The Thomson Orogen of eastern Australia is a major component of the Tasmanides and has historically been poorly understood and overlooked for exploration due to extensive sedimentary cover including the Eromanga Basin. To further understanding and encourage exploration of this area, Geoscience Australia, the Geological Survey of Queensland and the Geological Survey of New South Wales (NSW) have undertaken a major multidisciplinary geoscientific programme in the southern Thomson Orogen (STO) as a part of the UNCOVER initiative. A major outcome of this project has been the completion of twelve stratigraphic diamond drill holes between 2016 and 2017. SHRIMP U–Pb zircon dating of magmatic and metasedimentary rocks intersected by the boreholes provide new insights into the geological evolution and mineral prospectivity of this region. Geochronology of three intrusive rocks intersected by new boreholes in the NSW part of STO have late Silurian ages of ~425 Ma (Tongo 1), ~421 Ma (Janina 1) and ~421 Ma (Congararra 1). The age of the granodiorite intersected by Tongo 1 is within uncertainty of the intrusion-related Mo-W and later Au-base metal mineralisation at the Cuttaburra and F1 prospects located ~20 km southeast of the Tongo 1 borehole. Additionally, previously unknown volcanic events have been revealed by a dacitic ignimbrite (~387 Ma) in borehole GSQ Eulo 2 (Queensland) and a rhyolite (~395 Ma) in borehole, Milcarpa 1 (NSW). Detrital zircon geochronology has also played an important role in characterising undercover units such as the Werewilka Formation and Nebine Metamorphics, interpreted from geophysical data sets. This abstract was submitted to and presented at the 2018 Australian Geoscience Council Convention (AGCC) (https://www.agcc.org.au/)

<div>Archean crustal evolution, and its tectonic paradigm, can be directly linked to the evolution of the mantle, the hydrosphere-atmosphere, oxygenation of the Earth, and the formation and storage of ore deposits. Hence, it is vital to understand the evolution of the early crust if we are to understand our planet’s evolution as well as transformational events in its history.</div><div> The collection of vast amounts of isotopic data, especially U-Pb, Sm-Nd, Lu-Hf, and δ18O, over the last 30 years, has significantly advanced our understanding of crustal processes and their timing. However, we rarely look at these data in a spatial context. This study aims to constrain the time-space evolution of the south-east Superior Craton, Canada, by mapping the zircon Hf-O isotopes and trace element data from 148 Archean magmatic rocks (6340 total analyses).</div><div> In Lu-Hf space, the dataset demonstrates the highly juvenile nature of this region, with the majority of values between εHfi +6 and +2. When plotted spatially, the most juvenile data (+4 to +6 εHfi) delineate an E-W oriented zone, broadly in-line and sub-parallel to the Cadillac-Larder Lake and Porcupine-Destor structures. Surrounding this juvenile region is less juvenile crust (0 to +3 εHf). Corresponding δ18O values show that light to mantle-like data (3.0-5.6‰) correlate with the most juvenile crust imaged by the εHf, with heavier δ18O (5.8-7.5‰) plotting to the south, east and west of this zone. Zircon trace element proxies for hydration (Eu/Eu*), oxidation (ΔFMQ using Ti, Ce, U), and continental vs. oceanic origin (Ui/Yb) replicate the pattern observed in the Lu-Hf and δ18O. This suggests that, broadly, the SE Superior consists of a central E-W orientated juvenile zone consisting of the most reduced, least hydrated, least continental, and most high-temperature hydrothermally-altered crust. This zone is surrounded by crust which is more hydrated, oxidised, has a greater supracrustal δ18O component, and is slightly less juvenile. The major ore systems of the Abitibi subprovince, including VMS, gold and komatiite-hosted Ni-Cu-PGE systems, fall within the E-W highly-juvenile zone.</div><div> Current tectonic models for this region of the Superior Craton range from (1) long-lived Neoarchean subduction across the whole Abitibi tectono-thermal ‘event’ (2750-<2695 Ma) – ‘horizontal’ tectonics; and (2) a variety of non-arc processes such as plume-related crustal overthickening (i.e., oceanic plateau), sagduction/drip tectonics, and subcretion, amongst others – ‘vertical’ tectonics. Models combining arc and non-arc processes have also been suggested (i.e., plume-arc interaction), and our data broadly support a combined model. We propose the E-W zone delineated by the various geochemical data represents a paleo-rift zone, driven by ambient mantle or mantle plume processes. The dry, reduced, oceanic character of the zone appears to preclude an arc or back-arc setting prior to ca. 2.7 Ga. However, temporal changes in hydration, oxidation, and the increased heavy δ18O component at ca. 2.7 Ga suggest a major geodynamic shift, potentially marking the onset of subduction and associated compression. This is contribution 2020-050 of the Mineral Exploration Research Centre (MERC) Metal Earth project.</div><div> This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

<div>Lithospheric and crustal architecture — the framework of major tectonic blocks, terranes and their boundaries — represents a fundamental first-order control on major geological systems, including the location of world-class mineral camps. Traditionally, lithospheric and crustal architecture are constrained using predominantly geophysical methods. However, Champion and Cassidy (2007) pioneered the use of regional Sm–Nd isotopic data from felsic igneous rocks to produce isotopic contour maps of the Yilgarn Craton, demonstrating the effectiveness of ‘isotopic mapping’, and the potential to map ‘time-constrained’ crustal architecture. Mole et al. (2013) demonstrated the association between lithospheric architecture and mineral systems, highlighting the potential of isotopic mapping as a greenfield area selection tool. Additional work, using Lu-Hf isotopes (Mole et al., 2014), demonstrated that the technique could constrain a range of temporal events via ‘time-slice mapping’, explaining how Ni-Cu-PGE mineralized komatiite systems migrated with the evolving lithospheric boundary of the Yilgarn Craton from 2.9 to 2.7 Ga. Similar studies have since been conducted in West Africa (Parra-Avila et al., 2018), Tibet (Hou et al., 2015), and Canada (Bjorkman, 2017; Mole et al., 2021; 2022). This work continues in Geoscience Australia’s $225 million Exploring for the Future program (2016-present). Isotopic mapping, which forms an integral part of a combined geology-geophysics-geochemistry approach, is currently being applied across southeast Australia, covering the eastern Gawler Craton, Delamerian Orogen, and western Lachlan Orogen, encompassing more than 3 Gyrs of Earth history with demonstrable potential for large mineral systems.</div><div> <b>Reference(s):</b></div><div> Bjorkman, K.E., 2017. 4D crust-mantle evolution of the Western Superior Craton: Implications for Archean granite-greenstone petrogenesis and geodynamics. University of Western Australia, PhD Thesis, 134 pp.</div><div> Champion, D.C. and Cassidy, K.F., 2007. An overview of the Yilgarn Craton and its crustal evolution. In: F.P. Bierlein and C.M. Knox-Robinson (Editors), Proceedings of Geoconferences (WA) Inc. Kalgoorlie '07 Conference. Geoscience Australia Record 2007/14, Kalgoorlie, Western Australia, pp. 8-13.</div><div> Hou, Z., Duan, L., Lu, Y., Zheng, Y., Zhu, D., Yang, Z., Yang, Z., Wang, B., Pei, Y., Zhao, Z. and McCuaig, T.C., 2015. Lithospheric architecture of the Lhasa terrane and its control on ore deposits in the Himalayan-Tibetan orogen. Economic Geology, 110(6): 1541-1575.</div><div> Mole, D.R., Fiorentini, M.L., Cassidy, K.F., Kirkland, C.L., Thebaud, N., McCuaig, T.C., Doublier, M.P., Duuring, P., Romano, S.S., Maas, R., Belousova, E.A., Barnes, S.J. and Miller, J., 2013. Crustal evolution, intra-cratonic architecture and the metallogeny of an Archaean craton. Geological Society, London, Special Publications, 393: pp. 23-80.</div><div> Mole, D.R., Fiorentini, M.L., Thebaud, N., Cassidy, K.F., McCuaig, T.C., Kirkland, C.L., Romano, S.S., Doublier, M.P., Belousova, E.A., Barnes, S.J. and Miller, J., 2014. Archean komatiite volcanism controlled by the evolution of early continents. Proceedings of the National Academy of Sciences, 111(28): 10083-10088.</div><div> Mole, D.R., Thurston, P.C., Marsh, J.H., Stern, R.A., Ayer, J.A., Martin, L.A.J. and Lu, Y., 2021. The formation of Neoarchean continental crust in the south-east Superior Craton by two distinct geodynamic processes. Precambrian Research, 356: 106104.</div><div> Mole, D.R., Frieman, B.M., Thurston, P.C., Marsh, J.H., Jørgensen, T.R.C., Stern, R.A., Martin, L.A.J., Lu, Y.J. and Gibson, H.L., 2022. Crustal architecture of the south-east Superior Craton and controls on mineral systems. Ore Geology Reviews, 148: 105017.</div><div> Parra-Avila, L.A., Belousova, E., Fiorentini, M.L., Eglinger, A., Block, S. and Miller, J., 2018. Zircon Hf and O-isotope constraints on the evolution of the Paleoproterozoic Baoulé-Mossi domain of the southern West African Craton. Precambrian Research, 306: 174-188.</div><div> This Abstract was submitted/presented to the Target 2023 Conference 28 July (https://6ias.org/target2023/)

This Record presents new Sensitive High Resolution Ion MicroProbe (SHRIMP) U-Pb zircon results from the Mount Isa Orogen obtained under the auspices of the Geological Survey of Queensland-Geoscience Australia (GSQ-GA) National Collaboration Framework (NCF) geochronology project between July 2016 and June 2017. New results are presented from eight samples collected as part of ongoing regional mapping and geoscientific programs in the Mount Isa Orogen. GA work presented here represents part of the federally funded Exploring for the Future Program. As a part of ongoing geological mapping in the Mount Isa Orogen, the Geological Survey of Queensland (GSQ) and Geoscience Australia (GA) have undertaken a geochronology program to enhance the understanding of the geological evolution of the province. There are two focus areas as a part of this Record. The first focus area is north of Mount Isa, in the Kalkadoon-Leichhardt and Sybella domains (Figure i), and includes geochronology results from three mafic to intermediate rocks. The second focus area is south of Cloncurry, in the Kuridala–Selwyn and Marimo–Staveley domains (Figure i), and includes geochronology results from one leucogranite and four sedimentary rocks. For ease of reporting, these two focus areas are split into two themes 1) ‘mafic rocks’ for the three geochronology results north of Mount Isa; and 2) ‘Kuridala–Selwyn corridor’ for the five geochronology results south of Cloncurry. <b>Bibliographic Reference:</b> LEWIS, C.J., WITHNALL, I.W., HUTTON, L.J., BULTITUDE, R.J., SLADE, A.P., SARGENT, S., 2020. Summary of results. Joint GSQ–GA geochronology project: Mount Isa region, 2016–2017. <i>Queensland Geological Record</i><b> 2020/01</b>.

<div>This Record is the fourth of a series of reports detailing the results of U–Pb dating of samples collected during investigations of the Mary Kathleen Domain and adjacent areas of the Mount Isa Inlier in 2018–19 by the Geological Survey of Queensland and co-workers (Kositcin <em>et al</em>., 2019, 2021, Bodorkos <em>et al</em>., 2020). It presents new Sensitive High Resolution Ion Microprobe (SHRIMP) U–Pb geochronological results for five samples collected from the inlier. Two of the samples are from units in the Kalkadoon–Leichhardt Domain and the remaining three from units in the adjacent Mary Kathleen Domain (Figure i). The ages of these units are poorly constrained and various ages have been proposed for most of them by different investigators.</div><div> <b>Bibliographic Reference:</b> Kositcin, N., Bultitude, R. J., Purdy, D. J. 2023. <i>Summary of results. Joint GSQ–GA Geochronology Project: Kalkadoon–Leichhardt and Mary Kathleen Domains, 2018–2020. </i>GSQ Record 2023/04, Geological Survey of Queensland. GA Record 2023/41, Geoscience Australia, Canberra. http://dx.doi.org/10.26186/148600 https://geoscience.data.qld.gov.au/data/report/cr141810

<div>The Yilgarn Craton of Western Australia represents one of the largest pieces of Precambrian crust on Earth, and a key repository of information on the Meso-Neoarchean period. Understanding the crustal, tectonic, thermal, and chemical evolution of the craton is critical in placing these events into an accurate geological context, as well as developing holistic tectonic models for the Archean Earth. In this study, we collected a large U-Pb (420 collated samples) and Hf isotopic (2163 analyses) dataset on zircon to investigate the evolution of the craton. These data provide strong evidence for a Hadean-Eoarchean origin for the Yilgarn Craton from mafic crust at ca. 4000 Ma. This ancient cratonic nucleus was subsequently rifted, expanded and reworked by successive crustal growth events at ca. 3700 Ma, ca. 3300 Ma, 3000-2900 Ma, 2825-2800 Ma, and ca. 2730-2620 Ma. The <3050 Ma crustal growth events correlate broadly with known komatiite events, and patterns of craton evolution, revealed by Hf isotope time-slice mapping, image the periodic break-up of the Yilgarn proto-continent and the formation of rift-zones between the older crustal blocks. Crustal growth and new magmatic pulses were focused into these zones and at craton margins, resulting in continent growth via internal (rift-enabled) expansion, and peripheral (crustal extraction at craton margins) magmatism. Consequently, we interpret these major geodynamic processes to be analogous to plume-lid tectonics, where the majority of tonalite-trondhjemite-granodiorite (TTG) felsic crust, and later granitic crust, was formed by reworking of hydrated mafic rocks and TTGs, respectively, via a combination of infracrustal and/or drip-tectonic settings. While this process of crust formation and evolution is not necessarily restricted to a specific geodynamic system, we find limited direct evidence that subduction-like processes formed a major tectonic component, aside from re-docking the Narryer Terrane to the craton at ca. 2740 Ma. Overall, these 'rift-expansion' and 'craton margin' crustal growth process led to an intra-cratonic architecture of younger, juvenile terranes located internal and external to older, long-lived, reworked crustal blocks. This framework provided pathways that localized later magmas and fluids, driving the exceptional mineral endowment of the Yilgarn Craton.</div> This Abstract/Poster was submitted to & presented at the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

<div>Archean greenstone belts are a vital window into the tectonostratigraphic processes that operated in the early Earth and the geodynamics that drove them. However, the majority of greenstone belts worldwide are highly-deformed, complicating geodynamic interpretations. The volcano-sedimentary sequence of the 2775-2690 Ma Fortescue Group is different in that it is largely undeformed, offering a unique insight into the architecture of greenstone sequences. In the Fortescue magmatic rocks, geochemical signatures that in deformed belts in the Superior or Yilgarn Cratons might have been interpreted as arc-like, are explained by contamination of rift-related mantle and plume-derived magmas with Pilbara basement crust; understanding the wider geological and structural setting allows a more complete interpretation.</div><div> However, contamination of Fortescue magmas by an enriched sub-continental mantle lithosphere (SCLM) is an alternative hypothesis to the crustal contamination model. If demonstrated, the addition of sediments and fluids to the SCLM, required to form enriched/metasomaytised SCLM, would suggest active subduction prior to the Neoarchean. To test this hypothesis, we collected Hf-O isotopic data on zircons from felsic volcanic rocks throughout the Fortescue Group; if the contamination had a subducted sedimentary component (δ18O>20‰), then the O-isotopes should record a heavy signature.</div><div> The results show that the ca. 2775 Ma Mt Roe Formation has εHfi from 0 to -5.6, and δ18OVSMOW of +4.8- +0.3‰, with the majority of values <+3‰. The ca. 2765 Ma Hardey Formation (mostly sediments) has highly unradiogenic εHfi of -5 to -9.4, and δ18O of +7.8- +6.6‰. The ca. 2730 Ma Boongal Formation displays similar values as for Mt Roe, with εHfi +1.9 to -5.5 and δ18O +3.0 to -0.6‰. The ca. 2720 Ma Tumbiana Formation shows the greatest range in εHfi from +4.9 to -4.6, with δ18O +7.1- +0.7‰, with the majority between +4.5 and +2.5‰. Data from the 2715 Ma Maddina Formation are more restricted, with εHfi between +4.0 and -0.1, and δ18O +5.0- +3.8‰. The youngest formation, the 2680 Ma Jeerinah Formation, has εHfi +2.3 to -6.2, and δ18O +5.1 to -2.1‰.</div><div> Importantly, these data provide little evidence of a cryptic enriched SCLM source in the Fortescue magmas. Furthermore, the dataset contains some of the lightest δ18O data known for Archean zircon, highlighting a ca. 100 Myr period of high-temperature magma-water interaction, with long-term continental emergence implied by the trend to meteoric δ18O compositions. The exception to this is the Hardey Formation, which may have formed via crustal anatexis in a period of reduced heat-flow between the 2775-2665 and 2730-2680 Ma events. Data from the other formations show a broad trend of increasing δ18O and εHf from 2775 to 2680 Ma. We suggest this represents the effects of progressive cratonic rifting, allowing mantle-derived magmas to reach the surface less impeded, and also a decreasing role of meteoric water in the rift zone as the sea invades. As a result, the εHf and δ18O data from the Fortescue Group represent the evolving nature of an Archean rift zone, from an emergent volcanic centre, to a submarine environment.</div><div><br></div>This Abstract was submitted/presented to the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

This Record presents data collected between March and September 2018 as part of the ongoing Northern Territory Geological Survey–Geoscience Australia (NTGS–GA) SHRIMP geochronology project under the National Collaborative Framework (NCF) agreement and Geoscience Australia's Exploring for the Future Programme. Five new U–Pb SHRIMP zircon geochronological results derived from five samples of meta-igneous and metasedimentary rocks from MOUNT RENNIE (southwestern Aileron Province and northwestern Warumpi Province) in the Northern Territory are presented herein. All five samples are located at or close to the recently discovered greenfield Grapple and Bumblebee prospects that contain precious and base metal sulfide mineralisation. This Record represents the first attempt to provide temporal constraints on the country rocks that host or occur close to this mineralisation. <b>Bibliographic Reference:</b> Kositcin N, McGloin MV, Reno BL and Beyer EE, 2019. Summary of results. Joint NTGS–GA geochronology project: Cu-Au-Ag-Zn mineralisation in MOUNT RENNIE, Aileron and Warumpi provinces, March – September 2018. <i>Northern Territory Geological Survey</i>, <b>Record 2019-011</b>.

<div>This Record presents data collected as part of the ongoing Northern Territory Geological Survey–Geoscience Australia SHRIMP geochronology project under the National Collaboration Framework agreement. New U-Pb SHRIMP zircon geochronological results were derived from six samples of sedimentary rocks collected from two petroleum exploration drillholes (CBM 107-001 and CBM 107-002) that intersect the Pedirka Basin in the southeastern corner of the Northern Territory.</div><div><br></div><div>Geologically, this is a region in the Simpson Desert that encompasses several superimposed intracratonic sedimentary basins, which are separated by regional unconformities extending over areas of adjoining Queensland, South Australia and New South Wales. In the southeastern corner of the Northern Territory, the Pedirka Basin is one of three stacked basins. The exposed Mesozoic Eromanga Basin overlies the late Palaeozoic to Triassic Pedirka Basin, which is largely restricted to the subsurface, and in turn overlies the Palaeozoic pericratonic Warburton Basin (Munson and Ahmad 2013).</div><div><br></div><div>As the Pedirka Basin is almost entirely concealed beneath the Eromanga Basin, our current understanding of the geology in this southeastern corner of the Northern Territory is constrained by a limited number of exploration drillholes and 2D seismic coverage (Doig 2022). The samples described herein were collected to aid in defining the chronostratigraphy and sedimentary provenance characteristics of the Pedirka Basin.</div><div><br></div><div>BIBLIOGRAPHIC REFERENCE: Jones S.L., Jarrett A.J., Verdel C.S. and Bodorkos S. 2024. Summary of results. Joint NTGS–GA geochronology project: Pedirka Basin. Northern Territory Geological Survey, Record 2024-003.</div>

<div>This Record presents data collected in March 2022–February 2023 as part of the ongoing Northern Territory Geological Survey–Geoscience Australia SHRIMP geochronology project under the National Collaborative Framework agreement and Geoscience Australia’s <em>Exploring for the Future Program</em>. New U–Pb SHRIMP zircon geochronological results were derived from sedimentary rock chip samples of the Warburton Basin collected from four petroleum exploration wells (Beachcomber 1, Thomas 1, Simpson 1, Colson 1) in the southeastern corner of the Northern Territory. Geologically, this is a region in the Simpson Desert that encompasses several superimposed intracratonic sedimentary basins that are separated by regional unconformities that extend over areas of adjoining Queensland, South Australia and New South Wales. The exposed Mesozoic Eromanga Basin overlies the late Palaeozoic Pedirka Basin, which is largely restricted to the subsurface. The Warburton Basin is an early Palaeozoic pericratonic basin containing an early Cambrian and Ordovician succession (Edgoose and Munson, 2013), with possible Devonian rocks observed in some areas (Radke, 2009). As the Warburton Basin is entirely concealed beneath the Pedirka and Eromanga basins, our current understanding of the geology of the western Warburton Basin is constrained by the lack of surface exposures, the small number of well penetrations, limited biostratigraphic age control, and relatively sparse seismic data coverage. </div><div> The samples analysed herein were collected to aid in understanding the chronostratigraphy and provenance characteristics of the concealed Warburton Basin. All four sedimentary samples are dominated by Mesoproterozoic detritus (ca 1000–1300 Ma), have fewer zircons of Paleozoic age, and generally have sparse older Palaeoproterozoic–Archaean aged zircons. Samples from the two westernmost wells yielded 238U/206Pb maximum depositional ages of 469&nbsp;±&nbsp;9&nbsp;Ma (Colson 1) and 394&nbsp;±&nbsp;6&nbsp;Ma (Simpson 1). Samples from the two easternmost wells yielded older 238U/206Pb maximum depositional ages of 569&nbsp;±&nbsp;10&nbsp;Ma (Thomas 1) and 506&nbsp;±&nbsp;5&nbsp;Ma (Beachcomber 1). These data imply that known Devonian stratigraphy extends at least as far as the Simpson 1 well, but may not extend further east.</div><div><br></div><div>BIBLIOGRAPHIC REFERENCE: Kositcin N, Verdel C and Edgoose C, 2023. Summary of results. Joint NTGS–GA geochronology project: western Warburton Basin, March 2022–February 2023. <em>Northern Territory Geological Survey, Record </em>2023-006.</div><div><br></div><div><br></div>