The Herberton/Mount Garnet area is situated in north Queensland, southwest of Cairns (Fig. 1). It is bounded by latitudes 17°15'S and 17°45'S, and by longitudes 145°00'E and 145°30'E, and comprises 2885 sq km. The area is covered by the Herberton and Mount Garnet 1-mile Military map sheets, and lies within the Atherton 1:250,000 Sheet area. Almost the whole of the productive part of the Herberton Tinfield* is covered by the two 1-mile map sheets.

Legacy product - no abstract available

This web-enabled system allows researchers to retrieve fluid inclusion data from anywhere in the world. The concept is to build a free and widely available web-based library of fluid properties for a range of geological fluids. The database is being developed as an "open" project, which intends to bring together researchers interested in the properties of geological fluids or fluid inclusions.

Proceedings of papers presented at an industry workshop held in Perth, 20 June 2002. Edited by K.F. Cassidy

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Legacy product - no abstract available

Legacy product - no abstract available

This paper describes the highlights of AGSO's work in the North Pilbara Project, a joint AGSO-Western Australia Geological Survey (GSWA) effort conducted under the National Geoscience Mapping Accord (NGMA) between 1995 and 2000. One of the principal drivers for AGSO's research in the Pilbara was the possible inapplicability of exploration models and genetic interpretations of Archaean mineral deposits because these models were commonly based upon late Archaean examples. One of our goals was to document the differences between the late Archaean and the early-mid Archaean mineral systems, and to develop regional thematic synthesis datasets so that more robust models could be developed to encompass the entire Archaean era. These datasets, together with our research into new exploration tools, have, and continue to assist exploration in the Pilbara. Our results also have applications to other terranes.

Zn-Pb-Ag mineral deposits, which are the products of specific types of hydrothermal "mineral systems", are restricted in time and space in Australia. These deposits formed during three main periods: ~2.95 Ga, 1.69-1.58 Ga, and 0.50-0.35 Ga. The 1.69-1.58 Ga event, which was triggered by accretionary and rifting events along the southern margin of Rodinia, is by far the most significant, accounting for over 65% of Australia's Zn. With the exception of the 0.50-0.35 Ga event, major Australian Zn-Pb-Ag events do not correspond to major events globally. Over 95% of Australia's Zn-Pb-Ag resources were produced by just four mineral system types: Mt Isa-type (MIT: 56% of Zn), Broken Hill-type (BHT: 19%), volcanic-hosted massive sulfide (VHMS:12%), and Mississippi Valley-type (MVT: 8%). Moreover, just 4% of Australia's land mass produced over 80% of its Zn. The four main types of mineral systems can be divided into two groups, based on fluid composition, temperature and redox state. BHT and VHMS deposits formed from higher temperature (>200?C), reduced fluids, whereas MIT and MVT deposits formed from low temperature (<200?C), oxidized (H2S-poor) fluids. These fluid compositions and, therefore, the mineralization style are determined by the tectonic setting and composition of the basins that host the mineral systems. Basins that produce higher temperature fluids form in active tectonic environments, generally rifts, where active magmatism (both mafic and felsic) produces high heat flow that drives convective fluid circulation. These basins are dominated by immature siliciclastic and volcanic rocks with a high overall abundance of Fe2+. The high temperature of the convective fluids combined with the abundance of Fe2+ in the basin allows sulfate reduction, producing reduced, H2S-rich fluids. In contrast, basins that produce low temperature fluids are tectonically less active, generally intracratonic, extensional basins dominated by carbonated and mature siliciclastics with a relatively low abundance of Fe2+. Volcanic units, if present, occur in the basal parts of the basins. Because these have relatively low heat flows, convective fluid flow is less important, and fluid migration is dominated by expulsion of basinal brines in response to local and/or out-of-area tectonic events. Low temperatures and the lack of Fe2+ prevent inorganic sulfate reduction during regional fluid flow, producing oxidized fluids that are H2S-poor. The contrasting fluid types require different depositional mechanisms and traps to accumulate metals. The higher temperature, reduced VHMS and BHT fluids deposit meatls as a consequence of mixing with cold sewater. Mineralization occurs at or near the seafloor, with trapping efficiencies enhanced by sub-surface replacement or deposition in a brine pool. In contrast, the low temperature, oxidized MIT and MVT fluids precipitate metals through thermochemical sulfate reduction facilitated by hydrocarbons or organic matter. This process can occur at depth in the rock pile, for instance in failed petroeum traps, or just below the seafloor in pyritic, organic-rich muds. Mass balance calculations indicate that the size of a metal accumulation, although controlled at the first order by the mineral system container size, also depends on the efficiencies at which metals are extracted from the source and retained at the trap site. The shear size of minerals systems required to form giant deposits may partly explain why these deposits commonly occur by themselves, without significant satellite deposits. In addition to the size of the mineral system container, metal retention efficiency appears to be the most important determinant of the size of metal accumulations.

The Uranium Systems Project is a key part of the $59m Onshore Energy Security Program (OESP) underway at Geoscience Australia (2006-2011). The project has three objectives: (1) develop new understandings of processes and factors that control where and how uranium mineralisation formed, (2) map the distribution of known uranium enrichments and related rocks in Australia, and (3) assess the potential for undiscovered uranium deposits at regional to national scales. Objective (1) has been addressed initially by reviewing current classification schemes for uranium deposits. Most schemes emphasise differences in host rock type and list 15 or more deposit types. An alternative scheme is proposed that links the apparently separate deposit types in a continuum of possible deposit styles. Three end-member uranium mineral systems are: magmatic-, basin-, and metamorphic/metasomatic-related. Most recognised deposit styles can be considered as variants or hybrids of these three end-members. For example, sandstone hosted, unconformity-related and "Westmoreland" style deposits are viewed as members of basin-related uranium systems and which share a number of ore-forming processes. Identification of the spatial controls on uranium mineralisation is being investigated using numerical modelling, with the Frome Embayment of SA as a first case study. Mapping the distribution of uranium in objective (2) has commenced with the release of a new map of Australia showing the uranium contents of mainly outcropping igneous rocks, based on compilation of whole rock geochemical data. A clearer picture of uranium enrichments is also emerging through cataloguing of an additional >300 uranium occurrences in the MINLOC mineral occurrence database. Finally, the recently completed Australia-wide radiometric tie-line survey is providing a new continent-scale view of uranium, thorium and potassium distributions in surface materials. To assess potential for undiscovered uranium deposits, new OESP data in targeted regions of Australia are awaited, such as airborne EM, seismic and geochronology data.