Legacy product - no abstract available

Australia's North West Shelf (NW Shelf) has been the premier hydrocarbon exploration and production province for over 30 years. Despite the large number of geological studies completed in this region, numerous geological questions remain to be answered such as the provenance of reservoir units and how this relates to reservoir quality, extent and correlation. Submission of offshore sample material by explorers on the NW Shelf has allowed U-Pb age results to be determined; providing insights into the potential provenance and sedimentary transport pathways of various Triassic to Cretaceous reservoir facies. Initial results reveal that the proximal Pilbara, Yilgarn and Kimberly cratons were not major proto-sources during the Middle to Upper Triassic. The prospective, Mungaroo Formation appears to display a Triassic volcanic signature; the source of which remains enigmatic, but numerous grain characteristics suggest a source proximal to the Exmouth Plateau. Many samples show a Gondwana Assemblage age. Sediment sources of this age are absent on the Australian continent suggesting a distal origin - most likely the Antarctic and Indian blocks. Transport pathways, for the Triassic Mungaroo Formation, are interpreted as possibly northward through a proto-Perth Basin or north-westward through the Gascoyne-Hamersley-Pilbara regions. Other results suggest subtle differences in provenance of the sediments between the Exmouth Plateau and Rankin Platform, and that the provenance signatures of the Bonaparte, Canning and Perth basins show distinctively different provenance signatures.

The Mount Painter Province is located in the northern Flinders Ranges, South Australia and comprises deformed Proterozoic metasedimentary and igneous rocks.

This work forms part of a major internation multi-disciplinary study of the Permian -Triassic boundary, end-Permian mass extinction and Middle Permian-Early Triassic timescale calibration. Studies undertaken in the overarching program include biostratigraphy, isotope geochronology, magnetostratigraphy, and chemostratigraphy.

Abstract for 34th IGC

At the Sandpiper gold deposit in the Tanami region of northern Australia sericite is intimately intergrown with arsenopyrite in gold-bearing quartz veins and breccias, suggesting sericite crystallisation synchronous with gold-bearing fluid flow. This ore-stage sericite yields a 40Ar/39Ar plateau age of 1785 ± 16 Ma (1?? including all known systematic uncertainties). Recalculation using revised and more precise values for the 40K decay constants and the age of the Fish Canyon Sanidine standard shifts the age to 1792 ± 6 Ma (1???including all known systematic uncertainties). Given the possibility of post-mineralization isotopic resetting this age can be conservatively interpreted as a minimum constraint on the timing of gold deposition although, given local geological relationships and estimates for the argon retentivity of white mica, we consider complete isotopic resetting to be unlikely. The preferred interpretation is, therefore, that the sericite 40Ar/39Ar age indicates the timing of gold mineralization. The sericite age accords with a limited dataset of 207Pb/206Pb xenotime ages of ~1800 Ma from other gold deposits in the Tanami region, interpreted as mineralization ages. The agreement between independently-derived ages from several gold deposits lends support for a widespread gold-mineralizing event at ~1800 Ma in the Tanami region.

This GSQ-GA geochronology record presents a compilation of 16 new zircon U-Pb SHRIMP geochronological results from the Mount Isa and south Nicholson region, Queensland. This data was collected through the collaborative GSQ-GA geochronology project in August 2008 as part of the National Geoscience Accord (NGA) and in support of ongoing geoscientific investigations and regional geological mapping by the GSQ in the Mount Isa and south Nicholson regions. In addition, an appendix contains Sm-Nd whole rock analyses of selected samples. The acquisition of the Sm-Nd data in Appendix A was funded wholly by Geoscience Australia. A separate report for each sample is presented, which contain a brief geochronological interpretation as well as information on sample location and geological context. Three samples were analysed from the south Nicholson Basin from the WESTMORELAND and LAWN HILL 250K mapsheets, with an additional sample (Westmoreland Conglomerate) taken from the base of the Macarthur Basin. The twelve remaining samples were taken from various units in the greater Mount Isa region from the CLONCURRY, DOBYNN, DUCHESS, MOUNT ISA and URANDANGI 250K mapsheets. One sample was submitted for SHRIMP analysis but which failed to yield sufficient zircons for further investigation (rhyodacitic porphyry from within the Corella Formation).

This record contains zircon U-Pb geochronological data obtained between July 2001 and May 2003 on diamond drillcore from the Olympic Domain, Gawler Craton, South Australia. The data were collected as part of the Gawler Craton Project; a collaboration between Geoscience Australia (GA) and the Division of Mineral and Energy, Primary Industry and Resources, South Australia (PIRSA). The project aims to provide an improved geological and metallogenic framework for the Gawler Craton, with initial emphasis on the Olympic Domain. The term Olympic Domain (formerly 'Olympic Subdomain'; Daly et al. 1998) refers to the eastern extension of the Gawler Craton, concealed beneath Mesoproterozoic, Neoproterozoic and Cambrian sedimentary rocks of the Stuart Shelf. It also encompasses outcrop and subcrop of the Gawler Craton further south in the Moonta-Wallaroo region of the Yorke Peninsula. The sedimentary cover sequence of the Stuart Shelf is between about 300 and 1000 m thick, and the only knowledge of the underlying crystalline basement comprising the Olympic Domain is derived from exploratory drillholes. The long distances between drillholes impede inter-hole correlations. Thus U-Pb isotope dating of rocks intersected by (diamond) drillcore plays a key role in regional stratigraphic studies, establishing an absolute basis for temporal correlations across the Olympic Domain. This record describes the samples analysed and the analytical results obtained, and provides a brief discussion of their geochronological interpretation. The broader geological implications of the data will be published elsewhere.

The Broken Hill Exploration Initiative (BHEI) started in 1994 and is a joint effort between the New South Wales Department of Primary Industries - Mineral Resources, the South Australian Department of Primary Industry and Resources and the Commonwealth Government through Geoscience Australia. The aim of the BHEI is to provide a new generation of geoscientific data for the Curnamona Province, particularly the Broken Hill-Olary region, as a basis for more effective mineral exploration by industry. This initiative aims to provide the best possible knowledge and information-base for mineral and petroleum exploration investment in western New South Wales and eastern South Australia. The region will benefit from the application of new technologies and exploration methodologies to enhance knowledge of the geological controls of mineral deposit systems. BHEI conferences are held on a regular basis to highlight the geoscientific advances made during the life of the initiative. The contents of this Record are the extended abstracts of oral and poster papers presented at the BHEI conference that was held in Broken Hill on 26-28 September 2006.

Legacy product - no abstract available