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.

As part of the Australian Government's Onshore Energy Security Program and the Queensland Government's Smart Mining and Smart Exploration initiatives, deep seismic reflection surveys were conducted in North Queensland to establish the architecture and geodynamic framework of this area in 2006 (Mt Isa Survey; also involving OZ Minerals and pmd*CRC) and 2007 (Cloncurry-Georgetown-Charters Towers Survey; also involving AuScope). Nearly 2300 line km of seismic data were acquired during these surveys. Geochemical, geochronological and complementary geophysical studies were undertaken in support of the seismic acquisition. Overviews of the geology of North Queensland and more detailed descriptions and the results of these surveys are presented in Hutton et al. (2009a, b), Korsch et al. (2009a), Withnall et al. (2009a, b), Henderson and Withnall (2009), and Henderson et al. (2009). The purpose here is to use the new geodynamic insights inferred from these data to provide comments on the large-scale geodynamic controls on energy and other mineral potential in North Queensland. This contribution draws on geodynamic and metallogenic overviews presented by Korsch et al. (2009b) and Huston et al. (2009)

Magmatic-related uranium systems represent an uncommon, yet significant family of uranium mineral systems. Despite the extremely large size of some magmatic-related uranium deposits, the key processes controlling uranium deposition are poorly understood compared to other more common uranium deposit styles. Petrographic, geochemical and fluid inclusion studies have been undertaken at the Crocker Well granite-hosted uranium deposit in South Australia in order to better constrain the key processes in uranium mineralisation there. The results of this study allow a genetic model for the Crocker Well deposit to be proposed. Uranium mineralisation is interpreted to be associated with the intrusion of a volatile and sodium-rich pulse of magma, or with the localised release of a highly sodic fluid from the main granitic rocks in the area. Volatile saturation and fluid exsolution partitioned uranium and thorium into a magmatic-hydrothermal fluid phase, and initiated the creation of fractures, veins and breccia zones. These acted as fluid flow pathways for the magmatic fluid. Uranium deposition likely occurred as a result of temperature or pressure decrease. This genetic model has been translated into a number of mappable criteria which may be used in prospectivity studies for magmatic-related uranium systems. The presence of evidence suggesting the potential to generate a uranium-bearing magmatic fluid, evidence of permeable structures contemporary with igneous activity, and evidence of favourable host rocks are suggested as useful criteria.

Mineralizing events in the North Pilbara Terrain of Western Australia occurred between 3490 Ma and 2700 Ma and include the oldest examples in the world of many ore deposit types. The mineralizing events were pulsed and associated with major volcano-plutonic (volcanic-hosted massive sulfide [VHMS], porphyry Cu, Sn-Ta pegmatite, mafic-ultramafic-hosted Ni-Cu-PGE, Cr and V, and epithermal deposits) and deformation events (lode Au?Sb deposits). In many cases, the mineralizing events are associated with extension, either in rifts, pull-apart basins or back-arc basins. Although mineralizing events occurred throughout the evolution of the North Pilbara Terrain, the most significant deposits are related to the development of the Central Pilbara Tectonic Zone (CPTZ). The CPTZ is sandwiched between the older East and West Pilbara Granite-Greenstone Terranes. Four significant volcano-plutonic and three significant deformation events occurred in and around the CPTZ between 2950 and 2840 Ma, a relatively short period in the evolution of the North Pilbara Terrain. Mineralization in the East and West Pilbara Granite-Greenstone Terranes was less intense and occurred over a much longer period. Compared to other Archean granite-greenstone terranes, the North Pilbara Terrain is poorly endowed: the only known world-class deposit in this region is the Wodgina Ta-Sn deposit. This lack of major mineral deposits may relate to the low rate of crustal growth of the North Pilbara Terrain. If such is the case, then the long history of crustal development and extensive recycling in the Pilbara is responsible for both the diversity of mineral deposits therein and, partly, the apparent poor endowment of the North Pilbara Terrain.

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Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Tanami seismic survey ran from May through July 2005 under the supervision of ANSIR (National Research Facility for Earth Sounding). The survey consisted of 720 line-km along four regional deep seismic traverses, 05GA-T1 through to 05GA-T4, aimed at providing orthogonal three-dimensional control on the regional fault geometry. Geoscience Australia processed the data in the 12 months following the survey, using the DISCO/FOCUS seismic processing package. Considerable effort was expended on the most critical aspects for improving the seismic reflection image, namely refraction statics correction, several passes of velocity analysis, and partial pre-stack followed by post stack migration of the data. Partial pre-stack migration (also known as dip moveout or DMO correction) was necessary for simultaneous imaging of horizontal and steeply dipping reflectors. <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>

Assessment of geological, geochemical and isotopic data indicate that a subgroup of volcanic-hosted massive sulphide (VHMS) deposits has a major magmatic-hydrothermal source of ore fluids and metals. This group, which is characterised by high Cu and Au grades, is distinguished by aluminous advanced argillic alteration assemblages or metamorphosed equivalents. These characteristics are interpreted as the consequence of disproportionation of magmatic SO2. Other than deposits associated with advanced argillic alteration assemblages, the only deposit for which we ascribe a major magmatic-hydrothermal contribution is the Devonian Neves Corvo deposit. This deposit differs from other deposits in the Iberian Pyrite Belt and around the world in being extremely Sn-rich, Comparison with 'normal' VHMS deposits suggest that these subgroups of VHMS deposits may form in specialised tectonic environments. The Cu-Au-rich deposits appear to form adjacent to magmatic arcs, an environment conducive to the generation of hydrous, oxidised melts by melting metasomatised mantle in the wedge above the subducting slab. This contrasts with the back-arc setting of 'normal' VHMS deposits in which relatively dry granites formed by decompression melting drive seawater-dominated hydrothermal circulation. The tectonic setting of highly Sn-rich VHMS deposits such as Neves Corvo is less clear, however thick continental crust below the ore-hosting basin may be critical as it is in other Sn deposits.

Presentations from 'THE ISHIHARA SYMPOSIUM' held at GEMOC, MACQUARIE UNIVERSITY, JULY 22-24 2003; on a variety of topics ranging from general granite processes to mineralisation associated with magmatism.

Orogenesis in Phanerozoic systems is rapid, diachronous, episodic, and involves the switching of tectonic modes (extension-compression). In contrast, many Archaean orogens have traditionally been viewed as having developed by relatively simple, long-lived, mono-mode deformational processes. New results, however, reveal that the late Archaean eastern Yilgarn Craton (EYC) evolved episodically and rapidly, with a diachronous series of approximately E?W coaxial switches in tectonic mode. Tectonic mode switching changed stress regimes and resulted in the development of `late basins?, the emplacement of granites, and early orogenic gold mineralisation diachronously from east to west (NE?SW). Fluids were driven from the lower crust (and below) via large-scale crustal imbricating thrust faults. These fluids promoted the passage of a compression-extension couplet along a basal detachment by successively `lubricating? faults (preparing the ground), and facilitating a propagating wave of foreland surge (D2a) and hinterland extension (D2E) followed by inversion, uplift and annealing (D2b). In this way, orogenic Au and westward orogenic surge with associated tectonic mode switches are linked. We predict that the compres-sion-extension couplets and early orogenic gold mineralisation propagated from the east to the west diachronously at a rate of ~3-5 m.y. between domains from ~2670 Ma to ~2650 Ma. Multiple mineralising episodes are also a predicted consequence of the orogenic surge model.