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Geological Sciences Special Seminar: Redox to riches: The importance of understanding paleoredox history in exploration for basin-hosted metal deposits
Dr Sam Spinks is a Senior Research Geoscientist (geologist/geochemist) at the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia’s National science agency. Sam works in CSIRO’s Mineral Resources division, where he specializes in research into sediment-hosted ore deposit formation and exploration.
As the global population rapidly expands, the demand for minerals and metals has never been higher. Base metals such as Fe, Zn, Cu, and Mn, among others, are critical components of our cities and infrastructure, and cannot be replaced by other materials, so are the very fabric on which our civilization is built. The level of demand for these metals is not being met by sufficient numbers of new discoveries, and many of the known large-tonnage deposits have been exhausted or are rapidly depleting. Exploration for these metals has classically been focussed on exposed hard-rock terranes that are favourable for geophysical and geochemical exploration methods. However, some of the largest and highest-grade base metal deposits occur in sedimentary rocks, and the formation of these deposits can be fundamentally controlled by the paleoredox environment of the basin during sediment deposition.
The deposition of major metals such as Fe and Mn are intimately associated with changes in oceanic oxygen flux, whereas deposition of the chalcophile base metals (e.g. Zn, Cu, Pb) in black shale environments are linked to the complex dynamics between redox gradients and sulfur cycling in basinal fluids. Understanding these processes in a temporal and spatial context is critical to identifying prospective terranes for future mineral exploration, and will play a key part in the development of the next generation of geochemical and geophysical exploration methods.
This seminar will explore some recent industry-focussed research projects in the Precambrian terranes of Australia that have sought to understand aspects of oceanic and basin fluid paleoredox on the prospectivity for, and deposition of metal deposits.