<div>Although heavy mineral exploration techniques have been successfully used as exploration vectors to ore deposits around the world, exploration case studies and pre-competitive datasets relevant to Australian conditions are relatively limited. The Heavy Mineral Map of Australia (HMMA) project is a novel analytical campaign to determine the abundance and distribution of heavy minerals (SG>2.9 g/cc) in 1315 floodplain sediment samples collected from catchments across Australia during Geoscience Australia’s National Geochemical Survey of Australia (NGSA) project. Archived NGSA samples, which originated from, on average, 60 to 80 cm depth in floodplain landforms, were sub-sampled and subjected to dense media separation and automated SEM-EDS analysis in the John de Laeter Centre at Curtin University. Mineral assay data from all 1315 drainage samples will be publicly released by the end of 2023. </div><div><br></div><div>An initial data package released in August 2022 contains mineralogical assay data for 223 samples from the Darling–Curnamona–Delamerian (DCD) region of south-eastern Australia. That package identified over 140 heavy minerals from 29 million individual mineral observations. The number of mineral observations generated during the project required development of a novel Mineral Network Analysis (MNA) tool to allow end users to discover, visualise and interpret mineral co-occurrence relationships, potentially useful in exploration vectoring and targeting. The MNA tool can also be used to rapidly search the heavy mineral database to locate observations of potential economic significance. The co-occurrence of Zn-minerals indicative of high-grade metamorphism of base metal mineralisation (e.g., gahnite (Zn-spinel), ecandrewsite (Zn-ilmenite) and zincostaurolite (Zn-aluminosilicate)) from the region surrounding Broken Hill demonstrated the utility of the method. Zn-mineral co-occurrences not associated with known mineralisation were also noted and may represent targeting opportunities. </div><div><br></div><div>Heavy mineral data from parts of Queensland are scheduled for a separate public release in December 2022 and will be presented at the conference.&nbsp;</div> This Abstract was submitted/presented to the 2023 Australian Exploration Geoscience Conference 13-18 Mar (https://2023.aegc.com.au/)

Petroleum geochemical datasets and information are essential to government for evidence-based decision making on natural resources, and to the petroleum industry for de-risking exploration. Geoscience Australia’s newly built Data Discovery Portal (https://portal.ga.gov.au/) enables digital discoverability and accessibility to key petroleum geochemical datasets. The portal’s web map services and web feature services allow download and visualisation of geochemical data for source rocks and petroleum fluids, and deliver a petroleum systems framework for northern Australian basins. The Petroleum Source Rock Analytics Tool enables interrogation of source rock data within boreholes and field sites, and facilitates correlation of these elements of the petroleum system within and between basins. The Petroleum Systems Summary Assessment Tool assists the user to search and query components of the petroleum system(s) identified within a basin. The portal functionality includes customised data searches, and visualisation of data via interactive maps, graphs and geoscientific tools. Integration of the petroleum systems framework with the supporting geochemical data enables the Data Discovery Portal to unlock the value of these datasets by affording the user a one-stop access to interrogate the data. This allows greater efficiency and performance in evaluating the petroleum prospectivity of Australia’s sedimentary basins, facilitating and accelerating decision making around exploration investment to ensure Australia’s future resource wealth <b>Citation:</b> Edwards, D.S., MacFarlane, S.K., Grosjean, E., Buckler, T., Boreham, C.J., Henson, P., Cherukoori, R., Tracey-Patte, T., van der Wielen, S., Ray, J. and Raymond, O., 2020. Developing thermochemical models of Australia’s lithosphere. 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.

The Paleo- to Mesoproterozoic McArthur Basin and Mount Isa region of northern Australia (Figure 1) is richly-endowed with a range of deposit types (e.g., Ahmad et al., 2013; Geological Survey of Queensland, 2011). These include the basin-hosted base metal (Zn-Pb-Ag) deposits of the North Australian Zinc Belt, the richest zinc province in the world (Geological Survey of Queensland, 2011; Huston et al., 2006), as well as Cu (e.g., Mt Isa Copper) and IOCG (e.g., Ernest Henry) deposits (Geological Survey of Queensland, 2011). The giant size of the base metal deposits makes them attractive exploration targets and significant effort has been undertaken in understanding their genesis and setting and developing methodologies and data sets to aid in further discovery. As part of its Exploring for the Future program, Geoscience Australia is acquiring new, and reprocessing old, data sets to provide industry with new exploration tools for these basin-hosted Zn-Pb and Cu deposits, as well as iron-oxide copper-gold deposits. We have adopted a mineral systems approach (e.g., Huston et al., 2016) focussing on regional aspects such as source rocks, locations of mineral deposits, mineralisation haloes and footprints. Increased understanding of these aspects requires knowledge of the background variability of unaltered rocks within the basin. To assist in this we have undertaken a campaign of baseline geochemical studies, with over 800 new samples collected from sedimentary and igneous units of selected parts of the greater McArthur Basin–Mount Isa region. This has allowed us to document temporal and regional background geochemical (and mineralogical) variation within, and between sedimentary and igneous units. The main focus of this work was directed towards aspects of base metal mineralisation; a concurrent GA study (e.g., Jarrett et al., 2019) looking at aspects of hydrocarbon potential was undertaken in parallel. Appeared in Annual Geoscience Exploration Seminar (AGES) Proceedings, Alice Springs, Northern Territory 24-25 March 2020, p. 105

The annual offshore petroleum exploration acreage release is part of the government’s strategy to promote offshore oil and gas exploration. Each year, the government invites companies to bid for the opportunity to invest in oil and gas exploration in Australian waters. The 21 areas shown have been nominated by petroleum industry stakeholders to be considered for the 2021 acreage release. Areas nominated for release will not receive endorsement from government until submissions resulting from a public consultation process can be considered. This publication does not indicate a commitment to a particular course of action.

<div>A groundwater chemistry, regolith chemistry and metadata record for legacy geochemical studies over the southern Curnamona Province done by GA and partners as part of CRC LEME from 1999 to 2005, that was never fully released. This includes comprehensive groundwater chemistry from more than 250 bores in the Broken Hill region, containing physicochemical parameters, major and trace elements, and a suite of isotopes (34S, Pb, Sr, 18O, D). Recent work on this dataset (in 2021) has added hydrostratigraphic information for these groundwater samples. Also included is a regolith geochemistry dataset collected adjacent to some of the groundwater bores which tests the geochemical response of a range of different size fractions, depths and digests.</div>

A comprehensive compilation of rock, regolith and groundwater geochemistry across the Curnamona Province and overlying basins. This product is part of the Curnamona Geochemistry module of GA's Exploring for the Future program, which is seeking to understand geochemical baselines within the Curnamona Province to support mineral exploration under cover. Data is sourced from GA, CSIRO and state databases, and run through a quality control process to address common database issues (such as unit errors). The data has been separated by sample type and migrated into a standard data structure to make the data internally consistent. A central source for cleaned geochemical data in the same data format is a valuable resource for further research and exploration in the region.

<div>Strontium isotopes (87Sr/86Sr) are useful in the earth sciences (e.g. recognising geological provinces, studying geological processes) as well in archaeological (e.g. informing on past human migrations), palaeontological/ecological (e.g. investigating extinct and extant taxa’s dietary range and migrations) and forensic (e.g. validating the origin of drinks and foodstuffs) sciences. Recently, Geoscience Australia and the University of Wollongong have teamed up to determine 87Sr/86Sr ratios in fluvial sediments selected mostly from the low-density National Geochemical Survey of Australia (www.ga.gov.au/ngsa), with a few additional Northern Australia Geochemical Survey infill samples. The present study targeted the northern parts of Western Australia, the Northern Territory and Queensland in Australia, north of 21.5 °S. The samples were taken mostly from a depth of ~60-80 cm depth in floodplain deposits at or near the outlet of large catchments (drainage basins). A coarse grain-size fraction (&lt;2 mm) was air-dried, sieved, milled then digested (hydrofluoric acid + nitric acid followed by aqua regia) to release total strontium. Preliminary results demonstrate a wide range of strontium isotopic values (0.7048 &lt; 87Sr/86Sr &lt; 1.0330) over the survey area, reflecting a large diversity of source rock lithologies, geological processes and bedrock ages. Spatial distribution of 87Sr/86Sr shows coherent (multi-point anomalies and smooth gradients), large-scale (&gt;100 km) patterns that appears to be consistent, in many places, with surface geology, regolith/soil type and/or nearby outcropping bedrock. For instance, the extensive black clay soils of the Barkly Tableland define a &gt;500 km-long northwest-southeast-trending low anomaly (87Sr/86Sr &lt; 0.7182). Where carbonate or mafic igneous rocks dominate, a low to moderate strontium isotope signature is observed. In proximity to the outcropping Proterozoic metamorphic provinces of the Tennant, McArthur, Murphy and Mount Isa geological regions, conversely, high 87Sr/86Sr values (&gt; 0.7655) are observed. A potential link between mineralisation and elevated 87Sr/86Sr values in these regions needs to be investigated in greater detail. Our results to-date indicate that incorporating soil/regolith strontium isotopes in regional, exploratory geoscience investigations can help identify basement rock types under (shallow) cover, constrain surface processes (e.g. weathering, dispersion), and, potentially, recognise components of mineral systems. Furthermore, the resulting strontium isoscape and model derived therefrom can also be utilised in archaeological, paleontological and ecological studies that aim to investigate past and modern animal (including humans) dietary habits and migrations. &nbsp;The new spatial dataset is publicly available through the Geoscience Australia portal https://portal.ga.gov.au/.</div>

The annual offshore petroleum exploration acreage release is part of the government’s strategy to promote offshore oil and gas exploration. Each year, the government invites companies to bid for the opportunity to invest in oil and gas exploration in Australian waters. The 2020 acreage release consists of 42 areas offshore of the Northern Territory, Western Australia, Victoria and the Ashmore and Cartier Islands.

The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Offshore Energy Studies section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and facilitate exploration investment in Australia. The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018), Dorado 1 (2018), Dorado 2 (2019) and Dorado 3 (2019) wells in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata (Thompson, 2020; Thompson et al., 2015 and 2018). The current study aims to better understand this new petroleum system and establish its extent. As part of this program, a range of organic geochemical analyses were acquired on petroleum fluids from the Roc 1 and Roc 2 wells with these data released in this report.

The annual offshore petroleum exploration acreage release is part of the government’s strategy to promote offshore oil and gas exploration. Each year, the government invites companies to bid for the opportunity to invest in oil and gas exploration in Australian waters. The 2020 acreage release consists of 42 areas offshore of the Northern Territory, Western Australia, Victoria and the Ashmore and Cartier Islands.