Editors; Hoatson, D.M. and Lewis, B.C. Authors: Hoatson, D.M., Miezitis, Y., Jaireth, S. and Huston, D.L.
The major aims of this report are to review the distribution, geological characteristics, resources, and potential of PGEs in Australia, and provide a mineral-systems-based framework for successful low-risk exploration.
A mineral-system approach has been used to classify ~500 PGE deposits and occurrences documented in this report. This approach focuses on mineral-forming processes critical to the formation of a particular deposit. It differs from descriptive classifications in that it can be used to predict new areas and types of PGE mineralisation. The classification used is hierarchical in structure, with the highest-level category of deposits called 'Mineral-System Class'. There are twelve major classes that fall within the broad-mineral systems: Orthomagmatic (classes 1 to 7), Hydrothermal-Metamorphic (class 8), Regolith-Laterite (class 9), Placer (class 10), Astrobleme-related (class 11), and a final class with minor or unknown economic importance (class 12).
This report concludes that, as seen globally, mineralised stratabound layers in Precambrian layered mafic-ultramafic intrusions in Australia are considered to have high potential for a major economic PGE resource. Such layers are attractive targets as they display: lateral continuity; have uniform grades (1 g/t to 6 g/t Pt+Pd+Au) and thicknesses; contain a significant component of the elements Pt, Pd, Rh, Au; and have potential for large-tonnage multi-element deposits (PGEs, Cr, Cu, Ni, Co, Au). Large Igneous Provinces may also provide opportunities for major economic PGE resource discoveries, despite the challenges of: defining favourable mineralised environments across large areas and under cover; lack of reliable geochronological and geochemical data for identifying different phases of the magmatic system; and a general perception that the global type example (Norilsk-Talnakh in Russia) may be a 'unique' mineral system.
