The middle to lower Jurassic sequence in Australia's Surat Basin has been identified as a potential reservoir system for geological CO2 storage. The sequence comprises three major formations with distinctly different mineral compositions, and generally low salinity formation water (TDS<3000 mg/L). Differing geochemical responses between the formations are expected during geological CO2 storage. However, given the prevailing use of saline reservoirs in CCS projects elsewhere, limited data are available on CO2-water-rock dynamics during CO2 storage in such low-salinity formations. Here, a combined batch experiment and numerical modelling approach is used to characterise reaction pathways and to identify geochemical tracers of CO2 migration in the low-salinity Jurassic sandstone units. Reservoir system mineralogy was characterized for 66 core samples from stratigraphic well GSQ Chinchilla 4, and six representative samples were reacted with synthetic formation water and high-purity CO2 for up to 27 days at a range of pressures. Low formation water salinity, temperature, and mineralization yield high solubility trapping capacity (1.18 mol/L at 45°C, 100 bar), while the paucity of divalent cations in groundwater and the silicate reservoir matrix results in very low mineral trapping capacity under storage conditions. Formation water alkalinity buffers pH at elevated CO2 pressures and exerts control on mineral dissolution rates. Non-radiogenic, regional groundwater-like 87Sr/86Sr values (0.7048-0.7066) indicate carbonate and authigenic clay dissolution as the primary reaction pathways regulating solution composition, with limited dissolution of the clastic matrix during the incubations. Several geochemical tracers are mobilised in concentrations greater than found in regional groundwater, most notably cobalt, concentrations of which are significantly elevated regardless of CO2 pressure or sample mineralogy.

A major purpose of the study, as it appears to me at this time, is to ascertain the presence of geochemical anomalies in the area of (copper) mineralization. Such anomalies, if established, may be correlated with the dispersion train phenomena and with the dispersion halo of the ore, in an area known as mineralization. A comparable study may be undertaken then, depending on the advice of the team, in an area of suspected but not known, mineralization. Further investigations, beyond the reconnaissance stage, may be projected, in consultation with the team, on completion of the orientation study. This report contains the author's tentative remarks on a proposed reconnaissance in South Australia. Objectives, background to the work, methods, and proposed operations are discussed.

This was the first study of its kind, by the Commonwealth team. The study included demonstrations of the dithizone tests for traces of some heavy metals in the field environment, of operational and sampling procedures, and geochemical reconnaissance. Several reconnaissance traverses were sampled and examined. Extractable forms of copper and, in a very presumptive manner, extractable forms of lead and zinc were sought in the test materials. In addition, tests for copper, lead and zinc were made in some ignited and fused specimens. The testing procedure and results are described in this report.

The International Geo-Sample Number (IGSN) provides a globally unique identifier for physical samples used to generate analytical data. This unique identifier provides the ability to link each physical sample to any analytical data undertaken on that sample, as well as to any publications derived from any data derived on the sample. IGSN is particularly important for geochemical and geochronological data, where numerous analytical techniques can be undertaken at multiple analytical facilities not only on the parent rock sample itself, but also on derived sample splits and mineral separates. Australia now has three agencies implementing IGSN: Geoscience Australia, CSIRO and Curtin University. All three have now combined into a single project, funded by the Australian Research Data Services program, to better coordinate the implementation of IGSN in Australia, in particular how these agencies allocate IGSN identifiers. The project will register samples from pilot applications in each agency including the CSIRO National Collection of Mineral Spectra database, the Geoscience Australia sample collection, and the Digital Mineral Library of the John De Laeter Centre for Isotope Research at Curtin University. These local agency catalogues will then be aggregated into an Australian portal, which will ultimately be expanded for all geoscience specimens. The development of this portal will also involve developing a common core metadata schema for the description of Australian geoscience specimens, as well as formulating agreed governance models for registering Australian samples. These developments aim to enable a common approach across Australian academic, research organisations and government agencies for the unique identification of geoscience specimens and any analytical data and/or publications derived from them. The emerging pattern of governance and technical collaboration established in Australia may also serve as a blueprint for similar collaborations internationally.

The Walloon Coal Measures (WCM) in the Clarence-Moreton and the Surat basins in Qld and northern NSW contain up to approximately 600 m of mudstone, siltstone, sandstone and coal. Wide-spread exploration for coal seam gas (CSG) within both basins has led to concerns that the depressurisation associated with the resource development may impact on water resources in adjacent aquifers. In order to predict potential impacts, a detailed understanding of sedimentary basins hydrodynamics that integrates geology, hydrochemistry and environmental tracers is important. In this study, we show how different hydrochemical parameters and isotopic tracers (i.e. major ion chemistry, dissolved gas concentrations, 13C-DIC, 18O, 87Sr/86Sr, 3H, 14C, 2H and 13C of CH4) can help to improve the knowledge on groundwater recharge and flow patterns within the coal-bearing strata and their connectivity with over- or underlying formations. Dissolved methane concentrations in groundwaters of the WCM in the Clarence-Moreton Basin range from below the reporting limit (10 µg/L) to approximately 50 mg/L, and samples collected from nested bore sites show that there is also a high degree of vertical variability. Other parameters such as groundwater age measurements collected along distinct flow paths are also highly variable. In contrast, 87Sr/86Sr isotope ratios of WCM groundwaters are very uniform and distinct from groundwaters contained in other sedimentary bedrock units, suggesting that 87Sr/86Sr ratios may be a suitable tracer to study hydraulic connectivity of the Walloon Coal Measures with over- or underlying aquifers, although more studies on the systematic are required. Overall, the complexity of recharge processes, aquifer connectivity and within-formation variability confirms that a single tracer that cannot provide all information necessary to understand aquifer connectivity in these sedimentary basins, but that a multi-tracer approach is required.

Several belts of poorly-exposed igneous rocks occur in the Grampians-Stavely Zone of western Victoria, close to the interpreted Cambrian east Gondwana continental margin. Previous geochemical studies on the outcropping igneous rocks around Mount Stavely, Mount Dryden and in the Black Range have recognised characteristics similar to those found in modern magmatic arcs. These rocks are collectively considered to form part of a single Middle to Late Cambrian arc system, referred to as the Stavely Arc. While outcropping examples of the Stavely Arc magmas are well studied, the character of other (likely) arc-related rocks imaged by magnetic data beneath recent, thin cover has remained enigmatic. New geochemical data from a recent stratigraphic drilling program, together with analysis of rocks from government and industry drill holes has allowed for a more complete understanding of the Stavely Arc package. A range of rock associations have been recognised, including low-Ti boninite-like rocks, back-arc-related tholeiitic rocks, adakitic porphyry intrusives, serpentinites, and highly-depleted mafic to intermediate volcanics and intrusives. The majority of arc-related rocks comprise low- to high-K calc-alkaline basalt, andesite, dacite, and geochemically-related quartz diorite, which display similar N-MORB-normalised trace element patterns, LREE-enriched REE patterns and moderately evolved to weakly juvenile Nd isotopic compositions (Nd 500 Ma = -3.95 to +0.46). High-Al basalts intersected during stratigraphic drilling also show weakly-developed calc-alkaline compositions. However, these are distinguished from the other calc-alkaline rocks by higher Al2O3, N-MORB-like trace element patterns, relatively flat REE patterns and much more juvenile Nd isotopic compositions (Nd 500 Ma = +4.73 to +6.33). High-Al basalts are spatially associated with boninites intersected by mineral exploration drilling. The earliest geochronological evidence for Stavely Arc magmatism is provided by an isotopically juvenile felsic intrusive with an interpreted arc-related origin dated at ~510 Ma. This age is synchronous with tholeiitic dolerite from the western Grampians-Stavely Zone interpreted to have been emplaced in a back-arc extensional setting. Available ages for volcanic rocks of the Stavely Arc are only known from the Mount Stavely Belt, and show that arc magmatism reached maturity around ~505-500 Ma. Overall geochemical systematics suggest that the majority of calc-alkaline rocks of the Stavely Arc have affinities with modern island arcs with (limited) continental crust involvement. It is unlikely that the thickness of any pre-existing Precambrian crust was great, given the Nd isotopic compositions and lack of inherited Mesoproterozoic or older zircons. In comparison, the more juvenile isotopic characteristics, weakly-developed subduction-related features, and spatial association with boninites of the high-Al basalts are more consistent with a more primitive arc setting, and may represent an (early?) phase of Stavely Arc magmatism in which there was insignificant crustal involvement. Similar geochemical characteristics, ages, and inferred tectonic setting are consistent with the Stavely Arc forming part of a larger Middle to Late Cambrian arc system that also includes the Mount Wright Arc in New South Wales and the Jamison Volcanic Group (Selwyn Block) in central Victoria.

Top outlet sediments from the National Geochemical Survey of Australia (NGSA) have been extracted with Mobile Metal Ion (MMIR) solution and analyzed for over 50 elements including gold (Au). The MMIR Au results from this low density survey show discrete coherent anomalies for Au in the vicinity of many of Australia's known gold deposits, and in the vicinity of some minor gold occurrences. In several instances catchment outlet anomalies for Au have been recorded from areas not known to contain significant economic gold. Several large economic gold deposits are shown to not produce anomalies in catchment outlet samples. A survey of overbank samples in the Swan Avon Catchment of Western Australia at double the sampling density shows that low level anomalies (MMIR Au>1ppb) can be traced back to source using overbank sediments. Follow-up of one of the NGSA Au anomalies at Kent River in previously regarded non-auriferous terrain (western Albany-Fraser Belt) indicates a non-economic but perhaps geochemically significant Au anomaly with associated pathfinders including palladium. This may indicate that further exploration of the western part of Albany Fraser Belt for Au is warranted. The combination of catchment overbank samples and high-resolution MMIR technique has been shown to be effective at locating the source of gold anomalies from initial low-density continental and regional surveys.

A benthic sediment sampling survey (GA0356) to the nearshore areas of outer Darwin Harbour was undertaken in the period from 03 July to 14 September 2016. Partners involved in the survey included Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Department of Environment and Natural Resources within the Northern Territory Government (NT DENR) (formerly the Department of Land and Resource Management (DLRM)). This survey forms part of a four year (2014-2018) science program aimed at improving knowledge about the marine environments in the regions around Darwin and Bynoe Harbour’s through the collection and collation of baseline data that will enable the creation of thematic habitat maps to underpin marine resource management decisions. This project is being led by the Northern Territory Government and is supported by the INPEX-led Ichthys LNG Project, in collaboration with - and co-investment from GA and AIMS. The program builds upon an NT Government project (2011-2011) which saw the collection of baseline data (multibeam echosounder data, sediment samples and video transects) from inner Darwin Harbour. This dataset comprises total oxygen uptake and total carbon dioxide flux measurements from core incubation experiments on seabed sediments. Radke, L., Smit, N., Li, J., Nicholas, T., Picard, K. 2017. Outer Darwin Harbour Shallow Water Sediment Survey 2016: GA0356 – Post-survey report. Record 2017/06. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2017.006 This research was funded by the INPEX-led Ichthys LNG Project via the Northern Territory (NT) Government Department of Land Resource Management (DLRM) (now the Department of Environment and Natural Resources (DENR)), and co-investment from Geoscience Australia (GA) and Australian Institute of Marine Science (AIMS). We are grateful to the following agencies for providing boats and staff, and to the following personal for help with sample acquisition: NT DENR (Danny Low Choy and Rachel Groome), NT Fisheries (Wayne Baldwin, Quentin Allsop, Shane Penny, Chris Errily, Sean Fitzpatrick and Mark Grubert), NT Parks and Wildlife (Ray Chatto, Stewart Weorle, and Luke McLaren) and the Larrakia Rangers (Nelson Tinoco, Kyle Lewfat, Alan Mummery and Steven Dawson). Special thanks to the skippers Danny Low Choy, Wayne Baldwin, Stewart Weorle and Luke McLaren whose seamanship strongly guided the execution of this survey. AIMS generously allowed use of the aquarium and laboratory at the Arafura Timor Sea Research Facility, and Simon Harries and Kirsty McAllister helped with the setup. We would also like to acknowledge and thank GA colleagues including: Matt Carey, Ian Atkinson and Craig Wintle (Engineering and Applied Scientific Services) for the organisation of field supplies and the design of the new core incubation set-up. This dataset is published with the permission of the CEO, Geoscience Australia

Brumbys 1 was an appraisal well drilled and cored through Brumbys Fault at the CO2CRC Otway International Test Centre in 2018. The Otway Project is located in South West Victoria, on private farming property approximately 35 km southeast of Warrnambool and approximately 10 km northwest of the town of Peterborough. Total measured depth was 126.6 m (80 degrees). Sonic drilling enabled excellent core recovery and the borehole was completed as a groundwater monitoring well. Brumbys 1 cores through the upper Hesse Clay, Port Campbell Limestone and extends into the Gellibrand Marl. This dataset compiles the extensive analysis undertaken on the core. Analysis includes: Core log; Foram Analysis; Paleodepth; % Carbonate (CaCO3); X-Ray Fluorescence Spectrometry (XRF); Inductively Coupled Plasma Mass Spectrometry (ICP-MS); X-Ray Diffraction (XRD); Grain Size; Density; Surface Area Analysis (SAA); Gamma. Samples were taken at approximately 1-2 m intervals.

This service provides access to inorganic geochemistry data obtained from chemical analyses of rock and regolith samples collected during mapping and sampling programs in Australia. This service will provide a spatial distribution of the sample attributes as well as provide a spatial distribution of the analytical composition of the samples with respect to major elements, minor elements and rare earth elements. This service includes original inorganic geochemistry data levelled to reference datasets.