Summary of the Intrusive Lithostratigraphy and Geochronology of the Cupriferous Retreat Batholith, Clermont, Queensland
Robert H. Findlay
Lindisfarne, Tasmania 7015, Australia.
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The Clermont district of Queensland is well-known for historical small-scale copper and gold mining. The Neoproterozoic-Cambrian Anakie Metamorphic Group contain zones of lower greenschist facies metabasite hosting possible VMS copper shows together with limited outcrops of related ultramafic rocks with Ni/Pt/Pd possibilities. The Anakie Metamorphic Group is intruded by the predominantly granodioritic, monzonitic and gabbroic assemblage of the Middle-to-Late Devonian Retreat Batholith. In the study area these intrusive rocks display sporadic, fracture-hosted shows of malachite and azurite with associated “green-rock” alteration along a 14km strike length between the Rosevale and Consols-Savannah areas.
Between 2013 and 2015 Diatreme Resources Ltd, in a joint venture with Antofagasta PLC, carried out a detailed exploration programme involving 1:2000 and 1:5000 geological mapping supported by a limited petrological study, detailed study of approximately 14km of legacy and new diamond drill-core, RC and RAB drilling and geochronological studies along the cupriferous zone within the Retreat Batholith. This project not only has enabled a clear understanding of the timing of intrusion and mineralisation but has also given an indication of the possible sub-surface source for the mineralisation at the Rosevale prospect in this lithostratigraphically complex region. This project consolidated prior regional campaigns of investigations of soil geochemistry, geophysics, prior cored diamond and RC drilling and limited geological mapping by Diatreme Resources and precursor companies.
Keywords: Intrusive Lithostratigraphy, Geochronology, Mineralisation