Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Early Mesoproterozoic (1600 Ma - 1570 Ma) was a period of widespread compressional tectonism and high geothermal gradient metamorphism in the Australian Proterozoic. In the eastern half of the North Australian Craton, the bulk of Palaeoproterozoic terrains underwent high-temperature tectonism between 1600 Ma to 1550 Ma. In central Australia, the Chewings Orogeny (1600 Ma - 1570 Ma) was associated with approximately north-south shortening coeval with regional low-pressure high-temperature metamorphism up to granulite grade. In northeastern Australia, the Early Isan (1600 Ma - 1580 Ma), and Ewamin-Janan Orogenies (1585 Ma - 1555 Ma) in the Mt Isa and Georgetown and Yambo Inliers, respectively, were also associated with approximately north-south shortening and high geothermal gradient metamorphism. In the southern Australian Proterozoic, the Olarian Orogeny (1610 Ma - 1585 Ma) in the Curnamona Province was also characterised by high geothermal gradient metamorphism. <p>Related product:<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=64764">Evolution and metallogenesis of the North Australian Craton Conference Abstracts</p>

Annular to crescent-shaped low back scatter SAR slicks over carbonate reefs and shoals in the Timor Sea with slick `feathering', and within the coral spawning period for the region, are interpreted to be caused by a coral spawn event. In contrast, ocean current data and detailed swath bathymetry of the sea floor to the southeast of the coral spawn slicks suggest that elongate repeating slicks in this area are related to current flow over submarine channels. Assessment of these slicks in association with ancillary data, such as bathymetry, current velocities, weather and timing of scene capture allow a more robust interpretation of their origins. Through differentiating coral spawn and bathymetric slicks from oil and other biological slicks in shallow carbonate systems, such as the Timor Sea, petroleum and environmental assessments for these areas can be improved.

Map Index indicating the availability of the Department of Defence produced 50K topographic mapping. Folded copies only which are available free of charge. Product Specifications Coverage: Australia Currency: 2004 (PDF); 2004 (data) Coordinates: Geographical Datum: GDA94 Format: ArcInfo Export, ArcView Shapefile and MapInfo mid/mif; PDF (maps only); Paper Map (maps only) Medium: GIS Data Free online, free folded map or CD-ROM (fee applies) Forward Program: Updated annually

40Ar/39Ar dating of mica-bearing pyrite from thermally overprinted Archean gold deposits

Benthic habitats on the continental shelf are strongly influenced by exposure to the effects of surface ocean waves, and tidal, wind and density driven ocean currents. These processes combine to induce a combined flow bed shear stress upon the seabed which can mobilise sediments or directly influence organisms disturbing the benthic environment. Output from a suite of numerical models predicting these oceanic processes have been utilised to compute the combined flow bed shear stresses over the entire Australian continental shelf for an 8-year period (March 1997- February 2005 inclusive). To quantify the relative influence of extreme or catastrophic combined flow bed shear stress events and more frequent events of smaller magnitude, three methods of classifying the oceanographic levels of exposure are presented: 1. A spectral regionalisation method, 2. A method based on the shape of the probability distribution function, and 3. A method which assesses the balance between the amount of work a stress does on the seabed, and the frequency with which it occurs. Significant relationships occur between the three regionalisation maps indicating seabed exposure to oceanographic processes and physical sediment properties (mean grain size and bulk carbonate content), and water depth, particularly when distinction is made between regions dominated by high-frequency (diurnal or semi-diurnal) events and low-frequency (synoptic or annual) events. It is concluded that both magnitude and frequency of combined-flow bed shear stresses must be considered when characterising the benthic environment. The regionalisation outputs of the Australian continental shelf presented in this study are expected to be of benefit to quantifying exposure of seabed habitats on the continental shelf to oceanographic processes in future habitat classification schemes for marine planning and policy procedures.

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Nolan's Bore LREE/P/U deposit is located at 133° 14' 15"E ,22° 34' 40"S , approximately 135 km NNW of Alice Springs. The deposit was initially located in 1994 by PNC Exploration (Australia) Pty Ltd (Thevissen, 1995) and rediscovered by Arafura Resources NL in 1999 when the REE and phosphate potential of the deposit came to prominence. Current identified mineral resources (Indicated + Inferred, JORC compliant) stand at 18.6 Mt at 3.1% REO, 14% P2O5, and 0.021% U3O8 (Goulevitch, 2006). The deposit is open laterally and at depth. The bulk of the mineralisation is currently restricted to an area about 1500 m × 1100 m in extent, and this may increase if suspected continuity to other fluorapatite outcrops 500-600 m along strike to the SW is confirmed. A fluorapatite band located about one kilometre west of the main deposit does not appear to be linked at shallow depths to the main deposit as mineralisation is absent in the intervening area. <p>Related product:<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=64764">Evolution and metallogenesis of the North Australian Craton Conference Abstracts</p>

Evaluation of 40Ar-39Ar quartz ages: Implications for fluid inclusion retentivity and determination of initial 40Ar/36Ar values in Proterozoic samples

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Pine Creek Orogen (PCO) is part of the North Australian Craton and is correlated with other Palaeoproterozoic domains of northern Australia. Archaean (>2.5 Ga - 2.7 Ga) granite and metamorphics are overlain by Palaeoproterozoic strata comprising sandstone, mudstone, and minor carbonates and volcanics. Its age is constrained between 2.5 Ga and 1.86 Ga, and the succession is divided into two supergroups. The older Woodcutters Supergroup comprises <2.5 Ga to 2.02 Ga arenites, stromatolitic dolostone, and pyritic carbonaceous shale. The younger Cosmo Supergroup comprises BIF, mudstone, and tuff, succeeded by a monotonous flysch sequence. Zircons from the tuff beds provided an age of 1863 Ma, confirming a major depositional break of about 150 million years. <p>Related product:<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=64764">Evolution and metallogenesis of the North Australian Craton Conference Abstracts</p>

A ~ 6 minute movie showing the Geoscience Australia building from turning the sod to completion. The movie tells the story of the architectural details of the building in relation to the staff working within those environs. Flash movie 18.5MB, 6 minutes

Australian mineral exploration spending in 2004-05 rose by 31% to $1028.3 million of which 39.3% was spent on the search for new deposits. Total global non-ferrous mineral exploration budgets rose 38% to an estimated US$5.1 billion in 2005. Western Australia received 59% of Australian mineral exploration spending in 2004-05 as spending rose in all States except Victoria. Gold remained the main target but its share of spending was eroded by increased spending on nickel, copper, iron ore, coal and uranium. Exploration resulted in significant increases in resources at known deposits and a substantial number of drill intersections of economic interest, the most notable being the discoveries of copper-gold mineralisation at Carrapateena (Gawler Craton), mineral sand in the Eucla Basin, and gold at the Trident deposit (Yilgarn Craton).