Authors / CoAuthors
Thorne, J.P. | Highet, L.M. | Cooper, M. | Claoue-Long, J.C.
Abstract
The search for world-class magmatic Ni-PGE resources requires a systems framework at the continental scale, similar to that of the magmatic systems themselves that extends from the mantle to the explorable shallow crust. Geoscience Australia's recently completed, multi-year, compilation of mafic-ultramafic magmatic events for the Australian continent provides this 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 rock units and events. The full dataset has recently been released as a GIS at a nominal scale of 1:5 000 000 for users to analyse and overlay with 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 Australian State and Territory geological surveys, supplemented (particularly in the Phanerozoic) with surface geology distributions in some regions. The solid geology extents provide insight into the total areal extents of the magmatic systems under sedimentary cover. The ages of Australian magmatism range from the Eoarchean ~3730 Ma Manfred Event, confined within a domain of the Yilgarn Craton, Western Australia to widespread Cenozoic magmatism in eastern Australia. This chronology has been resolved into 74 magmatic events identified by coeval magmatism mostly within ±10 million year bands. They range in magnitude from the giant volumes of magma in large igneous provinces to events whose only known occurrence is a single dated rock. The Australian magmatic record also draws attention to concentrations of mafic-ultramafic magmatism in three distinct periods: in the Archean from ~2820-2665 Ma; in the Proterozoic from ~1870-1590 Ma; and in the Phanerozoic from ~530-225 Ma. These three narrow periods, which comprise 16% of Earth's history, contain 39 of the 74 magmatic events, 53% of the entire mafic-ultramafic magmatic event record of the continent. Relative to some other continents with comparable geology, Australia is under-represented in world-class discoveries of intrusion-hosted Ni, PGE and Cr mineral deposits. Explorers are encouraged to use the GIS to assess specific magmatic events for Ni-PGE-Cr potential in context with other exploration indicators such as geochemistry, crustal architecture, lithosphere thickness, possibly reactive country rocks, and the spatial distribution of erupted versus intruded magmatic components. Using this mineral systems approach offers a much larger footprint than a mineral deposit and can be applied in greenfield and undercover regions. 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. The events also provide an insight into the geodynamic development of the continent over time, and as such, may be useful in assessing mineral systems other than orthomagmatic Ni-PGE-Cr systems.
Product Type
nonGeographicDataset
eCat Id
79285
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- External PublicationAbstract
- ( Theme )
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- LIP
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2014-01-01T00:00:00
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notPlanned
Topic Category
geoscientificInformation
Series Information
Lineage
unknown
Parent Information
Extents
Reference System
GDA94 (geocentric) (EPSG:4348)
Spatial Resolution
Service Information
Associations
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Source Information
Thorne, J.P., Highet, L.M., Cooper, M., Claoue-Long, J.C., Hoatson, D.M., Jaireth, S., Huston, D.L., Gallagher, R. G. 2014. Australian Mafic-Ultramafic Magmatic Events Map, 1:5 000 000 scale [Digital Dataset]. Geoscience Australia, Commonwealth of Australia, Canberra. http://www.ga.gov.au