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The Ranger 1 unconformity-related uranium deposit in the Northern Territory of Australia is one of the world's largest uranium deposits and is currently Australia's second largest producer of uranium. Mineralisation at the Ranger, Jabiluka and other major unconformity-related deposits in the Alligator Rivers Uranium Field (ARUF) occurs in Paleoproterozoic metamorphic basement rocks immediately beneath the unconformity with the overlying and partly preserved Paleo- to Mesoproterozoic McArthur Basin. New geochronological data and observations of the relative timing of tectonothermal and hydrothermal events at the Ranger 1 number 3 orebody provide fresh insights on the spatial-temporal controls on ore formation in this deposit and more broadly in the ARUF. Uranium mineralisation and associated alteration at Ranger were fundamentally controlled by reactivated D1 shear zones that were initially localised by rheological contrasts and graphite-bearing units within the metasedimentary Cahill Formation. A new model of the Ranger 1 ore-forming mineral system attempts to reconcile the key features of the Ranger deposit and those of other major deposits and regional alteration in the ARUF. The results of the study demonstrate the importance of pre-ore structural and chemical architecture of the basement in controlling the location of uranium mineralisation. As in most recent models, McArthur Basin-derived, oxidised, diagenetic brines are envisaged as crucial in transporting uranium downwards into reduced basement rocks where uranium was deposited either by fluid-rock reaction and/or by fluid mixing. However, we propose a different architecture of fluid flow in which these basinal fluids penetrated extensive volumes of basement rocks beneath the unconformity to leach uranium, particularly from Archean felsic orthogneisses across basement paleo-highs. Possibly driven by convection and/or extensional tectonism during the period ~1725 Ma to ~1705 Ma the uranium was transported laterally through microfractures in this regional sub-unconformity alteration zone, along the unconformity, and via fault networks until chemical gradients were encountered in D1 shear zones in the Cahill Formation. Uraninite deposition at Ranger most likely resulted from reduction of ore fluids via reaction with pre-existing Fe2+-bearing minerals and/or via fluid mixing, although the evidence for mixing remains cryptic. Simultaneously, intense Mg metasomatism generated very acidic and silica-rich fluids that migrated laterally and downwards within the D1/D2 shear zones to dissolve and silicify adjacent carbonate rock units, explaining the observed spatial association of chloritic ore breccia adjacent to, and in places above, thinned and silicified carbonate rock units, both at the Ranger and Jabiluka deposits. The possible role of fluid mixing above and below the unconformity requires further study to better understand why no significant uranium deposits have yet been discovered within the McArthur Basin, a characteristic that appears to differentiate the ARUF from the Athabasca Basin in Canada.

This Record provides information to accompany the usage of two web-based map sheets showing the time-space distribution of Proterozoic Large Igneous Provinces (LIPs) in Australia. The maps should be studied in context with other maps in this national series: the Map of Australian Proterozoic Mafic-Ultramafic Magmatic Events (which presents all magmatic events, large and small), and the Map of Australian Archean Mafic-Ultramafic Magmatic Events, together with their accompanying Geoscience Australia Records. Together, these are a comprehensive source of primary information on the place of mafic-ultramafic magmatism in the evolution of the Australian continent, and will be of interest to explorers in the search of magmatic ore deposits of nickel, platinum-group elements, chromium, titanium, and vanadium.

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). Resource package contains: - Australian Proterozoic Mafic-Ultramafic Magmatic Events: Map Sheets 1 and 2 - Guide to Using the Australian Proterozoic Mafic-Ultramafic Magmatic Events Map - Spreadsheets of data that support the maps - A time series animation summarising all the mafic-ultramafic magmatic events

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A detailed mapping and geochemical and geochronological study of the Hiltaba Suite in the Tarcoola Region, South Australia, shows significant greater variation in composition than is allowable under the definition of Suite. By extending this work into the rest of the Gawler Craton using existing datasets, the Hiltaba ‘suite’ can be shown to be co-magmatic with the Gawler Range Volcanics. Together the magmatic rocks are grouped as the Gawler Range-Hiltaba Volcano-Plutonic event, and the intrusives themselves grouped as the Hiltaba Association Granitoids. A four-fold Supersuite classification is applied to both the intrusive and extrusive units. A great variation in compositions within the GRHVP reflects source and emplacement conditions. These variations can be correlated to different mineralisation styles observed in the Central Gawler Gold Province and the Olympic Copper-Gold Province.

Although there are several resources for storing and accessing geochronological data, there is no standard format for exchanging geochronology data among users. Current systems are an inefficient mixture of comma delimited text files, Excel spreadsheets and PDFs that assume prior specialist knowledge and force the user to laboriously and potentially erroneously extract the required data manually. With increasing demands for data interoperability this situation is becoming intolerable not only among researchers, but also at the funding agency level. Geoscience Australia and partners are developing a standard data exchange format for geochronological data based on XML (eXtensible Markup Language) technology that has been demonstrated in other geological data applications and is an important aspect of emerging international geoscience data format standards. This presentation will discuss developments at Geoscience Australia and the opportunities for participation. Key words: Geochronology, data management, metadata, standards.

Compilation of in-house SHRIMP U-Pb geochronology data for the eastern Yilgarn Craton

The 4-10 km-thick Bangemall Supergroup, comprising the Edmund and Collier groups, was deposited between 1620 Ma and 1070 Ma in response to intracratonic extensional reactivation of the Paleoproterozoic Capricorn compressional orogen. The supergroup can be further divided into six depositional packages bounded by unconformities or major marine flooding surfaces. Samples of each of the major sandstone units within these packages have been collected for detrital zircon provenance analysis. U-Pb dating of over 1200 detrital zircon grains has failed to identify any syndepositional magmatism, but provides an extensive dataset for evaluating the provenance history of the Bangemall Supergroup and implications for the Mesoproterozoic paleogeography of the West Australian Craton. Integration of this detrital zircon data with palaeocurrent data indicates that all source areas were located within the Mesoproterozoic West Australian Craton, with the main source area for the northern Bangemall Supergroup being the Gascoyne Complex and southern Pilbara Craton. All samples have prominent age modes in the 1850-1600 Ma range, indicating significant contribution from the northern Gascoyne Complex and coeval sedimentary basins. Some samples also display prominent modes in the 2780-2450 Ma range, consistent with derivation from the Fortescue and Hamersley groups. The provenance history of the Edmund Group records unroofing of the underlying basement, from the Gascoyne Complex to the Archean granites and greenstones of the Pilbara Craton. This results in detrital age-spectra in which the dominant modes become older upwards. In contrast, the Collier Group records unroofing of the underlying Edmund Group, and is characterized by age-spectra in which the dominant modes become younger upwards. These data imply that the West Australian Craton remained intact throughout the Mesoproterozoic assembly of Rodinia, and was the only source of detritus for the Bangemall Supergroup. Keywords: Bangemall Supergroup, Edmund Group, Collier Group, paleocurrents, provenance, zircon