Authors / CoAuthors
Cooper, M. | Thorne, J.P. | Highet, L.M. | Claoue-Long, J.C.
Abstract
Geoscience Australia has recently completed a multi-year compilation of Mafic-Ultramafic Magmatic Events for the Australian continent within a GIS framework. A detailed compilation of Phanerozoic mafic-ultramafic rock units and events has been appended to the previously published maps of Archean and Proterozoic mafic-ultramafic rocks and events. The full dataset has been released as a new GIS at a nominal scale of 1:5 000 000 for users to analyse and overlay other datasets. The delineation of magmatic events in this GIS is based on several hundred published ages of mafic and ultramafic igneous rocks using different isotopic systems and minerals. The foundation for the spatial distribution of rock units in the GIS are regional solid geology compilations from the State and Northern Territory geological surveys (available mainly for the Archean and Proterozoic), and surface geology distributions elsewhere (mainly for the Phanerozoic). The solid geology extents of units provide insights into the extent of the magmatic systems under sedimentary cover. Australian mafic-ultramafic magmatic events have been defined within resolvable bands of ±10 million years. Nineteen newly-formalised Phanerozoic mafic-ultramafic magmatic events range from the ~530 Ma Truro Event, named for the Truro Volcanics in southeast Australia, to the near-continuum of mafic magmatism during the Cenozoic in eastern Australia. Together with the existing event series for the Archean and Proterozoic, the complete magmatic event record of the continent now comprises 74 defined mafic-ultramafic magmatic events. This detailed compilation in both space and time is now the most complete record of mafic-ultramafic magmatic events for any continent. The GIS data are fully attributed to their sources. However, the geological datasets from the State and Northern Territory geological surveys use non-standardised attributes for rocks or solid geology, limiting the creation of a seamless nation-wide GIS dataset of mafic and ultramafic rocks. Nevertheless, the polygon attributes will allow the integration of the Mafic-Ultramafic Magmatic Events dataset with other national-scale datasets such as the national database of whole-rock geochemistry. Users may also link the new GIS data to the original attributed polygon data in State/Northern Territory GIS sources, because original map symbols were retained. Other attributes available for analysis include (but are not limited to) the presence or absence of ultramafic components within each defined magmatic event, Stratigraphic Units Database number, basic lithology, and the crustal domain within which each event is preserved (based on the Geoscience Australia Map of Australian Crustal Elements). Relative to some other continents with comparable geology, Australia appears to be under-represented in known mafic-ultramafic intrusion-hosted nickel, PGE and chromium mineral deposits. The primary intention of the GIS of Mafic-Ultramafic Magmatic Events is the provision of information for those investigating under-explored and potentially mineralised environments in Australia that may lead to redressing the discovery imbalance. The events also provide an insight into the geodynamic development of the continent over time.
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nonGeographicDataset
eCat Id
79207
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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- External PublicationAbstract
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2014-01-01T00:00:00
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