malachite resources nl

Malachite Resources NLMalachite Resources NL

INTRUSION-RELATED GOLD SYSTEMS IN INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT:THE NEW ENGLAND FOLD BELT:

Brett McKayBrett McKay

The Tooloom ExampleThe Tooloom Example

MALACHITE RESOURCES NLMALACHITE RESOURCES NL

• Classification of Intrusion-related gold systemsClassification of Intrusion-related gold systems

• Geological modelGeological model

• The Tooloom ExampleThe Tooloom Example

– PhoenixPhoenix

• Intrusion-related gold systems in the New Intrusion-related gold systems in the New

England England Fold BeltFold Belt

– metallogeny of NEFBmetallogeny of NEFB

– comparison with LFBcomparison with LFB

• Newly recognised prospectivity of NEFBNewly recognised prospectivity of NEFB


Intrusion-related gold system (IRGS) characteristics:Intrusion-related gold system (IRGS) characteristics:

• Au variably combined with Bi, Te, W, Mo, Sb, As

• Low sulphide content (<5%)

• Reduced mineral assemblage (Po, As, Py, Ilm, no Mag/Hem)

• Deposit and metal assemblage zoning: lateral & vertical

• Reduced I-type intrusives

• Intermediate to felsic

• WSnMo provinces

• Continental tectonic setting


Intrusion-related gold system (IRGS) characteristics:Intrusion-related gold system (IRGS) characteristics:

• Sheeted veins, stockworks, breccias, disseminations, skarns,

replacements, fissure veins

• Lateral and vertical metal zoning

– proximal Au-Bi-Te > Au-As > As-Sb-Au > Ag-Pb-Zn distal

– W±Mo at depth

– Au-Bi-Sb at shallower levels

• Examples:

– Donlin Creek: 28.5 Moz (measured & indicated resource)

– Pogo: 7 Moz (probable reserve)

– Fort Knox: 2.4 Moz (proven and probable reserve)

Modified from Hart et al., 2002

IRGS MODELIRGS MODEL

Modified from Lang et al., 2000

IRGS IRGS MODELMODEL


MAJOR IRGS DISTRICTS:MAJOR IRGS DISTRICTS:

Lang & Baker, 2001

Paleo-Tethys Closure Tintina Gold Belt

Eastern Australia

Bolivia


THE TOOLOOM EXAMPLE:THE TOOLOOM EXAMPLE:


THE TOOLOOM STORYTHE TOOLOOM STORY

• Hard rock sources barely touched

• Abandoned around 1870 Gympie

• Slipped into obscurity – few official records

• Minor alluvial gold mining continued until 2001

• Phoenix first recognised as a prospect in 2003

HISTORYHISTORY• Tooloom is a major goldfield, long forgotten

• First discovered in 1857 – 10,000 alluvial miners

• Coarse gold – many nuggets: largest 140 ozs

1 cm

Nuggets Nuggets from from

TooloomTooloom

DISCOVERY OF PHOENIX GOLD DEPOSIT IN 2005DISCOVERY OF PHOENIX GOLD DEPOSIT IN 2005


Simplified geological map of the Tooloom area

Intrusive centres

CullensCullensPhoenixPhoenix

Joes Joes GullyGully

FrasersFrasers


$1JOES GULLY INTRUSIVE JOES GULLY INTRUSIVE

CENTRECENTRE

• extensive alluvial deposits

• coarse Au intergrown with qtz

• sheeted qtz vein and stockworks outcropping upstream

• minor outcropping intrusives and dykes

• Frasers, Nine Mile, Back Creek

• extensive alluvial Au worked – Eight Mile

• Au-bearing qtz veins upstream

• visible Au in outcrop

• nearby intrusives hydrothermal system?

1 cm


20 c

Sheeted auriferous Sheeted auriferous quartz veinsquartz veins

FRASERS INTRUSIVE CENTREFRASERS INTRUSIVE CENTRE

GOLD

MALACHITE RESOURCES NLMALACHITE RESOURCES NLPHOENIX INTRUSIVE SYSTEMPHOENIX INTRUSIVE SYSTEM

• followup of multiple +20 ppb Au BLEG anomalies

• discovery of Phoenix Breccia

• 0.2 – 0.4 g/t Au from initial rock chips

• patchy Au in soils, low tenor

• coincident As-Sb-Bi-Cu soil anomaly, 1 km diameter

• large annular IP chargeability anomaly, > 400 m depth

• 2 km diameter aeromagnetic low

• Creek Zone → Au-Bi-As-Cu soil anomaly

• hornfelsed Emu Ck Fm sedimentary rocks contact aureole

• diss. and veinlet pyrrhotite-pyrite-arsenopyrite elevated Au

• 26 RC and diamond holes


AuAu AsAs

CuCu SbSb

PHOENIX SOIL PHOENIX SOIL GEOCHEMISTRYGEOCHEMISTRY


PHOENIX PROSPECTPHOENIX PROSPECT

Bi soil geochemistryBi soil geochemistry

• Bi in soil over breccia Bi in soil over breccia ==

gold at depthgold at depth

Breccia

The Creek Zone:The Creek Zone: larger but weaker Bi larger but weaker Bi anomaly (+Au-As-Sb)anomaly (+Au-As-Sb)

6837500 mN

44

40

00

mE

6835500 mN

44

20

00

mE

LEGEND

Au soil anomaly

outline of IP anomaly

road, track

river, creek

metres

0 400m

Enhanced heli-magimage, IP and gold

soil geochem atPhoenix Prosepct

GDA94/MGA Zone 56

drill hole with down hole trace



Breccia pipe

Main gold in soil anomaly

IP anomaly

Shear zone (controlling position of Phoenix Breccia?)

70K Tonalite

Emu Creek Fm sedimentary rocks


PHOENIX PROSPECT:PHOENIX PROSPECT:

Phoenix Breccia:Phoenix Breccia:

• 85 m true width, +300 m outcrop length

• elongate, pipe-like geometry

• eg. 48 m @ 2.21 g/t Au

• polymictic, angular to subrounded clasts

• was up to 20% open-space

• qtz-carb-sulphide infill, at least two episodes

• jig-saw textured, limited vertical movement

• weak to locally intense Se alteration → Au grades


The Phoenix breccia The Phoenix breccia in outcropin outcrop



PHOENIX PHOENIX PROSPECTPROSPECT

The Phoenix The Phoenix breccia in drill corebreccia in drill core



Late stibnite veins

Sulphide infill of open-space in breccia

The Phoenix breccia in The Phoenix breccia in drill coredrill core

MALACHITE RESOURCES NLMALACHITE RESOURCES NLIRGS CHARACTERISTICS OF PHOENIX SYSTEM:IRGS CHARACTERISTICS OF PHOENIX SYSTEM:

• Au-Bi-Sb-As association

• reduced mineral assemblage → Po-As-Py, no Mag/Hem

• low sulphide content <5%

• possible vertical metal zoning: Sb-Py, slight Au with depth

• located in mineralised contact aureole of buried intrusive?

• I-type, mod. reduced, felsic-intermediate intrusives in project area

• continental tectonic setting, post-orogenic

• W-Sn-Mo province (NEFB)

• mid-way between proximal and distal

• potential for range of other deposits

PHOENIX is part of a large Intrusion-related Gold SystemPHOENIX is part of a large Intrusion-related Gold System

Modified from Lang et al., 2000

Phoenix

IRGS IRGS MODELMODEL

Present erosional level at Phoenix

MALACHITE RESOURCES NLMALACHITE RESOURCES NLIRGS in NEW IRGS in NEW ENGLAND FOLD BELTENGLAND FOLD BELT

• Au, W, Sb, Sn, Mo and base metal occurrences

• Associated with intrusives:

– post orogenic

– I-type

– reduced

– felsic to intermediate

– low magnetic

– mid-Permian to early Triassic

• Veins, stockworks, pipes, disseminations, greisens, skarns

Tooloom


IRGS in NEW ENGLAND FOLD BELTIRGS in NEW ENGLAND FOLD BELT

Favourable granite geochemistry:Favourable granite geochemistry:

• Clarence River Supersuite → Tooloom

• Moonbi Supersuite → Timbarra; Tooloom?

• Uralla Supersuite

• Nundle Supersuite

• Gundle Belt

• Coastal Belt

• Various unnamed leucogranite intrusives

Various deposits associated with intrusives:Various deposits associated with intrusives:

• Kingsgate Mo-Bi; Glen Eden Mo-W-Sn; Taronga Sn


IRGS in the NEW ENGLAND FOLD BELTIRGS in the NEW ENGLAND FOLD BELT

Eg. TimbarraTimbarra

– best studied IRGS in NEFB (Mustard, 2001 & 2004)

– disseminated Au in miarolitic carapace of monzogranite of

Moonbi Supersuite

– strong Au correlation with Bi, Ag, Te

– weak Au correlation with Sb, Mo, As

– proximal i.e. within mineralising pluton

– only 60 km south-southwest of Phoenix

– Moonbi Supersuite outcrops in vicinity of Tooloom



Comparison of NEFB LFB

LFBLFB::

• Intensive exploration for porphyry Cu in 1960-70’s

• Arizona ‘light-bulb’ model

• unprospective for large Cu deposits

• later success with application of new model

Ordovician shoshonitic intrusives

Northparkes, Cadia



Comparison of NEFB LFB

NEFBNEFB::

• Very little exploration though application of wide-ranging

geological model

• Large Au deposits in Qld part Cracow, Mt Morgan, Gympie

• NSW part regarded as unprospective

• IRGS will rediscover the NEFB as prospective for large Au

deposits

PHOENIX could do for the NEFB what Northparkes did for the LFB!PHOENIX could do for the NEFB what Northparkes did for the LFB!

Malachite Resources NLMalachite Resources NL

INTRUSION-RELATED GOLD SYSTEMS IN INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT:THE NEW ENGLAND FOLD BELT:

Brett McKayBrett McKay

The Tooloom ExampleThe Tooloom Example

malachite resources nl

Documents

mile au

visible au

depth aubi

creek extensive alluvial

gt au polymictic

sbau agpb

alluvial minerscoarse

initial rock chips patchy