 0 2

Hm3 30 2 1 6 0 2 1 1 1 2 0 1

Hm3 31 2 1 6 0 2 0 1 0 1 0 1 Hm3 33 11 3 23 BQL 1 1 0 0 2 1 1

Hm1 91 12 4 27 BQL 8 2 5 2 8 2 6

Hm3 92 11 3 24 BQL 9 2 6 2 9 2 7 Hm3 93 12 4 25 BQL 8 2 5 2 8 2 6

Hm3 94 3 1 5 0 8 2 5 2 9 2 6

DE-04 -

54.45

Hm3 68 4 1 5 1 2 1 2 0 3 1 2 Hm2 70 4 2 9 1 2 1 2 1 3 1 2

Hm2 77 5 1 10 1 2 0 2 1 4 1 2

Hm3 75 5 1 7 1 2 0 2 1 3 1 2 Hm3 76 4 1 7 0 2 0 2 1 1 0 2

Hm3 79 4 1 8 1 2 0 2 1 2 0 2

DE-06 -

28.65

Hm2 130 28 8 61 BQL 20 5 14 6 21 5 15

Hm2 132 27 8 59 BQL 19 4 13 6 20 5 14 Hm2 128 35 10 77 BQL 25 6 17 7 27 6 19

Hm2 129 17 5 37 BQL 12 3 8 4 13 3 9

Hm2 131 39 11 86 BQL 28 6 20 8 30 7 21

DE-08 - 86.27

Hm2 58 10 3 20 BQL 7 1 4 2 7 2 5

Hm2 60 16 5 34 BQL 11 2 7 3 12 3 9

Hm1 74 12 4 26 BQL 8 2 6 2 9 2 7 Hm1 85 19 6 40 BQL 13 3 9 4 14 3 10

Hm1 76 16 5 34 BQL 11 2 7 3 12 3 9

Hm1 84 20 6 42 BQL 14 3 9 4 15 3 11

DE-11 -

113.9








128

Continuation



LS-02 - 12.9

Hm1 21 6 8 3 3 102 6 282 93892 1119 BQL 183

Hm2 24 4 5 2 2 85 5 273 59129 912 BQL 152 Hm1 28 4 5 2 2 94 6 377 19497 1040 BQL 168

Hm2 29 3 4 2 1 92 6 446 46769 1006 BQL 165

Hm2 31 4 5 2 2 122 7 1475 138379 1330 BQL 217 Hm2 32 5 6 2 2 95 7 104 41703 1040 BQL 170

LS-08 - 94.5

Hm1 10 BQL BQL BQL BQL 79 4 730 52036 822 BQL 152


Hm3 14 BQL BQL BQL BQL 78 4 792 16507 804 BQL 149 Hm1 38 BQL BQL BQL BQL 71 4 490 10516 748 BQL 128


LS-09 - 121.2 Hm3 106 5 6 3 2 79 5 587 3821 865 BQL 142 Hm3 119 9 11 5 4 118 8 820 3594 1280 BQL 211

LS-11 - 147








LS-12 - 147






LS-13 - 154.65

Hm3 27 1 1 1 1 71 3 2994 52151 757 BQL 155

Hm3 35 1 1 1 1 66 3 1323 23303 717 8 144

Hm3 24 3 1 0 1 98 4 1640 143757 1029 BQL 216

Hm3 28 1 1 0 0 70 3 2223 87971 751 BQL 154

Hm3 32 1 1 0 0 21 1 1679 10030 229 2 46

Hm3 33 2 1 0 0 95 4 2404 87890 1049 12 209

LS-14 - 167.5

Hm1 10 43 41 16 18 64 2 2231 3248 684 5 143

Hm1 12 36 32 13 11 89 4 950 4873 945 7 197

Hm1 13 34 27 10 9 65 3 908 15502 697 6 144 Hm1 14 2 1 1 1 BQL BQL BQL BQL BQL BQL BQL

LS-15 - 168.25

Hm3 14 BQL 4 BQL BQL 92 6 665 33059 1010 BQL 176

Hm3 16 BQL 3 BQL BQL 79 5 504 29808 873 BQL 152

Hm3 28 BQL 5 BQL BQL 73 5 514 36288 796 BQL 141 Hm3 29 BQL 3 BQL BQL 72 5 897 16356 781 BQL 137

Hm3 31 BQL 3 BQL BQL 77 5 749 40807 836 BQL 148

Hm3 33 BQL 3 BQL BQL 64 4 336 6475 691 BQL 123 Hm3 47 BQL 3 BQL BQL 85 5 2150 27320 920 BQL 161

LS-19 - 200.35

Hm1 50 BQL 2 BQL BQL 78 5 1783 28722 849 BQL 150

Hm2 61 BQL 10 BQL BQL 67 4 1026 13314 817 4 143 Hm2 62 BQL 20 BQL BQL 71 3 477 5338 859 5 152

Hm2 64 BQL 3 BQL BQL 70 3 1707 20809 843 8 150

Hm2 66 BQL 2 BQL BQL 53 2 695 3809 641 10 114 Hm1 68 BQL 3 BQL BQL 100 6 1432 13638 1208 13 211

LS-20 - 203.2

Hm1 46 2 2 1 1 146 6 1368 6536 1653 BQL 316

Hm1 47 1 1 0 1 107 5 1343 48741 1200 8 231

Hm1 48 2 2 1 1 87 4 1396 21060 990 8 189

Hm1 58 2 2 1 0 79 4 615 15635 911 8 171

Hm2 59 3 4 1 1 73 3 500 7382 841 7 157 Hm1 64 1 2 1 1 93 4 612 54347 1075 8 199

Hm1 67 1 2 1 1 99 4 411 45412 1135 11 212

Hm1 71 2 3 1 1 103 5 608 88597 1182 11 218

129

Continuation



LS-20 - 203.2

Hm1 49 2 2 1 0 103 5 14 1024 1174 10 223

Hm1 50 1 2 1 1 82 4 11 808 935 8 177 Hm1 51 1 1 1 0 98 4 13 975 1121 9 211

Hm1 60 2 2 1 1 70 3 10 691 798 11 150

Hm1 66 2 2 1 1 92 4 12 916 1065 8 198 Hm1 72 8 10 5 4 102 5 14 1012 1185 10 219

LS-21 - 210.3 Hm1 23 3 2 1 0 101 6 12 1037 1111 BQL 196

DE-02 - 28.65

Hm3 25 3 2 1 1 86 5 10 719 936 BQL 167

Hm3 26 1 0 0 82 5 10 686 893 BQL 158 Hm3 32 2 2 1 0 79 4 9 667 867 BQL 151

Hm3 34 3 2 1 1 81 5 10 695 890 BQL 151

Hm3 40 1 2 1 1 87 5 11 759 958 BQL 162 Hm3 41 2 1 0 0 66 4 8 576 719 BQL 122

Hm3 43 2 1 1 0 82 5 9 714 901 BQL 150

Hm3 44 1 1 0 1 72 4 8 618 773 BQL 131

Hm3 48 2 2 0 1 79 4 9 694 861 BQL 142

Hm3 50 2 2 1 1 83 5 10 734 908 BQL 151

Hm3 52 1 1 1 1 80 4 9 703 881 BQL 143 Hm3 59 1 1 0 0 74 4 9 663 814 BQL 134

Hm3 60 1 1 0 0 77 4 9 687 837 BQL 138

Hm3 61 2 2 0 1 98 6 11 876 1084 BQL 176 Hm3 62 1 2 1 1 85 5 10 769 933 BQL 153

Hm3 63 1 2 0 0 76 4 9 687 839 BQL 137

Hm3 24 2 2 1 0 86 5 10 722 940 BQL 167 Hm3 30 1 1 1 0 69 4 8 576 762 BQL 132

Hm3 31 2 2 0 0 88 5 10 749 984 BQL 170

Hm3 33 2 1 0 0 82 5 10 699 908 BQL 156 Hm1 91 5 7 3 2 79 4 9 798 866 BQL 144

Hm3 92 6 8 3 3 78 5 9 795 859 BQL 143

Hm3 93 6 7 3 2 77 5 9 787 858 BQL 141 Hm3 94 6 7 3 2 92 6 10 926 994 BQL 166

DE-04 - 54.45

Hm3 68 2 2 1 1 97 6 12 998 1074 BQL 187

Hm2 70 2 2 1 1 105 7 13 1091 1157 BQL 203 Hm2 77 2 2 1 1 91 6 11 953 1000 BQL 175

Hm3 75 1 2 0 1 106 7 13 1102 1178 BQL 206

Hm3 76 2 1 0 1 102 7 12 1072 1132 BQL 198 Hm3 79 2 2 1 1 126 8 16 1315 1405 BQL 244

DE-06 - 28.65

Hm2 130 16 19 9 7 127 7 15 1310 1384 BQL 227

Hm2 132 15 18 8 6 190 11 23 1980 2067 BQL 342

Hm2 128 19 23 11 8 119 7 15 1226 1289 BQL 212 Hm2 129 10 11 5 4 136 8 16 1407 1472 BQL 242

Hm2 131 22 26 12 9 131 9 16 1351 1430 BQL 235

DE-08 - 86.27

Hm2 58 4 6 2 2 103 7 12 1006 1117 BQL 185 Hm2 60 7 9 4 3 137 9 17 1359 1503 BQL 249

Hm1 74 6 7 3 2 104 7 12 1041 1129 BQL 189

Hm1 85 9 11 5 4 93 6 11 939 1003 BQL 169 Hm1 76 8 9 4 3 90 6 11 910 996 BQL 163

Hm1 84 10 12 5 4 98 6 12 989 1066 BQL 178

DE-11 - 113.9








130

Continuation



LS-02 - 12.9

Hm1 21 1656 5 20 2 BQL BQL BQL BQL BQL BQL BQL

Hm2 24 1368 4 20 1 BQL BQL BQL BQL BQL BQL BQL Hm1 28 1504 5 18 1 BQL BQL BQL BQL BQL BQL BQL



LS-08 - 94.5

Hm1 10 1746 5 12 1 1 BQL BQL BQL BQL BQL BQL


Hm3 14 1620 5 16 1 1 BQL BQL BQL BQL BQL BQL Hm1 38 1236 4 10 1 BQL BQL BQL BQL BQL BQL BQL


LS-09 - 121.2 Hm3 106 1330 4 18 1 1 BQL BQL BQL BQL BQL BQL Hm3 119 1954 6 19 2 2 BQL BQL BQL BQL BQL BQL

LS-11 - 147



Hm3 60 2409 7 26 2 4 BQL BQL BQL BQL BQL BQL Hm3 15 2052 6 21 3 4 BQL BQL BQL BQL BQL BQL





LS-12 - 147



Hm3 72 1262 4 16 1

BQL BQL BQL BQL BQL BQL Hm3 71 1256 4 14 2 5 BQL BQL BQL BQL BQL BQL



LS-13 - 154.65

Hm3 27 1395 4 15 1 BQL 0 1 BQL 1 15 4

Hm3 35 1286 4 12 1 2 0 1 BQL 1 14 4

Hm3 24 1950 6 18 2 BQL 1 2 BQL BQL 20 6 Hm3 28 1391 4 13 1 BQL 0 1 BQL 0 13 4

Hm3 32 409 1 4 0 0 0 0 BQL 0 5 1

Hm3 33 1878 5 17 2 1 1 2 BQL 1 22 5

LS-14 - 167.5

Hm1 10 1297 4 16 1 1 0 1 BQL 1 14 4 Hm1 12 1780 5 19 BQL 1 BQL 2 BQL 1 19 4

Hm1 13 1311 4 15 1 1 0 1 BQL 1 15 4


LS-15 - 168.25






LS-19 - 200.35


Hm2 61 1292 4 13 BQL 0 0 2 11 1 19 3

Hm2 62 1358 4 13 1 1 0 2 12 1 18 4 Hm2 64 1359 4 12 1 1 0 2 BQL 1 18 4

Hm2 66 1027 3 8 1 0 BQL 1 BQL 1 BQL 2 Hm1 68 1921 5 22 1 1 BQL 2 16 2 26 6

LS-20 - 203.2 Hm1 46 2817 8 28 3 BQL BQL 3 BQL 2 BQL 8

Hm1 47 2049 6 26 1 1 1 2 BQL 2 26 6

Hm1 48 1676 5 23 3 1 1 2 BQL 1 21 5

Hm1 58 1531 4 15 1 1 0 1 BQL 1 18 4

Hm2 59 1417 4 14 1 0 0 1 BQL 1 18 4

Hm1 64 1784 5 15 1 1 1 2 BQL 1 22 BQL

Hm1 67 1924 6 26 2 1 1 2 BQL 1 24 7

Hm1 71 1982 6 19 1 1 0 2 BQL 1 27 6

131

Continuation



Hm1 49 1993 6 19 2 1 1 2 BQL 1 26 5

LS-20 - 203.2

Hm1 50 1594 5 19 2 1 0 2 BQL 1 21 5 Hm1 51 1899 5 25 2 1 1 2 BQL 1 26 5

Hm1 60 1354 4 15 1 1 0 2 BQL 1 18 3

Hm1 66 1793 6 23 2 1 0 1 BQL 1 23 5 Hm1 72 2004 6 19 2 1 0 2 BQL 1 25 6

LS-21 - 210.3 Hm1 23 1702 5 17 2 8 BQL BQL BQL BQL BQL BQL

DE-02 - 28.65


















DE-04 - 54.45




Hm3 76 1740 6 22 1 BQL BQL BQL BQL BQL BQL BQL Hm3 79 2155 7 25 2 23 BQL BQL BQL BQL BQL BQL

DE-06 - 28.65





DE-08 - 86.27





DE-11 - 113.9 Hm1 31 1333 4 15 1 4 BQL BQL BQL BQL BQL BQL

DE-11 - 113.9







132

Table C.3- Quality control. Average (Av.), standard deviation (std) and coefficient of variation (C.V.)

for the secondary standard BCR-2G. Group I Group II

Element BCR-2G

measured Av. Std Obs.

BCR-2G Reported

C.V.

BCR-2G measured Av.

Std Obs. BCR-2G Reported

C.V.

Sc45 39.3 2.06 12 33.5 117 Na23 29980 866 31 23150 129

Ti47 15321 778 42 13567 113 Mg24 22760 536 31 21702 105

V51 444 13.2 42 418 106 Al27 78696 1961 31 71309 110 Cr52 19.1 6.73 4 15.9 121 Si28 274872 9431 31 252180 109

Mn55 1722 27.5 42 1522 113 P31 1679 224 31 1567 107

Co59 41.3 3.53 39 37.3 111 K39 16458 374 31 14724 112 Ni60 BDL - 0 12.6 - Ca43 55416 1756 31 50865 109

Cu63 26.8 6.36 12 19.7 137 Ca44 55298 1981 31 50865 109 Zn66 137 4.18 12 130 106 Sc45 39.3 2.36 31 33.5 117

Rb85 45.1 15.4 42 46.0 98 Ti47 15006 223 31 13567 111

Sr88 386 16.5 51 337 114 Ga71 25.7 1.18 31 22.1 116 Y89 39.3 1.87 51 36.1 109 Ge72 5.28 0.804 4 1.46 362

Zr90 207 4.74 51 187 111 As75 BDL - 0 0.860 -

Nb93 15.6 1.77 12 12.4 125 Rb85 51.6 1.42 31 46.0 112 Mo95 148 64.1 39 251 59 Sr88 378 6.04 31 337 112

Ba137 720 122 51 684 105 Cd111 0.430 - 1 0.690 62

La139 27.3 1.55 51 25.1 109 Ce140 57.7 2.19 51 53.1 109

Pr141 7.56 0.539 51 6.83 111

Nd146 31.6 2.11 51 28.3 112

Sm147 7.69 1.26 50 6.55 117

Eu153 2.23 0.302 51 1.99 112

Gd157 7.57 1.31 38 6.81 111

Tb159 1.15 0.185 51 1.08 107

Dy163 7.13 0.649 51 6.42 111

Ho165 1.42 0.206 51 1.31 108

Er166 3.95 0.486 51 3.67 108

Tm169 0.569 0.128 49 0.534 106

Yb172 3.63 0.658 48 3.39 107

Lu175 0.544 0.099 42 0.505 108

Hf178 5.29 0.580 51 4.97 106

W182 0.611 0.432 41 0.465 131

Pb208 6.77 1.47 51 10.6 64

Th232 6.19 1.15 51 5.83 106

U238 2.08 0.447 51 1.68 124

133

Appendix D– Supplementary figures

Figure D.1- (a) Hm3 surrounding a chert dissolution pod (backscattered electron). (b) Hm3

surrounding a quartz-filled ptigmatic veinlet (backscattered electron). (c) Foliation-defining

lepdoblastic Hm3 (bottom) (backscattered electron). (d) Hm3 associated with secondary phases and

porosity (backscattered electron). Mineral abbreviations: Al-Phosphates (Al-Ph); chert (Cht); goethite

(Go).

134

Figure D.2- PAAS-normalized REE diagrams of hematites from the siliceous (a, b, d) and carbonaceous facies (c, e, f). The REE patterns are consistent

within individual samples (series LS- and DE-) for all stages and textures. Complete data is presented in appendix E.

135

Appendix E- MUQ-normalized data and diagnostic features

Table E. MUQ-normalized rare earth element (REE) and trace element (TE) data. Neighboring spots with similar compositions were grouped together to

decrease uncertainty. Sample LS-02 LS-08 LS-09 LS-11 Stage Hm1 Hm2 Hm2 Hm1 Hm3 Hm3 Hm1 Hm3 Hm3 Hm3 Hm2 Hm3

Texture matrix vein nodule matrix lamination matrix matrix Matrix vein matrix

ID 21,28 24,29 31,32 10 11 14 38 43 106 119 15 16 17-18 23 26 51 53,54 56,57 59 60

REE

La 0.116 0.073 1.26 0.300 0.209 0.049 0.091 0.036 BQL 0.587 0.066 0.330 0.080 1.21 0.073 1.16 0.129 0.080 0.048 1.03

Ce 0.100 0.057 0.885 1.73 0.198 0.048 0.071 0.024 0.031 0.447 0.042 0.265 0.040 0.498 0.037 0.374 0.054 0.030 0.022 0.415

Pr BQL BQL 1.26 0.225 0.278 0.065 0.109 0.049 BQL 0.755 0.084 0.402 0.072 0.965 0.096 0.708 0.121 0.054 0.051 0.778

Nd BQL BQL 1.22 0.173 0.316 0.077 0.180 0.052 BQL 1.03 0.087 0.511 0.092 1.11 0.145 0.609 0.151 0.071 0.068 0.988

Pm BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sm BQL BQL BQL 0.257 0.615 0.174 0.135 0.138 BQL BQL 0.313 0.767 0.195 0.815 0.224 0.625 0.214 0.122 0.151 0.990

Eu BQL BQL BQL 0.369 0.879 0.109 0.248 0.066 BQL BQL 0.194 0.605 0.107 0.841 0.197 1.08 0.229 0.127 0.210 0.847

Gd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Tb 0.444 0.192 0.848 0.727 2.06 0.181 0.286 0.118 0.081 1.93 0.275 0.788 0.152 0.778 0.113 2.58 0.228 0.181 0.110 1.49

Dy BQL BQL 1.41 0.761 2.30 0.136 0.284 0.160 BQL 2.76 0.127 0.964 0.188 1.10 0.219 3.87 0.194 0.094 0.115 1.67

Y 0.530 0.207 2.33 1.73 5.94 0.168 0.320 0.141 0.137 3.06 0.182 1.86 0.216 1.76 0.182 6.93 0.183 0.135 0.114 2.87

Ho BQL BQL 1.83 1.02 3.32 0.148 0.393 0.184 BQL BQL 0.180 0.820 0.176 1.23 0.161 5.32 0.266 0.093 0.143 2.11

Er BQL BQL 1.85 1.51 3.64 0.184 0.386 0.160 BQL 2.78 0.175 0.941 0.200 1.13 0.175 5.82 0.346 0.153 0.211 2.26

Tm BQL BQL BQL 1.39 4.02 0.176 0.371 0.206 BQL BQL 0.412 1.35 0.278 1.24 0.249 5.10 0.219 0.319 0.431 2.22

Yb BQL BQL BQL 1.96 4.76 0.369 0.351 0.335 BQL BQL 0.280 0.874 0.271 1.19 0.489 6.20 0.269 0.332 0.354 1.25

Lu BQL BQL BQL 2.24 6.10 0.398 0.392 0.324 BQL BQL 0.237 0.918 0.274 0.898 0.237 5.55 0.259 0.284 0.327 1.61

Anomalies

Pr/Yb - - - 0.11 0.06 0.17 0.31 0.15 - - 0.30 0.46 0.26 0.81 0.20 0.11 0.45 0.16 0.14 0.62

Y/Ho (unnormalized) - - 33.2 44.3 46.7 29.8 21.2 20.0 - - 26.4 59.2 32.0 37.4 29.6 34.0 17.9 38.0 20.7 35.5

Y/Y* (Y/(Dy+Ho)) - - 0.72 0.97 1.06 0.59 0.47 0.41 - 1.11 0.59 1.04 0.59 0.76 0.48 0.75 0.40 0.72 0.44 0.76

Ce/Ce* (Ce/0.5(La+Pr)) - - 0.70 6.59 0.81 0.85 0.71 0.56 - 0.67 0.56 0.72 0.53 0.46 0.44 0.40 0.43 0.45 0.44 0.46

Pr/Pr* (Pr/0.5(Ce+Nd)) - - 1.20 0.24 1.08 1.03 0.87 1.30 - 1.03 1.30 1.04 1.08 1.20 1.05 1.44 1.18 1.07 1.13 1.11

La/La* (La/3Pr-2Nd) - - 0.33 1.88 - - 1.62 - - 0.26 - - - 0.96 - 1.33 - - - 2.91

Gd/Gd* (Gd/0.33Sm + 0.67Tb) - - - - - - - - - - - - - - - - - - - -

Eu/Eu* (Eu/0.67Sm+0.33Tb) - - - 0.90 0.80 0.62 1.34 0.50 - - 0.65 0.78 0.59 1.05 1.05 0.85 1.05 0.90 1.53 0.73

136

Continuation Sample LS-02 LS-08 LS-09 LS-11 Stage Hm1 Hm2 Hm2 Hm1 Hm3 Hm1 Hm3 Hm3 Hm3 Hm2 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm2 Hm3 Hm3

Texture matrix vein nodule matrix matrix matrix matrix matrix vein matrix matrix matrix matrix matrix matrix matrix vein matrix matrix matrix

ID 21,28 24,29 31,32 10 11 14 38 43 106 119 15 16 17-18 23 26 51 53,54 56,57 59 60

TE

Na BQL 243 BQL BQL BQL BQL 203 BQL 158 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mg 59.2 30.2 209.2 81.1 25.0 19.5 34.8 16.9 26.3 13.4 12.1 9.9 17.4 12.8 18.6 96.3 20.1 16.4 18.5 131

Al 0.004 0.004 0.009 0.008 0.014 0.009 0.005 0.008 0.006 0.009 0.004 0.003 0.003 0.005 0.004 0.024 0.004 0.003 0.003 0.003 Si 0.180 0.168 0.285 0.165 0.096 0.052 0.033 0.092 0.012 0.011 0.237 0.194 0.173 0.359 0.301 0.629 0.478 0.565 0.531 0.392

P BQL 18054 BQL BQL BQL 16297 12115 BQL 11583 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

K BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Ca BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sc BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ti 0.021 0.013 0.031 0.025 0.050 0.023 0.017 0.021 0.025 0.051 0.011 0.010 0.010 0.017 0.018 0.015 0.012 0.016 0.011 0.009 V 0.310 0.380 0.241 0.454 0.510 0.473 0.448 0.427 0.358 0.435 0.346 0.338 0.296 0.382 0.352 0.323 0.303 0.284 0.266 0.274

Cr BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mn 0.072 0.080 0.263 2.356 0.379 0.131 0.048 0.080 0.239 0.402 BQL BQL BQL BQL BQL BQL 0.491 0.093 BQL BQL Co BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ni BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

TE

Cu 0.396 0.502 0.217 0.716 1.58 1.69 0.741 0.867 1.06 0.741 0.418 0.472 0.544 0.506 0.477 0.299 0.636 0.368 0.494 0.587

Zn BQL BQL BQL BQL BQL BQL 0.003 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Ga BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sr 0.136 0.126 0.880 0.241 0.323 0.163 0.259 0.159 0.273 0.327 0.100 0.172 0.147 0.404 0.114 0.285 0.135 BQL 0.114 0.428

Zr 0.062 0.043 0.065 0.030 0.066 0.045 0.035 0.032 0.033 BQL 0.031 0.030 0.022 0.034 0.034 BQL BQL BQL BQL BQL

Nb BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mo BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL Cd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ba 0.092 0.045 1.263 0.302 0.118 0.032 0.062 0.019 BQL BQL 0.015 0.266 0.040 0.676 0.014 0.361 0.192 0.023 0.020 0.541

Hf BQL BQL BQL 0.092 0.147 0.050 0.062 0.034 BQL BQL 0.113 0.034 0.027 0.073 0.043 0.094 0.106 0.081 0.045 0.073 W BQL BQL BQL 0.074 0.169 0.138 0.113 0.113 BQL BQL 0.069 0.058 0.166 0.119 0.144 0.131 0.184 0.163 0.238 0.206

Pb BQL BQL BQL 0.114 0.078 0.041 0.054 0.072 BQL BQL 0.087 0.081 0.084 0.084 0.076 0.119 0.150 0.099 0.052 0.089

Th BQL BQL BQL 0.117 0.085 0.016 0.019 0.018 BQL BQL 0.014 0.035 0.011 0.042 0.011 0.055 0.027 0.013 0.020 0.062 U BQL BQL BQL 0.061 0.102 0.152 0.040 0.060 BQL BQL 0.022 0.071 0.055 0.088 0.085 0.081 0.094 0.059 0.110 0.095

Ratios Zr/Hf (unnormalized) - - - 12.3 16.8 33.7 21.1 36.0 - - 10.3 33.7 30.9 17.1 30.0 - - - - -

Th/U (unnormalized) - - - 7.51 3.28 0.407 1.84 1.15 - - 2.54 1.95 0.758 1.88 0.512 2.65 1.14 0.835 0.723 2.56

137

Continuation Sample LS-12 LS-13 LS-14 LS-15 LS-19 LS-20 Stage Hm3 Hm3 Hm3 Hm3 Hm2 Hm1 Hm1 Hm1 Hm3 Hm3 Hm1 Hm2 Hm2 Hm2 Hm1 Hm1 Hm1 Hm1 Hm2 Hm1

Texture nodule nodule peloid nodule peloid nodule nodule nodule nodule nodule nodule peloid peloid peloid matrix matrix matrix matrix peloid matrix

ID 63,64 69,71,

72 77 80,81

24,27,28, 32,33,35

10 12,13 14 14,16 28,29, 31,33

47 50 61,62 64 66 68 46,47 48-51,

58 59 60

REE

La 0.041 0.057 0.129 0.040 0.017 4.63 2.66 0.280 0.082 0.071 0.018 0.028 1.34 0.622 0.043 0.209 0.111 0.076 0.305 0.051

Ce 0.031 0.049 0.070 0.034 0.007 1.25 0.635 0.076 0.025 0.021 0.005 0.021 0.960 0.564 0.031 0.152 0.087 0.058 0.256 0.044

Pr 0.057 0.087 0.167 0.057 BQL 3.51 2.34 0.265 0.100 0.077 0.028 0.035 1.23 0.920 0.045 0.197 0.112 0.079 0.346 0.077

Nd 0.065 0.097 0.230 0.115 BQL 3.21 1.98 0.286 0.118 0.098 0.038 0.048 1.71 1.18 0.051 0.240 0.105 0.097 0.479 BQL


Sm 0.113 0.206 0.376 0.089 BQL BQL BQL BQL 0.229 0.158 0.099 0.068 2.45 1.30 0.094 0.260 BQL BQL BQL BQL

Eu 0.135 0.175 0.299 0.113 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Gd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Tb 0.189 0.230 0.475 0.191 BQL BQL BQL BQL 0.312 0.214 0.076 0.113 2.12 2.20 0.136 0.313 BQL BQL BQL BQL

Dy 0.166 0.287 0.224 0.132 BQL BQL BQL 0.360 0.222 0.138 0.115 0.102 2.65 2.60 0.112 0.467 0.284 0.295 0.489 BQL

Y 0.158 0.295 0.343 0.140 0.041 8.38 4.84 0.630 0.266 0.129 0.048 0.107 4.43 3.56 0.171 0.582 0.419 0.240 1.10 0.176

Ho 0.184 0.262 0.541 0.197 BQL BQL BQL 0.328 0.157 0.186 0.090 0.116 3.48 2.42 0.189 0.541 BQL BQL BQL BQL

Er 0.203 0.291 0.617 0.272 BQL BQL BQL BQL 0.230 0.200 0.089 0.122 4.24 2.83 0.172 0.564 0.432 BQL 0.855 BQL

Tm 0.363 0.458 0.765 0.255 BQL BQL BQL BQL BQL BQL BQL BQL BQL 2.02 BQL BQL BQL BQL BQL BQL

Yb 0.285 0.387 0.345 0.294 BQL BQL BQL BQL 0.312 0.232 0.172 0.145 2.76 1.56 0.197 0.569 0.566 BQL 1.54 BQL

Lu 0.200 0.456 0.776 0.306 BQL BQL BQL BQL BQL BQL BQL BQL BQL 1.65 BQL BQL BQL BQL BQL BQL

Anomalies

Pr/Yb 0.20 0.23 0.48 0.20 - - - - 0.32 0.33 0.16 0.24 0.45 0.59 0.23 0.35 0.20 - 0.22 -

Y/Ho (unnormalized) 22.3 29.4 16.5 18.5 - - - 50.1 44.3 18.1 13.9 24.0 33.2 38.5 23.6 28.1 - - - -

Y/Y* (Y/(Dy+Ho)) 0.45 0.54 0.45 0.43 - - - 0.92 0.70 0.40 0.23 0.49 0.72 0.71 0.57 0.58 1.48 0.81 2.24 -

Ce/Ce* (Ce/0.5(La+Pr)) 0.62 0.68 0.48 0.70 - 0.31 0.25 0.28 0.28 0.29 0.23 0.68 0.75 0.73 0.70 0.75 0.78 0.75 0.78 0.69

Pr/Pr* (Pr/0.5(Ce+Nd)) 1.20 1.19 1.11 0.77 - 1.57 1.79 1.46 1.39 1.30 1.29 1.01 0.92 1.06 1.10 1.01 1.17 1.02 0.94

La/La* (La/3Pr-2Nd) - - - - - 0.44 0.38 0.35 - - - - - 3.75 - 2.92 0.33 0.32 0.29 0.22

Gd/Gd* (Gd/0.33Sm + 0.67Tb) - - - - - - - - - - - - - - - - - - - -

Eu/Eu* (Eu/0.67Sm+0.33Tb) 0.98 0.82 0.73 0.93 - - - - - - - - - - - - - - - -

138

Continuation Sample LS-12 LS-13 LS-14 LS-15 LS-19 LS-20 Stage Hm3 Hm3 Hm3 Hm3 Hm2 Hm1 Hm1 Hm1 Hm3 Hm3 Hm1 Hm2 Hm2 Hm2 Hm1 Hm1 Hm1 Hm1 Hm2 Hm1

Texture nodule nodule peloid nodule peloid nodule nodule nodule nodule nodule nodule peloid peloid peloid matrix matrix matrix matrix peloid matrix

ID 63,6 69,71,

72 77 80,81

24,27, 28,32,

33, 35

10 12,13 14 14-16 28,29,

31,33 47 50 61,62 64 66 68 46,47

48-51,

58 59 60

TE

Na 230 1350 BQL 194 512 1011 2690 BQL 240 276 324 213 457 120 891 1169 29227 300 780 320

Mg 174 177 394 76.4 3871 3996 17823 BQL 608 427 15037.1 10017.8 8384.8 2467.5 8173.7 41235.3 4901.9 14453.2 5394.3 16632.7

Al 0.006 0.007 0.006 0.009 0.022 0.024 0.010 BQL 0.006 0.007 0.023 0.019 0.008 0.019 0.008 0.016 0.015 0.015 0.005 0.010

Si 0.301 0.153 1.92 0.131 0.214 0.010 0.032 BQL 0.100 0.079 0.087 0.091 0.030 0.066 0.012 0.043 0.088 0.103 0.023 0.047

P 22071 196898 507503 14487 12122 BQL 17834 BQL 54482 13017 BQL 22066 BQL BQL 15112 BQL BQL BQL 12571 BQL

K BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ca 3.66 64.5 95.6 0.0 15.1 13.0 103 BQL 13.6 4.7 58.1 45.0 42.2 10.6 35.4 150 19.1 51.1 17.9 53.8

Sc BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.369 BQL 0.556 BQL BQL

Ti 0.017 0.020 0.031 0.021 0.039 0.011 0.011 BQL 0.046 0.020 0.028 0.047 0.015 0.026 0.012 0.051 0.054 0.053 0.011 0.034

V 0.472 0.482 0.449 0.480 BQL BQL BQL BQL 0.445 0.498 0.417 0.476 0.454 0.628 0.376 0.494 BQL BQL BQL BQL

Cr BQL BQL BQL BQL 0.049 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.193 BQL BQL

Mn 0.268 0.314 4.86 0.146 BQL BQL BQL BQL 0.220 0.707 BQL 0.689 38.5 0.756 1.411 3.906 BQL BQL BQL BQL

Co BQL BQL BQL BQL 0.034 BQL 0.078 BQL BQL BQL BQL BQL 0.126 0.065 0.084 0.367 0.110 0.218 0.176 0.222

Ni BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.610 BQL BQL BQL BQL BQL BQL BQL

Cu 0.922 2.09 5.98 0.773 0.052 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Zn BQL BQL BQL BQL 0.214 0.155 BQL BQL BQL BQL BQL BQL 0.130 0.171 BQL 0.430 0.178 0.154 BQL BQL

Ga BQL BQL BQL BQL 0.040 0.046 0.030 BQL BQL BQL BQL 0.061 0.032 BQL BQL BQL BQL BQL BQL BQL

Sr 0.195 0.191 0.376 0.186 0.686 96.8 53.8 7.65 0.287 1.19 BQL 0.421 10.3 2.02 1.32 2.29 0.509 1.05 6.58 0.406

Zr 0.058 0.058 0.117 0.059 0.040 BQL 0.128 0.019 BQL BQL BQL 0.032 BQL 0.052 BQL BQL 0.039 0.029 0.017 0.041

Nb BQL BQL BQL BQL 0.020 BQL BQL BQL 0.048 0.058 0.058 0.068 0.153 0.175 0.042 0.112 BQL BQL BQL BQL

Mo BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Cd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ba 0.044 0.028 0.033 0.034 0.760 0.576 0.305 16.2 BQL BQL BQL BQL BQL 0.050 0.109 0.000 0.028 2.11 2.89 0.490

Hf 0.057 0.044 0.205 0.058 BQL BQL BQL BQL 0.089 0.095 0.132 0.045 0.374 0.071 0.026 0.039 BQL BQL BQL BQL

W 0.184 0.194 0.863 0.238 BQL BQL BQL BQL 0.142 0.158 0.094 0.156 0.481 0.100 0.219 0.131 BQL BQL BQL BQL

Pb 0.112 0.111 0.103 0.125 0.873 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.090 BQL BQL

Th 0.033 0.043 0.123 0.043 0.031 BQL BQL 0.056 0.012 0.018 0.013 0.004 0.127 0.039 0.011 0.016 BQL BQL BQL BQL

U 0.053 0.055 0.053 0.044 BQL BQL BQL BQL 0.064 0.055 0.049 0.028 0.131 0.064 0.019 0.023 BQL 0.145 BQL BQL

Zr/Hf (unnormalized) 37.6 49.2 21.4 37.7 - - - - - - - 26.1 - 27.2 - - - - - -

Th/U (unnormalized) 2.47 3.02 9.13 3.80 - - - - 0.772 1.29 1.00 0.633 3.81 2.39 2.22 2.81 - - - -

139

Continuation Sample LS-20 LS-21 DE-02 Stage Hm1 Hm1 Hm1 Hm1 Hm1 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm1 Hm1

Texture matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix

ID 64 66,67 71 72 23 24 25 26 30-33 34 41-42 43-44 48 50 52 59 60 61 91-92 93-94

REE

La 0.169 0.077 0.092 BQL 0.091 BQL 0.256 0.037 0.053 0.032 0.053 0.047 0.144 BQL 0.481 0.241 0.022 0.062 0.654 0.330

Ce 0.116 0.065 0.080 0.076 0.102 BQL 0.236 0.032 0.050 0.019 0.035 0.044 0.105 0.043 0.273 0.116 0.020 0.049 0.508 0.186

Pr 0.122 0.086 BQL BQL 0.092 BQL 0.281 BQL 0.063 BQL 0.041 BQL 0.200 0.052 0.396 0.283 BQL 0.078 0.615 0.353

Nd 0.138 0.119 BQL BQL 0.105 BQL 0.292 BQL 0.089 BQL 0.073 0.081 0.134 BQL 0.447 0.375 BQL 0.081 0.619 BQL


Sm BQL BQL BQL BQL BQL BQL 0.407 BQL BQL BQL BQL BQL BQL BQL BQL 0.564 BQL BQL BQL BQL

Eu BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Gd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 1.17 BQL BQL BQL BQL

Tb BQL BQL BQL BQL BQL BQL 0.434 BQL BQL BQL BQL BQL BQL BQL BQL 1.15 BQL BQL 0.646 0.379

Dy BQL BQL 0.385 BQL BQL BQL 0.727 BQL 0.178 BQL BQL BQL 0.375 BQL 0.430 1.42 BQL BQL BQL BQL

Y 0.497 0.233 0.548 0.325 0.279 BQL 1.04 0.136 0.230 0.141 0.136 0.141 1.04 0.138 0.661 2.39 0.129 0.197 1.11 0.801

Ho 0.393 BQL 0.492 BQL BQL BQL 0.680 BQL 0.311 BQL BQL BQL BQL BQL 0.680 1.71 BQL BQL BQL BQL

Er BQL BQL BQL BQL BQL BQL 1.04 BQL 0.269 BQL BQL BQL 0.804 BQL BQL 1.86 BQL BQL BQL BQL

Tm BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 1.22 BQL BQL 1.73 BQL BQL BQL BQL

Yb BQL BQL BQL BQL BQL BQL 0.858 BQL 0.465 BQL BQL BQL 0.812 BQL BQL 2.00 BQL BQL BQL BQL

Lu BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 1.63 BQL BQL 1.57 BQL BQL BQL BQL

Anomalies

Pr/Yb - - - - - - 0.33 - 0.13 - - - 0.25 - - 0.14 - - - -

Y/Ho (unnormalized) 33.0 - 29.1 - - - 39.7 - 19.3 - - - - - 25.3 36.4 - - - -

Y/Y* (Y/(Dy+Ho)) 1.26 - 0.62 - - - 0.74 - 0.47 - - - 2.76 - 0.60 0.76 - - - -

Ce/Ce* (Ce/0.5(La+Pr)) 0.80 0.80 - - 1.11 - 0.88 - 0.86 - 0.74 - 0.61 - 0.62 0.44 - 0.70 0.80 0.55

Pr/Pr* (Pr/0.5(Ce+Nd)) 0.96 0.93 - - 0.89 - 1.07 - 0.90 - 0.77 - 1.68 - 1.10 1.15 1.20 1.09 -

La/La* (La/3Pr-2Nd) 0.46 0.30 - - 0.33 - 8.52 - 0.28 - 0.43 - 0.24 - 0.40 - - 0.26 0.35 0.31

Gd/Gd* (Gd/0.33Sm + 0.67Tb) - - - - - - - - - - - - - - - 1.22 - - - -

Eu/Eu* (Eu/0.67Sm+0.33Tb) - - - - - - - - - - - - - - - - - - - -

140

Continuation Sample LS-20 LS-21 DE-02 Stage Hm1 Hm1 Hm1 Hm1 Hm1 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm3 Hm1 Hm1

Texture matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix matrix

ID 64 66,67 71 72 23 24 25 26 30-33 34 41-42 43-44 48 50 52 59 60 61 91-92 93-94

TE

Na 471 527 349 395 284 293 0 291 177 207 189 398 189 BQL 209 468 421 BQL 312 BQL

Mg 33430.3 24000.7 32009.5 33341.9 21707.9 68.1 68.9 54.8 50.5 51.1 65.6 101.1 74.8 27.1 50.5 60.3 111.8 32.5 100.3 52.9

Al 0.007 0.066 0.007 0.006 0.005 0.008 0.010 0.008 0.008 0.014 0.011 0.008 0.009 0.013 0.007 0.008 0.012 0.007 0.019 0.017

Si 0.172 0.132 0.281 0.123 0.147 0.011 0.015 0.011 0.011 0.033 0.012 0.012 0.007 0.015 0.010 0.014 0.039 0.050 0.163 0.050

P BQL 15687 BQL BQL BQL 15598 13861 16876 12756 22016 14705 17457 13726 12262 11325 14002 13357 BQL 20989 BQL

K BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ca 96.5 75.6 101 129 73.1 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sc 0.503 BQL 0.383 0.392 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.300 0.268

Ti 0.023 0.018 0.022 0.019 0.035 0.029 0.036 0.020 0.029 0.021 0.040 0.021 0.029 0.039 0.029 0.019 0.018 0.032 0.045 0.063

V BQL BQL BQL BQL 0.640 0.451 0.440 0.536 0.478 0.465 0.537 0.547 0.431 0.573 0.503 0.500 0.530 0.532 0.509 0.542

Cr BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mn BQL BQL BQL BQL 1.910 0.054 0.021 0.039 0.032 0.023 0.041 0.040 BQL 0.073 0.035 0.023

0.027 0.085 0.078

Co 0.383 0.305 0.404 0.401 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ni BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Cu BQL BQL BQL BQL 6.020 1.830 1.808 1.002 2.461 7.922 1.505 0.928 1.518 2.183 2.425 0.748 1.536 2.189 12.187 2.293

Zn 0.189 0.528 0.289 0.235 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ga BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sr 1.167 1.275 2.410 1.648 1.316 1.765 0.450 0.353 0.429 0.265 0.315 0.484 0.753 0.334 2.000 2.590 0.299 0.522 4.538 1.267

Zr 0.040 0.024 0.010 0.000 0.062 0.046 0.044 0.051 0.047 0.036 0.040 0.052 0.038 0.059 0.056 0.042 0.041 0.046 0.068 0.063

Nb BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mo BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Cd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ba 0.022 0.103 1.566 0.283 0.029 0.827 0.169 0.046 0.063 0.036 0.058 0.176 0.424 0.069 1.176 0.943 0.048 0.138 3.350 0.655

Hf BQL BQL BQL BQL BQL BQL 0.194 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

W BQL BQL BQL BQL BQL BQL BQL 0.331 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Pb BQL BQL BQL BQL 0.133 BQL 0.094 BQL 0.059 BQL 0.083 0.083 BQL BQL 0.093 0.206 BQL BQL BQL BQL

Th BQL BQL BQL BQL BQL BQL 0.065 BQL BQL BQL BQL BQL 0.034 BQL 0.084 BQL BQL BQL BQL BQL

U BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.180 BQL BQL BQL BQL

Zr/Hf (unnormalized) - - - - - - 8.408 - - - - - - - - - - - - - Th/U (unnormalized) - - - - - - - - - - - - - - - - - - - -

141

Continuation Sample DE-04 DE-06 DE-08 DE-11 Stage Hm3 Hm1 Hm2 Hm2 Hm2 Hm1 Hm2 Hm1 Hm1 Hm1 Hm1 Hm1 Hm3 Hm1

Texture matrix matrix nodule Nodule nodule matrix matrix matrix matrix matrix matrix nodule nodule matrix

ID 75,76,79 68 70 77 128-132 76-77 58,60,61 74 84,85 31,32 35 43 48,50-52 61,62

REE

La 0.045 0.034 0.032 0.336 0.127 0.169 0.454 0.130 0.316 0.169 0.062 0.071 0.210 0.060

Ce 0.038 0.036 0.026 0.260 0.128 0.149 0.469 0.137 0.325 0.141 0.064 0.057 0.176 0.051

Pr BQL BQL BQL 0.298 BQL BQL 0.556 BQL 0.687 0.209 0.070 0.065 0.272 0.070

Nd 0.092 BQL BQL 0.237 BQL BQL 0.701 BQL 0.805 0.229 0.088 0.105 0.328 0.091

Pm BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sm BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.290 0.108 0.190 0.380 0.157

Eu BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.255 0.169 0.127 0.402 0.135

Gd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Tb BQL BQL BQL BQL 0.543 0.399 1.10 0.929 0.798 0.455 0.154 0.239 0.532 0.170

Dy BQL BQL BQL 0.913 BQL BQL BQL BQL BQL 0.549 0.136 0.143 0.643 0.224

Y 0.176 0.154 0.092 1.14 1.45 0.599 1.44 1.72 1.27 0.716 0.174 0.251 0.944 0.184

Ho BQL BQL BQL 1.02 BQL BQL BQL BQL BQL 0.684 0.157 0.303 0.657 0.230

Er BQL BQL BQL 1.37 BQL BQL BQL 1.67 BQL 0.651 0.157 0.231 0.760 0.334

Tm BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.727 0.296 0.471 0.802 0.296

Yb BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.738 0.197 0.538 0.685 0.368

Lu BQL BQL BQL 1.92 BQL BQL BQL BQL BQL 0.663 0.429 0.306 0.852 0.459

Anomalies

Pr/Yb - - - - - - - - - 0.28 0.35 0.12 0.40 0.19

Y/Ho (unnormalized) - - - 29.0 - - - - - 27.4 28.9 21.6 37.5 20.9

Y/Y* (Y/(Dy+Ho)) - - - 0.59 - - - - - 0.58 0.59 0.56 0.73 0.40

Ce/Ce* (Ce/0.5(La+Pr)) - - - 0.82 - - 0.93 - 0.65 0.74 0.98 0.84 0.73 0.79

Pr/Pr* (Pr/0.5(Ce+Nd)) - - - 1.20 - - 0.95 - 1.22 1.13 0.92 0.80 1.08 0.98

La/La* (La/3Pr-2Nd) - - - 0.38 - - 0.27 - 0.15 3.55 - - 3.68 -

Gd/Gd* (Gd/0.33Sm + 0.67Tb) - - - - - - - - - - - - - -

Eu/Eu* (Eu/0.67Sm+0.33Tb) - - - - - - - - - 0.74 1.38 0.62 0.93 0.83

142

Continuation Sample DE-04 DE-06 DE-08 DE-11

Stage Hm3 Hm1 Hm2 Hm2 Hm2 Hm1 Hm2 Hm1 Hm1 Hm1 Hm1 Hm1 Hm3 Hm1 Texture matrix matrix nodule nodule nodule matrix matrix matrix matrix matrix matrix nodule nodule matrix

ID 75,76,79 68 70 77 128-132 76-77 58,60,61 74 84,85 31,32 35 43 48,50-52 61,62

TE

Na BQL BQL BQL BQL 236 BQL 252 BQL 193 BQL BQL BQL BQL BQL

Mg 30.4 17.4 14.5 65.6 229 1810 1582 621.6 966 15.3 18.9 19.8 18.2 18.0

Al 0.010 0.008 0.003 0.004 0.050 0.018 0.015 0.018 0.019 0.006 0.006 0.005 0.006 0.006

Si 0.172 0.121 0.345 0.152 0.398 0.559 0.302 0.209 0.126 0.168 0.122 0.134 0.208 0.106

P 14846 BQL BQL BQL 54933 BQL 59555 34723 63780 BQL BQL BQL BQL BQL

K BQL BQL BQL BQL 1271 321 BQL BQL 349 BQL BQL BQL BQL BQL

Ca BQL BQL BQL BQL BQL 18 11 7 14 BQL BQL BQL BQL BQL

Sc BQL BQL BQL 0.311 BQL BQL 0.338 BQL BQL BQL BQL BQL BQL BQL

Ti 0.020 0.058 0.008 0.009 0.178 0.046 0.046 0.035 0.042 0.023 0.027 0.016 0.022 0.022

V 0.450 0.381 0.291 0.215 0.516 0.559 0.482 0.504 0.565 0.419 0.422 0.385 0.434 0.427

Cr BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mn 0.027 0.028 BQL 0.039 1.09 0.507 2.579 0.118 0.161 BQL BQL BQL BQL BQL

Co BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ni BQL BQL BQL BQL 0.366 BQL BQL BQL BQL BQL BQL BQL BQL BQL

Cu 2.76 1.38 1.19 1.30 3.49 1.448 1.197 0.815 0.966 0.767 0.753 0.949 0.855 0.880

Zn 0.048 BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ga BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Sr 0.466 0.456 0.139 0.246 0.151 0.287 0.871 0.190 0.401 0.245 0.182 0.211 0.289 0.200

Zr 0.048 0.054 0.049 0.050 0.841 0.132 0.250 0.124 0.126 0.061 0.058 0.072 0.067 0.055

Nb BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Mo BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Cd BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL BQL

Ba 0.057 0.059 0.054 0.054 BQL BQL 0.058 BQL BQL 0.236 0.021 0.025 0.054 0.043

Hf BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.080 0.045 0.033 0.085 0.071

W BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.159 0.150 0.075 0.120 0.184

Pb BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.056 0.070 0.059 0.077 0.077

Th BQL BQL BQL BQL BQL BQL 0.373 BQL BQL 0.056 0.015 0.017 0.055 0.014

U BQL BQL BQL BQL BQL BQL BQL BQL BQL 0.039 0.027 0.036 0.044 0.064

Zr/Hf (unnormalized) - - - - - - - - - 28.5 47.9 81.5 29.6 28.8

Th/U (unnormalized) - - - - - - - - - 5.64 2.27 1.84 4.94 0.889

143

Appendix F– Factor analysis

Tables F.1- EMP data. Sample Field ID Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

LS-13

C1_Hem-1 1 BDL 0.396 0.218 0.016 87.0 0.145 0.026 0.096 0.003 BDL

C1_Hem-2 2 0.041 0.519 0.415 BDL 87.0 0.143 0.063 0.084 0.011 BDL C1_Hem-3 3 BDL 0.395 0.757 0.013 86.4 0.176 0.071 0.109 0.002 0.031

C1_Hem-4 1 BDL 0.378 0.35 0.01 86.9 0.109 0.151 0.102 0.007 BDL

C1_Hem-5 2 BDL 0.42 0.324 0.011 87.2 0.104 0.028 0.131 0.004 BDL C1_Hem-6 3 BDL 0.325 0.281 0.029 86.6 0.149 0.049 0.192 0.017 0.037

C2_Hem-7 4 BDL 6.17 0.254 0.006 82.1 0.097 0.009 0.2 0.018 BDL

C2_Hem-8 5 BDL 5.94 0.231 0.01 82.7 0.147 0.065 0.202 0.012 BDL C2_Hem-9 6 0.003 0.487 0.292 0.006 86.3 0.18 0.073 0.236 0.017 0.002

C2_Hem-10 7 BDL 1.81 0.366 0.031 86.0 0.124 0.029 0.273 0.013 0.046

C2_Hem-11 8 BDL 0.434 0.402 0.025 86.8 0.109 BDL 0.163 0.003 0.028 C2_Hem-13 10 0.014 0.493 0.667 0.001 86.2 0.086 0.098 0.131 0.02 0.049

C2_Hem-14 11 BDL 1.50 0.29 0.018 85.5 0.098 0.059 0.235 0.007 0.037

C3_Hem-15 12 BDL 0.782 0.302 0.01 86.8 0.101 0.028 0.08 0.005 BDL C3_Hem-16 13 BDL 0.267 0.176 BDL 87.7 0.122 0.017 0.038 0.006 BDL

C3_Hem-17 14 BDL 0.245 0.385 0.007 87.7 0.08 BDL 0.093 0.017 0.032

C3_Hem-18 15 BDL 0.273 0.422 0.017 88.0 0.104 0.033 0.067 0.024 0.01

LS-15

C4_Hem-19 16 0.023 0.371 0.216 BDL 86.1 0.166 BDL 0.383 0.018 0.054

C4_Hem-20 17 0.003 0.346 0.455 0.013 85.3 0.159 0.007 0.589 0.017 0.054

C4_Hem-21 18 BDL 0.294 0.126 0.173 85.7 0.166 0.04 0.938 0.008 BDL C5_Hem-22 19 BDL 0.273 0.158 0.002 88.8 0.051 BDL 0.058 BDL BDL

C5_Hem-23 20 BDL 1.53 0.24 0.019 87.1 0.046 0.057 0.025 0.014 0.02

C5_Hem-24 21 BDL 0.519 0.173 0.029 87.6 0.116 0.04 0.075 0.004 0.011 C5_Hem-25 22 BDL 1.95 0.064 BDL 87.4 0.105 0.039 0.155 0.007 0.04

C5_Hem-26 23 0.006 0.385 0.103 0.022 87.6 0.159 0.014 0.264 0.011 BDL

C5_Hem-27 24 BDL 0.82 0.075 0.41 83.9 0.157 0.058 1.62 0.004 0.039 C5_Hem-28 25 BDL 0.46 0.147 0.016 87.8 0.135 0.046 0.28 0.014 BDL

C6_Hem-29 26 0.049 0.393 0.211 BDL 87.0 0.137 BDL 0.096 0.006 BDL


C6_Hem-34 31 BDL 1.28 0.068 BDL 87.4 0.189 0.016 0.174 0.007 BDL

C6_Hem-35 32 BDL 0.417 0.085 0.01 88.2 0.132 0.051 0.123 0.004 0.03

LS-20

C7_Hem-36 33 BDL 0.311 0.213 0.041 87.5 0.127 BDL 0.228 BDL 0.059

C7_Hem-37 34 BDL 0.581 0.089 0.016 87.5 0.176 0.028 0.12 0.006 BDL

C7_Hem-38 35 0.037 0.429 0.056 BDL 86.9 0.161 0.009 0.118 BDL 0.026 C7_Hem-39 36 0.017 0.372 0.1 BDL 86.0 0.165 0.011 0.119 0.019 0.044

C7_Hem-40 37 0.003 0.669 0.147 0.028 87.7 0.186 0.076 0.311 0.005 0.045

C7_Hem-41 38 BDL 0.379 0.137 0.014 87.0 0.134 0.053 0.235 BDL 0.047 C7_Hem-42 43 0.04 0.339 0.105 0.034 86.8 0.154 0.026 0.385 0.001 0.041

C7_Hem-43 44 BDL 0.396 0.167 0.01 87.1 0.134 0.076 0.208 0.013 0.04

C7_Hem-44 45 0.012 0.375 0.093 0.027 87.5 0.176 0.103 0.282 0.001 0.047

LS-11

C1_Hem-1 1 BDL 0.622 0.074 BDL 87.4 0.073 BDL 0.084 0.014 0.056 C1_Hem-2 2 BDL 2.73 0.033 BDL 86.3 0.082 0.059 0.12 0.021 BDL

C1_Hem-3 3 BDL 8.94 0.022 BDL 81.2 0.081 0.028 0.059 BDL 0.009

C1_Hem-4 4 BDL 0.914 0.059 BDL 88.2 0.07 0.04 0.096 0.006 BDL C1_Hem-5 5 BDL 6.58 0.052 0.005 82.5 0.101 BDL 0.071 0.002 BDL

C2_Hem-6 6 BDL 0.79 0.071 BDL 87.8 0.066 0.017 0.074 0.008 BDL C2_Hem-7 7 BDL 0.272 0.099 BDL 88.1 0.039 0.02 0.045 0.003 0.006

C2_Hem-8 8 BDL 0.49 0.124 BDL 88.0 0.001 0.01 0.035 0.015 BDL

C2_Hem-9 9 BDL 0.317 0.13 BDL 87.7 0.036 0.029 0.041 0.002 BDL C2_Hem-10 10 BDL 0.241 0.117 BDL 88.2 0.037 BDL 0.012 0.01 BDL

C2_Hem-11 11 BDL 0.303 0.149 BDL 87.9 0.01 BDL 0.04 0.002 0.008

C2_Hem-12 12 BDL 0.322 0.115 BDL 88.3 0.055 0.009 0.043 0.005 0.026 C2_Hem-13 13 BDL 0.269 0.079 BDL 87.9 0.059 0.04 0.099 BDL 0.001

DE-06

C3_Hem-14 14 BDL 5.21 0.226 0.031 82.7 0.005 0.156 0.041 0.025 BDL

C3_Hem-15 15 BDL 2.9 0.28 0.006 85.3 0.023 0.19 0.051 0.029 0.038

C3_Hem-16 16 BDL 1.09 0.364 0.003 86.5 0.017 0.351 0.026 0.023 0.031 C3_Hem-17 17 BDL 1.29 0.478 0.02 86.3 0.009 0.367 0.033 0.026 0.069

LS-12

C4_Hem-18 18 BDL 0.577 0.115 0.014 87.8 0.161 0.037 0.116 0.004 0.042

C4_Hem-19 19 BDL 0.361 0.191 BDL 88.3 0.053 0.062 0.021 0.012 0.04

C4_Hem-20 20 BDL 0.667 0.061 BDL 87.5 0.205 0.015 0.208 0.005 0.04

C4_Hem-21 21 0.022 0.691 0.108 0.001 87.6 0.169 0.029 0.168 0.003 0.02

C4_Hem-22 22 0.007 0.902 0.18 0.009 87.0 0.211 0.012 0.173 0.011 BDL

C4_Hem-23 23 0.016 0.527 0.098 BDL 87.6 0.188 0.001 0.085 0.009 0.053

C4_Hem-24 24 BDL 0.633 0.052 0.002 87.9 0.175 0.02 0.136 BDL 0.049

DE-11

C5_Hem-25 25 BDL 4.58 0.128 0.007 84.7 0.093 BDL 0.14 BDL BDL

C5_Hem-26 26 BDL 4.96 0.049 BDL 84.3 0.133 0.004 0.145 0.007 BDL C5_Hem-27 27 BDL 3.88 0.097 BDL 85.7 0.151 0.026 0.13 0.004 0.009

144

Continuation Sample Field ID Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

DE-11

C5_Hem-28 28 BDL 0.683 0.149 0.034 88.3 0.094 0.034 0.121 0.014 0.008

C5_Hem-29 29 BDL 3.86 0.071 0.01 85.7 0.092 0.01 0.125 0.015 0.002

C5_Hem-30 30 BDL 1.09 0.114 BDL 87.5 0.1 0.052 0.083 BDL 0.025 C5_Hem-31 31 BDL 3.33 0.116 0.013 86.5 0.105 0.038 0.098 BDL 0.012

LS-09

C6_Hem-32 32 BDL 0.627 0.127 BDL 87.2 0.219 0.053 0.182 0.008 BDL

C6_Hem-33 33 BDL 0.475 0.086 0.011 87.9 0.215 0.038 0.217 0.002 0.031

C6_Hem-34 34 BDL 2.90 0.127 0.008 85.8 0.251 0.101 0.156 0.005 0.023 C6_Hem-35 35 0.001 0.563 0.057 0.005 87.3 0.23 0.033 0.152 0.009 BDL

C6_Hem-36 36 BDL 0.817 0.186 0.033 87.3 0.117 0.077 0.184 0.003 0.029

C6_Hem-37 37 BDL 5.70 0.222 BDL 83.3 0.067 0.066 0.018 0.016 0.038

DE-02

C1_Hem-1 1 BDL 0.317 0.141 BDL 88.6 0.172 0.05 0.084 0.006 BDL

C1_Hem-2 2 BDL 0.6 0.155 BDL 88.2 0.167 0.043 0.077 0.01 0.008

C1_Hem-3 3 BDL 0.516 0.126 0.008 87.9 0.14 0.042 0.102 BDL BDL C1_Hem-4 4 BDL 0.406 0.164 0.025 87.4 0.181 0.007 0.19 0.006 BDL

C1_Hem-5 5 BDL 0.434 0.125 BDL 87.9 0.166 0.018 0.136 0.006 0.004

C1_Hem-6 6 BDL 0.38 0.263 BDL 87.5 0.065 0.044 0.092 BDL 0.005 C1_Hem-7 7 BDL 0.445 0.315 0.009 88.0 0.134 BDL 0.11 BDL 0.015

C2_Hem-8 8 BDL 0.658 0.219 0.016 88.2 0.124 0.026 0.135 0.009 0.003

C2_Hem-9 9 BDL 0.3 0.103 BDL 88.8 0.119 0.032 0.11 0.006 0.03 C2_Hem-10 10 BDL 3.58 0.31 0.018 85.3 0.068 0.113 0.161 0.001 0.038

C2_Hem-11 11 BDL 0.34 0.105 0.011 87.6 0.16 0.01 0.099 0.009 BDL

C2_Hem-12 12 BDL 0.514 0.336 0.01 88.2 0.068 0.115 0.063 BDL 0.025 C2_Hem-13 13 BDL 2.49 0.339 BDL 86.1 0.035 0.135 0.04 0.002 0.009

C3_Hem-14 14 BDL 5.81 0.11 0.033 84.2 0.051 0.035 0.055 0.013 0.024


C4_Hem-17 17 BDL 1.51 0.147 BDL 87.1 0.017 0.022 0.037 0.014 0.034

Normalized data following Templeton (2011). Data normalization with SPSS. Sample Field ID Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

LS-13

C1_Hem-1 1 0 0.59 0.26 0.05 86.4 0.14 0.03 0.1 0 0

C1_Hem-2 2 0.02 1.37 0.4 -0.02 86.5 0.14 0.1 0.06 0.01 0 C1_Hem-3 3 0 0.51 0.6 0.04 85.9 0.18 0.11 0.13 0 0.03

C1_Hem-4 1 0 0.24 0.35 0.03 86.3 0.11 0.15 0.13 0.01 0

C1_Hem-5 2 0 0.77 0.33 0.03 86.7 0.1 0.04 0.2 0.01 0 C1_Hem-6 3 0 -0.35 0.3 0.07 86.1 0.14 0.08 0.31 0.02 0.03

C2_Hem-7 4 0 5 0.28 0.01 83.7 0.1 -0.01 0.32 0.02 0 C2_Hem-8 5 0 4.69 0.27 0.03 84.3 0.14 0.1 0.33 0.01 0

C2_Hem-9 6 0.01 1.11 0.31 0.01 85.9 0.19 0.11 0.39 0.02 0.01

C2_Hem-10 7 0 2.81 0.37 0.08 85.5 0.12 0.04 0.43 0.01 0.04 C2_Hem-11 8 0 0.89 0.39 0.06 86.2 0.11 -0.04 0.26 0 0.03

C2_Hem-13 10 0.02 1.2 0.49 0 85.7 0.09 0.12 0.2 0.02 0.05

C2_Hem-14 11 0 2.62 0.3 0.05 85.2 0.1 0.09 0.38 0.01 0.03 C3_Hem-15 12 0 2.07 0.31 0.03 86.2 0.1 0.04 0.04 0.01 0

C3_Hem-16 13 0 -1.95 0.23 -0.02 87.5 0.12 0.02 -0.1 0.01 0

C3_Hem-17 14 0 -2.26 0.38 0.02 87.6 0.08 -0.04 0.09 0.02 0.03 C3_Hem-18 15 0 -1.29 0.41 0.05 88.3 0.1 0.05 0.01 0.02 0.02

LS-15

C4_Hem-19 16 0.02 0.06 0.25 -0.02 85.6 0.17 -0.04 0.49 0.02 0.05

C4_Hem-20 17 0.01 -0.14 0.43 0.04 85.2 0.15 -0.01 0.55 0.02 0.05

C4_Hem-21 18 0 -1.09 0.16 0.12 85.4 0.17 0.07 0.61 0.01 0 C5_Hem-22 19 0 -1.29 0.21 0.01 90.4 0.06 -0.04 -0.01 0 0

C5_Hem-23 20 0 2.74 0.28 0.06 86.7 0.05 0.09 -0.18 0.01 0.02

C5_Hem-24 21 0 1.37 0.22 0.07 87.4 0.11 0.07 0.03 0.01 0.02 C5_Hem-25 22 0 2.94 0.03 -0.02 86.9 0.11 0.06 0.24 0.01 0.04

C5_Hem-26 23 0.01 0.4 0.11 0.06 87.4 0.15 0.01 0.4 0.01 0

C5_Hem-27 24 0 2.22 0.06 0.16 84.5 0.15 0.09 0.76 0.01 0.03 C5_Hem-28 25 0 1.01 0.19 0.05 87.8 0.13 0.07 0.44 0.01 0

C6_Hem-29 26 0.03 0.46 0.24 -0.02 86.5 0.13 -0.04 0.1 0.01 0

C6_Hem-30 27 0 -0.07 0.12 0.02 87.7 0.14 0.02 0.41 0 0 C6_Hem-31 28 0 -0.5 -0.06 -0.02 89.7 0.16 0.05 0.29 0.01 0

C6_Hem-34 31 0 2.5 0.04 -0.02 86.9 0.2 0.01 0.28 0.01 0

C6_Hem-35 32 0 0.72 0.07 0.03 88.9 0.12 0.08 0.18 0.01 0.03

LS-20

C7_Hem-36 33 0 -0.77 0.25 0.11 87.0 0.12 -0.04 0.36 0 0.06

C7_Hem-37 34 0 1.58 0.08 0.05 87.2 0.18 0.04 0.17 0.01 0

C7_Hem-38 35 0.02 0.82 0 -0.02 86.3 0.16 -0.01 0.16 0 0.03 C7_Hem-39 36 0.02 0.12 0.1 -0.02 88.2 0.16 0 0.16 0.02 0.04

C7_Hem-40 37 0.01 1.92 0.19 0.07 87.6 0.2 0.11 0.47 0.01 0.04

C7_Hem-41 38 0 0.29 0.18 0.04 86.5 0.13 0.08 0.38 0 0.04 C7_Hem-42 43 0.02 -0.27 0.12 0.1 86.1 0.15 0.03 0.52 0 0.04

C7_Hem-43 44 0 0.59 0.22 0.03 86.6 0.13 0.11 0.34 0.01 0.04

C7_Hem-44 45 0.01 0.18 0.09 0.07 87.3 0.18 0.13 0.46 0 0.04

145

Continuation Sample Field ID Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

LS-11

C1_Hem-1 1 0 1.68 0.06 -0.02 87.0 0.08 -0.04 0.06 0.01 0.06

C1_Hem-2 2 0 3.08 -0.09 -0.02 85.8 0.09 0.09 0.17 0.02 0

C1_Hem-3 3 0 6.89 -0.12 -0.02 83.2 0.08 0.04 -0.01 0 0.02 C1_Hem-4 4 0 2.33 0.02 -0.02 88.6 0.08 0.07 0.1 0.01 0

C1_Hem-5 5 0 5.49 -0.01 0.01 83.9 0.1 -0.04 0.01 0 0

C2_Hem-6 6 0 2.12 0.05 -0.02 87.7 0.07 0.02 0.02 0.01 0 C2_Hem-7 7 0 -1.53 0.1 -0.02 88.5 0.05 0.02 -0.04 0 0.02

C2_Hem-8 8 0 1.16 0.15 -0.02 88.4 -0.01 0 -0.12 0.01 0

C2_Hem-9 9 0 -0.63 0.18 -0.02 87.7 0.04 0.04 -0.06 0 0 C2_Hem-10 10 0 -2.75 0.15 -0.02 89.1 0.05 -0.04 -0.29 0.01 0

C2_Hem-11 11 0 -0.87 0.2 -0.02 88.1 0.02 -0.04 -0.08 0 0.02

C2_Hem-12 12 0 -0.42 0.14 -0.02 89.5 0.06 -0.01 -0.05 0.01 0.03 C2_Hem-13 13 0 -1.72 0.07 -0.02 88.1 0.07 0.07 0.12 0 0.01

DE-06

C3_Hem-14 14 0 4.1 0.27 0.08 84.1 0 0.16 -0.06 0.02 0

C3_Hem-15 15 0 3.24 0.29 0.01 85.0 0.04 0.17 -0.03 0.03 0.03

C3_Hem-16 16 0 2.39 0.36 0.01 86.0 0.03 0.18 -0.16 0.02 0.03

C3_Hem-17 17 0 2.56 0.45 0.06 85.8 0.01 0.23 -0.14 0.02 0.08

LS-12

C4_Hem-18 18 0 1.53 0.14 0.04 87.8 0.16 0.06 0.15 0.01 0.04 C4_Hem-19 19 0 0 0.24 -0.02 89.2 0.06 0.1 -0.2 0.01 0.04

C4_Hem-20 20 0 1.87 0.02 -0.02 87.1 0.21 0.01 0.34 0.01 0.04

C4_Hem-21 21 0.02 2.02 0.13 0 87.3 0.17 0.04 0.27 0 0.02 C4_Hem-22 22 0.01 2.28 0.23 0.02 86.4 0.21 0.01 0.28 0.01 0

C4_Hem-23 23 0.02 1.44 0.1 -0.02 87.5 0.2 -0.02 0.08 0.01 0.05

C4_Hem-24 24 0 1.77 -0.01 0.01 87.9 0.18 0.02 0.22 0 0.05

DE-11

C5_Hem-25 25 0 3.83 0.18 0.02 84.9 0.09 -0.04 0.22 0 0

C5_Hem-26 26 0 3.96 -0.03 -0.02 84.8 0.13 -0.02 0.23 0.01 0

C5_Hem-27 27 0 3.6 0.09 -0.02 85.3 0.14 0.03 0.19 0.01 0.02

C5_Hem-28 28 0 1.97 0.2 0.1 89.3 0.09 0.05 0.18 0.01 0.02

C5_Hem-29 29 0 3.5 0.05 0.03 85.4 0.09 0 0.19 0.01 0.01

C5_Hem-30 30 0 2.44 0.14 -0.02 87.1 0.1 0.08 0.05 0 0.02

C5_Hem-31 31 0 3.32 0.15 0.04 86.1 0.11 0.06 0.11 0 0.02

LS-09

C6_Hem-32 32 0 1.72 0.17 -0.02 86.7 0.23 0.08 0.29 0.01 0

C6_Hem-33 33 0 1.06 0.08 0.03 88.0 0.22 0.06 0.35 0 0.03

C6_Hem-34 34 0 3.16 0.17 0.02 85.5 0.29 0.12 0.25 0.01 0.02

C6_Hem-35 35 0.01 1.49 0.01 0.01 86.8 0.25 0.05 0.23 0.01 0

C6_Hem-36 36 0 2.17 0.24 0.09 86.8 0.11 0.12 0.3 0 0.03

C6_Hem-37 37 0 4.26 0.26 -0.02 84.4 0.07 0.1 -0.24 0.02 0.03

DE-02

C1_Hem-1 1 0 -0.63 0.19 -0.02 90.0 0.17 0.08 0.06 0.01 0

C1_Hem-2 2 0 1.63 0.21 -0.02 88.7 0.17 0.07 0.03 0.01 0.02 C1_Hem-3 3 0 1.3 0.16 0.02 88.2 0.14 0.07 0.13 0 0

C1_Hem-4 4 0 0.67 0.21 0.06 86.9 0.19 -0.01 0.31 0.01 0

C1_Hem-5 5 0 0.89 0.16 -0.02 87.9 0.17 0.02 0.22 0.01 0.01 C1_Hem-6 6 0 0.35 0.29 -0.02 87.2 0.07 0.07 0.08 0 0.02

C1_Hem-7 7 0 0.96 0.32 0.02 88.4 0.13 -0.04 0.14 0 0.02

C2_Hem-8 8 0 1.82 0.26 0.05 89.0 0.12 0.03 0.21 0.01 0.01 C2_Hem-9 9 0 -0.98 0.11 -0.02 91.6 0.12 0.05 0.14 0.01 0.03

C2_Hem-10 10 0 3.41 0.32 0.05 85.1 0.08 0.13 0.25 0 0.03

C2_Hem-11 11 0 -0.2 0.12 0.03 87.3 0.15 0 0.12 0.01 0 C2_Hem-12 12 0 1.25 0.34 0.03 88.8 0.08 0.14 0 0 0.02

C2_Hem-13 13 0 3.01 0.34 -0.02 85.7 0.04 0.14 -0.08 0 0.02

C3_Hem-14 14 0 4.45 0.13 0.09 84.7 0.06 0.05 -0.02 0.01 0.02 C3_Hem-15 15 0 3.71 0.22 0.04 84.8 0.09 0.01 0.05 0.02 0

C4_Hem-16 16 0 2.87 -0.05 -0.02 86.0 0.12 0.05 0.25 0.01 0

C4_Hem-17 17 0 2.68 0.19 -0.02 86.6 0.03 0.03 -0.11 0.01 0.03

Tables F.2- Factor analysis of EMP elements. Data processing with XLSTAT 2014.5.03.

Correlation matrix (Pearson). Values in bold are different from 0 with a significance level alpha=0.05. Variables Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

Na2O 1 -0.134 0.044 -0.117 -0.058 0.309 -0.150 0.221 0.098 0.178

SiO2 -0.134 1 -0.169 0.032 -0.674 -0.072 0.219 -0.034 0.099 -0.055 Al2O3 0.044 -0.169 1 0.270 -0.118 -0.204 0.304 -0.109 0.219 0.204

MgO -0.117 0.032 0.270 1 -0.237 0.086 0.212 0.466 -0.027 0.161

FeO -0.058 -0.674 -0.118 -0.237 1 0.030 -0.161 -0.195 -0.205 -0.021 P2O5 0.309 -0.072 -0.204 0.086 0.030 1 -0.102 0.631 -0.070 -0.024

TiO2 -0.150 0.219 0.304 0.212 -0.161 -0.102 1 -0.062 0.194 0.162

CaO 0.221 -0.034 -0.109 0.466 -0.195 0.631 -0.062 1 -0.054 0.108 K2O 0.098 0.099 0.219 -0.027 -0.205 -0.070 0.194 -0.054 1 0.072

MnO 0.178 -0.055 0.204 0.161 -0.021 -0.024 0.162 0.108 0.072 1

146

Kaiser-Meyer-Olkin measure of sampling adequacy. Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO KMO

0.502 0.407 0.424 0.481 0.439 0.515 0.586 0.463 0.665 0.564 0.473

Cronbach's alpha: 0.225.

Reproduced correlation matrix.

Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

Na2O 0.744 -0.165 0.016 -0.200 -0.024 0.429 -0.196 0.286 0.320 0.256 SiO2 -0.165 0.857 -0.176 0.047 -0.762 -0.093 0.214 0.003 0.203 -0.191

Al2O3 0.016 -0.176 0.664 0.312 -0.023 -0.267 0.449 -0.102 0.314 0.434

MgO -0.200 0.047 0.312 0.792 -0.234 0.189 0.367 0.525 -0.113 0.235 FeO -0.024 -0.762 -0.023 -0.234 0.809 -0.048 -0.313 -0.208 -0.319 -0.025

P2O5 0.429 -0.093 -0.267 0.189 -0.048 0.709 -0.276 0.705 -0.138 0.049

TiO2 -0.196 0.214 0.449 0.367 -0.313 -0.276 0.476 -0.059 0.233 0.229

CaO 0.286 0.003 -0.102 0.525 -0.208 0.705 -0.059 0.858 -0.148 0.142

K2O 0.320 0.203 0.314 -0.113 -0.319 -0.138 0.233 -0.148 0.518 0.261

MnO 0.256 -0.191 0.434 0.235 -0.025 0.049 0.229 0.142 0.261 0.384

Residual correlation matrix.

Na2O SiO2 Al2O3 MgO FeO P2O5 TiO2 CaO K2O MnO

Na2O 0.256 0.032 0.029 0.084 -0.033 -0.120 0.046 -0.065 -0.221 -0.078

SiO2 0.032 0.143 0.006 -0.015 0.088 0.021 0.005 -0.037 -0.104 0.136

Al2O3 0.029 0.006 0.336 -0.042 -0.095 0.064 -0.145 -0.008 -0.095 -0.231 MgO 0.084 -0.015 -0.042 0.208 -0.003 -0.104 -0.155 -0.059 0.086 -0.074

FeO -0.033 0.088 -0.095 -0.003 0.191 0.078 0.152 0.013 0.115 0.004

P2O5 -0.120 0.021 0.064 -0.104 0.078 0.291 0.174 -0.073 0.068 -0.073 TiO2 0.046 0.005 -0.145 -0.155 0.152 0.174 0.524 -0.003 -0.039 -0.066

CaO -0.065 -0.037 -0.008 -0.059 0.013 -0.073 -0.003 0.142 0.094 -0.034

K2O -0.221 -0.104 -0.095 0.086 0.115 0.068 -0.039 0.094 0.482 -0.189 MnO -0.078 0.136 -0.231 -0.074 0.004 -0.073 -0.066 -0.034 -0.189 0.616

Eigenvalues.

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10

Eigenvalue 2.055 1.984 1.555 1.218 0.874 0.781 0.663 0.425 0.266 0.178

Variability (%) 20.552 19.844 15.546 12.184 8.743 7.809 6.628 4.253 2.660 1.782

Cumulative % 20.552 40.397 55.942 68.126 76.869 84.678 91.306 95.558 98.218 100.000

0

20

40

60

80

100

0

0.5

1

1.5

2

2.5

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10

Cu

mu

lati

ve v

aria

bili

ty (

%)

Eige

nva

lue

axis

Scree plot

147

Eigenvectors.

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10

Na2O -0.009 0.340 0.149 -0.628 -0.139 0.188 0.404 0.482 0.116 -0.067

SiO2 -0.389 -0.164 -0.557 -0.088 -0.207 -0.077 0.063 -0.089 0.423 -0.514

Al2O3 -0.278 -0.184 0.531 -0.016 0.191 0.374 0.345 -0.491 0.065 -0.256 MgO -0.413 0.197 0.192 0.503 0.062 0.257 -0.170 0.426 0.442 0.161

FeO 0.530 0.033 0.358 0.157 0.084 -0.332 -0.070 0.129 0.374 -0.535

P2O5 -0.027 0.591 -0.082 -0.064 0.212 -0.334 0.158 -0.465 0.381 0.310 TiO2 -0.387 -0.226 0.179 0.120 0.093 -0.681 0.422 0.248 -0.193 0.066

CaO -0.242 0.598 -0.023 0.152 0.098 -0.017 -0.147 -0.004 -0.530 -0.499

K2O -0.258 -0.150 0.124 -0.507 0.530 -0.140 -0.572 0.070 0.075 -0.017 MnO -0.210 0.067 0.407 -0.148 -0.739 -0.217 -0.358 -0.195 0.025 0.061

Factor patterns. Values in bold represent the factor with largest squared cosine.

F1 F2 F3 F4 Initial communality Final communality Specific variance

Na2O -0.012 0.479 0.186 -0.693 1.000 0.744 0.256

SiO2 -0.558 -0.231 -0.695 -0.097 1.000 0.857 0.143

Al2O3 -0.399 -0.260 0.662 -0.018 1.000 0.664 0.336 MgO -0.592 0.277 0.239 0.555 1.000 0.792 0.208

FeO 0.760 0.047 0.447 0.173 1.000 0.809 0.191

P2O5 -0.038 0.832 -0.102 -0.071 1.000 0.709 0.291 TiO2 -0.554 -0.318 0.224 0.133 1.000 0.476 0.524

CaO -0.347 0.842 -0.028 0.168 1.000 0.858 0.142

K2O -0.370 -0.211 0.154 -0.559 1.000 0.518 0.482 MnO -0.301 0.094 0.508 -0.163 1.000 0.384 0.616

Cronbach's alpha.

F1 F2 F3 F4

Cronbach's alpha -0.212 0.774 -0.021 0.179

Correlations between variables and factors.

F1 F2 F3 F4

Na2O -0.012 0.479 0.186 -0.693

SiO2 -0.558 -0.231 -0.695 -0.097 Al2O3 -0.399 -0.260 0.662 -0.018

MgO -0.592 0.277 0.239 0.555

FeO 0.760 0.047 0.447 0.173 P2O5 -0.038 0.832 -0.102 -0.071

TiO2 -0.554 -0.318 0.224 0.133

CaO -0.347 0.842 -0.028 0.168 K2O -0.370 -0.211 0.154 -0.559

MnO -0.301 0.094 0.508 -0.163

Factor pattern coefficients.

F1 F2 F3 F4

Na2O -0.009 0.340 0.149 -0.628

SiO2 -0.389 -0.164 -0.557 -0.088

Al2O3 -0.278 -0.184 0.531 -0.016 MgO -0.413 0.197 0.192 0.503

FeO 0.530 0.033 0.358 0.157

P2O5 -0.027 0.591 -0.082 -0.064 TiO2 -0.387 -0.226 0.179 0.120

CaO -0.242 0.598 -0.023 0.152

K2O -0.258 -0.150 0.124 -0.507

MnO -0.210 0.067 0.407 -0.148

Results after the Varimax rotation.

Rotation matrix.

D1 D2 D3 D4

D1 -0.721 -0.286 -0.632 -0.003

D2 -0.196 0.934 -0.201 0.220

D3 -0.645 -0.017 0.743 0.176 D4 -0.161 0.212 0.092 -0.959

Percentage of variance after Varimax rotation.

D1 D2 D3 D4

Variability (%) 18.224 19.555 17.687 12.660

Cumulative % 18.224 37.779 55.466 68.126

148

Factor pattern after Varimax rotation. Values in bold represent the factor with largest squared cosine.

Values in bold correspond for each variable to the factor for which the squared cosine is the largest.

D1 D2 D3 D4

Na2O -0.093 0.300 -0.014 0.803

SiO2 0.912 -0.065 -0.127 -0.078 Al2O3 -0.086 -0.144 0.794 0.077

MgO 0.129 0.542 0.547 -0.427

FeO -0.873 -0.145 -0.142 -0.080 P2O5 -0.058 0.775 -0.225 0.234

TiO2 0.296 -0.114 0.592 -0.156

CaO 0.076 0.922 0.045 0.021 K2O 0.299 -0.213 0.339 0.518

MnO -0.103 0.131 0.533 0.268

Cronbach's alpha.

D1 D2 D3 D4

Cronbach's alpha -4.137 0.774 0.528 0.179

Correlations between variables and factors after Varimax rotation.

D1 D2 D3 D4

Na2O -0.093 0.300 -0.014 0.803 SiO2 0.912 -0.065 -0.127 -0.078

Al2O3 -0.086 -0.144 0.794 0.077

MgO 0.129 0.542 0.547 -0.427 FeO -0.873 -0.145 -0.142 -0.080

P2O5 -0.058 0.775 -0.225 0.234

TiO2 0.296 -0.114 0.592 -0.156 CaO 0.076 0.922 0.045 0.021

K2O 0.299 -0.213 0.339 0.518

MnO -0.103 0.131 0.533 0.268

Factor pattern coefficients after Varimax rotation.

D1 D2 D3 D4

Na2O -0.028 0.104 -0.008 0.620

SiO2 0.520 -0.040 -0.145 -0.027

Al2O3 -0.107 -0.077 0.464 0.060 MgO 0.008 0.307 0.310 -0.378

FeO -0.479 -0.059 -0.012 -0.082

P2O5 -0.017 0.386 -0.127 0.137 TiO2 0.115 -0.052 0.319 -0.114

CaO 0.028 0.474 0.021 -0.041

K2O 0.161 -0.147 0.167 0.435 MnO -0.093 0.052 0.313 0.197

149

Factor scores after Varimax rotation. Values in bold represent the factor with largest squared cosine.

D1 D2 D3 D4 D1 D2 D3 D4 D1 D2 D3 D4

1 -0.288 0.309 -0.134 -1.111 3 2.700 -0.648 -1.946 -0.491 2 1.478 -0.693 -1.150 0.360

2 0.035 -0.375 0.343 1.952 4 0.041 -0.854 -1.062 -0.315 8 -0.522 0.134 0.210 -0.611

3 -0.447 0.415 1.833 -0.587 5 1.941 -0.282 -2.049 -0.748 9 -2.106 -0.474 -0.195 0.063 1 0.042 -0.329 1.017 -0.569 6 0.120 -1.050 -1.195 -0.162 10 0.950 0.209 1.061 -1.112

2 -0.125 -0.147 0.330 -0.433 7 -1.553 -1.043 -0.595 -0.569 11 -0.531 0.155 -0.661 -0.330

3 -0.073 0.596 1.511 0.163 8 -0.476 -1.974 -0.723 -0.262 12 -0.772 -0.681 0.983 -1.149

4 2.211 -0.125 -0.336 0.517 9 -0.952 -1.267 -0.594 -0.772 13 0.669 -1.446 0.565 -0.629

5 1.918 0.422 0.079 -0.440 10 -1.937 -1.880 -0.785 0.018 14 1.630 -0.341 0.275 -0.886

6 0.515 0.722 0.683 1.488 11 -1.418 -1.345 -0.565 -0.457 15 1.529 -0.617 -0.117 0.161 7 0.619 1.008 1.350 -0.424 12 -1.449 -1.237 -0.335 0.191 16 1.007 -0.079 -1.511 -0.117

8 -0.521 0.637 0.576 -0.794 13 -1.296 -0.557 -0.604 -0.748 17 0.361 -1.612 -0.110 0.179

10 0.219 -0.330 2.145 2.814 14 2.142 -1.336 1.344 -0.641 1 -0.217 -0.633 -0.451 -0.657

11 0.857 0.509 1.041 -0.400 15 1.677 -1.679 1.656 0.992 7 -1.095 0.111 -0.218 -0.602

12 0.398 -0.531 0.143 -0.401 16 0.863 -1.916 1.785 0.352 45 -0.542 1.856 0.617 -0.221

13 -1.171 -1.005 -0.369 0.136 17 0.752 -1.581 3.631 0.316 6 -0.651 -0.764 0.161 -0.517

14 -1.389 -0.670 1.003 0.752 18 -0.286 0.360 0.327 -0.140

15 -1.145 -0.676 1.522 0.217 19 -1.167 -1.724 0.734 0.170

16 -0.188 1.072 0.233 3.357 20 0.043 0.840 -0.930 0.576 17 -0.126 1.266 1.558 1.848 21 -0.214 0.918 -0.766 1.335

18 -0.025 2.155 0.637 -1.227 22 0.356 0.937 -0.624 0.855

19 -2.157 -0.818 -0.706 -0.978 23 -0.490 0.465 -0.647 2.674

20 0.463 -1.178 0.911 -0.686 24 -0.472 0.791 -0.762 -0.336

21 -0.141 -0.134 0.663 -0.686 25 1.033 0.122 -1.147 -0.852

22 0.510 -0.148 -0.494 0.256 26 1.542 0.014 -1.928 0.106 23 -0.343 1.195 -0.444 0.237 27 1.165 -0.084 -0.903 0.284

24 1.203 2.766 1.015 -1.446 28 -0.540 0.262 0.711 -1.122

25 -0.187 0.794 0.094 -0.778 29 1.165 -0.026 -0.875 -0.368 26 -0.399 0.050 -0.888 3.076 30 0.102 -0.599 -0.539 -0.553

27 -0.768 0.884 -0.825 -1.003 31 0.648 0.098 -0.236 -1.013

28 -1.088 0.233 -1.388 -0.175 32 0.308 0.610 -0.742 0.160 31 0.469 0.497 -1.571 0.149 33 -0.592 1.395 -0.438 -0.698

32 -0.664 0.061 0.100 -0.367 34 1.066 1.258 -0.124 0.119

33 -1.262 1.495 1.097 -1.016 35 0.234 1.106 -1.276 0.868

34 0.147 0.584 -0.632 -0.568 36 0.128 0.855 1.059 -1.508

35 -0.330 0.644 -1.358 1.733 37 1.766 -1.919 0.538 0.907

36 -0.766 0.132 -0.272 3.013 1 -1.383 -0.431 -0.398 -0.060 37 -0.042 1.715 0.904 0.483 2 -0.474 -0.451 -0.220 0.221

38 -0.400 0.959 0.539 -0.809 3 -0.477 0.095 -0.556 -1.067

43 -0.578 2.303 0.507 0.627 4 -0.235 1.063 -0.313 -0.485 44 -0.101 0.517 0.973 -0.141 5 -0.450 0.095 -0.751 0.198

150

Tables F.3- LA-ICP-MS data. Elements and spots with more than 25% of the observations under the

quantitation limit were excluded. The remaining values below the quantitation limit were set to half

the local value. W and Pb were excluded to decrease dimensionality. Sample ID V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th

LS-02 31 30.1 480 78.4 16.4 320 0.4 95.1 1475 138379 317 197 11.5 0.88 0.33

32 27.7 90.1 172 9.38 680 0.32 301 104 41703 191 304 2.49 1.08 0.26

LS-08

10 54.5 2554 34.3 6.01 120 0.17 76.8 729 52036 206 217 23.2 0.49 1.3 11 61.2 411 45.8 13.1 46.7 0.29 23.6 1249 30315 404 281 51.1 0.78 0.95

14 56.8 142 23.2 8.89 12.5 0.43 18.5 791 16507 191 18.1 54.7 0.26 0.18

38 53.8 51.6 36.8 6.95 24.7 0.11 32.9 490 10516 142 31.6 24.0 0.33 0.21 43 51.3 86.6 22.5 6.45 7.44 0.17 16 775 29107 168 13.7 28.1 0.18 0.2

LS-11

47 54.7 9.09 27 7.05 10.9 0.1 17.1 769 9731 196 9.99 16.2 0.14 0.17

53 38.7 23.9 3.61 2.55 23.8 0.26 21.5 374 100564 62.2 34.5 30.5 0.89 0.35

60 32.9 20.3 60.8 2.16 214 0.27 123 268 123639 73.3 229 19 0.39 0.69

15 41.5 12.7 14.1 6.2 5.79 0.06 11.4 354 74699 86.9 20.0 13.5 0.6 0.16

16 40.5 12.6 24.4 6.04 105 0.2 9.37 311 61247 83.2 130 15.3 0.18 0.39

17 37.5 9.89 20.7 4.01 15.9 0.14 19.1 279 39729 65.3 19.4 18.5 0.17 0.08

18 33.5 10.0 21.1 4.93 16.1 0.17 13.8 337 69338 92.1 22.2 16.7 0.12 0.16

23 45.8 14.6 57.4 6.68 267 0.25 12.1 503 113328 140 200 16.4 0.39 0.47

26 42.2 13.5 16.2 6.84 5.71 0.24 17.6 360 95059 147 22.3 15.4 0.23 0.12

LS-12

64 56.9 366. 29.1 11.3 26.0 0.17 244 466 85547 126 17.0 33.0 0.27 0.48

69 51.3 780 28.6 11.3 8.3 0.2 111 518 53779 146 15.1 28.1 0.14 0.35

72 59.3 130 31.3 11.8 9.62 0.18 211 553 35403 125 40.0 153 0.21 0.62

71 63.1 111 21.3 11.8 14.9 0.09 182 907 55822 228 20.8 21.1 0.36 0.45

80 59.8 158 21.5 11.6 14.5 0.15 32.5 1069 42520 183 17.1 23.7 0.23 0.47

81 55.5 27.7 31.2 11.8 12.7 0.1 112 552 39941 160 16.1 26.4 0.39 0.48

LS-15

14 42.3 238 66.7 0.98 3.17 0.17 773 665 33059 107 9.39 1.24 0.4 0.07 16 64.5 8.15 14.8 0.88 2.72 0.19 378 504 29808 640 6.37 1.24 0.55 0.21

28 50.7 648 264 1.76 4.19 0.2 964 514 36288 168 39.4 1.24 0.63 0.36

29 73.3 9.88 30.3 1.08 2.52 0.18 34.6 897 16356 114 10.9 1.24 0.68 0.13 31 54.7 886 215 1.07 2.41 0.13 36.1 749 40807 273 13.6 1.24 0.38 0.18

33 60.4 11.8 2.32 1.29 2.8 0.11 581 336 6475 106 7.15 1.24 0.33 0.13

47 50.1 11.5 2.36 1.26 2.19 0.14 14237 2150 27320 230 5.61 1.24 0.7 0.14

LS-19

50 57.2 747 59.8 6.3 0.86 0.08 9485 1783 28722 382 10.2 0.79 0.24 0.05

61 54.5 14883 988 5.51 7.97 0.27 258 1026 13315 168 261 0.52 1.24 1.28

64 75.3 819 287 10.3 19.7 0.18 2336 1707 20809 211 267 0.71 0.38 0.43

66 45.1 1529 187 1.24 43.3 0.05 7739 695 3809 98.3 14.9 0.5 0.14 0.12

68 59.3 4235 326 0.15 2.05 0.06 39040 1432 13638 412 56.3 0.92 0.21 0.18

DE-02

25 52.8 22.8 63.8 8.66 66.9 0.09 65.2 943 4878 291 85.2 58.5 1.03 0.72

48 51.7 2.67 107 7.62 168 0.09 70.9 839 2129 236 61.0 49.1 0.19 0.38

52 60.3 37.5 284 11.1 466 0.1 47.8 672 3118 233 79.3 78.5 0.37 0.93

59 60.0 24.9 368 8.44 373 0.51 57.1 707 4302 157 137 24.2 0.23 0.07

24 54.1 59.0 251 9.12 327 0.07 64.5 725 3383 233 37.5 59.2 0.25 0.12

DE-04 77 25.8 42.3 34.9 9.96 21.3 0.12 62.1 347 48072 75.5 90.2 42.1 0.35 0.17

DE-11

31 50.4 10.9 41.8 11.8 179 0.07 14.21 554 54577 191 99.7 26.5 0.59 1.14 32 50.2 10.3 27.8 12.4 7.37 0.15 14.7 547 51671 191 20.0 23.1 0.26 0.1

49 53.7 14.1 55.8 13.3 33.7 0.12 18.0 537 60396 171 204 30.0 0.67 1.68

50 52.8 14.2 27.0 13.4 10.56 0.16 21.8 613 40048 192 35.8 25.2 0.34 0.25 52 50.4 16.7 37.0 12.3 20.7 0.1 11.9 532 58520 223 40.6 26.4 0.48 0.33

62 51.4 19.0 27.4 10.4 15.3 0.17 12.5 587 32194 206 18.9 24.5 0.38 0.17

35 50.6 9.11 25.9 11.6 8.19 0.08 17.9 582 38623 224 19.3 24.4 0.24 0.17

43 46.2 12.1 30.0 14.3 9.76 0.1 18.7 455 42178 129 24.2 30.7 0.18 0.19

48 51.5 14.1 44.3 14.6 20.65 0.12 14.6 495 103210 141 25.4 29.0 0.32 0.21 61 51.0 152 29.3 11.4 18.52 0.19 21.5 453 34565 150 22.8 32.4 0.38 0.15

151

Normalized data following Templeton (2011). Data normalized with SPSS. Sample ID V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th

LS-02

31 34.9 2598 217 21.66 273 0.34 4036 1347 145105 335 157 9.74 0.79 0.46

32 32.9 1499 240 8.81 508 0.32 7052 -142 51760 205 339 8.18 0.96 0.43

LS-08

10 54.7 4425 102 5.58 204 0.19 3712 899 60679 244 182 24.8 0.59 1.12

11 65.5 2437 151 13.61 175 0.3 351 1234 33372 371 249 57.8 0.76 0.88 14 57.6 1872 -18 8.36 47.8 0.37 -1583 997 22255 221 26.2 61.0 0.33 0.29

38 53.6 1151 118 7.24 141 0.13 959 465 13304 147 80.3 27.3 0.38 0.38

43 49.4 1381 -28.6 6.55 -13.9 0.19 -3486 971 29852 185 -7.56 38.3 0.13 0.34

LS-11

47 56.1 -2802 19.9 7.46 40.6 0.11 -3069 946 10702 232 -39.2 15.5 0.01 0.22

53 39.8 597 -153 4.47 133 0.27 -5878 358 89657 -23.3 84.6 44.7 0.83 0.5

60 36.5 378 187 4.16 240 0.29 5057 -16.6 111001 28.4 193 20.9 0.53 0.77 15 41.5 -677 -129 6.07 -31.9 0.01 -8938 295 78971 67.9 49.7 11.2 0.64 0.16

16 40.7 -809 -8.1 5.83 193 0.24 -10755 126 73543 56.8 144 12.7 0.13 0.57

17 38.9 -1971 -77.7 4.77 83.1 0.16 -912 64.2 45074 8.15 40.6 19.6 0.08 -0.13 18 37.7 -1765 -64.0 5.05 90.1 0.19 -5485 221 76145 77.7 58.5 18.2 -0.12 0.16

23 44.3 -70.5 169 6.78 255 0.27 -6865 513 101029 135 165 16.9 0.53 0.64

26 42.3 -549 -92.8 7.01 -41.6 0.26 -2674 328 85592 158 62.9 14.1 0.25 -0.01

LS-12

64 58.3 2286 54.0 10.24 149 0.19 6193 440 82086 123 16.0 50.4 0.35 0.69 69 49.9 3166 45.7 9.99 10.6 0.24 4367 580 62602 153 4.82 39.8 0.01 0.5

72 59.7 1744 94.4 11.98 18.4 0.21 5798 685 40118.9 116 102 104 0.2 0.74

71 67.0 1620 -51.4 12.33 69.0 0.08 5420 1083 66664 270 54.1 22.2 0.43 0.61 80 61.3 2004 -39.7 10.91 62.0 0.17 656 1190 55218 200 21.2 26.1 0.25 0.64

81 57 817 86.4 11.34 54.9 0.11 4707 664 46728 175 10.5 34 0.53 0.69

LS-15

14 43.0 2141 206 0.99 -63.0 0.19 8609 789 36781 102 -49.9 1.17 0.56 -0.21 16 69.0 -3230 -109 0.12 -88.3 0.23 7526 535 31629 510 -79.8 1.17 0.6 0.38

28 48.4 2771 298 3.84 -51.9 0.24 9248 558 41773 179 98.0 1.17 0.66 0.53

29 72.2 -2205 78.4 2.21 -103 0.21 1261 1053 20183 110 -21.8 1.17 0.7 0.06 31 56.1 3669 266 1.66 -120 0.15 1562 922 50067 312 -14.4 1.17 0.48 0.29

33 64.2 -1091 -232 3.49 -75.0 0.13 8041 177 7877 94.8 -62.8 1.17 0.38 0.06

47 45.6 -1243 -184 3.1 -141 0.16 13879 1981 26169 277 -106 1.17 0.73 0.1

LS-19

50 58.9 2959 177 6.31 -211 0.06 12061 1553 28034 351 -30 -11.45 0.29 -0.36

61 55.24 7353.57 586.57 5.32 -5.45 0.29 6609.53 1151.35 15730.7 189.74 205.99 -20.36 1.23 1.01

64 82.88 3399.25 342.01 9.27 104.31 0.21 9988.83 1427.92 24245.7 250.19 222.92 -15.31 0.48 0.59 66 43.69 3996.59 252.76 2.68 166.06 -0.03 10886.7 831.68 -2809.2 86.59 -1.18 -28.17 0.01 -0.01

68 60.43 5087.5 373.21 -1.23 -168.8 0.01 20095.6 1285.33 18015.2 402.75 112.01 104.41 0.2 0.29

DE-02

25 52.54 487.74 196.84 8.13 184.08 0.08 3081.36 1115.93 4761.54 322.66 127.19 64.84 0.88 0.8

48 51.5 -3892.7 228.42 7.69 215.17 0.08 3394.03 1024.23 -24153 301.79 116.91 55.05 0.18 0.55 52 63.11 927.45 318.17 9.74 363.33 0.11 1862.7 810.17 -14181 292.88 121.96 77.7 0.44 0.84

59 62.13 707.04 421.49 7.91 320.94 0.47 2164.26 853.54 145105 168.8 150.71 28.66 0.25 -0.21

24 54.13 1265.26 281.52 8.58 293.54 0.04 2772.76 875.82 -7735.1 284.68 93.48 69.88 0.31 -0.01

DE-04 77 29.78 1038.79 110.37 9.04 126.21 0.14 2467.34 259.95 56995.4 44 132.64 52.61 0.42 0.22

DE-11

31 47 -1403.9 134.72 11.65 227.18 0.04 -4917.3 705.65 64592.4 216.01 138.33 36.82 0.62 0.94

32 46.15 -1576.8 37.28 13.14 -22.72 0.17 -3928 643.36 58812.9 210.68 45.17 23.47 0.33 -0.08

49 53.06 -304.38 160.07 14.16 157.59 0.14 -1933.7 622.35 71116.5 194.94 173.15 42.97 0.68 1.49 50 52.02 -186.31 10.84 14.83 33.34 0.17 42.46 767.93 48391.2 226.92 89.03 32.64 0.4 0.41

52 47 155.99 126.53 12.71 118.8 0.11 -7762.9 601.13 68832.1 256.47 107.23 35.39 0.57 0.46

62 50.46 267.32 28.67 9.5 76.07 0.19 20095.6 747.08 35087.4 238.25 31.14 31.29 0.48 0.22 35 47.83 -2474.5 1.54 10.91 2.72 0.06 -2296.6 726.34 43423.6 263 35.92 29.97 0.29 0.22

43 44.96 -946.8 70.32 15.7 25.93 0.11 -1243.1 414.25 53475.2 129.28 71.58 46.46 0.13 0.32

48 50.98 -425.14 143.03 17.05 111.51 0.14 -4402.4 489.3 94582.3 141.23 75.91 41.35 0.36 0.38 61 48.9 43.49 62.21 10.5 97.19 0.23 -270.21 387.07 38456.1 163.46 67.24 48.36 0.48 0.12

152

Tables F.4- Factor analysis of selected LA-ICP-MS trace elements. Data processing with XLSTAT

2014.5.03.

Correlation matrix (Pearson). Values in bold are different from 0 with a significance level alpha=0.05. Variables V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th

V 1 0.156 0.154 -0.069 -0.251 -0.039 0.282 0.500 -0.377 0.471 -0.149 0.056 0.013 0.148

Mn 0.156 1 0.573 -0.079 -0.018 0.132 0.437 0.321 -0.021 0.110 0.288 -0.039 0.247 0.225

Sr 0.154 0.573 1 0.016 0.314 0.095 0.275 0.259 -0.096 0.250 0.541 0.036 0.256 0.215 Zr -0.069 -0.079 0.016 1 0.375 0.076 -0.324 0.028 0.336 0.082 0.331 0.291 0.031 0.300

Ba -0.251 -0.018 0.314 0.375 1 0.253 -0.242 -0.304 0.228 -0.118 0.701 0.209 0.145 0.371

U -0.039 0.132 0.095 0.076 0.253 1 -0.066 -0.120 0.494 -0.126 0.326 -0.110 0.257 0.070 Mg 0.282 0.437 0.275 -0.324 -0.242 -0.066 1 0.404 -0.338 0.332 -0.133 -0.064 0.144 -0.117

Al 0.500 0.321 0.259 0.028 -0.304 -0.120 0.404 1 -0.305 0.622 -0.175 -0.033 0.152 0.016

Si -0.377 -0.021 -0.096 0.336 0.228 0.494 -0.338 -0.305 1 -0.307 0.251 -0.103 0.075 0.064 Ti 0.471 0.110 0.250 0.082 -0.118 -0.126 0.332 0.622 -0.307 1 -0.006 0.124 0.188 0.121

REE -0.149 0.288 0.541 0.331 0.701 0.326 -0.133 -0.175 0.251 -0.006 1 0.193 0.384 0.536

Cu 0.056 -0.039 0.036 0.291 0.209 -0.110 -0.064 -0.033 -0.103 0.124 0.193 1 -0.183 0.266

Hf 0.013 0.247 0.256 0.031 0.145 0.257 0.144 0.152 0.075 0.188 0.384 -0.183 1 0.407

Th 0.148 0.225 0.215 0.300 0.371 0.070 -0.117 0.016 0.064 0.121 0.536 0.266 0.407 1

Kaiser-Meyer-Olkin measure of sampling adequacy. V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th KMO

0.668 0.599 0.672 0.638 0.742 0.531 0.760 0.730 0.649 0.714 0.725 0.541 0.587 0.613 0.668

Cronbach's alpha: 0.664.

Reproduced correlation matrix.

V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th

V 0.572 0.168 0.137 0.028 -0.292 -0.165 0.346 0.640 -0.356 0.618 -0.175 0.077 0.123 0.100

Mn 0.168 0.640 0.631 -0.215 0.109 0.157 0.487 0.281 -0.142 0.205 0.359 -0.130 0.403 0.202 Sr 0.137 0.631 0.720 -0.053 0.323 0.097 0.392 0.210 -0.162 0.213 0.554 0.092 0.383 0.377

Zr 0.028 -0.215 -0.053 0.657 0.403 0.165 -0.428 -0.026 0.302 0.151 0.368 0.363 0.118 0.451

Ba -0.292 0.109 0.323 0.403 0.701 0.211 -0.296 -0.349 0.291 -0.191 0.720 0.327 0.179 0.485 U -0.165 0.157 0.097 0.165 0.211 0.609 -0.125 -0.084 0.568 -0.127 0.333 -0.324 0.432 0.158

Mg 0.346 0.487 0.392 -0.428 -0.296 -0.125 0.619 0.453 -0.425 0.322 -0.110 -0.184 0.165 -0.088

Al 0.640 0.281 0.210 -0.026 -0.349 -0.084 0.453 0.747 -0.345 0.687 -0.172 -0.029 0.231 0.098

Si -0.356 -0.142 -0.162 0.302 0.291 0.568 -0.425 -0.345 0.699 -0.329 0.283 -0.222 0.243 0.113

Ti 0.618 0.205 0.213 0.151 -0.191 -0.127 0.322 0.687 -0.329 0.698 -0.049 0.159 0.195 0.234

REE -0.175 0.359 0.554 0.368 0.720 0.333 -0.110 -0.172 0.283 -0.049 0.856 0.245 0.394 0.588 Cu 0.077 -0.130 0.092 0.363 0.327 -0.324 -0.184 -0.029 -0.222 0.159 0.245 0.592 -0.176 0.336

Hf 0.123 0.403 0.383 0.118 0.179 0.432 0.165 0.231 0.243 0.195 0.394 -0.176 0.502 0.294

Th 0.100 0.202 0.377 0.451 0.485 0.158 -0.088 0.098 0.113 0.234 0.588 0.336 0.294 0.549

Residual correlation matrix.

V Mn Sr Zr Ba U Mg Al Si Ti REE Cu Hf Th

V 0.428 -0.013 0.017 -0.098 0.042 0.126 -0.064 -0.140 -0.021 -0.146 0.026 -0.021 -0.110 0.047 Mn -0.013 0.360 -0.058 0.135 -0.127 -0.025 -0.049 0.041 0.121 -0.096 -0.072 0.091 -0.155 0.023

Sr 0.017 -0.058 0.280 0.069 -0.009 -0.002 -0.117 0.049 0.066 0.037 -0.014 -0.056 -0.127 -0.163

Zr -0.098 0.135 0.069 0.343 -0.028 -0.090 0.104 0.054 0.033 -0.069 -0.036 -0.072 -0.087 -0.151 Ba 0.042 -0.127 -0.009 -0.028 0.299 0.042 0.054 0.045 -0.063 0.073 -0.020 -0.118 -0.034 -0.114

U 0.126 -0.025 -0.002 -0.090 0.042 0.391 0.059 -0.036 -0.074 0.001 -0.007 0.214 -0.174 -0.088

Mg -0.064 -0.049 -0.117 0.104 0.054 0.059 0.381 -0.050 0.087 0.010 -0.023 0.119 -0.021 -0.029 Al -0.140 0.041 0.049 0.054 0.045 -0.036 -0.050 0.253 0.040 -0.065 -0.003 -0.005 -0.080 -0.082

Si -0.021 0.121 0.066 0.033 -0.063 -0.074 0.087 0.040 0.301 0.022 -0.032 0.119 -0.168 -0.049 Ti -0.146 -0.096 0.037 -0.069 0.073 0.001 0.010 -0.065 0.022 0.302 0.043 -0.035 -0.008 -0.113

REE 0.026 -0.072 -0.014 -0.036 -0.020 -0.007 -0.023 -0.003 -0.032 0.043 0.144 -0.052 -0.010 -0.052

Cu -0.021 0.091 -0.056 -0.072 -0.118 0.214 0.119 -0.005 0.119 -0.035 -0.052 0.408 -0.007 -0.070 Hf -0.110 -0.155 -0.127 -0.087 -0.034 -0.174 -0.021 -0.080 -0.168 -0.008 -0.010 -0.007 0.498 0.113

Th 0.047 0.023 -0.163 -0.151 -0.114 -0.088 -0.029 -0.082 -0.049 -0.113 -0.052 -0.070 0.113 0.451

Eigenvalues.

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14

Eigenvalue 3.254 3.030 1.680 1.199 0.942 0.765 0.724 0.642 0.438 0.368 0.316 0.258 0.207 0.176

Variability (%) 23.241 21.642 12.001 8.564 6.732 5.467 5.174 4.587 3.130 2.628 2.254 1.843 1.478 1.259 Cumulative % 23.241 44.884 56.885 65.448 72.180 77.648 82.822 87.409 90.538 93.166 95.420 97.263 98.741 100

153

Eigenvectors.

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14

V -0.279 0.253 0.182 -0.242 -0.012 -0.475 -0.224 0.452 0.236 0.002 0.358 0.164 -0.263 0.080

Mn -0.032 0.379 -0.301 0.202 -0.281 -0.062 0.492 0.182 -0.034 0.061 -0.143 -0.365 -0.449 -0.068

Sr 0.064 0.429 -0.135 0.316 -0.214 0.222 -0.203 0.246 -0.277 0.012 0.322 0.213 0.373 -0.364 Zr 0.275 0.081 0.389 -0.337 -0.265 0.351 0.215 0.041 0.405 0.308 0.248 -0.248 0.152 -0.083

Ba 0.416 0.142 0.120 0.207 0.003 0.116 -0.425 -0.033 0.349 -0.016 -0.360 0.209 -0.440 -0.254

U 0.251 0.082 -0.356 -0.377 -0.261 -0.468 -0.323 -0.150 -0.063 0.243 -0.211 -0.245 0.255 -0.120 Mg -0.299 0.257 -0.229 0.181 -0.142 -0.068 0.054 -0.514 0.600 -0.183 0.099 0.123 0.210 0.069

Al -0.313 0.316 0.079 -0.310 -0.161 0.244 0.068 0.044 -0.126 0.254 -0.526 0.440 0.075 0.227

Si 0.352 -0.106 -0.220 -0.388 -0.323 0.034 0.235 -0.041 -0.089 -0.509 0.175 0.421 -0.166 0.016 Ti -0.230 0.327 0.248 -0.284 0.000 0.215 -0.286 -0.259 -0.247 -0.484 -0.011 -0.422 -0.135 -0.103

REE 0.402 0.313 -0.003 0.167 0.043 0.034 -0.146 0.031 -0.059 -0.060 0.086 -0.113 0.071 0.809 Cu 0.094 0.083 0.535 0.226 -0.263 -0.397 0.164 -0.454 -0.325 0.168 0.099 0.178 -0.103 -0.034

Hf 0.118 0.305 -0.247 -0.247 0.583 0.090 0.100 -0.326 -0.112 0.338 0.302 0.143 -0.239 -0.105

Th 0.237 0.305 0.222 -0.047 0.418 -0.294 0.363 0.169 0.102 -0.323 -0.294 0.017 0.373 -0.191

Factor pattern. Values in bold represent the factor with largest squared cosine.

F1 F2 F3 F4 Initial communality Final communality Specific variance

V -0.503 0.440 0.236 -0.265 1.000 0.572 0.428 Mn -0.058 0.660 -0.391 0.222 1.000 0.640 0.360

Sr 0.116 0.746 -0.175 0.346 1.000 0.720 0.280

Zr 0.497 0.141 0.504 -0.369 1.000 0.657 0.343 Ba 0.751 0.247 0.156 0.226 1.000 0.701 0.299

U 0.453 0.143 -0.461 -0.412 1.000 0.609 0.391

Mg -0.539 0.448 -0.297 0.198 1.000 0.619 0.381 Al -0.564 0.550 0.102 -0.340 1.000 0.747 0.253

Si 0.635 -0.185 -0.285 -0.425 1.000 0.699 0.301

Ti -0.415 0.570 0.322 -0.311 1.000 0.698 0.302 REE 0.725 0.545 -0.004 0.183 1.000 0.856 0.144

Cu 0.170 0.145 0.693 0.247 1.000 0.592 0.408

Hf 0.212 0.530 -0.321 -0.271 1.000 0.502 0.498 Th 0.427 0.531 0.288 -0.052 1.000 0.549 0.451

Cronbach's alpha.

F1 F2 F3 F4

Cronbach's alpha 0.036 0.636 0.219

0

20

40

60

80

100

0

0.5

1

1.5

2

2.5

3

3.5

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14

Cu

mu

lati

ve v

aria

bili

ty (

%)

Eige

nva

lue

axis

Scree plot

154

Correlations between variables and factors.

F1 F2 F3 F4

V -0.503 0.440 0.236 -0.265

Mn -0.058 0.660 -0.391 0.222

Sr 0.116 0.746 -0.175 0.346 Zr 0.497 0.141 0.504 -0.369

Ba 0.751 0.247 0.156 0.226

U 0.453 0.143 -0.461 -0.412 Mg -0.539 0.448 -0.297 0.198

Al -0.564 0.550 0.102 -0.340

Si 0.635 -0.185 -0.285 -0.425 Ti -0.415 0.570 0.322 -0.311

REE 0.725 0.545 -0.004 0.183

Cu 0.170 0.145 0.693 0.247 Hf 0.212 0.530 -0.321 -0.271

Th 0.427 0.531 0.288 -0.052

Factor pattern coefficients. F1 F2 F3 F4

V -0.279 0.253 0.182 -0.242

Mn -0.032 0.379 -0.301 0.202 Sr 0.064 0.429 -0.135 0.316

Zr 0.275 0.081 0.389 -0.337

Ba 0.416 0.142 0.120 0.207 U 0.251 0.082 -0.356 -0.377

Mg -0.299 0.257 -0.229 0.181

Al -0.313 0.316 0.079 -0.310 Si 0.352 -0.106 -0.220 -0.388

Ti -0.230 0.327 0.248 -0.284

REE 0.402 0.313 -0.003 0.167 Cu 0.094 0.083 0.535 0.226

Hf 0.118 0.305 -0.247 -0.247

Th 0.237 0.305 0.222 -0.047

Results after the Varimax rotation.

Rotation matrix. D1 D2 D3 D4

D1 -0.572 -0.077 0.691 0.434

D2 0.548 0.695 0.445 0.136 D3 0.308 -0.492 0.567 -0.584

D4 -0.527 0.518 0.044 -0.672

Percentage of variance after Varimax rotation.

D1 D2 D3 D4

Variability (%) 17.623 15.801 19.279 12.745 Cumulative % 17.623 33.424 52.703 65.448

Factor pattern after Varimax rotation. Values in bold represent the factor with largest squared cosine.

D1 D2 D3 D4

V 0.741 0.091 -0.030 -0.118

Mn 0.158 0.770 0.042 0.143

Sr 0.106 0.775 0.329 0.021 Zr 0.142 -0.380 0.676 0.188

Ba -0.365 0.154 0.728 0.117

U -0.106 0.078 0.097 0.763

Mg 0.358 0.601 -0.333 -0.133

Al 0.835 0.199 -0.102 -0.001

Si -0.329 -0.257 0.176 0.703

Ti 0.813 0.108 0.136 -0.081

REE -0.214 0.419 0.750 0.268

Cu 0.066 -0.125 0.586 -0.478 Hf 0.213 0.370 0.189 0.533

Th 0.163 0.167 0.692 0.124

Cronbach's alpha.

D1 D2 D3 D4

Cronbach's alpha 0.773 0.692 0.736 0.533

155

Correlations between variables and factors after Varimax rotation.

D1 D2 D3 D4

V 0.741 0.091 -0.030 -0.118

Mn 0.158 0.770 0.042 0.143

Sr 0.106 0.775 0.329 0.021 Zr 0.142 -0.380 0.676 0.188

Ba -0.365 0.154 0.728 0.117

U -0.106 0.078 0.097 0.763 Mg 0.358 0.601 -0.333 -0.133

Al 0.835 0.199 -0.102 -0.001

Si -0.329 -0.257 0.176 0.703 Ti 0.813 0.108 0.136 -0.081

REE -0.214 0.419 0.750 0.268

Cu 0.066 -0.125 0.586 -0.478 Hf 0.213 0.370 0.189 0.533

Th 0.163 0.167 0.692 0.124

Factor pattern coefficients after Varimax rotation.

D1 D2 D3 D4

V 0.328 -0.071 0.028 0.019

Mn -0.040 0.363 -0.039 0.033 Sr -0.070 0.369 0.088 -0.085

Zr 0.192 -0.287 0.283 0.104

Ba -0.158 0.091 0.257 -0.070 U 0.043 -0.021 -0.053 0.458

Mg 0.035 0.288 -0.142 -0.060

Al 0.367 -0.037 -0.017 0.104 Si -0.011 -0.158 -0.004 0.414

Ti 0.372 -0.088 0.093 0.033

REE -0.110 0.188 0.240 0.020 Cu 0.015 -0.067 0.301 -0.350

Hf 0.119 0.094 0.005 0.315

Th 0.097 0.005 0.264 0.010

Factor scores after Varimax rotation. Values in bold represent the factor with largest squared cosine.

D1 D2 D3 D4 D1 D2 D3 D4

31 0.893 -0.276 1.179 2.876 29 0.780 -0.363 -1.490 0.482

32 -1.821 1.792 1.188 1.097 31 0.609 0.821 -1.214 0.283

10 0.234 1.048 0.753 0.470 33 -0.223 -0.634 -1.763 -0.515 11 1.669 0.177 1.762 0.776 47 1.689 -0.552 -2.065 0.643

14 0.658 -0.537 -0.001 0.286 50 1.506 0.550 -1.927 -0.209

38 -0.506 0.333 0.056 -0.773 61 0.512 3.193 -0.081 1.636 43 0.125 -0.642 -0.436 -0.446 64 1.557 1.455 0.165 0.629

47 0.424 -1.249 -0.504 -0.978 66 -1.237 1.846 -1.474 -1.647

53 -1.338 -0.263 -0.205 1.047 68 1.058 2.210 -0.253 -2.433

60 -2.032 0.903 0.295 0.991 25 0.887 0.508 1.182 -0.822

15 -1.060 -1.029 -0.656 0.075 48 0.360 -0.152 0.960 -1.996

16 -1.719 -0.669 0.265 0.288 52 0.500 0.675 1.829 -1.733 17 -1.919 -0.649 -0.933 -0.669 59 -0.307 0.405 0.170 2.017

18 -1.636 -1.028 -0.532 -0.280 24 0.014 0.666 0.822 -2.046

23 -0.920 -0.078 0.632 1.165 77 -1.756 0.373 0.249 -0.574 26 -0.754 -0.997 -0.851 0.806 31 -0.033 -0.570 1.399 -0.277

64 -0.150 -0.101 0.334 0.028 32 0.027 -1.291 -0.226 0.214

69 -0.227 -0.155 -0.220 -0.112 49 0.348 -0.384 1.859 0.328

72 0.180 -0.150 1.072 -1.048 50 0.502 -0.939 0.447 0.141

71 1.325 -0.633 0.223 0.150 52 0.062 -0.740 0.860 0.152

80 0.921 -0.692 0.069 0.179 62 0.363 0.376 -0.544 -0.158 81 0.389 -0.251 0.201 -0.221 35 0.284 -1.305 0.008 -0.626

14 -0.671 1.095 -1.992 0.168 43 -0.475 -1.058 0.535 -0.708

16 1.776 -1.011 -1.391 0.547 48 -0.168 -1.119 0.875 0.257 28 -0.302 1.505 -0.780 0.618 61 -0.400 -0.411 0.148 -0.079

geochemical and petrological constraints on the …

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