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 2021 acreage release consists of 21 areas offshore of Western Australia, Victoria, Tasmania and the Ashmore and Cartier Islands.

Major oxides provide valuable information about the composition, origin, and properties of rocks and regolith. Analysing major oxides contributes significantly to understanding the nature of geological materials and processes (i.e. physical and chemical weathering) – with potential applications in resource exploration, engineering, environmental assessments, agriculture, and other fields. Traditionally most measurements of oxide concentrations are obtained by laboratory assay, often using X-ray fluorescence, on rock or regolith samples. To expand beyond the point measurements of the geochemical data, we have used a machine learning approach to produce seamless national scale grids for each of the major oxides. This approach builds predictive models by learning relationships between the site measurements of an oxide concentration (sourced from Geoscience Australia’s OZCHEM database and selected sites from state survey databases) and a comprehensive library of covariates (features). These covariates include: terrain derivatives; climate surfaces; geological maps; gamma-ray radiometric, magnetic, and gravity grids; and satellite imagery. This approach is used to derive national predictions for 10 major oxide concentrations at the resolution of the covariates (nominally 80 m). The models include the oxides of silicon (SiO2), aluminium (Al2O3), iron (Fe2O3tot), calcium (CaO), magnesium (MgO), manganese (MnO), potassium (K2O), sodium (Na2O), titanium (TiO2), and phosphorus (P2O5). The grids of oxide concentrations provided include the median of multiple models run as the prediction, and lower and upper (5th and 95th) percentiles as measures of the prediction’s uncertainty. Higher uncertainties correlate with greater spreads of model values. Differences in the features used in the model compared with the full feature space covering the entire continent are captured in the ‘covariate shift’ map. High values in the shift model can indicate higher potential uncertainty or unreliability of the model prediction. Users therefore need to be mindful, when interpreting this dataset, of the uncertainties shown by the 5th-95th percentiles, and high values in the covariate shift map. Details of the modelling approach, model uncertainties and datasets are describe in an attached word document “Model approach uncertainties”. This work is part of Geoscience Australia’s Exploring for the Future program that provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. These data are published with the permission of the CEO, Geoscience Australia.

This package contains presentations given during NT Resources week, at the Uncovering East Tennant workshop held in Darwin on September 3, 2019, and Mining the Territory, September 5, 2019. The presentation given by Andrew Heap at the Mining the Territory forum is a high level overview of the data collection and activities of GA and it's collaborative partners across Northern Australia in conjunction with the Exploring for the Future (EFTF) program. The workshop, held in collaboration with the Northern Territory Geological Survey, outlined new mineral exploration opportunities in the East Tennant area, which lies beneath the Barkly Tableland and extends approximately 250 km east of Tennant Creek. The East Tennant area has been the focus of geochemical, geological and geophysical data acquisition as part of Geoscience Australia's Exploring for the Future program. This free event showcased new science insights for the East Tennant area and how this under-explored region has opportunities for greenfield mineral discoveries.

The values and distribution patterns of the strontium (Sr) isotope ratio 87Sr/86Sr in Earth surface materials is of use in the geological, environmental and social sciences. Ultimately, the 87Sr/86Sr ratio of any mineral or biological material reflects its value in the rock that is the parent material to the local soil and everything that lives in and on it. In Australia, there are few large-scale surveys of 87Sr/86Sr available, and here we report on a new, low-density dataset using 112 catchment outlet (floodplain) sediment samples covering 529,000 km2 of inland southeastern Australia (South Australia, New South Wales, Victoria). The coarse (<2 mm) fraction of bottom sediment samples (depth ~0.6-0.8 m) from the National Geochemical Survey of Australia were fully digested before Sr separation by chromatography and 87Sr/86Sr determination by multicollector-inductively coupled plasma-mass spectrometry. The results show a wide range of 87Sr/86Sr values from a minimum of 0.7089 to a maximum of 0.7511 (range 0.0422). The median 87Sr/86Sr (± robust standard deviation) is 0.7199 (± 0.0112), and the mean (± standard deviation) is 0.7220 (± 0.0106). The spatial patterns of the Sr isoscape observed are described and attributed to various geological sources and processes. Of note are the elevated (radiogenic) values (≥~0.7270; top quartile) contributed by (1) the Palaeozoic sedimentary country rock and (mostly felsic) igneous intrusions of the Lachlan geological region to the east of the study area; (2) the Palaeoproterozoic metamorphic rocks of the central Broken Hill region; both these sources contribute fluvial sediments into the study area; and (3) the Proterozoic to Palaeozoic rocks of the Kanmantoo, Adelaide, Gawler and Painter geological regions to the west of the area; these sources contribute radiogenic material to the region mostly by aeolian processes. Regions of low 87Sr/86Sr (≤~0.7130; bottom quartile) belong mainly to (1) a few central Murray Basin catchments; (2) some Darling Basin catchments in the northeast; and (3) a few Eromanga geological region-influenced catchments in the northwest of the study area. The new spatial dataset is publicly available through the Geoscience Australia portal (https://portal.ga.gov.au/restore/cd686f2d-c87b-41b8-8c4b-ca8af531ae7e).

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)

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 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.

<div>Geoscience Australia’s Exploring for the Future (EFTF) program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential.</div><div><br></div><div>The Stansbury Basin is a relatively underexplored basin in southern South Australia. Stansbury West 1 was drilled on the east coast of Yorke Peninsula to test the basal Permian sands and Paleozoic carbonate known to contain traces of hydrocarbon gas and residual oil. The well encountered no significant hydrocarbons and was abandoned as dry. A known occurrence of hydrogen-rich natural gas was discovered nearly a century ago in a well to the north of Stansbury West 1. Also potential hydrogen gas enrichment in the near-surface in the surrounds of the Stansbury West 1 drillhole has been proposed using satellite imagery and land surface features.</div><div><br></div><div>The study of natural hydrogen gas occurrences is a focus for the second phase of the EFTF program (2020–2024) and the fluid inclusion stratigraphy (FIS) technique of Fluid Inclusion Technology (Schlumberger) provides a convenient method to measure the well's complete downhole section for both hydrocarbon non-hydrocarbon gases that have been geologically trapped in fluid inclusions and then mechanically released in the laboratory.</div><div><br></div><div>Geoscience Australia have undertaken (via the service provider, FIT Schlumberger) stratigraphic reconstructions of bulk volatile chemistry from fluid inclusions from the drillhole Stansbury West 1, Stansbury Basin. FIS analysis was performed on 270 cuttings and core samples from 15.24 to 1743.53 metres, including 4.9 metres of Archean gneiss and granitic basement at the base of the drillhole.</div><div><br></div><div>This ecat record releases the final report containing the results of fluid inclusion stratigraphy and thin section analyses, raw data files (*.LAS) and rock descriptions by FIT Schlumberger (Company reference number FI220025a).</div>

Understanding the character of Australia's extensive regolith cover is crucial to the continuing success of mineral exploration. We hypothesize that the regolith contains geochemical fingerprints of processes related to the development and preservation of mineral systems at a range of scales. We test this hypothesis by analysing the composition of surface sediments within greenfield regional (southern Thomson Orogen) and continental (Australia) study areas. In the southern Thomson Orogen area, the first principal component (PC1) derived in our study (Ca, Sr, Cu, Mg, Au, and Mo at one end; rare earth elements (REEs) and Th at the other) is very similar to the empirical vector successfully used by a local company exploring for Cu-Au mineralisation (enrichment in Sr, Ca and Au concomitant with depletion in REEs). Mapping the spatial distribution of PC1 in the region reveals several areas of elevated values and possible mineralisation potential. One of the strongest targets in the PC1 map is located between Brewarrina and Bourke in northern New South Wales. Here both historical and recent exploration drilling has intersected mineralisation with up to 1 % Cu, 0.1 g/t Au, and 717 ppm Zn, purportedly related to a volcanic arc setting. The analysis of a comparable geochemical dataset at the continental scale yields a similar PC1 (Ca, Sr, Mg, Cu, Au, and Mo at one end; REEs and Th at the other) to the regional study. Mapping PC1 at the continental scale shows patterns that (1) are compatible with the regional study, and (2) reveal several geological regions possibly with an enhanced potential for this style of Cu-Au mineralisation. These include well-endowed mineral provinces such as the Curnamona, southern Pilbara, and Capricorn regions, but also some greenfield regions such as the Albany-Fraser/western Eucla, western Murray, and Eromanga geological regions. We conclude that the geochemical composition of Australia's regolith may hold critical information pertaining to mineralisation within/beneath it.

<div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential.</div><div><br></div><div>The Paleo to Mesoproterozoic Birrindudu Basin is an underexplored frontier basin located in northwestern Northern Territory and northeastern Western Australia. The Birrindudu Basin is a region of focus for the second phase of the EFTF program (2020–2024) as it contains strata of similar age to the prospective McArthur Basin, South Nicholson region and Mount Isa Province, but remains comparatively poorly understood.</div><div><br></div><div>Geoscience Australia have undertaken (via the service provider, FIT, Schlumberger) stratigraphic reconstructions of bulk volatile chemistry from fluid inclusions from the drillhole WLMB001B, Birrindudu Basin, located in the northwest Northern Territory.</div><div><br></div><div>This ecat record releases the final report containing the results of fluid inclusion stratigraphy, thin section and microthermometry analyses, raw data files (*.LAS) and rock descriptions by FIT Schlumberger. Company reference number FI230004a.</div>