Update on Chillagoe Mining District Research: Dec 7, 2017

Transcription

1 Update on Chillagoe Mining District Research: Dec 7, 2017 Peter Illig 1, Zhaoshan Chang 1 1 EGRU James Cook University, Townsville QLD 4811, Australia Introduction to Chillagoe Deposits Regional introduction Red Dome skarn porphyry deposit Mungana skarn porphyry deposit Redcap skarn prospects King Vol skarn deposit

2 Chillagoe Formation = Shallow Marine Deposits Chillagoe located western margin of Hodgkinson Province Adjacent to Palmerville Fault (North Australia Craton boundary) Intersection of Kennedy Igneous Association intrusions and limestone. From Hendersen et al., 2013 From Jell et al., 2013 Chillagoe Formation = Shallow Marine Deposits Chillagoe located western margin of Hodgkinson Province Adjacent to Palmerville Fault (North Australia Craton boundary) Intersection of Kennedy Igneous Association intrusions and limestone. From Hendersen et al., 2013

3 Chillagoe Resources Redcap Mungana Red Dome Red Dome produced 15Mt at 2.0 g/t Au, 0.5% Cu and 15 g/t Ag. Mungana produced 700kt at 11.1% Zn, 1.8% Cu, 1.0% Pb, 1.0 g/t Au, 80 g/t Ag Red Dome 69.2 Mt Mungana 48.7 Mt Redcap 3.8 Mt King Vol 3Mt 0.63 g/t Au 0.7 g/t Au 4.8% Zn 11.9% Zn 0.24% Cu 0.19% Cu 0.7% Cu 0.8% Cu 5.2 g/t Ag 13.3 g/t Ag 0.2% Pb 0.6% Pb 0.1g/t Au 30 g/t Ag Chillagoe Resources Redcap Mungana Causative Intrusions Red Dome Larger Plutons (no deposits)

4 Chillagoe Resources Redcap Mungana Red Dome

5

6 Now onto Mungana Au + Pb Zn Ag Cu

7 Two Overprinting Deposits Au Porphyry Zn Pb Cu Ag Skarn Base Metal Resources Hosted By Skarn Majority of garnet analyses between % andradite Core photo from Lehrmann, 2012

8 UST at edges of porphyry UST cut by A veins

9 Gold hosted in Arsenopyrite rich A veins with variable K Feldspar Halos Photomicrographs from Lehrmann, 2012 Crackle Breccia at shallowest depths Shreddy biotite/epidote alt n overprinted by sericite alt n. Latest is brecciation and cpx + wollastonite infill.

10 Medium grained granite at depth Base metal skarn preceded Au porphyry by ~18 million years Three porphyry body ages overlap inferred as one body at depth Granite body is latest does not appear to be related to base metal skarn Source of base metal skarn undiscovered and at depth

11 Now onto Redcap Zn Cu Pb Au Redcap Surface Geology Redcap fault dips southwest at ~35 degrees Skarn is located at sedimentary contacts and along Redcap fault. WHICH INTRUSION IS CAUSATIVE??? Ages from Lehrmann (2012) and Bultitude et al. (1993). Ruddygore Granodiorite Pluton 2.6 km southeast

12 A A Fault locations are interpretive. A A Fault locations are interpretive.

13 Two Skarn Affinities Present Throughout Prospect Earliest skarn is garnet + magnetite + chalcopyrite + sphalerite Late pyroxene + pyrrhotite + chalcopyrite + gold Two Skarn Affinities Present Throughout Prospect Earliest skarn is garnet + magnetite + chalcopyrite + sphalerite Late pyroxene + pyrrhotite + chalcopyrite + gold

14 Two Skarn Affinities Present Throughout Prospect Earliest skarn is garnet + magnetite + chalcopyrite + sphalerite Late pyroxene + pyrrhotite + chalcopyrite + gold Two Skarn Affinities Present Throughout Prospect Earliest skarn is garnet + magnetite + chalcopyrite + sphalerite Late pyroxene + pyrrhotite + chalcopyrite + gold

15 Two Skarn Affinities Present Throughout Prospect Garnet skarn contains diopside rich pyroxene Pyroxene po skarn contains hedenbergite rich pyroxene 34 analyses between Ad n=41 n=192 Gt mt sph skarn Px po skarn Where is the source? Ages from Lehrmann (2012)

16 Pyroxene Compositions Point Downdip A A Hd94 Hd75 Hd79 Interpretation assumes no significant post mineralisation displacement

17 Pyroxene Compositions Point Downdip B B Interpretation assumes no significant post mineralisation displacement NOT SOURCE! Source of px po skarn is downdip and southwest. Source of gt sph mt remains unknown. NOT SOURCE! Ruddygore Granodiorite Pluton 2 km southeast

18 King Vol Zn Pb Cu Ag Skarn King Vol Zn Pb Cu Ag Skarn

19 Base metal skarn and massive sulfide body located on contact of sandstone and limestone. Potassium bearing Amphibole + sphalerite sample submitted for Ar Ar dating. Products of Project Products of project will be: Geochem, geochron, structural synthesis of deposits Deposit scale sections and surface maps U Pb geochronology of porphyries and plutons of district New 1:12,500 A0 Sheet Geologic Map C O isotopes and permeability data for Chillagoe Marbles and Limestones how to employ both in carbonate exploration Awaiting Ar Ar age for King Vol, Re Os for Redcap, permeability measurements for carbonates

20 THANK YOU Photo from Auctus Minerals