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.

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.

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.

This Record presents new zircon U-Pb geochronological data, obtained using a Sensitive High Resolution Ion MicroProbe (SHRIMP), and thin section descriptions for nine samples of plutonic and volcanic rocks of 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 2010/11 and 2011/12.

<p>The Mesoproterozoic Roper Group of the McArthur Basin has excellent petroleum potential, but its poorly constrained post-depositional history has hampered resource exploration and management. The Derim Derim Dolerite occupies an important position in the regional event chronology, having intruded the Roper Group prior to deformation associated with the ‘Post-Roper Inversion’ event. It was assigned a magmatic crystallisation age of 1324 ± 4 Ma (uncertainties are 95% confidence unless otherwise indicated) in 1997, based on unpublished Sensitive High Resolution Ion Micro Probe (SHRIMP) U-Pb analyses of dolerite-hosted baddeleyite from sample 97106010, collected from the Derim Derim Dolerite type locality in outcrop within the northwestern McArthur Basin. Herein, we refine these data via Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) analysis of baddeleyites plucked from the SHRIMP grain-mounts, which yielded a precise mean 207Pb/206Pb date of 1327.5 ± 0.6 Ma. This date is significantly older than a baddeleyite U-Pb ID-TIMS date of 1313.8 ± 1.3 Ma recently obtained from dolerite ALT-05, sampled in Pacific Oil and Gas Ltd drillhole Altree 2, near the northern margin of the Beetaloo Sub-basin, and 200 km south of 97106010. This pair of results indicates that Derim Derim Dolerite magmatism spanned at least 10-15 Ma. Previously documented geochemical variation in Mesoproterozoic mafic rocks across the Northern Territory (such as the 1325 ± 36 Ma (2σ) Galiwinku Dolerite in the northern McArthur Basin, 1316 ± 40 Ma phonolites intruding the eastern Pine Creek Orogen, and 1295 ± 14 Ma gabbro in the Tomkinson Province) may reflect episodic pulses of magmatism hitherto obscured by the low precision of the available isotopic dates. <p><b>Citation:</b> Bodorkos, S., Yang, B., Collins, A.S., Crowley, J., Denyszyn, S.W., Claoue-Long, J.C., Anderson, J.R. and Magee, C., 2020 Precise U–Pb baddeleyite dating of the Derim Derim Dolerite: evidence for episodic mafic magmatism in the greater McArthur Basin. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

This Record presents new Sensitive High Resolution Ion MicroProbe (SHRIMP) U–Pb zircon results 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. This Record presents results from six newly analysed samples, in support of ongoing regional mapping and geoscientific programs led by GSQ in the Georgetown, Coen and Cairns regions. Three magmatic samples were analysed from unnamed rhyolite dykes within the Georgetown region (Gilberton 1:250 000 sheet SE5416), two samples (one magmatic and one metasedimentary) from the Coen region(Coen SD5408), and one metasedimentary sample from the Cairns region (Innisfail SE5506). A summary of each sample is presented, each containing information on sample location and geological content, geochronology results, as well as a brief geochronological interpretation. <b>Bibliographic Reference:</b> Christopher J. Lewis, Courteney R. Dhnaram, Dominic D. Brown, Robert J. Bultitude, Vladimir A. Lisitsin. Summary of Results. Joint GSQ–GA Geochronology Project: Georgetown, Coen and Cairns regions, 2016–2017. <i>Queensland Geological Record</i><b> 2021/05</b>.

The EARTHTIME initiative has enabled improvements in high-precision ID-TIMS U-Pb geochronology, demonstrating SI-traceable calibrations with rigorous uncertainty estimation. In a similar fashion, the LA-ICP-MS U-Pb community have reassessed their uncertainty estimation and workflow to try to harmonise better practice in quantification and interpretation across the community. The SHRIMP community has a current imperative to rewrite its data handling software providing an opportunity to review ion-microprobe U-Pb workflow and uncertainty estimation methods. This work will provide the perfect platform to integrate SHRIMP U-Pb dating practices with more recent data handling approaches to ensure harmony and comparability of output between SHRIMP, LA-ICP-MS and ID-TIMS methods. SHRIMP and LA-ICP-MS data acquisition and processing appear to be very similar. Both methods are relative techniques, requiring calibration to matrix-matched primary reference materials analysed under the same conditions at the same time. Measurement uncertainties are similar, calibration requirements are similar and potential system drift has similar effects and impact on data and concomitant uncertainty estimation. For these and other reasons, we are interrogating SHRIMP and recently published LA-ICP-MS U-Pb data handling workflows to compare approaches, learn mutual lessons, and understand the uncertainty propagation requirements of each method such that a complete understanding of the comparability of U-Pb data obtained by the two methods can be ascertained. We will highlight results to date in describing the SHRIMP and LA-ICP-MS U-Pb data handling workflows in tandem allowing data comparison between the two methods to be properly quantified thereby enabling direct quantification and comparison with ID-TIMS reported ages. In this way, U-Pb geochronology will be a more rigorously applied tool from the highest spatial resolution to highest precision, expanding and building on the EARTHTIME initiative to date. This abstract was submitted to/presented at the 2017 Goldschmidt Conference (https://goldschmidt.info/2017/)

Xenotime (YPO4) occurs in a wide range of geological environments, but its potential to establish the timing of mineralisation and sediment diagenesis has been the focus of most recent studies. Xenotime in these settings usually has a low uranium content (typically < 1000 ppm) and occurs as microscopic crystals (< 20 μm diameter), either individually or as outgrowths on a zircon substrate. Large radius ion microprobes, such as the SHRIMP or Cameca 1270/1280, that have high sensitivity and spatial resolution, are well suited for the U–Pb–Th analysis of xenotime from such environments. SIMS U–Pb–Th analyses of xenotime, however, are prone to significant U–Pb–Th matrix effects (ME) that are related to the wide natural range of U (0–6 wt%) and rare earth element (REE) (ΣREE: 12–22 wt%) concentrations in this mineral. For SHRIMP U–Pb–Th xenotime analyses, a 1 wt% increase in U concentration, relative to the U–Pb–Th calibration reference material (RM), will on average cause a corresponding increase in the measured 206Pb/238U and 208Pb/232Th of approximately 15% and 14% respectively. Similarly, a 1 wt% contrast in ΣREE causes an increase of about 1.2% in 206Pb/238U and about 1.7% in 208Pb/232Th. Correction for these chemically-induced matrix effects requires the concurrent analysis of three xenotime reference materials (RMs) which have known ages and a range of U and ΣREE contents that have been determined accurately by electron probe microanalysis (EPMA). A least squares methodology is used to derive correction coefficients that relate the SHRIMP U–Pb–Th ME to the U and ΣREE concentrations for the RMs. Crucial to the success of this technique is the use of one dimensional (1-D) calibrations using 206Pb+/270[UO2]+ and 208Pb+/248[ThO]+. Processing is carried out in two steps: the first derives the correction coefficients to matrix correct the 206Pb+/270[UO2]+ and 208Pb+/248[ThO]+ ratios, the second processes the matrix corrected ratios to determine 206Pb/238U and 208Pb/232Th. <b>Citation:</b> A.J. Cross, I.S. Williams, SHRIMP U–Pb–Th xenotime (YPO4) geochronology: A novel approach for the correction of SIMS matrix effects, <i>Chemical Geology</i>, Volume 484, 2018, Pages 81-108, ISSN 0009-2541, https://doi.org/10.1016/j.chemgeo.2017.12.017.

This web service provides access to the Geoscience Australia (GA) ISOTOPE database containing compiled age and isotopic data from a range of published and unpublished (GA and non-GA) sources. The web service includes point layers (WFS, WMS, WMTS) with age and isotopic attribute information from the ISOTOPE database, and raster layers (WMS, WMTS, WCS) comprising the Isotopic Atlas grids which are interpolations of the point located age and isotope data in the ISOTOPE database.

This Record presents data collected in September 2019 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 (EFTF) Program. Two new U–Pb SHRIMP zircon geochronological results derived from two samples of the Balbirini Dolostone (southern McArthur Basin, Northern Territory) are presented herein. The Balbirini Dolostone is part of the early Mesoproterozoic Nathan Group, and is a thick unit of interbedded dolostone and dolomitic siliciclastic rocks that include evaporitic redbeds. The two samples were collected in June 2019 from the type section of the Balbirini Dolostone in southern BAUHINIA DOWNS (MALLAPUNYAH). <b>Bibliographic Reference:</b> Kositcin N, and Munson TJ, 2020. Summary of results. Joint NTGS–GA geochronology project: Balbirini Dolostone, southern McArthur Basin, June 2019–September 2019. <i>Northern Territory Geological Survey</i>, <b>Record 2020-002</b>.