This Record contains new zircon and monazite U-Pb geochronological data obtained via Sensitive High-Resolution Ion Micro Probe (SHRIMP) from nine samples of volcanic, volcaniclastic and plutonic igneous rocks of the central Lachlan Orogen and the New England Orogen, New South Wales. These data were obtained during the reporting period July 2014-June 2015, under the auspices of the collaborative Geochronology Project between the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA), which is part of the National Collaboration Framework (NCF).

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).

A regional hydrocarbon prospectivity study was undertaken in the onshore Canning Basin in Western Australia as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to driving investment in resource exploration. As part of this program, significant work has been carried out to deliver new pre-competitive data including new seismic acquisition, drilling of a stratigraphic well, and the geochemical analysis of geological samples recovered from exploration wells. A regional, 872 km long 2D seismic line (18GA-KB1) acquired in 2018 by Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), images the Kidson Sub-basin of the Canning Basin. In order to provide a test of geological interpretations made from the Kidson seismic survey, a deep stratigraphic well, Barnicarndy 1, was drilled in 2019 in a partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the Barnicarndy Graben, 67 km west of Telfer, in the southwest Canning Basin. Drilling recovered about 2100 m of continuous core from 580 mRT to the driller’s total depth (TD) of 2680.53 mRT. An extensive analytical program was carried out to characterise the lithology, age and depositional environment of these sediments. This data release presents organic geochemical analyses undertaken on rock extracts obtained from cores selected from the Barnicarndy 1 well. The molecular and stable isotope data carbon and hydrogen will be used to understand the type of organic matter being preserved, the depositional facies and thermal maturity of the Lower Ordovician sedimentary rocks penetrated in this well. This information provides complementary information to other datasets including organic petrological and palynological studies.

Australia has been, and continues to be, a leader in isotope geochronology and geochemistry. While new isotopic data is being produced with ever increasing pace and diversity, there is also a rich legacy of existing high-quality age and isotopic data, most of which have been dispersed across a multitude of journal papers, reports and theses. Where compilations of isotopic data exist, they tend to have been undertaken at variable geographic scale, with variable purpose, format, styles, levels of detail and completeness. Consequently, it has been difficult to visualise or interrogate the collective value of age and isotopic data at continental-scale. Age and isotopic patterns at continental scale can provide intriguing insights into the temporal and chemical evolution of the continent (Fraser et al, 2020). As national custodian of geoscience data, Geoscience Australia has addressed this challenge by developing an Isotopic Atlas of Australia, which currently (as of November 2020) consists of national-scale coverages of four widely-used age and isotopic data-types: 4008 U-Pb mineral ages from magmatic, metamorphic and sedimentary rocks 2651 Sm-Nd whole-rock analyses, primarily of granites and felsic volcanics 5696 Lu-Hf (136 samples) and 553 O-isotope (24 samples) analyses of zircon 1522 Pb-Pb analyses of ores and ore-related minerals These isotopic coverages are now freely available as web-services for use and download from the GA Portal. While there is more legacy data to be added, and a never-ending stream of new data constantly emerging, the provision of these national coverages with consistent classification and attribution provides a range of benefits: vastly reduces duplication of effort in compiling bespoke datasets for specific regions or use-cases data density is sufficient to reveal meaningful temporal and spatial patterns a guide to the existence and source of data in areas of interest, and of major data gaps to be addressed in future work facilitates production of thematic maps from subsets of data. For example, a magmatic age map, or K-Ar mica cooling age map sample metadata such as lithology and stratigraphic unit is associated with each isotopic result, allowing for further filtering, subsetting and interpretation. The Isotopic Atlas of Australia will continue to develop via the addition of both new and legacy data to existing coverages, and by the addition of new data coverages from a wider range of isotopic systems and a wider range of geological sample media (e.g. soil, regolith and groundwater).

<div>Scientific studies undertaken on core from the Barnicarndy 1 well drilled in 2019 in the onshore Canning Basin in Western Australia as part of the Exploring for the Future program have shown that the well penetrated a thick section of the early Ordovician Nambeet Formation which contains abundant fossils reflective of deposition in an open marine environment. Although the calcareous shales are organically poor (average total organic carbon content 0.17 wt%) processing of 42 drill core samples recovered a plethora of acid-resistant, organic-walled microfossils. Seven core samples with the highest organic content were analysed for their molecular (biomarker) fossils and stable isotopic composition to provide insights into the type of organic matter preserved, and the redox conditions of the sediments during deposition.</div><div><br></div>This Abstract was submitted/presented to the 2022 Australian Organic Geochemistry Conference 27-29 November (https://events.csiro.au/Events/2022/October/5/Australian-Organic-Geochemistry-Conference)

Plutonium (Pu) interactions in the environment are highly complex. Site-specific variables play an integral role in determining the chemical and physical form of Pu, and its migration, bioavailability, and immobility. This paper aims to identify the key variables that can be used to highlight regions of radioecological sensitivity and guide remediation strategies in Australia. Plutonium is present in the Australian environment as a result of global fallout and the British nuclear testing program of 1952 – 1958 in central and west Australia (Maralinga and Monte Bello islands). We report the first systematic measurements of 239+240Pu and 238Pu activity concentrations in distal (≥1,000 km from test sites) catchment outlet sediments from Queensland, Australia. The average 239+240Pu activity concentration was 0.29 mBq.g -1 (n = 73 samples) with a maximum of 4.88 mBq.g -1. 238Pu/239+240Pu isotope ratios identified a large range (0.02 – 0.29 (RSD: 74%)) which is congruent with the heterogeneous nuclear material used for the British nuclear testing programme at Maralinga and Montebello Islands. The use of a modified PCA relying on non-linear distance correlation (dCorr) provided broader insight into the impact of environmental variables on the transport and migration of Pu in this soil system. Primary key environmental indicators of Pu presence were determined to be actinide/lanthanide/heavier transition metals, elevation, electrical conductivity (EC), CaO, SiO2, SO3, landform, geomorphology, land use, and climate explaining 81.7% of the variance of the system. Overall this highlighted that trace level Pu accumulations are associated with the coarse, refractive components of Australian soils, and are more likely regulated by the climate of the region and overall soil type. <b>Citation:</b> Megan Cook, Patrice de Caritat, Ross Kleinschmidt, Joёl Brugger, Vanessa NL. Wong, Future migration: Key environmental indicators of Pu accumulation in terrestrial sediments of Queensland, Australia,<i> Journal of Environmental Radioactivity</i>, Volumes 223–224, 2020, 106398,ISSN 0265-931X, https://doi.org/10.1016/j.jenvrad.2020.106398

The National Geochemical Survey of Australia (NGSA) is Australia’s first national-scale geochemical survey. It was delivered to the public on 30 June 2011, after almost five years of stakeholder engagement, strategic planning, sample collection, preparation and analysis, quality assurance/quality control, and preliminary data analytics. The project was comprehensively documented in seven initial open-file reports and six data and map sets, followed over the next decade by more than 70 well-cited scientific publications. This review compiles the body of work and knowledge that emanated from the project to-date as an indication of the impact the NGSA had over the decade 2011-2021. The geochemical fabric of Australia as never seen before has been revealed by the NGSA. This has spurred further research and stimulated the mineral exploration industry. This paper also critically looks at operational decisions taken at project time (2007-2011) that were good and perhaps – with the benefit of hindsight – not so good, with the intention of providing experiential advice for any future large-scale geochemical survey of Australia or elsewhere. Strengths of the NGSA included stakeholder engagement, holistic approach to a national survey, involvement of other geoscience agencies, collaboration on quality assurance with international partners, and targeted promotion of results. Weaknesses included gaining successful access to all parts of the nation, and management of sample processing in laboratories. <b>Citation:</b> Patrice de Caritat; The National Geochemical Survey of Australia: review and impact. <i>Geochemistry: Exploration, Environment, Analysis </i>2022;; 22 (4): geochem2022–032. doi: https://doi.org/10.1144/geochem2022-032 This article appears in multiple journals (Lyell Collection & GeoScienceWorld)

This study assesses the effect of chemical abrasion on in-situ mass spectrometric isotopic and elemental analyses in zircon. Chemical abrasion improves the U-Pb systematics of SIMS (Secondary Ion Mass Spectrometry) analyses of reference zircons, while leaving other isotopic systems largely unchanged. SIMS ²⁰⁶Pb/²³⁸U ages of chemically abraded reference materials TEMORA-2, 91500, QGNG, and OG1 are precise to within 0.25 to 0.4%, and are within uncertainty of chemically abraded TIMS reference ages, while SIMS ²⁰⁶Pb/²³⁸U ages of untreated zircons are within uncertainty of TIMS reference ages where chemical abrasion was not used. Chemically abraded and untreated zircons appear to cross-calibrate within uncertainty using all but one possible permutations of reference materials, provided that the corresponding chemically abraded or untreated reference age is used for the appropriate material. In the case of reference zircons QGNG and OG1, which are slightly discordant, the SIMS U-Pb ages of chemically abraded and untreated material differ beyond their respective 95% confidence intervals. SIMS U-Pb analysis of chemically abraded zircon with multiple growth stages are more difficult to interpret. Treated igneous rims on zircon crystals from the S-type Mount Painter Volcanics are much lower in common Pb than the rims on untreated zircon grains. However, the analyses of chemically abraded material show excess scatter. Chemical abrasion also changes the relative abundance of the ages of zircon cores inherited from the sedimentary protolith, presumably due to some populations being more likely to survive the chemical abrasion process than others. We consider these results from inherited S-type zircon cores to be indicative of results for detrital zircon grains from unmelted sediments. Trace element, &delta;¹⁸O, and εHf analyses were also performed on these zircons. None of these systems showed substantial changes as a result of chemical abrasion. The most discordant reference material, OG1, showed a loss of OH as a result of chemical abrasion, presumably due to dissolution of hydrous metamict domains, or thermal dehydration during the annealing step of chemical abrasion. In no case did zircon gain fluorine due to exchange of lattice-bound substituted OH or other anions with fluorine during the HF partial dissolution phase of the chemical abrasion process. As the OG1, QGNG, and TEMORA-2 zircon samples are known to be compositionally inhomogenous in trace element composition, spot-to-spot differences dominated the trace element results. Even the 91500 megacrystic zircon pieces exhibited substantial chip-to-chip variation. The LREE in chemically abraded OG1 and TEMORA-2 were lower than in the untreated samples. Ti concentration and phosphorus saturation ((Y+REE)/P) were generally unchanged in all samples. <b>Citation:</b> Kooymans, C., Magee Jr., C. W., Waltenberg, K., Evans, N. J., Bodorkos, S., Amelin, Y., Kamo, S. L., and Ireland, T.: Effect of chemical abrasion of zircon on SIMS U–Pb, &delta;¹⁸O, trace element, and LA-ICPMS trace element and Lu–Hf isotopic analyses, Geochronology, 6, 337–363, https://doi.org/10.5194/gchron-6-337-2024, 2024.

<div>Lead isotopic data implies that Th and U were fractionated from one another in Earth's early history, however, the origin of this fractionation is poorly understood. We report new <em>in-situ</em> Pb isotope data from orthoclase in 144 granites, sampled across the Archean Yilgarn Craton to characterize its Pb isotope variability and evolution. Granite Pb isotope compositions reveal three Pb sources, a mantle derived Pb reservoir and two crustal Pb reservoirs, distinguished by their implied source 232Th/238U (κPb). High-κPb granites reflect sources with high 232Th/238U (~4.7) and are largely co-located with Eoarchean–Paleoarchean crust. The Pb isotope compositions of most granites, and those of VHMS and gold ores, define a mixing array between a mantle Pb source and a Th-rich Eoarchean-Paleoarchean source. Pb isotope modelling indicates that the high-κPb source rocks experienced Th/U fractionation at ~3.3 Ga. As Th/U fractionation in the Yilgarn Craton must have occurred before Earth’s atmosphere was oxygenated, subaerial weathering cannot explain the apparent differences in their geochemical behavior. Instead, the high Th/U source reflects Eoarchean–Paleoarchean rocks that experienced prior high-temperature metamorphism, partial melting, and melt loss in the presence of a Th-sequestering mineral like monazite. Archean Pb isotope variability thus has its origins in open-system high-temperature metamorphic processes responsible for the differentiation and stabilization of Earth’s continental crust.</div> <b>Citation:</b> M.I.H. Hartnady, C.L. Kirkand, S.P. Johnson, R.H. Smithies, L.S. Doucet, D.R. Mole; <i>Origin of Archean Pb isotope variability through open-system Paleoarchean crustal anatexis</i>. Geology 2023; doi: https://doi.org/10.1130/G51507.1

<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)