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Malachite Resources NL

INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT:. The Tooloom Example. Brett McKay. Malachite Resources NL. MALACHITE RESOURCES NL. Classification of Intrusion-related gold systems Geological model The Tooloom Example Phoenix

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Malachite Resources NL

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

  2. MALACHITE RESOURCES NL • Classification of Intrusion-related gold systems • Geological model • The Tooloom Example • Phoenix • Intrusion-related gold systems in the New England Fold Belt • metallogeny of NEFB • comparison with LFB • 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. IRGS MODEL Modified from Hart et al., 2002

  6. IRGS MODEL Modified from Lang et al., 2000

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

  8. MALACHITE RESOURCES NL • THE TOOLOOM EXAMPLE:

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

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

  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. MALACHITE RESOURCES NL 20 c GOLD 1 cm Sheeted auriferous quartz veins FRASERS INTRUSIVE CENTRE • Frasers, Nine Mile, Back Creek • extensive alluvial Au worked – Eight Mile • Au-bearing qtz veins upstream • visible Au in outcrop • nearby intrusives  hydrothermal system?

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

  16. MALACHITE RESOURCES NL Breccia pipe IP anomaly Main gold in soil anomaly Shear zone (controlling position of Phoenix Breccia?) PHOENIX PROSPECT 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. 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

  18. MALACHITE RESOURCES NL PHOENIX PROSPECT The Phoenix breccia in outcrop

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

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

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

  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 • 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 1960-70’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. INTRUSION-RELATED GOLD SYSTEMS IN THE NEW ENGLAND FOLD BELT: The Tooloom Example Brett McKay Malachite Resources NL

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