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

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.

Australia's nickel sulfide industry has had a fluctuating history since the discovery in 1966 of massive sulfides at Kambalda in the Eastern Goldfields of Western Australia. Periods of buoyant nickel prices and high demand, speculative exploration, and frenetic investment (the 'nickel boom' years) have been interspersed by protracted periods of relatively depressed metal prices, exploration inactivity, and low discovery rates. Despite this unpredictable evolution, the industry has had a significant impact on the world nickel scene with Australia having a global resource of nickel metal from sulfide ores of not, vert, similar 12.9 Mt, five world-class deposits (> 1 Mt contained Ni), and a production status of number three after Russia and Canada. More than 90% of the nation's known global resources of nickel metal from sulfide sources were discovered during the relative short period of 1966 to 1973. Australia's nickel sulfide deposits are associated with ultramafic and/or mafic igneous rocks in three major geotectonic settings: (1) Archean komatiites emplaced in rift zones of granite-greenstone belts; (2) Precambrian tholeiitic mafic-ultramafic intrusions emplaced in rift zones of Archean cratons and Proterozoic orogens; and (3) hydrothermal-remobilized deposits of various ages and settings. The komatiitic association is economically by far the most important, accounting for more than 95% of the nation's identified nickel sulfide resources. The ages of Australian komatiitic- and tholeiitic-hosted deposits generally correlate with three major global-scale nickel-metallogenic events at not, vert, similar 3000 Ma, not, vert, similar 2700 Ma, and not, vert, similar 1900 Ma. These events are interpreted to correspond to periods of juvenile crustal growth and the development of large volumes of primitive komatiitic and tholeiitic magmas caused by large-scale mantle overturn and mantle plume activities. There is considerable potential for the further discovery of komatiite-hosted deposits in Archean granite-greenstone terranes including both large, and smaller high-grade (5 to 9% Ni) deposits, that may be enriched in PGEs (2 to 5 g/t), especially where the host ultramafic sequences are poorly exposed. Analysis of the major komatiite provinces of the world reveals that fertile komatiitic sequences are generally of late Archean (not, vert, similar 2700 Ma) or Paleoproterozoic (not, vert, similar 1900 Ma) age, have dominantly Al-undepleted (Al2O3/TiO2 = 15 to 25) chemical affinities, and often occur with sulfur-bearing country rocks in dynamic high-magma-flux environments, such as compound sheet flows with internal pathways facies (Kambalda-type) or dunitic compound sheet flow facies (Mt Keith-type). Most Precambrian provinces in Australia, particularly the Proterozoic orogenic belts, contain an abundance of sulfur-saturated tholeiitic mafic ± ultramafic intrusions that have not been fully investigated for their potential to host basal Ni-Cu sulfides (Voisey's Bay-type mineralization). The major exploration challenges for finding these deposits are to determine the pre-deformational geometries and younging directions of the intrusions, and to locate structural depressions in the basal contacts and feeder conduits under cover. Stratabound PGE-Ni-Cu ± Cr deposits hosted by large Archean-Proterozoic layered mafic-ultramafic intrusions (Munni Munni, Panton) of tholeiitic affinity have comparable global nickel resources to many komatiite deposits, but low-grades (< 0.2% Ni). There are also hydrothermal nickel sulfide deposits, including the unusual Avebury deposit in western Tasmania, and some potential for 'Noril'sk-type' Ni-Cu-PGE deposits associated with major flood basaltic provinces in western and northern Australia.

A seismic survey using Australian National Seismic Imaging Resource (ANSIR) Hemi60 Vibroseis vehicles, ARAM24 acquisition equipment and Pelton controllers was carried in the Curnamona province of South Australia over two periods, August 2003 and July 2004. A total of 197.6 km of 2-D data was collected to 18 seconds two way time over a single line at 60 fold CDP coverage. The project was undertaken to meet the objectives of ANSIR proposal 03-02R as lodged by researchers from Primary Industries and Resource, South Australia (PIRSA), Office of Minerals, Energy and Petroleum, SA. The principal scientific objective of this survey was to provide a regional crustal seismic image of the Curnamona Province. This dataset will assist in the understanding of the geological architecture and resource potential of the region particularly in areas under cover. This line links with a seismic transect in the Broken Hill Block undertaken by Australian Geological Survey Organisation (AGSO) in 1996 and provides a future opportunity for an eventual east-west continuation across the Adelaide Geosyncline and the Gawler Craton. The survey was funded by PIRSA, Office of Minerals, Energy and Petroleum, SA and the Predictive Minerals Discovery Cooperative Research Centre (pmd*CRC) with project supervision undertaken by ANSIR and in-kind support from Geoscience Australia (GA).

The EQRM is a computer program for modelling probabilisticseismic hazard and risk. It has formed the basis of all recent hazard and risk assessments conducted by Geoscience Australia. In this manual we describe the methodology behind the program and how to use it.

This map is produced fro the Australian Fisheries Management Authority to assist in their enforcement of Australia's Maritime Bounadries. It has an explanation of the maritime boundaries and their coordinates in the Arafura Sea and Torres Strait. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.

This map is produced for the Australian Fisheries Management Authority to assist with their enforcement of Australia's Maritime Boundaries. On this side is an explanation of the applicable maritime boundaries and a list of their coordinates in the Timor and Arafura Seas. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.

This map is produced fro the Australian Fisheries Management Authority to assist in their enforcement of Australia's Maritime Bounadries. It has an explanation of the maritime boundaries and their coordinates in the Arafura Sea and Torres Strait. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.

This map is produced fro the Australian Fisheries Management Authority to assist in their enforcement of Australia's Maritime Bounadries. It has lots of icons to explain to Indonesian fishermen where that can and cannot fish in the Arafura Sea and Torres Strait. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.

This map is produced for the Australian Fisheries Management Authority to assist with their enforcement of Australia's Maritime Boundaries. On this side is an explanation of the applicable maritime boundaries and a list of their coordinates in the Timor and Arafura Seas. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.