Legacy product - no abstract available

From 1995 to 2000 information from the federal and state governments was compiled for Comprehensive Regional Assessments (CRA), which formed the basis for Regional Forest Agreements (RFA) that identified areas for conservation to meet targets agreed by the Commonwealth Government with the United Nations. These 3 CDs were created as part of GA's contribution to the Eden, NSW CRA. CD1 contains original and final versions of all data coverages and shapefiles used in the project, Published Graphics files in ArcInfo (.gra), postscript (.ps) and Web ready (.gif) formats, all Geophysical Images and Landsat data and final versions of documents provided for publishing. CD2 contains the DEFUNCT directories, data that has been modified or replaced in the final version. CD3 contains the INTEGRTN directory, integration data used for evaluating options.

Australia's mineral resources are an important component of its wealth, and a long term perspective of what is likely to be available for mining is a prerequisite for formulating sound policies on resources and land-access. The national resource stocks are quantified in the annual online publication: Australia's Identified Mineral Resources: http://www.australianminesatlas.gov.au/aimr/index.jsp. This provides Geoscience Australia's assessments using its national mineral resource classification system, which is based on the McKelvey resource classification system used by the United States Geological Survey (USGS). It defines known mineral resources according to two parameters: degree of geological assurance and degree of economic feasibility of exploitation. Companies listed on the Australian Securities Exchange are required to report publicly on Ore Reserves and Mineral Resources under their control, using the Joint Ore Reserves Committee Code (JORC; see http://www.jorc.org/). This system is compatible with the national system. Data reported for individual deposits by mining companies generally provide a short term commercial perspective. They are compiled in Geoscience Australia's national mineral resources database and used in the preparation of the annual national assessments of Australia's mineral resources. This involves aggregating JORC categories from company reports into larger categories in the national system.

Updated map showing Australia's gold resoruces

This Bulletin presents an account of the general geology, stratigraphy, structure, and mineral resources of the Brock's Creek district, Northern Territory. The general geological mapping of the district was carried out by the Aerial, Geological, and Geophysical Survey of Northern Australia in 1939, and a brief account of the results then obtained has been published (A.G.G.S.N.A., 1939). Some further mapping was carried out in 1950. The most important sedimentary rocks of the district are believed to be of Lower Proterozoic age and have been called the Brocks Creek Group (Noakes, 1949). They are dominantly argillaceous in type, but contain sandy formations as well as thin beds of conglomerate and limestone. Numerous sills of amphibolite, which are of igneous origin, are found within the sedimentary sequence. The sediments and interrelated amphibolites probably attain a thickness of 18,000 feet. Unconformably overlying the Brock's Creek Group is a comparatively thin formation of quartzite which is probably late Proterozoic, in age and is known as the Ruldiva Quartzite. Horizontally bedded Lower Cretaceous sandstone and shale up to 200 feet, thick is found capping mesas ill the district. In the north-eastern section of the area mapped is a concordant body of granite (Brock's Creek Granite), roughly circular in shape at the surface, and haying an average diameter of approximately six miles. A smaller area of concordant granite occurs near Mt. Shoobridge in the south-western portion of the area mapped. A discordant cross-cutting granite (Margaret Granite) cuts through the Brock's Creek sediments in the south-eastern portion of the district and exends for many miles to the south. The Buldiva Quartzite is only gently folded and is not intruded by igneous rocks, but the Brocks Creek Group has been subjected to considerable folding and faulting. The fold axes trend north-westerly or northerly, and marked cleavage has been produced parallel to the fold axes. The fine-grained sediments have been converted into schist in many places. Comparatively broad domal and basin-shape1 folds dominate the general structure of the district, but some anticlinal folds have been comparatively tightly compressed---e.g., the Howley Anticline. Within the 300 square miles of country mapped, it was found that deposits of gold and copper occur within, or close to, one formation, which may be repeated from place to place by folding and faulting. The favourable formation is a graphitic slate but is closely associated with a thin band of conglomerate and is normally associated also with sills of amphibolite. A limestone commonly occurs above or below the graphitic slate, but is lenticular in habit. Ore is commonly found in domal and anticlinal structures within these beds, especially near the more crenulated portions of the structure.

Diagenetic processes in sedimentary basins are capable of generating a spectrum of closely-related mineral systems such as unconformity-related uranium, Westmoreland-style uranium, sediment-hosted stratiform copper (Kupfersheifer), and stratiform zinc-lead-silver deposits. A close spatial association between uranium and copper deposits has been observed in many regions. Examples include: Rum Jungle uranium field where four deposits (Dyson U, Whites U-Cu-Co-Ni, Intermediate U-Cu and Browns Pb-Zn-Cu-Co-Ni) occur within ~ 2 kms of each other (McCready et al., 2004); Paterson Orogen which contains unconformity-related uranium mineralisation (such as Kintyre) and many copper deposits (such as Nifty) and lead-zinc prospects; Westmoreland uranium field hosting copper and uranium deposits; Athabasca Basin in Canada where both polymetallic and monometallic ores contain anomalous concentrations of base metals (Jefferson et al, 2007). At the other end of the spectrum the Kupfersheifer-style copper system, contain uranium-enriched zones. The richest known uranium deposit of this type is Shinkolobwe (~ 30000 t of U3O8) in the Katanga Province, Zambian Copper Belt.

Legacy product - no abstract available

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.

Hyperspectral airborne images from the Eastern Fold Belt of the Mount Isa Inlier, were validated as new tool for the detection of Iron oxide Cu-Au (IOCG) related alteration. High resolution mineral maps derived from hyperspectral imaging (4.5m/pixel) enables the recognition of various types of hydrothermal alteration patterns and the localisation of fluid pathways. Four different types of hydrothermal alteration patterns were identified with the hyperspectral mineral maps: (1) Metasomatic 1: White mica mineral maps were applied to map the spatial distribution of regional sodic-calcic alteration in metasedimentary successions of the Soldiers Cap Group in the Snake Creek Anticline. (2) Metasomatic 2: Alteration zoning is evident from albitised granites, assigned to the Williams-Naraku Suite, along the Cloncurry Fault show characteristic absorption features in the shortwave infrared range (SWIR) and can be detected with white mica mineral maps (white mica composition, white mica content, white mica crystallinity index).

Lower Proterozoic sedimentary, metamorphic, and igneous rocks of the Pine Creek Geosyncline and Nimbuwah Complex form the basement rocks of the Bathurst Terrace. To the west of the Bathurst Terrace, along the eastern edge of the adjoining Bonaparte Gulf Basin, Phanerozoic sedimentation commenced in the Early Permian and led to the accumulation of a conformable sequence comprising the Kulshill, Hyland Bay, and Mount Goodwin Formations, and an unnamed Middle to Upper Triassic formation. It was not until the Late Jurassic that the sea transgressed onto the Bathurst Terrace to deposit the Petrel Formation, followed by the Bathurst Island Formation in the Cretaceous, and the Van Diemen Sandstone in the Early Tertiary. In the Late Cretaceous and Tertiary, chemical weathering produced an extensive cover of laterite. Mineral sands containing ilmenite, zircon, and rutile occur along the northern and western coasts of Bathurst and Melville Islands. Uneconomical deposits of bauxite crop out on the northern headlands of Cobourg Peninsula and Croker Island. In addition, uneconomical deposits of uranium, manganese, phosphate, limestone, clay, and hydrocarbons have been found in the area. Subartesian water is available on Bathurst and Melville Islands from aquifers in the Van Diemen Sandstone, and artesian water was discovered in the Marligur Member of the Bathurst Island Formation in the southern Cobourg Peninsula Sheet area.