FREE event: MRIWA Tech Talk - Minerals Systems Analysis: 12 July, 2018 in Perth
Part 1 - Mineral system analysis in the Halls Creek Orogen: insights from geodynamic modelling, geophysical interpretation, and isotopes. Presented by Fariba Kohanpour.
The mineral systems approach allows identification and prioritization of the critical components for mineral prospectivity analysis from cratonic to deposit scales. To carry out mineral systems analysis, the key controlling processes on the formation and preservation of mineral systems must be understood. These processes include aspects as large scale as lithospheric enrichment and geodynamic drivers linked to the formation and break up of supercontinents. Other controlling processes, such as the requirement of specific lithologies or structures as mineralisation traps may require detail geological/geophysical analysis. In this contribution, we focus on:
- Tectonic evolution of the Halls Creek Orogen by applying geodynamic numerical modelling;
- Formation of major structures through time that act as fluid conduits of mineralising fluids to sites of ore deposition;
- Structural controls on gold and nickel mineral systems to understand depositional trap sites for mineralisation;
- Magmatic evolution of the Halls Creek Orogen by applying geodynamic models and isotope analysis that informs ideas about fertility.
Part 2 - Defining and navigating Au systems in the Eastern Goldfields, WA: “Are we there yet?". Presented by Dr John Walshe, Chief Research Scientist, CSIRO Mineral Resources.
Sometime in the life of the Australian Geodynamics Co-operative Research Centre (1993-2000) the question was asked: “Why is the deposit there?” The vision was to answer the question and find the next gold deposit!
The legacy of the AGCRC, the pmd*CRC (2002-2008) and six MERIWA/MRIWA projects over more than a decade and a half (2002-2018: M358, M377, M400, M410, M452 and M494) is a systematic, science driven, mineral-systems approach to answering the “Why is the deposit there?” question. The AGCRC and pmd*CRC championed the “5 Questions” approach to describing a system. This approach focused on understanding how the chemical system that does the “real” work of sourcing, transporting and depositing the gold operated within 4D architectural constraints (3D plus time) defined by the geology. The ideal is a scale-integrated 4D model of the mineral system: mapped architecture, flow paths, aquicludes, fluid flow history, deposit-camp-scale chemical gradients.
The MERIWA/MRIWA projects have focused on the practical task of learning to map the chemical system at the deposit to camp-scale with the view to providing explorers with robust tools for navigating camps to detect the deposits and realising the value in mature camps. Technological developments in mineral mapping make it possible to map the mineralogical architecture of camps with increasing effectiveness and efficiency. The challenge remains to invert maps of mineralogy to maps of chemical gradients (redox, pH, activities of volatile species) to provide a critical layer of chemical understanding and industry with the robust layer of mineralogical/chemical knowledge needed to navigate from the camp-scale to the high grade resources. This contribution provides an update on camp-scale mapping in Archean Au systems in the Yilgarn, WA and the developing understanding of the salient chemical parameters controlling fluid pathways and sites of Au deposition.