The Layered Geology of Australia web map service is a seamless national coverage of Australia’s surface and subsurface geology. Geology concealed under younger cover units are mapped by effectively removing the overlying stratigraphy (Liu et al., 2015). This dataset is a layered product and comprises five chronostratigraphic time slices: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic, and Pre-Neoproterozoic. As an example, the Mesozoic time slice (or layer) shows Mesozoic age geology that would be present if all Cenozoic units were removed. The Pre-Neoproterozoic time slice shows what would be visible if all Neoproterozoic, Paleozoic, Mesozoic, and Cenozoic units were removed. The Cenozoic time slice layer for the national dataset was extracted from Raymond et al., 2012. Surface Geology of Australia, 1:1 000 000 scale, 2012 edition. Geoscience Australia, Canberra.

Mineral deposits are the products of lithospheric-scale processes. Imaging the structure and composition of the lithosphere is therefore essential to better understand these systems, and to efficiently target mineral exploration. Seismic techniques have unique sensitivity to velocity variations in the lithosphere and mantle, and are therefore the primary means available for imaging these structures. Here, we present the first stage of Geoscience Australia's passive seismic imaging project (AusArray), developed in the Exploring for the Future program. This includes generation of compressional (P) and shear (S) body-wave tomographic imaging models. Our results, on a continental scale, are broadly consistent with a priori expectations for regional lithospheric structure and the results of previously published studies. However, we also demonstrate the ability to resolve detailed features of the Australian lithospheric mantle underneath the dense seismic deployments of AusArray. Contrasting P- and S-wave velocity trends within the Tennant Creek – Mount Isa region suggest that the lithospheric root may have undergone melt-related alteration. This complements other studies, which point towards high prospectivity for iron oxide–copper–gold mineralisation in the region. <b>Citation: </b>Haynes, M.W., Gorbatov, A., Hejrani, B., Hassan, R., Zhao, J., Zhang, F. and Reading, A.M., 2020. AusArray: imaging the lithospheric mantle using body-wave tomography. 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.

As Australia and the world transition to net zero emissions, hydrogen will continue to grow in importance as a clean energy source, with underground hydrogen storage (UHS) expected to be a key component of this new industry. Salt (halite) caverns are a preferred storage option for hydrogen, given their scale, stability and the high injection and withdrawal rates they can support. The use of salt caverns for storing gas is an established industry in North America and Europe but not in Australia, where exploration for suitable storage locations is in the initial frontier stages. Australia’s known major halite deposits occur in Neoproterozoic and Paleozoic sequences and are predominantly located in western and central Australia. This analysis has identified potential in eastern Australia in addition to the proven thick halite in the Adavale Basin, Queensland. Building on Geoscience Australia’s previous salt studies in the Canning, Polda and Adavale basins, this study expands the portfolio of areas prospective for halite in onshore and offshore basins using both direct and indirect evidence. The study correlates paleogeography and paleoclimate reconstructions with evidence of salt in wells, and in geophysical and geochemical data. Salt cavern design for UHS, the solution mining process, and the preferred salt deposits are also discussed. The results will provide pre-competitive information through a comprehensive inventory of areas that may be prospective for UHS. Published in The APPEA Journal 63 285-304 https://doi.org/10.1071/AJ22153

Geoscience Australia, in collaboration with state governments, will be carrying out airborne electromagnetic (AEM) surveys in western South Australia, southern NT and eastern WA during 2022. This scientific research is being carried out to obtain data that will enhance understanding of geology and natural resources of the region. This information will support future resource management decision-making. This survey has been expanded into Western Australia with funding from the Geological Survey of Western Australia, combined with valuable in-kind support from the South Australian and Northern Territory geological surveys. <p>

The South Nicholson region, which includes the Paleoproterozoic Isa Superbasin, the Mesoproterozoic South Nicholson Group and overlying younger sediments, is sparsely explored and has recently come into increased focus as a result of the Australian Government’s Exploring for the Future program. Previous exploration has identified potential shale gas plays within the River and Lawn supersequences of the Isa Superbasin in northwest Queensland’s northern Lawn Hill Platform region. Understanding mineralogy is important for characterising shale reservoirs, as mechanical properties such as shale brittleness are influenced by mineral composition. Mineralogy can, therefore, be utilised as a proxy for mechanical properties that are crucial to minimising risks associated with exploring for and developing shale reservoirs. This study utilises three different methods for calculating brittleness; XRD mineralogy, XRF major element geochemistry, and geomechanical properties. Results indicate highly variable mineralogy within the analysed samples, demonstrating heterogeneity in shale brittleness throughout the studied supersequences. Brittleness calculated from XRD analysis ranges from ductile to brittle with zones of brittle shales present in all supersequences. Increasing quartz and decreasing clay content is the dominant control on shale brittleness in the studied samples. Correlation between XRF major element geochemistry and XRD mineralogy is demonstrated to be moderate to poor, with brittleness derived from XRF major element geochemistry observed to be significantly higher than brittleness derived from XRD mineralogy. Conversely, brittleness derived from geomechanical properties agrees closely with XRD mineralogy derived brittleness. Hence, XRF major element geochemistry data are not recommended in the South Nicholson region to calculate brittleness. Analysis of brittleness indices from this study, in combination with total organic carbon content drawn from regional geochemical analysis in the South Nicholson region, identifies potential shale gas target intervals in the River, Term, and Lawn supersequences. Data presented on correlated well sections highlights intervals of exploration interest within these supersequences, being those depths where high organic content, brittle rocks are identified. The rocks that meet this criteria are primarily constrained to the already known potential shale gas plays of the River and Lawn supersequences. Recent data from Geoscience Australia implies that these potential shale gas plays are likely to extend from the northern Lawn Hill Platform, where they have been primarily identified to date, underneath the South Nicholson Basin and into the Carrara Sub-basin, significantly increasing their lateral extent. <b>Citation:</b> A. H. E. Bailey, A. J. M. Jarrett, L. Wang, B. L. Reno, E. Tenthorey, C. Carson & P. Henson (2022) Shale brittleness within the Paleoproterozoic Isa Superbasin succession in the South Nicholson region, Northern Australia, <i>Australian Journal of Earth Sciences, </i>DOI: 10.1080/08120099.2022.2095029

NDI Carrara 1 is a deep stratigraphic well completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI), in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first stratigraphic test of the Carrara Sub-Basin, a newly discovered depocentre in the South Nicholson region. The well intersected Proterozoic sediments with numerous hydrocarbon shows, likely to be of particular interest due to affinities with the known Proterozoic plays of the Beetaloo Sub-basin and the Lawn Hill Platform, including two organic-rich black shales and a thick sequence of interbedded black shales and silty-sandstones. Alongside an extensive suite of wireline logs, continuous core was recovered from 283.9 m to total depth at 1750.8 m, providing high-quality data to support comprehensive analysis. Presently, this includes geochronology, geochemistry, geomechanics, and petrophysics. Rock Eval pyrolysis data demonstrates the potential for several thick black shales to be a source of hydrocarbons for conventional and unconventional plays. Integration of these data with geomechanical properties highlights potential brittle zones within the fine-grained intervals where hydraulic stimulation is likely to enhance permeability, identifying prospective Carrara Sub-basin shale gas intervals. Detailed wireline log analysis further supports a high potential for unconventional shale resources. Interpretation of the L210 and L212 seismic surveys suggests that the intersected sequences are laterally extensive and continuous throughout the Carrara Sub-basin, potentially forming a significant new hydrocarbon province and continuing the Proterozoic shale play fairway across the Northern Territory and northwest Queensland. This abstract was submitted and presented at the 2022 Australian Petroleum Production and Exploration Association (APPEA), Brisbane (https://appea.eventsair.com/appea-2022/)

The AusArray program aims to install small temporary passive seismic stations every 200 km across Australia. The seismic stations will passively measure small natural vibrations that travel through the Earth to help scientists understand the distribution and composition of rocks beneath the ground. Seismometers are sensitive instruments used to measure small natural vibrations that travel through the Earth caused by earthquakes, waves breaking on the shore and even wind. The data collected are analysed to create a three-dimensional model of the Earth’s subsurface. Passive seismic data can be used to model the Earth‘s structure, which is used to infer the geological history and assess the resource potential and natural hazards of the region.

This study was commissioned by Geoscience Australia (GA) to produce a report on source rock maturity and maceral/organoclast assemblages for a suite of rock samples from from the MinEx CRC National Drilling Initiative (NDI) Carrara 1 drill hole in the Northern Territory, Australia. 25 samples consisting of 24 drill core samples and 1 drill cutting sample were studied using organic petrological methods to evaluate the organic matter type, content, thermal maturity and hydrocarbon potential. Vitrinite was absent in all the samples and variable amounts of bitumen was present throughout the stratigraphic section studied. Fluorescing lamalginite was present in the upper part of the section and no bioclasts were detected in the samples from the lower section. Vitrinite reflectance equivalents calculated from bitumen reflectance indicated that upper part of the section containing lamalginite is early to mid-mature and the lower part of the section is over-mature. Good potential for liquid hydrocarbons may exist in the upper part of the section and the overmature lower part of the stratigraphic section could be gas prone.

One of the aims of the Exploring for the Future (EFTF) program is to characterise the geochemistry of sedimentary and volcanic units, overbank sediments and groundwater in northern Australia to de-risk resource exploration and inform decision making. Underpinning this effort has been the generation of high-quality geochemical data from Geoscience Australia’s laboratories. A streamlined workflow from sample collection to reporting ensures that samples are processed consistently and to a high standard, and use of rigorously tested methodologies and appropriate QA/QC practices ensures data quality. This abstract highlights many of the processes undertaken in the laboratories, ranging from new sample preparation procedures (including automated milling and setting up temporary remote processing facilities) to organic geochemistry, mineralogy, inorganic geochemistry and geochronology. The laboratories were also instrumental in assisting with fieldwork, outsourcing sample analyses and storing data in corporate databases. The large volume of new data generated over the EFTF program has been used to characterise the geology and geochemistry of a range of rocks, regolith, oils, gas and groundwater, and has been instrumental in increasing knowledge of the resource potential of northern Australia and informing decision making. <b>Citation:</b> Jarrett, A.J.M., Thun, C., Champion, D.C., Boreham, C.J., Main, P., Waltenberg, K., Schroder, I., Bastrakov, E., DiBugnara, D., Long, I., Chen, J., Hong, Z., Sohn, J., Jinandasa, N., Palatty, P.,Webber, S., Webster, T., Byass, J., Gilmore, S., Williamson, A., Tubby, J., Long, R., Linehan, B. and Magee, C., 2020. Generation of high-quality data for energy, minerals and groundwater by Geoscience Australia’s laboratories. 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 Major Crustal Boundaries web service displays the synthesized output of more than 30 years of acquisition of deep seismic reflection data across Australia, where major crustal-scale breaks have been interpreted in the seismic reflection profiles, often inferred to be relict sutures between different crustal blocks. The widespread coverage of the seismic profiles now provides the opportunity to construct a map of major crustal boundaries across Australia.