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Updated:
26 August 2005
North Australia Project: Marginal mobile belts
Southern Arunta geophysical interpretationObjective:To provide geophysical interpretation of the Mt Rennie, Mt Leibig, Lake Mackay and Mt Doreen 1:250 000 sheets in conjunction with NTGS's South Arunta project. BackgroundThe southwest part of the Arunta Province is poorly exposed and the last major mapping program was in the 1960s. The Northern Territory Geological Survey (NTGS) commenced an integrated multidisciplinary regional geoscience study in the southern Arunta in 2000. This area is important in determining the relationships of major blocks within the Arunta and the relationship between the Arunta and the Tanami Region because there is potential that the lode Au mineralising event in the Tanami extends into this area. This module will work closely with the NTGS South Arunta project. Arunta mafic igneous suitesObjective:To constrain the Proterozoic mafic-ultramafic magmatic systems within the event chronology of the Arunta Province, and to provide a geoscientific framework for assessing the prospectivity and resource potential of the intrusions. Background:Field investigations by Geoscience Australia, as part of the National Geoscience Agreement with the Northern Territory Geological Survey, have evaluated the geological setting and economic potential of Proterozoic mafic-ultramafic intrusions in the Arunta Province of central Australia. The intrusions form large homogeneous gabbroic bodies, folded high-level mafic sills, steeply dipping amphibolite sheets, and relatively undeformed ultramafic plugs with alkaline and tholeiitic affinities. This study aims to characterise the intrusions on the basis of U-Pb geochronology, metamorphic-structural histories, and parent magma compositions, and to establish a regional stratigraphic framework that can be integrated with other NAR datasets. This study will also determine the economic potential of the intrusions for hosting platinum-group element (PGE), chromium, nickel, copper and cobalt mineralisation similar to intrusions in other nearby Proterozoic provinces (Musgrave Block, Halls Creek Orogen-East Kimberleys). Historically, the Arunta Province has generally been regarded as having low potential for mineralising systems associated with mafic-ultramafic rocks because of its high-grade metamorphic character and protracted tectonothermal history spanning more than 1500 Ma. However, field observations and preliminary geochemical studies indicate that intrusions from the western and central Arunta have some potential for Ni-Cu-Co sulphide deposits, whereas the eastern Arunta appears to be more prospective for orthomagmatic and hydrothermal PGE mineralisation. These results, for the first time, highlight geographical differences in mineral prospectivity, and the PGE potential of the eastern Arunta.
Eastern Arunta Cu-Zn-Pb depositsObjectiveTo assess the significance of small base metal occurrences in the eastern Arunta, including the Oonagalabi and Jervois deposits. The origin and geological controls on these deposits will be established so that their potential can be assessed. Background:Small, stratiform Cu-Zn-Pb deposits in the eastern Arunta Province have been interpreted as volcanic-hosted massive sulphide (Oonagalabi, Edward Creek, Warren et al., 1994, AGSO Journal of Australian Geology and Geophysics: 15, 501-509) or as Broken Hill-type (Jervois, Mackie, 1984, Proceedings Darwin Conference, Australasian Institute of Mining and Metallurgy Transactions, 323-328) deposits. Lead isotope model ages (Warren et al., 1994, op. cit.) and preliminary U-Pb zircon ages of the host rocks (S.-S. Sun, pers. comm.) indicate a probable syngenetic origin, possibly with two distinct ages at ca. 1800 Ma (Edward Creek, Johansson's and Jervois) and ca 1750 Ma (Oonagalabi). These deposits are associated with metamorphosed siliceous and chloritic alteration zones (Warren et al., op. cit.). The same alteration assemblages form regional stratiform units that can be traced several kilometres and may be the reaction zones associated with the volcanic-hosted massive sulphide mineral system. Related links |