Existing age constraints for geological events in the Tanami Block come predominantly from U-Pb geochronology of i) detrital zircons in sediments, and ii) magmatic zircons in granitoids. These constraints have been used together with observed and inferred geological relationships to help constrain timing of stratigraphy, magmatism, deformation, metamorphism and Aumineralisation (e.g. Vandenburg et al., 2001). Ongoing GA/NTGS zircon geochronology is continuing to refine our understanding of the stratigraphy and magmatic history of the Tanami, with attendant implications for tectonic evolution. In this regard it is noteworthy that detrital zircon ages of ~1815 Ma from the Killi Killi formation require either (or both) a revision of existing stratigraphy, or that the so-called Tanami Orogenic Event significantly post-dates ~1815 Ma, in contrast to previous estimates of ~1845 - 1830 Ma. However, detrital and magmatic zircons can provide no direct constraints on timing of deformation, metamorphism and Au-mineralisation, and consequently our current understanding of these processes in the Tanami region is relatively poor, despite being critical to predictive exploration models.

Legacy product - no abstract available

The minerals industry presently provides 49% of Australia's export income. Although most of this income is derived from the bulk commodities, the earliest mining in Australia was of precious and base metals. The first major mining boom in Australia, the Victorian gold rush, and later rushes to silver-lead deposits at Broken Hill and gold deposits at Kalgoorlie, laid the foundations of Australia's wealth in the latter half of the 1800s. These mining booms had major consequences in the founding of provincial cities such as Bendigo, Ballarat and Kalgoolie and funding early growth of Melbourne and Perth. These and subsequent mineral discoveries were major drivers in opening up regional and inland Australia, not only for mining, but also for agriculture and tourism. Analysis of major Australian mineral provinces indicate that despite differences in metallogeny and geological setting, these provinces share many common features, including an association with margins of crustal blocks; an association with (inverted) extensional faults, many of which penetrate the crust; a common association with mantle-derived magmas or fluids; a temporal association with plate reconfigurations; localisation of ores by chemical or physical gradients; and an association with major fluid flow caused by either thermal or tectonic events. Major mineral provinces are products of the supercontinent cycle and developed preferentially along the margins of crustal blocks. Localisation of deposits is controlled by the basinal, structural and chemical architecture developed during these processes. Formation of major provinces may be the consequence of unusual processes or events that overprint the supercontinent cycle. The Eastern Goldfields gold province is related to amalgamation of the first supercontinent, Kenorland, and the Australian zinc belt Olympic Cu-Au-U province relates to the first break-up after to GOE. The Victorian goldfields appear to be associated with Au-enriched sources.

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.

No abstract available

Excursion Guidebook

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>

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.

No abstract available