The Kulumadau epithermal breccia-hosted gold deposit, Woodlark Island, Papua New Guinea
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Date
2015-03-18
Journal Title
Journal ISSN
Volume Title
Publisher
AusIMM
Abstract
The Kulumadau deposit represents an intermediate-sulfidation epithermal gold deposit (3.8 Mt at 2.3 g/t, Ag:Au = 1). Mineralisation is primarily confined to hydrothermal breccias within preexisting fault zones, where it is disseminated throughout a hydrothermal matrix comprising chlorite-quartz-adularia-illite-I/S clays-calcite-pyrite. The host sequence represents numerous mid-Miocene pyroclastic flow eruptions within a tectonically active emergent shallow marine to subaerial depositional setting. Subsequent growth faulting was responsible for debris avalanches, which were subsequently cut by reverse faults. Faults were exploited by hydrothermal fluids, with the heightened porosity at the juncture between faults and debris material facilitating boiling of the ore constituents. Fluid inclusion studies suggest that fluid mixing between meteoric fluids and magmatic fluids, accompanied by boiling, were the primary mechanisms for gold deposition. The occurrence of anhydrite/gypsum as late-stage veins and their sulfur and oxygen isotopic values indicate post-mineralisation mixing of sea water with hydrothermal fluids.
Description
Keywords
Gold, Geologic deposits, Papua New Guinea, Geologic faults, Fluids, Mineralization, Clays
Citation
Burkett, D., Graham, I., Spencer, L., Lennox, P., Cohen, D., Zwingmann, H., Lau, F., Kelly B., & Cendon D. I. (2015). The Kulumadau epithermal breccia-hosted gold deposit, Woodlark Island, Papua New Guinea. Paper presented to the PACRIM 2015, Hong Kong, China, 18-21 March 2015.