This Record presents 40Ar/39Ar chronologic results acquired in support of collaborative regional geoscientific investigations and mapping programs conducted by Geoscience Australia (GA) and the Northern Territory Geological Survey (NTGS). Argon isotopic data and interpretations from hornblende, muscovite, and biotite from seven samples collected from the Aileron Province in ALCOOTA , HUCKITTA, HALE RIVER, and ILLOGWA CREEK in the Northern Territory are presented herein. The results complement pre-existing geochronological constraints from U–Pb zircon and monazite analyses of the same or related samples, and provide new constraints on the thermal and deformation history of the Aileron Province. Three samples (2003082017, 2003082021, 2003083040) were taken from ALCOOTA in the northeastern portion of the Aileron Province. Biotite in sample 2003082017 from the ca 1.81 Ga Crooked Hole Granite records cooling below 320–280°C at 441 ± 5 Ma. Biotite in sample 2003082021 from the ca 1.73 Ga Jamaica Granite records cooling below 320–280°C at or after 414 ± 2 Ma. Muscovite in sample 2003083040 from the Delny Metamorphics, which were deposited after ca 1.82 Ga and preserve evidence for metamorphism at ca 1.72 Ga and 1.69 Ga, records cooling below 430–390°C at 399 ± 2 Ma. The fabrics preserved in the samples from the Crooked Hole Granite and Delny Metamorphics are interpreted to have formed due to dynamic metamorphism related to movement on the Waite River Shear Zone, an extension of the Delny Shear Zone, during the Palaeoproterozoic. Portions of the northeastern Aileron Province are unconformably overlain by the Neoproterozoic–Cambrian Georgina Basin, indicating these samples were likely at or near the surface by the Neoproterozoic. Together, these data indicate that rocks of the Aileron Province in ALCOOTA were subjected to heating above ~400°C during the Palaeozoic. Two samples (2003087859K, 2003087862F) of exoskarn from an indeterminate unit were taken from drillhole MDDH4 in the Molyhil tungsten–molybdenum deposit in central HUCKITTA. The rocks hosting the Molyhil tungsten–molybdenum deposit are interpreted as ca 1.79 Ga Deep Bore Metamorphics and ca 1.80 Ga Yam Gneiss. They experienced long-lived metamorphism during the Palaeoproterozoic, with supersolidus metamorphism observed until at least ca 1.72 Ga. Hornblende from sample 2003087859K indicates cooling below 520–480°C by 1702 ± 5 Ma and may closely approximate timing of skarn-related mineralisation at the Molyhil deposit; hornblende from sample 2003087862F records a phase of fluid flow at the Molyhil deposit at 1660 ± 4 Ma. The Salthole Gneiss has a granitic protolith that was emplaced at ca 1.79 Ga, and experienced alteration at ca 1.77 Ga. Muscovite from sample 2010080001 of Salthole Gneiss from the Illogwa Shear Zone in ILLOGWA CREEK records cooling of the sample below ~430–390°C at 327 ± 2 Ma. This may reflect the timing of movement of, or fluid flux along, the Illogwa Shear Zone. An unnamed quartzite in the Casey Inlier in HALE RIVER has a zircon U–Pb maximum depositional age of ca 1.24 Ga. Muscovite from sample HA05IRS071 of this unnamed quartzite yields an age of 1072 ± 8 Ma, which likely approximates, or closely post-dates, the timing of deformation in this sample; it provides the first direct evidence for a Mesoproterozoic episode of deformation in this part of the Aileron Province.

This Record presents new U–Pb geochronological data, obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP), from 43 samples of predominantly igneous rocks collected from the East Riverina region of the central Lachlan Orogen, New South Wales. The results presented herein correspond to the reporting period July 2016–June 2020. This work is part of an ongoing Geochronology Project, conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaborative Framework agreement, to better understand the geological evolution and mineral prospectivity of the central Lachlan Orogen in southern NSW (Bodorkos et al., 2013; 2015; 2016, 2018; Waltenberg et al., 2019).

A review of mineral exploration trends, activities and discoveries in Australia in 2021.

The discovery of strategically located salt structures, which meet the requirements for geological storage of hydrogen, is crucial to meeting Australia’s ambitions to become a major hydrogen producer, user and exporter. The use of the AusAEM airborne electromagnetic (AEM) survey’s conductivity sections, integrated with multidisciplinary geoscientific datasets, provides an excellent tool for investigating the near-surface effects of salt-related structures, and contributes to assessment of their potential for underground geological hydrogen storage. Currently known salt in the Canning Basin includes the Mallowa and Minjoo salt units. The Mallowa Salt is 600-800 m thick over an area of 150 × 200 km, where it lies within the depth range prospective for hydrogen storage (500-1800 m below surface), whereas the underlying Minjoo Salt is generally less than 100 m thick within its much smaller prospective depth zone. The modelled AEM sections penetrate to ~500 m from the surface, however, the salt rarely reaches this level. We therefore investigate the shallow stratigraphy of the AEM sections for evidence of the presence of underlying salt or for the influence of salt movement evident by disruption of near-surface electrically conductive horizons. These horizons occur in several stratigraphic units, mainly of Carboniferous to Cretaceous age. Only a few examples of localised folding/faulting have been noted in the shallow conductive stratigraphy that have potentially formed above isolated salt domes. Distinct zones of disruption within the shallow conductive stratigraphy generally occur along the margins of the present-day salt depocentre, resulting from dissolution and movement of salt during several stages. This study demonstrates the potential AEM has to assist in mapping salt-related structures, with implications for geological storage of hydrogen. In addition, this study produces a regional near-surface multilayered chronostratigraphic interpretation, which contributes to constructing a 3D national geological architecture, in support of environmental management, hazard mapping and resource exploration. <b>Citation: </b>Connors K. A., Wong S. C. T., Vilhena J. F. M., Rees S. W. & Feitz A. J., 2022. Canning Basin AusAEM interpretation: multilayered chronostratigraphic mapping and investigating hydrogen storage potential. In: Czarnota, K (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/146376

This map shows the location and status, as at 31 December 2021, of Australian operating mines, mines under development and mines under care and maintenance. Developing mines are deposits where the project has a positive feasibility study, development has commenced or all approvals have been received. Mines under care and maintenance have known resource estimations and may be mined or developed in the future.

Drilling in the Geoscience Australia Exploring for the Future East Tennant project was conducted as part of the MinEx CRC National Drilling Initiative. Ten stratigraphic boreholes were drilled for scientific purposes in the region around the Barkly Roadhouse in the Northern Territory. Where possible, the boreholes were comprehensively wireline logged to obtain petrophysical data on the cover and basement rocks to help improve knowledge and geophysical models of the region. Formation density data obtained by wireline logging were validated using laboratory-based bulk density data obtained by Archimedes method on diamond drill core samples at Geoscience Australia. Results of the validation show that wireline-logged formation density data and Archimedes wet bulk density data are in good general agreement in the first five boreholes drilled (NDIBK01, NDIBK02, NDIBK03, NDIBK04 and NDIBK05). Difficult drilling and some lost drilling equipment meant that boreholes NDIBK06, NDIBK07 and NDIBK09 could not be cased properly, or could not be re-entered, and thus formation density wireline logs could not be obtained in these holes. Boreholes NDIBK08 and NDIBK10 were wireline logged, however formation density results from these last two holes were problematic. Wireline formation density results for borehole NDIBK08 are shown to be too high due to miscalibration of the wireline formation density tool, and results from borehole NDIBK10 cannot be robustly assessed because of a lack of sufficient Archimedes bulk density data needed to provide statistical relevance and validate the wireline formation density data.

One of the aims of the Exploring for the Future program is to promote the discovery of new mineral deposits in undercover frontiers. Iron oxide–copper–gold mineral systems are a desirable candidate for undercover exploration, because of their potential to generate large deposits with extensive alteration footprints. This mineral potential assessment uses the mineral systems concept: developing mappable proxies of required theoretical criteria, combined to demonstrate where conditions favourable for mineral deposit formation are spatially coincident. This assessment uses a 2D geographical information system workflow to map the favourability of the key mineral system components. Two outputs were created: a comprehensive assessment, using all available spatial data; and a coverage assessment, which is constrained to data that have no reliance on outcrop. The results of these assessment outputs were validated with spatial statistics, demonstrating how the assessment can predict the presence of known ore deposits. Both assessment outputs present new areas of interest with prospectivity in under-explored regions of undercover northern Australia. The intended aims are already being realised, as this tool has aided area selection for pre-competitive stratigraphic drilling as part of the MinEx CRC National Drilling Initiative. <b>Citation:</b> Murr, J., Skirrow, R.G., Schofield, A., Goodwin, J., Coghlan, R., Highet, L., Doublier, M.P., Duan, J. and Czarnota, K., 2020. Tennant Creek – Mount Isa IOCG mineral potential assessment. 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.

Exploring for the Future (EFTF) is an ongoing multiyear initiative by the Australian Government, conducted by Geoscience Australia, in partnership with state and Northern Territory government agencies and other partner research institutes. The first phase of the EFTF program (2016-2020) aimed to improve Australia’s desirability for industry investment in resource exploration in frontier or ‘greenfield’ regions across northern Australia. As part of the program, Geoscience Australia employed a range of both established and innovative techniques to gather new precompetitive data and information to develop new insight into the energy, mineral and groundwater resource potential across northern Australia. To maximise impact and to stimulate industry exploration activity, Geoscience Australia focussed activities in greenfield areas where understanding of resource potential was limited. In order to address this overarching objective under the EFTF program, Geoscience Australia led acquisition of two deep crustal reflection seismic surveys in the South Nicholson region, an understudied area of little previous seismic data, straddling north-eastern Northern Territory and north-western Queensland. The first survey, L210 South Nicholson 2D Deep Crustal Seismic Survey acquired in 2017, consisted of five overlapping seismic lines (17GA-SN1 to SN5), totalling ~1100 line-km. Survey L210 linked directly into legacy Geoscience Australia seismic lines (06GA-M1 and 06GA-M2) in the vicinity of the world-class Pb-Zn Century Mine in Queensland. The results from survey L210 profoundly revised our geological understanding of the South Nicholson region, and led to the key discovery of an extensive sag basin, the Carrara Sub-basin, containing highly prospective late Paleoproterozoic to Mesoproterozoic rocks with strong affinities with the adjacent Mount Isa Province and Lawn Hill Platform. To complement and expand on the outstanding success of the South Nicholson survey and to continue to explore the resource potential across the underexplored and mostly undercover South Nicholson and Barkly regions, a second seismic survey was acquired in late 2019, the Barkly 2D reflection survey (L212). The Barkly seismic survey comprises five intersecting lines (19GA-B1 to B5), totalling ~813 line-km, extending from the NT-QLD border in the south-east, near Camooweal, to the highly prospective Beetaloo Sub-basin in the north-west. The survey ties into the South Nicholson survey (L210), the recently acquired Camooweal 2D reflection seismic survey by the Geological Survey of Queensland and industry 2D seismic in the Beetaloo Sub-basin, leveraging on and maximising the scientific value and impact on all surveys. The Barkly reflection seismic data images the south-western margin of the Carrara Sub-basin and identified additional previously unrecognised, structurally-disrupted basins of Proterozoic strata, bounded by broadly northeast trending basement highs. Critically, the survey demonstrates the stratigraphic continuity of highly prospective Proterozoic strata from the Beetaloo Sub-basin into these newly discovered, but as yet unevaluated, concealed basins and into the Carrara Sub-basin, further attesting to the regions outstanding potential for mineral and hydrocarbon resources. This survey, in concert with the South Nicholson seismic survey and other complementary EFTF funded regional geochemical, geochronology and geophysical data acquisition surveys, significantly improves our understanding of the geological evolution, basin architecture and the resource potential of this previously sparsely studied region.

Geognostics OZ SEEBASE depth‐to‐economic basement model of Australia and ancillary datasets. In this update, basement is defined as the top of igneous or metamorphic crust at the base of undeformed sediments, regardless of age. Note that in deeper parts of some basins, such as the greater McArthur Basin, the deepest section may be metasedimentary. Data provided by Geognostics, 2021. OZ SEEBASE® 2021 (Version 1, May 2021). Geognostics Australia Pty Ltd, https://www.geognostics.com/oz‐seebase‐2021. Web Map Service layers include: - Depth to Basement Image - Depth to Basement Grid - Sediment Thickness Grid - Derivative OZ SEEBASE Sediment Thickness Grid - Basement Thickness Grid Disclaimer: The conclusions and recommendations expressed in this Geognostics digital release represent the opinions of the authors based on the data available to them. No liability is accepted for the total accuracy of this report or related datasets, nor any commercial decisions or actions made resulting from this report.

NDI Carrara 1 is a deep stratigraphic drill hole (~1751m) 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 test of the Carrara Sub-basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys (L210 in 2017 and L212 in 2019) recently acquired as part of the Exploring for the Future program. The drill hole intersected approximately 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This report presents inorganic geochemical analyses undertaken by Geoscience Australia on selected rock samples, collected at roughly 4 m intervals.