Mineral systems of Australia: an overview of resources, settings and processes

Author： Jaques A. L. Jaireth S. Walshe J. L.

ISSN： 0812-0099

Source： Australian Journal of Earth Sciences, Vol.49, Iss.4, 2002-08, pp. : 623-660

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Abstract

Australia produces more than 22 mineral commodities from a wide variety of deposit types, but >90% of the value of mine production is obtained from just 10 commodities. Both production and resources are underpinned by a few major deposit classes and a small number of world‐class deposits. Most major deposits lie in highly endowed metallogenic provinces and formed at discrete intervals during major metallogenic epochs, notably: 2.7–2.6 Ga, 2.4–2.2 Ga, 1.7–1.6 Ga, 1.2 Ga, 500–480 Ma, 440–420 Ma, 380–350 Ma, 320–280 Ma, 240–220 Ma and 100–0 Ma. These lie within the global metallogenic epochs that have previously been shown to coincide with the accretion and breakup of the major continents. Many of the major metallogenic provinces formed by accretion during convergent tectonic regimes and can be linked to particular orogenic events and/or changes in the apparent polar wander path. Giant deposits appear to have formed from large systems commonly located at major crustal structures. The interplay of source, transport and trap is critical. Formation of ore bodies occurs when hydrothermal fluids are released in a focused manner, migrate along ‘open' transport zones, and interact with suitable traps to deposit metals. Typically this occurs late in the tectonic evolution of the province or basin and may be associated with uplift and/or basin inversion. The efficiency of the trap site is a key factor in determining ore‐deposit size, and is enhanced by major physical and chemical contrasts between trap and fluid. Emplacement of mineralised intrusions and migration of mineralising fluids occurs in response to geodynamic triggers involving changes to the stress regime that may include far‐field stresses propagated across the Australian continent. With the exception of supergene deposits, mineralisation typically appears to have occurred within short time frames (