• Geology and Mineralisation of the Chatree Epithermal Gold-Silver Deposit,


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    • Abstract: Geology and Mineralisation of the Chatree Epithermal Gold-Silver Deposit,Petchabun Province, Central ThailandGrace Cumming¹, Ron James2, Abhisit Salam3, Khin Zaw4, Sebastien Meffre4,Weerasak Lunwongsa5, Saranya Nuanla-ong6

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Geology and Mineralisation of the Chatree Epithermal Gold-Silver Deposit,
Petchabun Province, Central Thailand
Grace Cumming¹, Ron James2, Abhisit Salam3, Khin Zaw4, Sebastien Meffre4,
Weerasak Lunwongsa5, Saranya Nuanla-ong6
1
Consulting Geologist for Akara Mining Limited (Exploration), Research Assistant, CODES ARC Centre for
Excellence in Ore Deposits, University of Tasmania, 7001 Hobart, Australia, [email protected],
2
General Manager Exploration, Kingsgate Consolidated Limited, Suite 801, Level 8, 14 martin Place, Sydney,
NSW, Australia, 2000, [email protected],
3
PhD Candidate, CODES ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Australia
7001, [email protected],
4
Associate Professor, CODES ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart,
Australia 7001, [email protected],
5
Senior Exploration Geologist, Issara Mining Limited, 156/9 – 10 Moo 11 T. Dongkui, A. Chondan, Petchabun
67190, Thailand, [email protected]
6
Senior Exploration Geologist, Issara Mining Limited, 156/9 – 10 Moo 11 T. Dongkui, A. Chondan, Petchabun
67190, Thailand, [email protected]
ABSTRACT
Gold and silver mineralisation at the Chatree low sulphidation deposit is hosted in
andesitic volcanic and volcaniclastic rocks and characterised by multiple
hydrothermal alteration assemblages and quartz-carbonate (chlorite-adularia)
replacements, veins and breccias. The ore-bearing veins are influenced by
intersecting structures and host rock lithologies. Emplacement of the host succession
occurred at 250 ± 6 Ma (dated with Laser Ablation ICP-MS U-Pb zircon techniques),
which was closely followed by mineralisation at 250.9 ± 0.8 Ma based on the
analysis of adularia from coarse-grained quartz-sulphide (chalcopyrite-pyrite-
sphalerite) veins using laser ablation Ar-Ar methods.
INTRODUCTION
The Chatree epithermal gold-silver deposit, central Thailand, is associated
with a volcanic centre that spans approximately 7.5 by 2.5 km. The deposit consists of
seven defined prospect areas and multiple open cut pits. The mineral resource
contains 1.6 g/t of Au and 13 g/t of Ag, and together with the previously mined ore,
totals almost five million ounces of gold, making it the largest hard-rock Au resource
in Thailand. Studies of the sulphide mineral assemblages have classified the deposit
as low sulphidation epithermal (based on Heald, Foley and Hayba, 1987) with
sulphide content generally less than 3 % and low base metal contents ( than 100 m thick, with a lithic rich base, massive fiamme pyroclastic processes.
and lithic rich interior and finely laminated, finer grained fiamme rich siltstone upper.
Polymictic mud Grey – green variably altered quartz phyric mudstone matrix supports variably Deposition from mass flow
matrix breccia hydrothermally altered poorly sorted, sub-rounded to angular, pebble to boulder processes.
andesite, rhyolite, mudstone, clastic clasts and chlorite altered fragments. Beds are 10 -
20 m thick, with finer base, coarse interior and fine upper portion
Quartz rich Lens – ragged shaped Fiamme are 1 – 4 cm across and composed of quartz (30% ), Rapid emplacement by
fiamme breccia plagioclase (30%). Beds are 40 – 60 m thick with a lithic rich base, a massive fiamme subaqueous silicic syn-
rich interior and fine laminated upper portion. Lateral extent is no more than 750m eruptive pyroclastic processes
from south to north. from a dome seated eruption.
Volcaniclastic Less than


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