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>.

This Record presents new U-Pb geochronological data, obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP), from six samples of igneous rocks and four samples of sedimentary rocks, collected from south-central New South Wales. The work is part of an ongoing Geochronology Project, conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaborative Framework (NCF) agreement, to better understand the geological evolution of the central Lachlan Orogen in the East Riverina region. The results presented herein correspond to the reporting period July 2015-June 2016.

The nature of the substrate below the northern Lachlan Orogen and the southern Thomson Orogen is poorly understood. We investigate the nature of the mid- to lower-crust using O and Lu-Hf isotopes on zircons from magmatic rocks which intrude these regions, and focus on the 440–410 Ma time window to minimise temporal effects while focussing on spatial differences. Over the entire region, O-isotope values range from δ18O = 5.52‰ to 10.14‰, and Lu-Hf from εHft = -8.1 to +8.5. In the northern Lachlan Orogen and much of the southern Thomson Orogen, magmatic rocks with low εHft (c. -8 to -4) and elevated δ18O (c. 9 to 10‰) reflect a supracrustal source. Magmatic rocks intruding the Warratta Group in the western part of the Thomson Orogen also have low εHft (c. -10 to -6) but more subdued δ18O (c. 7‰), indicating a distinct supracrustal source in this region. In the northeast Lachlan Orogen, magmatic rocks record mixing of the supracrustal source with input from a juvenile source (εHft as high as +8.5, δ18O as low as 5.52‰), most likely of “Macquarie Arc”-type affinity. Samples in the west-southwest Thomson Orogen also record some evidence of juvenile input (εHft as high as +0.2, δ18O as low as 6.51‰), likely the Mount Wright Arc of the Koonenberry Belt. Our results show that internal isotopic variation within the Lachlan and the Thomson orogens is much greater than the difference between the two orogens. <b>Citation:</b> K. Waltenberg, S. Bodorkos, R. Armstrong & B. Fu (2018) <i>Mid- to lower-crustal architecture of the northern Lachlan and southern Thomson orogens: evidence from O–Hf isotopes, </i>Australian Journal of Earth Sciences, 65:7-8, 1009-1034, DOI: 10.1080/08120099.2018.1463928

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>.

This Record presents new U Pb geochronological data, obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP), from nine samples of sedimentary rocks collected from the Paleo- to Neoproterozoic Birrindudu and Victoria Basins, and underlying basement from the Victoria River catchment region, northwest Northern Territory. The newly acquired U–Pb SHRIMP data are discussed and integrated with existing detrital zircon geochronology to assist in the determination of maximum depositional ages and sedimentary provenance during the evolution of the Birrindudu and Victoria Basins, and contribute to lithostratigraphic correlations with other Proterozoic basins across northern Australia (e.g., the greater McArthur Basin and the Centralian Superbasin, Walter et al., 1995; Munson et al., 2013; Carson, 2013; Munson, 2016).

This Record contains new zircon U-Pb geochronological data, obtained via Sensitive High-Resolution Ion Micro Probe (SHRIMP), from two samples of metamorphosed felsic igneous rocks of the Proterozoic Pinjarra Orogen (Western Australia), intersected in diamond drillcore at the base of deep petroleum exploration wells penetrating the Paleozoic sedimentary successions of the Perth Basin. In the southern Perth Basin, petroleum exploration well Sue 1 was terminated at depth 3074.2 m, in crystalline basement rocks of the southern Pinjarra Orogen. Abundant zircon from a biotite-bearing felsic orthogneiss at depth 3073.2-3073.7 m yielded a complex array of U-Pb isotopic data, indicative of significant post-crystallisation disturbance of the isotopic system. A Discordia regression fitted to the array yielded an upper intercept date of 1076 ± 35 Ma (all quoted uncertainties are 95% confidence intervals unless specified otherwise) interpreted to represent magmatic crystallisation of the igneous precursor to the orthogneiss, and a lower intercept date of 680 ± 110 Ma which is our best estimate of the age of the tectonothermal event responsible for post-crystallisation disturbance of the U-Pb system. Crust of known Mesoproterozoic age is rare in the southern Pinjarra Orogen: pre-1000 Ma igneous crystallisation ages in the Leeuwin Complex were previously known only from two c. 1090 Ma garnet-bearing orthogneisses at Redgate Beach (Nelson, 1999), 30 km west of Sue 1. All other dated outcrops have revealed Neoproterozoic (780-680 Ma) granitic protoliths reworked by Early Cambrian (540-520 Ma) magmatism, deformation and metamorphism (Nelson, 1996, 2002; Collins, 2003). In the northern Perth Basin, petroleum exploration well Beagle Ridge 10A was terminated at depth 1482 m, in crystalline basement rocks of the northern Pinjarra Orogen. A leucocratic orthogneiss sampled within the interval 1464.0-1467.0 m yielded only sparse zircon, but four of the seven grains analysed yielded a weighted mean 207Pb/206Pb date of 1092 ± 27 Ma, interpreted to represent magmatic crystallisation of the igneous precursor to the orthogneiss. Our data show no evidence for Neoproterozoic U-Pb resetting of the c. 1090 Ma zircons: where present, post-crystallisation isotopic disturbance is predominantly geologically recent. The two newly dated samples are located at opposite ends of the Perth Basin (about 470 km apart), and although the two magmatic crystallisation ages are imprecise, the date of 1092 ± 27 Ma from the Beagle Ridge 10A leucocratic orthogneiss is indistinguishable from the date of 1076 ± 35 Ma from the Sue 1 felsic orthogneiss. Furthermore, both rocks contain inherited zircon of Mesoproterozoic age (1620-1180 Ma in Sue 1; 1290-1210 Ma in Beagle Ridge 10A), indicating the presence of pre-1100 Ma crustal components in their parent magmas. This is consistent with a suite of Paleoproterozoic Sm-Nd model ages determined by Fletcher et al. (1985) on buried Pinjarra Orogen orthogneisses, which span 2.01 ± 0.06 Ga to 1.78 ± 0.04 Ga in the north (near BMR Beagle Ridge 10A), and including a model age of 1.80 ± 0.04 Ga from a sample of granitic gneiss obtained from Sue 1. Fletcher et al. (1985) argued that the consistency of 2.1-1.8 Ga Nd model ages obtained from crystalline basement in drillcore beneath the southern and northern Perth Basin, and from outcrop in the Northampton Complex and Mullingarra Complex of the northern Pinjarra Orogen, indicated a similar or shared crustal evolution. Our new U-Pb zircon data support this model, expanding the known extent of 1100-1050 Ma felsic magmatism in both the southern and northern Pinjarra Orogen, and indicating that Neoproterozoic tectonothermal overprinting appears to be restricted to the Leeuwin Complex, with no corresponding event discernible in the northern Pinjarra Orogen.

<div>The first ca. 2.2 billion years of Earth history saw significant change; from a water-world dominated by an anoxic atmosphere and tonalitic continents, to the exposed landmasses, oxygenated atmosphere, and granitic crust of the Paleoproterozoic. Precisely when, and how, these major changes occurred, remain some of the most important and controversial questions in modern geoscience. Here, we present an extensive new zircon U-Pb-Hf-O isotopic and trace element dataset from Earth’s largest preserved Archean continent, the Superior Craton, Canada. These data record a number of fundamental geochemical changes through time and indicate a major geological and geodynamic transition occurred toward the end of Archean, at ca. 2.7 Ga. Our data show that, at&nbsp;&gt;2704–2695&nbsp;Ma, the southern Superior Craton had juvenile εHf, light to mantle-like δ18O, low (Eu/Eu*)/Y (drier/shallower crust), reduced ΔFMQ, less continental initial-U (Ui)/Yb, and more mantle-like Ui/Nb. At ca. 2704–2695&nbsp;Ma, there is a marked transition in multiple datasets, including increases in δ18O, (Eu/Eu*)/Y, ΔFMQ, Ui/Yb and Ui/Nb data, together with more distinct arc-like trace element trends. These data reveal that at 2.7 Ga there was an increase in: (1) continental surface weathering, supported by increased sedimentation at &lt;2.68 Ga, (2) oxidized and hydrous magmatism, and (3) surface material in magma sources. Together, these observations suggest a major geodynamic transition from ‘vertical’ tectonics (sagduction, drips) to north-dipping subduction at 2.7 Ga. The increase in δ18O suggests that proximal continental crust, probably in the northern Superior Craton, became emergent at this time, an inference supported by detrital zircon geochronology. Hence, this dataset links major geodynamic change to the emergence of continental crust and the rise of more oxidized magmatism. These fundamental changes to the Earth’s surface environment, tectonics, and atmosphere at 2.7 Ga, provide evidence for an Earth systems turning-point at the end of the Neoarchean.</div> This Abstract was submitted/presented to the 2022 Specialist Group in Geochemistry, Mineralogy and Petrology (SGGMP) Conference 7-11 November (https://gsasggmp.wixsite.com/home/biennial-conference-2021)

<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>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>

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/)