Geochronology
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The Congararra 2 borehole was drilled approximately 73 km NNW of Bourke, NSW/ The borehole was designed to test aeromagnetic anomalies in the basement rocks, test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data, and to test pre-drilling geophysical cover thickness estimates.
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This Record presents new zircon U-Pb geochronological data, obtained using a Sensitive High Resolution Ion MicroProbe (SHRIMP) for thirty-five samples of plutonic rocks from the New England Orogen, New South Wales. The work was carried out under the auspices of the National Geoscience Accord, as a component of the collaborative Geochronology Project between the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) during the reporting periods 2012-2014.
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The late Permian Wandsworth Volcanic Group (WVG) in the southern New England Orogen (SNEO) is dominated by a monotonous series of amalgamated rhyodacitic to felsic eruptives, with minor interbedded flows, intrusives and sediments. The area enclosing known exposures of the WVG cover more than 30,000 km2, with a minimum thickness of 2 km. The top of the succession, as well as the vast majority of the pile representing non-welded material, has not been preserved. Field relationships indicate a broadly contemporaneous (though not necessarily genetic) relationship with late Permian granite magmatism, while Triassic plutons (typically in the range 246-243 Ma) intrude the WVG. SHRIMP U-Pb zircon dating indicates ages around 256.4 ± 1.6 Ma for basal units of the WVG, and 254.1 ± 2.2 Ma for the youngest preserved member of the WVG (Dundee Rhyodacite), defining a short period of substantial intermediate to acid eruptive volcanism. The compositionally unevolved Drake Volcanics to the northeast are older (264.4 ± 2.5 Ma) while those at Halls Peak are older still (Early Permian). Granites of the I-type Moonbi and Uralla Supersuites are dominantly 256-251 Ma and thus overlap in timing (and space) with the WVG event. Interestingly, many mineralized leucogranites (e.g. Parlour Mountain, Oban River, Gilgai) which were formerly regarded as Triassic are now established as synchronous with the Moonbi and Uralla Supersuites and the WVG. The age range of eruption of the WVG permitted by the SHRIMP results (~6 Ma) has been further constrained by CA-ID-TIMS U-Pb zircon analysis which yielded oldest and youngest ages of 255.54 ± 0.16 Ma and 253.26 ± 0.15 Ma respectively, indicating a maximum eruptive time range of ~2 Ma for the preserved pile. Our new results coincide with those determined from CA-ID-TIMS dating of tuffs in the Sydney and Gunnedah Basins. WVG exposures at Attunga are exactly (within ~0.1 Ma) coincident with the age of tuffs within the Trinkey Formation located in the Gunnedah Basin to the west, and the Dundee Rhyodacite is similarly closely matched to the thick Awaba Tuff in the Sydney Basin. Notably, much of the late Permian volcanic and plutonic magmatism in the SNEO is restricted to a remarkably small time range, which coincides exactly with the range of ash fall events in the Sydney and Gunnedah Basins, and possibly further afield. This suggests the SNEO, and the WVG in particular, was the dominant source of volcanic material erupted into these adjacent basins. Further, the adjacent basins may provide a more complete record of Permo-Triassic magmatism in the SNEO than currently preserved within the orogen itself.
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This report presents new Sensitive High Resolution Ion Micro Probe (SHRIMP) U-Pb geochronological results obtained during the Geological Survey of Queensland-Geoscience Australia (GSQ-GA) Geochronology project between July 2010 and June 2012. A total of 24 samples were analysed, in support of ongoing regional geoscientific investigations and mapping programs by the GSQ. This report documents detailed results for each sample individually, encompassing sample location and geological context, a description of the target mineral for geochronology, the relevant analytical data, and a brief geochronological interpretation. A summary of all results from this study is presented in Table i, and the sample locations are shown in Figure i. The analysed samples are from regions extending from the Eulo Ridge, an exposed part of the mainly concealed Thomson Orogen in south-western Queensland, to the Charters Towers and Greenvale regions in the north and the Mount Isa region in the north-west (Figure i). The work was carried out to provide an improved time framework for updated interpretations of the geology of selected parts of the state.
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This Record presents data collected as part of the ongoing NTGS-GA geochronology project between July 2014 and June 2015 under the National Collaborative Framework (NCF). In total, five new U-Pb SHRIMP zircon and titanite geochronological results derived from four samples from the Arunta Region in the Northern Territory are presented herein (Table 1; Figure 1). Three samples were collected from JERVOIS RANGE in HUCKITTA1 in the eastern Arunta Region, and comprise metasedimentary and metaigneous rocks. The fourth sample analysed is an igneous rock from drillcore in TOBERMOREY.
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This Record documents the efforts of the Geological Survey of Victoria (GSV) and Geoscience Australia (GA) in compiling a geochronology (age) compilation for Victoria, describing both the dataset itself and the process by which it is incorporated into the continental-scale Isotopic Atlas of Australia. The Isotopic Atlas draws together age and isotopic data from across the country and provides visualisations and tools to enable non-experts to extract maximum value from these datasets. Data is added to the Isotopic Atlas in a staged approach with priorities determined by GA- and partner-driven focus regions and research questions. This dataset, which was primarily compiled by GSV and has been supplemented with data compiled by GA during the 2013–2017 Stavely Project, is a foundation for the second phase of the Exploring for the Future initiative over 2020–2024, particularly the Darling-Curnamona-Delamerian Project.
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Herein we present the results of a national compilation of mineral deposits (available in Excel or CSV format) for Australia. The deposits were selected as they have substantial endowment (i.e. pre-mining mineral resource) and/or detailed geological information is available. For each deposit (or, in some cases, district) the dataset includes information on: 1. Name (including synonyms), location and GA identifying numbers; 2. Tectonic province that hosts the deposit; 3. Type(s) and age(s) of mineralising events that produced/affected the deposit (including metadata on ages); 4. The metal/mineral endowment of the deposit; 5. Host rocks to the deposit; 6. Spatially and/or temporally associated magmatic rocks; 7. Spatially and temporally associated alteration assemblages (mostly proximal, but, in some cases, regional assemblages); 8. The Fe-S-O minerals present in the deposit and relative abundances where known; 9. Sulfate minerals present; 10. Peak metamorphic grade; 11. Data sources; and 12. Comments. This document presents more detailed descriptions of the metadata presented in the compilation. The dataset is presented in Appendix A. Appendix B presents a national classification of geological provinces based mostly on existing State survey classifications; Appendix C presents a deposit classification based on the classification proposed by Hofstra et al. (2021); and Appendix D presents mineral abbreviations used in the dataset.
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This Record presents new zircon U Pb geochronological data obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP) from rocks sampled within the Wau 1:100 000 map sheet area, which is located on the Papuan Peninsula in eastern Papua New Guinea. Exposure in the Wau Bulolo region comprises low-grade Mesozoic metasedimentary rocks of the Owen Stanley Metamorphics, which are intruded by the mid-Miocene Morobe Granodiorite batholith, and overlain by Pliocene sedimentary and volcanic rocks of the Wau Basin. The map sheet area contains the Morobe Goldfield (from which more than 3.2 Moz of alluvial gold has been mined) and the Hidden Valley epithermal Au-Ag deposit (which has a total gold resource in excess of 3 Moz), and lies about 70 km south-southeast of the giant mid-Miocene Wafi-Golpu porphyry Cu-Au deposit (>26 Moz Au and 9 Mt Cu). The geochronological data in this Record were generated as part of a collaborative project between Geoscience Australia (GA) and the Mineral Resources Authority (MRA) of Papua New Guinea in 2012. Four samples were analysed: two from the Pliocene Bulolo Volcanics and one from the Miocene Morobe Granodiorite to establish precise, accurate magmatic crystallisation ages, and one metasandstone from the Mesozoic Owen Stanley Metamorphics for detrital zircon provenance analysis. Sample locations, descriptions, and U Pb SHRIMP results are summarised in Table 1.1.
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In this Record new U-Pb SHRIMP zircon results are presented from nine samples from western South Australia and eastern Western Australia. This geochronological study was undertaken to provide temporal constraints on the crystalline basement geology beneath the Nullarbor Plain, to assist in geological interpretation of a reflection seismic transect (13GA-EG1) between the Albany-Fraser Province in the west and the central Gawler Craton in the east. This seismic line transects a region in which the crystalline basement geology is entirely buried beneath Neoproterozoic to Cenozoic sedimentary rocks. Consequently, the age, tectonic evolution and mineral potential of the crystalline basement in this region is very poorly understood. The new results complement the very limited pre-existing geochronology data from the Coompana Province and Madura Province, and provide a basis for comparison of geological ages in these provinces with the geological histories reconstructed for the adjacent provinces of the Gawler Craton to the east and the Albany-Fraser Province to the west.
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Geoscience Australia has compiled U-Pb datasets from disparate sources into a single, standardised and publicly-available U–Pb geochronology compilation for all Australia. The national maps presented in this poster expand upon the data coverage previously compiled by Anderson et al. (2017) and Jones et al. (2018), which covered northern and western Australia only. This extension of a national coverage has been achieved through the development of Geoscience Australia’s Interpreted Ages database. In this database, there are now >4000 U–Pb sample points compiled from across Australia, with significant datasets to come from the southern Australia regions. These will be available to the public in the coming months through the Exploring for the Future Data Discovery Portal (eftf.ga.gov.au).