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Malachite Resources NL INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT: Brett McKay The Tooloom Example.

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Presentation on theme: "Malachite Resources NL INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT: Brett McKay The Tooloom Example."— Presentation transcript:

1 Malachite Resources NL INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT: Brett McKay The Tooloom Example

2 MALACHITE RESOURCES NL Classification of Intrusion-related gold systems Geological model Geological model The Tooloom Example The Tooloom Example – Phoenix Intrusion-related gold systems in the New England Fold Belt Intrusion-related gold systems in the New England Fold Belt – metallogeny of NEFB – comparison with LFB Newly recognised prospectivity of NEFB Newly recognised prospectivity of NEFB

3 MALACHITE RESOURCES NL 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 W Sn Mo provinces Continental tectonic setting

4 MALACHITE RESOURCES NL 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)

5 Modified from Hart et al., 2002 IRGS MODEL

6 Modified from Lang et al., 2000 IRGS MODEL

7 MALACHITE RESOURCES NL MAJOR IRGS DISTRICTS: Lang & Baker, 2001 Paleo-Tethys Closure Tintina Gold Belt Eastern Australia Bolivia

8 MALACHITE RESOURCES NL THE TOOLOOM EXAMPLE:

9 MALACHITE RESOURCES NL THE 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 HISTORY Tooloom is a major goldfield, long forgotten First discovered in 1857 – 10,000 alluvial miners Coarse gold – many nuggets: largest 140 ozs DISCOVERY OF PHOENIX GOLD DEPOSIT IN 2005

10 MALACHITE RESOURCES NL Simplified geological map of the Tooloom area Intrusive centres Cullens Phoenix Joes Gully Frasers

11 MALACHITE RESOURCES NL $1 JOES GULLY INTRUSIVE CENTRE extensive alluvial deposits coarse Au intergrown with qtz sheeted qtz vein and stockworks outcropping upstream minor outcropping intrusives and dykes

12 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 MALACHITE RESOURCES NL 20 c Sheeted auriferous quartz veins FRASERS INTRUSIVE CENTRE GOLD

13 MALACHITE RESOURCES NL PHOENIX 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

14 MALACHITE RESOURCES NL Au As Cu Sb PHOENIX SOIL GEOCHEMISTRY

15 MALACHITE RESOURCES NL PHOENIX PROSPECT PHOENIX PROSPECT Bi soil geochemistry Bi in soil over breccia = Bi in soil over breccia = gold at depth Breccia The Creek Zone: larger but weaker Bi anomaly (+Au-As-Sb) larger but weaker Bi anomaly (+Au-As-Sb)

16 MALACHITE RESOURCES NL PHOENIX PROSPECT Breccia pipe Main gold in soil anomaly IP anomaly Shear zone (controlling position of Phoenix Breccia?) 70K Tonalite Emu Creek Fm sedimentary rocks

17 MALACHITE RESOURCES NL PHOENIX PROSPECT: Phoenix Breccia: 85 m true width, +300 m outcrop length elongate, pipe-like geometry eg 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

18 MALACHITE RESOURCES NL The Phoenix breccia in outcrop PHOENIX PROSPECT

19 MALACHITE RESOURCES NL PHOENIX PROSPECT The Phoenix breccia in drill core

20 MALACHITE RESOURCES NL PHOENIX PROSPECT Late stibnite veins Sulphide infill of open- space in breccia The Phoenix breccia in drill core

21 MALACHITE RESOURCES NL 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 System

22 Modified from Lang et al., 2000 Phoenix IRGS MODEL Present erosional level at Phoenix

23 MALACHITE RESOURCES NL IRGS in NEW ENGLAND 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

24 MALACHITE RESOURCES NL IRGS in NEW ENGLAND FOLD BELT 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: Kingsgate Mo-Bi; Glen Eden Mo-W-Sn; Taronga Sn

25 MALACHITE RESOURCES NL IRGS in the NEW ENGLAND FOLD BELT Timbarra Eg. Timbarra – 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

26 MALACHITE RESOURCES NL IRGS in the NEW ENGLAND FOLD BELT Comparison of NEFB LFB LFB : Intensive exploration for porphyry Cu in s Arizona light-bulb model unprospective for large Cu deposits later success with application of new model Ordovician shoshonitic intrusives Northparkes, Cadia

27 MALACHITE RESOURCES NL IRGS in the NEW ENGLAND FOLD BELT Comparison of NEFB LFB NEFB : 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!

28 Malachite Resources NL INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT: Brett McKay The Tooloom Example


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