Initial lead isotope ratios from Archean volcanic-hosted massive sulfide (VHMS) and lode gold deposits and neodymium isotope model ages from igneous rocks from the geological provinces that host these deposits identify systematic spatial and temporal patterns, both within and between the provinces. The Abitibi-Wawa Subprovince of the Superior Province is characterized by highly juvenile lead and neodymium. Most other Archean provinces, however, are characterized by more evolved isotopes, although domains within them can be characterized by juvenile isotope ratios. Metal endowment (measured as the quantity of metal contained in geological resources per unit surface area) of VHMS and komatiite-associated nickel sulfide (KANS) deposits is related to the isotopic character, and therefore the tectonic history, of provinces that host these deposits. Provinces with extensive juvenile crust have significantly higher endowment of VHMS deposits, possibly as a consequence of higher heat flow and extension-related faults. Provinces with evolved crust have higher endowment of KANS deposits, possibly because such crust provided either a source of sulfur or a stable substrate for komatiite emplacement. In any case, initial radiogenic isotope ratios can be useful in predicting the endowment of Archean terranes for VHMS and KANS deposits. Limited data suggest similar relationships may hold in younger terranes.

Presented at the Evolution and metallogenesis of the North Australian Craton Conference, 20-22 June 2006, Alice Springs. The Early Mesoproterozoic (1600 Ma - 1570 Ma) was a period of widespread compressional tectonism and high geothermal gradient metamorphism in the Australian Proterozoic. In the eastern half of the North Australian Craton, the bulk of Palaeoproterozoic terrains underwent high-temperature tectonism between 1600 Ma to 1550 Ma. In central Australia, the Chewings Orogeny (1600 Ma - 1570 Ma) was associated with approximately north-south shortening coeval with regional low-pressure high-temperature metamorphism up to granulite grade. In northeastern Australia, the Early Isan (1600 Ma - 1580 Ma), and Ewamin-Janan Orogenies (1585 Ma - 1555 Ma) in the Mt Isa and Georgetown and Yambo Inliers, respectively, were also associated with approximately north-south shortening and high geothermal gradient metamorphism. In the southern Australian Proterozoic, the Olarian Orogeny (1610 Ma - 1585 Ma) in the Curnamona Province was also characterised by high geothermal gradient metamorphism. <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>

This project is based on the recognition that combinations of specific granite types and distinctive host rocks tend to be associated with certain types of Au, Cu, Zn, Pb, Sn and W mineralisation. Rarely is Proterozoic mineralisation hosted by granites themselves, for the most part being hosted in the country rock, often three or more kilometres from the nearest known granite. There is an apparent host rock control on the deposition of metals: this can be both compositional and also controlled by the competency of the host lithologies. This compositional host rock control has been documented by Stuart-Smith et al. (1993 - Geology and mineral deposits of the Cullen Mineral field, AGSO Bull. 229) for the Pine Creek Inlier and noted in the eastern Mount Isa Inlier by Wyborn and Heinrich (1993 - The relationship between late-tectonic felsic intrusives and Cu-Au mineralisation in the Eastern Fold Belt, Mount Isa Inlier, Trans Royal Soc Edinburgh, Earth Sci, 83, 201-209). This project collated data on the Proterozoic granites and their comagmatic volcanics, the mineralogical composition of the rocks that they intrude and briefly assessed the style and type of mineralisation present within 5 kms of an outcrop of granite. All data collated in the reports is built into the accompanying GIS, and essentially each item listed in the report is converted into a searchable item within the GIS. This project has aimed to provide the data and interpretations to show the following: 1) Which Proterozoic granites have metallogenic potential, 2) What commodities they are likely to be associated with, and 3) Where the better host rocks are located that are likely to host potential mineralisation. <p>Related material<a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=33388">The metallogenic potential of Australian Proterozoic granites. GA Record 2001/012.</a></p>

The global distribution of mineral deposits in cratons, belts and districts shows that they are not equally and uniformly endowed with metal. Some cratons are highly fertile (e.g. Yilgarn Craton for Archaean greenstone gold and nickel) and there are those which are almost barren (e.g. Archaen greenstone belts in the Pilbara Craton). Within belts the distribution is equally non-uniform. For instance more than 80% of gold resources in the Yilgarn are concentrated in the Kalgoorlie Terrane of the Eastern Goldfields. At a first level the total endowment can be used to compare mineralised belts and districts, however the distribution of deposit sizes in them can provide a second level constraint on their fertility, in particular the nature and intensity of metal accumulation versus metal dispersion. More enigmatic from this point of view are belts and districts in which the total metal endowment is contained in one or two giant and/or super-giant deposits, such as the Broken Hill in New South Wales, Norilsk-Talnakh in Western Siberia, and Olympic Dam in South Australia. These mjaor deposits represent single "bull elephants" in an "elephant country". Cumulative frequency distribution curves of metals of major mineralized cratons, belts and districts are used to compare the nature of their metal endowment. The analysis shows that the curves of "elephant-bearing" belts and districts are remarkably different from those of "average" belts and districts, and that regional and/or district scale geological factors could have played a significant role in controlling metal endowment. A comparison of curves for belts and districts with similar endowment can be used to assess potential for yet to be discovered deposits and to assess their relative size.

To assist the mining industry during the current buoyant times of historically high nickel and platinum-group element prices, Geoscience Australia has produced two web-based map sheets (at 1:5 million and 1:10 million scales) that show the spatial distribution of Proterozoic (2500 Ma to 545 Ma) mafic-ultramafic magmatic events in Australia. The maps illustrate for the first time, the continental extent and age relationships of Proterozoic mafic and ultramafic rocks and their associated mineral deposits. These rocks have been assigned to thirty Magmatic Events (ME) that range in age from the Early Palaeoproterozoic ~2455 Ma (ME 1) to the Early Cambrian ~520 Ma (ME 30). Record 2008/15 (Geocat 66624) is a user guide for the `Australian Proterozoic Mafic-Ultramafic Magmatic Events' map (Geocat 66114). It compiles all the geological and geochronological data that underpins the information portrayed on the map. The key objectives of this user guide are to: - summarise the scope, scientific rationale, and methodology of the study; - describe the digital datasets (e.g., solid geology, geological province, geochronology, mineral resources, geophysics, etc) that underpin the information portrayed on the maps; and - document the attribution data and publications used for characterising and assigning magmatic events to the Proterozoic mafic-ultramafic units. <h3>Related products:</h3><a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=66114">Australian Proterozoic Mafic-Ultramafic Magmatic Events: Map Sheets 1 and 2</a> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=70461">Proterozoic Mafic-Ultramafic Magmatic Events Resource Package</a> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=69347">Archean Mafic-Ultramafic Magmatic Events Resource Package</a> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=69935">Guide to using the Australian Archean Mafic-Ultramafic Magmatic Events Map</a> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=69213">Proterozoic Large Igneous Provinces: Map Sheets 1 and 2</a> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=70008">Guide to using the Map of Australian Proterozoic Large Igneous Provinces</a>

In the recent past, geologists have been inclined to confine their study to the structural traps and openings which localize individual ore shoots and have tended to neglect most other features, including considerations of ore genesis. L.C. Graton has recently remarked that "the out-standing unfilled need lying ahead is the discovery of new mineralized districts". In this connection he speaks of "the all-important standpoint of genetic understanding". As a contribution towards filling this need, the following points, relating to mineralization in the Cobar-Nymagee province, are here presented for consideration.

No abstract available

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.

Australia holds the world's largest resources of uranium recoverable at low cost, principally in the uranium-rich Olympic Dam iron oxide Cu-Au (IOCG) deposit together with the Ranger and Jabiluka unconformity-related deposits and Yeelirrie surface-related deposit. Despite this impressive inventory, resources of several other styles of uranium deposits appear to be under-represented in Australia relative to geologically similar regions elsewhere in the world. In particular, Australia has no known giant uranium deposits hosted by Mesozoic or younger sedimentary basins, although recent discoveries in the Frome Embayment have significantly increased total resources of `sandstone' uranium in the region. Major deposits directly related to magmatic processes also appear to be under-represented, given the abundance of unusually uranium-rich igneous rocks in Australia. The Australian Government's Onshore Energy Security Program (OESP 2006-2011) is providing pre-competitive geoscientific data and new area selection concepts to assist in reducing exploration risk and to support an assessment of onshore energy and uranium potential. This report examines the key processes controlling where and how uranium mineralisation occurs in Australia and elsewhere. Based on this process understanding and on descriptions of well-documented systems, we develop generalised models of three distinct families of uranium mineral systems, including exploration criteria. The purpose of the report is to present a revised framework for a fresh assessment of Australia's uranium mineral potential. This systems-based approach, when combined with empirical data, provides a means of identifying previously unrecognised uranium provinces or districts. The report has three parts. First, the fundamental chemical controls on uranium transport and deposition in aqueous geological systems are reviewed. Second, a new scheme of classification of uranium deposits is proposed (see below). Third, each of three families of uranium mineral systems, plus hybrid systems, is described in terms of ore-forming processes, essential components of the mineral system, and mappable criteria. Exploration models for key systems are presented in figures and tables.

Metallogenic, geologic and isotopic data indicate secular changes in the character of VHMS deposits relate to changes in tectonic processes, tectonic cycles, and changes in the hydrosphere and atmosphere. The distribution of these deposits is episodic, with peaks at 2740-2680 Ma, 1910-1840 Ma, 510-460 Ma and 370-355 Ma that correspond to the assembly of Kenorland, Nuna, Gondwana and Pangea. Quiescent periods of VHMS formation correspond to periods of supercontinent stability. Large ranges in source 238U/204Pb that characterize VHMS deposits in the Archean and Proterozoic indicate early (Hadean to Paleoarchean) differentiation. A progressive decrease in - variability suggests homogenisation with time of these differentiated sources. Secular increases in the amount of lead and decreases in 100Zn/(Zn+Pb) relate to an increase in felsic-dominated sequences as hosts to deposits and an absolute increase in the abundance of lead in the crust with time. The increase in sulfate minerals in VHMS deposits from virtually absent in the Meso- to Neoarchean to relatively common in the Phanerozoic relates to oxidation of the hydrosphere. Total sulfur in the oceans increased, resulting in an increasingly important contribution of seawater sulfur to VHMS ore fluids with time. Most sulfur in Archean to Paleoproterozoic deposits was derived by leaching rocks below deposits, with little contribution from seawater, resulting in uniform, near-zero-permil values of 34Ssulfide. In contrast the more variable values of younger deposits reflect the increasing importance of seawater sulfur. Unlike Meso- to Neoarchean deposits, Paleoarchean deposits contain abundant barite, which is inferred to have been derived from photolytic decomposition of atmospheric SO2 and does not reflect overall oxidised oceans. Archean and Proterozoic seawater was more salty than Phanerozoic, particularly upper Phanerozoic, seawater. VHMS fluids ore fluids reflect this, also being saltier in Precambrian deposits.