Globally supracrustal sedimentary rocks are known to preferentially precipitate gold between 2400 Ma and 1800 Ma (Goldfarb et al. 2001). The Palaeoproterozoic Tanami and Pine Creek regions of Northern Australia host one world-class gold deposit and many other gold deposits in anomalously iron-rich marine mudstones (Figure 1). New fluid-rock modelling at temperatures between 275 - 350C suggest a strong correlation between gold grade and these Palaeoproterozoic iron-rich, fine-grained sedimentary rocks.

Assessment of mineral potential in the Regional Forest Agreement Areas (RFAs) required collating mineral potential tract maps of individual deposit styles to produce composite, cumulative and weighted composite and cumulative maps. To achieve that an Avenue-script based ArcView extension was created to combine grids of mineral potential tract maps. The grids were combined to generate maps which showed either the highest (weighted or non-weighted) or cumulated (weighted or non-weighted) values. Resources and Advice Decision Support System (RADSS) combines features of the ArcView extension used in mineral potential assessments in RFAs and ASSESS. It is an ArcView extension with a 'Wizard'-like main dialog that leads the user through the process of creating an output. The system has the capacity to combine GIS-layers (raster and vector) to produce various mineral potential and other suitability maps.

Legacy product - no abstract available

A diverse range of mineralisation, including porphyry and epithermal deposits, intrusion-related gold and other metal deposits, iron oxide-copper-gold (IOCG) deposits and orogenic gold deposits all have linkages to crustal growth and magmatic arcs. Furthermore, all of these deposit types are associated with fluids containing H2O, CO2 and NaCl in varying and differing proportions. In all cases, it can be argued that magmas are a key source of hydrothermal fluids for these types of mineral system, and that subduction processes are critical to controlling fluid chemistries, the metal-bearing capabilities of the fluids and depositional processes. The differences on typical/bulk fluid chemistries between deposit types can be explained in part by differences in the P-T conditions of fluid segregation from its magmatic source. The most significant control here is the pressure at which fluid forms from the magma as this has a strong effect on fluid CO2/H2O values. This is clearly exemplified by the rare occurrence of readily detectable CO2 in deep porphyry systems (Rusk et al., 2004). On the other hand, fluid Cl contents (which strongly influence its base metal carrying capacity) are very sensitive to the magma's bulk composition. However, only some subduction-related magmas are fertile, and the differences do not seem to be due solely to variations in effectiveness of depositional processes. So what controls the volatile content of the magmas? Isotopic and other evidence, in particular for S and Cl, shows (unsurprisingly) that the greater contents of these elements in arc magmas compared to other melts is due to contributions from subducted materials, although there may be additional, lower crustal sources of Cl. Variations in the budget of volatiles subducted may thus play a role in controlling the chemistry of magmas and associated hydrothermal fluids, but variations within individual arcs suggests that again this is not the entire story.

An orogenic cycle typically follows a sequence of events or stages. These are basin formation and magmatism during extension, inversion and crustal thickening during contractional orogenesis, and finally extensional collapse of the orogen. The Archaean granite-greenstone terranes of the Eastern Yilgarn Craton (EYC) record a major deviation in this sequence of events. Within the overall contractional stage, the EYC underwent a lithospheric-scale extensional event between 2665 Ma and 2655 Ma, resulting in changes to the entire orogenic system. These changes associated with regional extension include: the crustal architecture; greenstone stratigraphy; granite magmatism; thermo-barometry (PTt paths); and structure. Synchronous with these changes was the deposition of the first significant gold, and it is likely that the intra-orogenic extensional event was one of the critical factors in the region's world-class gold endowment.

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. This CD was created as part of GA's contribution to the Central Highlands CRA. It contains 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.

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.

Abstract The Palaeoproterozoic, from 2100 to 1800 Ma, is recognised as the third largest period of orogenic gold mineralization. In contrast to earlier Archean orogenic gold episodes which occur predominantly in greenstone terranes, supracrustal sedimentary rocks became increasingly important as hosts in the Palaeoproterozoic. Unusually iron-rich 1840 Ma marine mudstones in the Tanami region host one world class gold deposit and many other gold deposits. Fluid-rock modelling at 350°C suggest a strong correlation between gold grade and these iron-rich, fine-grained sedimentary rocks and suggest that gold may precipitate in the iron-rich sediments in the first stage of mineralization, before remobilization of the gold further enhances the grade of the deposit. New regional stratigraphic correlations for similar iron-rich rocks to those in the Tanami region are suggested with ~1860 Ma gold-bearing stratigraphy in the Pine Creek region and potentially with ~1860 Ma host rocks in the Tennant region. These Northern Australian Palaeoproterozoic iron-rich sedimentary rocks could be linked globally to similar aged iron-rich and gold-bearing sedimentary rocks in Homestake, U.S., Ghana, West Africa and elsewhere. From about 2400 to 1800 Ma the Palaeoproterozoic is also marked by the occurrence of mainly Superior-style BIF's, which are attributed to the progressive oxygenation of the deep oceans resulting in the global scrubbing of iron from the oceans. The high iron concentrations noted in pre-1800 Ma marine sediments in Northern Australia could also be related to this same process and help explain the anomalous concentration of orogenic Au deposits from 2100 to 1800 Ma.

DRAFT Australia's Resources Supporting Economic Growth in the Nation and the Region Paul J Kay Geoscience Australia A new book on Australia's geology viewed through the lens of human activity has been prepared by Geoscience Australia for the 34th International Geological Congress (IGC). Geological factors influencing the nation's recent economic development make up one chapter of the IGC book. Australia's long geological history, fringing passive margins, limited recent deformation and overall landscape stability has formed and preserved a vast quantity of high quality bulk commodity resources. The nation's educated workforce, system of government and legal framework has provided a sound, stable foundation allowing the geological legacy to be utilised through a large export industry for societal and national benefit. The bulk resources of coal, iron, aluminium and liquefied natural gas (LNG) account for more than 50 percent of Australia's export earnings, sustaining the nation's economic success and the lifestyle of the Australian people. Mining has been a cornerstone of the Australian economy since the 19th century gold rushes and importance the resources sector has increased markedly since the mid 20th century, largely a consequence of accelerating export income from the bulk commodities. The industrialisation of Asia has provided the demand, driving infrastructure investment in remote regions of Australia. Advances in technology combined with massive economies of scale and sound public policy have enabled access to the resource and helped to satiate the growing regional market. Responding to changes in the existing status quo, be they trade or societal, will require ongoing interactions between the geosciences and other disciplines to maintain and improve Australia's standard of living.