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Australia through time: a summary of its tectonic and metallogenic evolution

2012; International Union of Geological Sciences; Volume: 35; Issue: 1 Linguagem: Inglês

10.18814/epiiugs/2012/v35i1/004

2586-1298

David L. Huston, R.S. Blewett, D.C. Champion,

Geochemistry and Geologic Mapping

related controversies.We also link Australia's geological heritage, including its resources, as well as its geography, flora and fauna, to this tectonic narrative.Much of the geology of Australia is the consequence of the amalgamation and break-up of supercontinents and supercratons through geological time, such as Vaalbara, Kenorland, Nuna (Columbia), Rodinia and Pangea (including Gondwana) (Figure 1).Supercontinent history has not only controlled the distribution of resources, petroleum, coal and minerals, but has surprising influences on processes that have shaped Australia in the past and are shaping Australia now.Australia, for example, shares many floral and faunal affinities with South America and Africa, but few with northern hemisphere continents (e.g., Couper, 1960;Fooden, 1972).The breakup of Pangea isolated Australia from Eurasia and North America.Moreover, when Australia broke away from Antarctica, the resulting seaway opened to allow polar circulation of ocean currents and ultimately the formation of the Antarctic ice cap (Livermore et al. 2005), making Australia, and the world, drier and cooler (Fujioka and Chappell, 2010).Continental Australia grew predominantly from W-E, with Archean rocks mostly in the W, Proterozoic rocks in the centre, and Phanerozoic rocks in the E. The western two-thirds of the continent consist of three mostly Precambrian elements (see Table 1 for definitions), the West Australian, North Australian and South Australia elements, whereas the eastern one-third is made up of the Tasman Element (Figure 2).These spatial and temporal growth patterns are consistent with supercontinent and supercraton growth, particularly Kenorland, Nuna and Pangea-Gondwana.The distribution of Australia's energy and mineral resources (Figure 2) is also governed by this broad pattern, with each of the four major cratonic elements characterised by distinctive deposit assemblages, both in time and in composition.The Australian continent evolved in four broad time periods, namely: 3800-2200 Ma, 2200-1300 Ma, 1300-700 Ma, and 700-0 Ma.The first period saw the growth of nuclei about which cratonic elements grew, whereas the latter three periods involved the amalgamation and dispersal of Nuna, Rodinia and Pangea-Gondwana, respectively.In the sections below we present a history of the growth of the present-day Australian continent using this framework, although noting that in many cases there is significant uncertainty and disagreement about specific details and, indeed, about whether some of these processes occurred at all.This geohistory provides context for events that have shaped and changed Australia and the Earth, including the evolution of life and changes in the composition of the atmosphere and hydrosphere.As they have been increasingly linked to geodynamic processes, the evolution of Australia's mineral andThe geological evolution of Australia is closely linked to supercontinent cycles that have characterised the tectonic evolution of Earth, with most geological and metallogenic events relating to supercontinent/ supercraton assembly and breakup.Australia mainly grew from W-E, with two major Archean cratons, the Yilgarn and Pilbara cratons, forming the oldest part of the continent in the West Australian Element.The centre of the continent consists of the mainly Paleoproterozoic-Mesoproterozoic North and South Australian elements, whereas the E is dominated by the Neoproterozoic-Mesozoic Tasman Element.The West, North and South Australian elements initially assembled during the Paleoproterozoic amalgamation of Nuna, and the Tasman Element formed mostly as a Paleozoic accretionary margin during the assembly of Gondwana-Pangea.Australia's present position as a relatively stable continent resulted from the breakup of Gondwana.Australia is currently moving northward toward SE Asia, probably reflecting the earliest stages of the assembly of the next supercontinent, Amasia.Australia's resources, both mineral and energy, are linked to its tectonic evolution and the supercontinent cycle.Australia's most important Au province is the product of the assembly of Kenorland, whereas its major Zn-Pb-Ag deposits and iron oxide-Cu-Au deposits formed as Nuna broke up.The diverse metallogeny of the Tasman Element is a product of Pangea-Gondwana assembly and most of Australia's hydrocarbon resources are a consequence of the breakup of this supercontinent.