The characterisation of benthic habitats based on their abiotic (physical and chemical) attributes remains poorly defined in the marine environment, but is becoming increasingly central in the development of marine management plans in Australia and elsewhere in the world. The current study tested this link between physical and biological datasets for the southern Gulf of Carpentaria, Australia. The results presented were based on a range of physical factors, including the sediment composition (grain size and carbonate content), sediment mobility, water depth and organic carbon flux, and their relationship to the distribution and diversity of benthic macrofauna was tested. The results reveal the importance of process-based indices, such as sediment mobility, in addition to other environmental factors in defining the distribution of the benthic macrofauna. The distribution of the benthic macrofauna changes gradationally across the south-eastern Gulf, associated with changes in the per cent mud and gravel, the seabed exposure and the water depth. Patterns of diversity also reveal the importance of physical processes such as sediment mobility in defining benthic habitats. The species' environment relationships observed at the small scale of the current study are consistent with broader associations observed for other organisms within the Gulf.

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.

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

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.

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 North Australian Craton (NAC; Myers et al. 1996) includes Palaeoproterozoic orogens and basins in northern Australia including the Halls Creek, Pine Creek, McArthur, Mount Isa, Tennant Creek, Tanami, and Aileron (northern Arunta) geological regions. Archean basement to the NAC crops out in the Pine Creek and Tanami regions, with ages in the range 2.67 Ga - 2.50 Ga. An early phase of basin development at 2.05-2.00 Ga is reflected in the basal units of the Pine Creek Orogen. The nature of the basement remains unclear across much of the NAC, although geophysical and isotopic evidence suggests widespread presence of thick Neoarchean to Palaeoproterozoic continental crust. Recent work by the Northern Territory Geological Survey and Geoscience Australia , particularly the Arunta and Tanami Regions, has provided important new constraints on the tectonic evolution of the North Australian Craton. Current evidence suggest that most of the NAC was a coherent entity by 1.86-1.83 Ga, when large areas of the craton was covered by thick sedimentary packages which now form regionally important hosts for gold mineralisation. In the Northern Territory, apparent correlations are now possible between packages at 1.865-1.860 Ga (Finniss River and South Alligator Groups, Waramunga Formation, Junalki Formation), 1.84-1.83 Ga (Lander Rock Formation, Killi Killi Formation, lower Ooradidgee Group), and 1.82-1.80 Ga (Ware Group, Hatches Creek Group, Strangways Metamorphic Complex). Tectonism throughout much of the Northern Territory in this period was dominated by intraplate tectonics, although these are likely to have been driven by events at the northern and western margins of the craton, such as the postulated collision between the Kimberley and North Australian Cratons at 1.83 Ga (Sheppard et al. 1999). <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>

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Tanami Region (TANAMI and THE GRANITES 1:250 000 map sheet areas) is centrally located within the North Australian Craton and contains a gold-mineralised Palaeoproterozoic orogenic sequence. Page et al (1995) postulated Neo-Archaean granitic gneiss as basement to the Tanami Group, although no lower sedimentary contact has been observed. <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>

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The 2005 Tanami Seismic Collaborative Research Project produced four regional deep seismic reflection traverses, 05GA-T1 through 05GA-T4, totalling 724 line-km. Traverse 05GA-T1, a 354.3 km long northwest-southeast regional transect started in Western Australia and ended in the Northern Territory. It was located close to Tanami Gold's Bald Hills deposits and Newmont's Tanami and The Granites mine sites. This traverse provided cross-strike information on the geometry of the Coomarie and Frankania granite complexes as well as many of the region's fault systems. The traverse ended at the southern edge of the Willowra Gravity Ridge. The cross-traverses, 05GA-T2 (101.8 km long), 05GA-T3 (179.2 km long) and 05GA-T4 (84.4 km long) provide orthogonal three-dimensional control on the geometry of the region's main fault systems. The project objectives are to: - Image the geometry of the main faults; - Determine a deformation sequence for these faults; - Identify any through-going crustal structures; - Determine stratigraphic thicknesses of the Tanami Group and granite body geometries; - Determine relationships of the various stratigraphic packages to controlling structures; - Investigate the relationship of mineralised domains to crustal scale structures; - Identify Archaean basement and its relationship to the overlying Tanami Group stratigraphy; - Investigate the character of the Tanami-Arunta boundary. <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>

Noble gas and halogen constraints on mineralizing fluids of metamorphic versus surficial origin: Mt Isa, Australia

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Warumpi Province is an east-trending 1690 Ma - 1600 Ma terrane which extends for >500 km along the southwestern margin of the Arunta Region. It is interpreted to be an exotic terrane that accreted onto the southern margin of the North Australian Craton (NAC) at 1640 Ma (Scrimgeour et al 2005a). The evolution of the Warumpi Province from 1690 Ma to 350 Ma has been constrained through integrated lithological, structural and metamorphic mapping, geochemical and isotopic analysis, and geophysical interpretation (Scrimgeour et al 2005b). The Warumpi Province has been subdivided into three domains that have differing protolith ages and structural and metamorphic histories: the amphibolite facies Haasts Bluff Domain in the south and east, the granulite facies Yaya Domain in the north, and the greenschist facies Kintore Domain in the west. The Warumpi Province can be viewed as greenfields in terms of minerals exploration and has the potential to host a variety of mineralisation styles including base metals (BHT, VMS), IOCG, and diamonds. No modern mineral exploration has been undertaken within the Warumpi Province. <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>