The AusAEM Year 1 NT/QLD Airborne Electromagnetic Survey covers the Newcastle Waters and Alice Springs 1:1 Million map sheets in the Northern Territory, plus the Normanton and Cloncurry 1:1 Million map sheets in Queensland. The survey was flown at 20 kilometre line spacing and entails approximately 60,000 line kilometres of data in total. The data were acquired in 2017 and 2018 by CGG Aviation (Australia) Pty. Ltd. (CGG), under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. The data were also processed by CGG. This Tranche 1 data release package only contains approximately the first one third (19,500 line kilometres) of the survey data that were acquired between August 4 and October 7, 2017. The AusAEM Year 1 NT/QLD survey also included over 1,500 line kilometres of infill flying, that was funded by private exploration companies, in certain infill blocks within the survey area. These infill blocks and data are not part of this data release due to confidentiality agreements. The survey was commissioned by Geoscience Australia as part of the Exploring for the Future (EFTF) program. The EFTF program is led by Geoscience Australia (GA), in collaboration with the Geological Surveys of the Northern Territory, Queensland, South Australia and Western Australia, and is investigating the potential mineral, energy and groundwater resources in northern Australia and South Australia. The EFTF is a four-year $100.5 million investment by the Australian Government in driving the next generation of resource discoveries in northern Australia, boosting economic development across this region. This Data Release Package (Tranche 1, Phase 1) contains the final survey deliverables produced by the contractor CGG, including: (a) the operations and processing report, (b) final processed electromagnetic, magnetic and elevation point located line data, (c) final processed electromagnetic, magnetic and elevation grids, (d) conductivity estimates generated by the EM Flow® conductivity depth imaging algorithm, (e) graphical multiplots of line data and EM Flow® conductivity sections, (f) graphical stacked EM Flow® conductivity sections, (h) ESRI shapefiles containing the flight line locations. Future data release packages will contain data flown after October 7 2017 (Tranche 2, etc.) and further derived products (Phase 2, etc.).

To meet the increasing demand for natural resources globally, industry faces the challenge of exploring new frontier areas that lie deeper undercover. Here, we present an approach to, and initial results of, modelling the depth of four key chronostratigraphic packages that obscure or host mineral, energy and groundwater resources. Our models are underpinned by the compilation and integration of ~200 000 estimates of the depth of these interfaces. Estimates are derived from interpretations of newly acquired airborne electromagnetic and seismic reflection data, along with boreholes, surface and solid geology, and depth to magnetic source investigations. Our curated estimates are stored in a consistent subsurface data repository. We use interpolation and machine learning algorithms to predict the distribution of these four packages away from the control points. Specifically, we focus on modelling the distribution of the base of Cenozoic-, Mesozoic-, Paleozoic- and Neoproterozoic-age stratigraphic units across an area of ~1.5 million km2 spanning the Queensland and Northern Territory border. Our repeatable and updatable approach to mapping these surfaces, together with the underlying datasets and resulting models, provides a semi-national geometric framework for resource assessment and exploration. <b>Citation:</b> Bonnardot, M.-A., Wilford, J., Rollet, N., Moushall, B., Czarnota, K., Wong, S.C.T. and Nicoll, M.G., 2020. Mapping the cover in northern Australia: towards a unified national 3D geological model. 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.

For the AusAEM Year 1 survey an inertial measurement unit (IMU) was installed for the first time on the TEMPEST receiver bird to measure its orientation and to augment GPS derived positioning of the receiver. This has given us the opportunity to develop better quality control and calibration procedures, which would otherwise not be possible. Theoretical modelling of the primary field on high altitude zero-lines, using the full position/orientation information, revealed discrepancies between observed and modelled data. It alerted us to time-lag parallaxes between EM and bird position/orientation data, some spurious IMU data on many pre-flight zero-lines, and a coordinate system sign convention inconsistency. The modelling also revealed systematic differences that we could attribute to the calibration of the receiver pitch and EM data scaling. We developed an inversion algorithm to solve for a receiver pitch offset and an EM scaling calibration parameter, for each zero-line, which minimised the systematic discrepancies. It eventuated that the calibration parameters fell into five distinct populations explicable by significant equipment changes. This gave us the confidence to use the medians of these populations as parameters to calibrate the data. The work shows the value of the new receiver bird orientation data and the importance of accurate IMU calibration after any modification. It shows the practical utility of quantitative modelling in the quality control workflow. It also demonstrates how modelling and inversion procedure can be used to successfully diagnose calibration issues in fixed-wing AEM data. Presented at the 2019 Australasian Exploration Geoscience Conference

This animation shows how Airborne Electromagnetic Surveys Work, when conducted by a rotary wing (helicopter) aircraft. It is part of a series of Field Activity Technique Engagement Animations. The target audience are the communities that are impacted by our data acquisition activities. There is no sound or voice over. The 2D animation includes a simplified view of what AEM equipment looks like, what the equipment measures and how the survey works.

<p>Geoscience Australia commissioned the AusAEM Year 1 NT/QLD survey as part of the Exploring for the Future (EFTF) program, flown over parts of the Northern Territory and Queensland. The EFTF program is led by Geoscience Australia (GA), in collaboration with the Geological Surveys of the Northern Territory, Queensland, South Australia and Western Australia. The program was designed to investigate the potential mineral, energy and groundwater resources in northern Australia and South Australia. <p>The survey was flown during the 2017-2018 field season, using the TEMPEST® airborne electromagnetic (AEM) system operated by CGG Aviation (Australia) Pty. Ltd under contract to Geoscience Australia. AusAEM Year 1 was acquired with a 20-kilometre line separation and collected over 60,000 line kilometres of data in total. The AusAEM Year 1 NT/QLD survey also includes over 1,500 line kilometres of infill flying, which, was funded by private exploration companies in certain infill blocks within the survey area. The data from these infill blocks are now part of Geoscience Australia release to the public domain, for use in the minerals, energy and groundwater sectors. <p> Previously Released data (Phase 1) <p>In December 2018, we released a package, which contains data from the AusAEM Year 1 NT/QLD Airborne Electromagnetic Survey Phase 1. <p>This data package, with eCat ID 124092 titled “AusAEM Year 1 NT/QLD Airborne Electromagnetic Survey, TEMPEST® airborne electromagnetic data and Em Flow® conductivity estimates”. The package contains a) survey logistics and processing report, b) final processed electromagnetic, magnetic and elevation point located line data, c) processed electromagnetic, magnetic and elevation grids, d) point located conductivity estimates from EM Flow®, e) multi-plots of line data and conductivity sections, all produced by the contractor CGG Aviation (Australia) Pty. These products are downloadable from Geoscience Australia’s website: (See http://www.ga.gov.au/metadata-gateway/metadata/record/gcat_124092). <p>The data provides new insights into vast areas in Northern Australia that have not been extensively explored previously. <p>Current Release (Phase 2) <p>This Phase 2 data release package contains results from inverting the electromagnetic data in the Phase 1 release. The inversion results were generated using Geoscience Australia's sample-by-sample layered-earth (1D) inversion, a deterministic regularized gradient-based algorithm, which we call GALEISBS (Brodie, 2016). <p>For the inversion of TEMPEST AEM data we have conventionally inverted the total (primary plus secondary) measured X-and Z-component data simultaneously to produce a single smooth layered conductivity model. To achieve convergence and derive an acceptable model and acceptable data misfits, we have found that it is necessary to solve for three geometry parameters; (1) Transmitter (Tx) –Receiver (Rx) horizontal in-line and 2) vertical separations and 3) the receiver pitch. This is the case even with the new Rx bird IMU measurements and calibrated data (Ley-Cooper et.al, 2019.). <p>We have extended the GALEISBS functionality to allow inversion of the vector sum of the X- and Z-component data. The rationale of modifying the algorithm is to eliminate the need to solve for Rx pitch, since the vector sum of the X- and Z-component data are insensitive to the Rx pitch. In doing this, we are gaining some robustness by not having to solve for one of the geometry parameters; however, the trade-off is that we are in essence losing the information implicit in the vector component data. <p>The inversions we deliver here we derived from a recently implemented XZ–vector-sum inversion, described in Ley-Cooper et.al, 2019. <p>The GALEISBS inversion products are available for download in parts based on the type of derived product. These are zipped into the following three files: <p>1. galeisbs_vector_sum_point_located_data_ascii.zip <p>2. galeisbs_vector_sum_point_located_data_geosoft.zip <p>3. galeisbs_vector_sum_sctions.zip <p>4. galeisbs_vector_sum_gocad_sgrids.zip

AusAEM-WA, Murchison Airborne Electromagnetic Survey Blocks: SkyTEM® airborne electromagnetic data and GALEI inversion conductivity estimates The accompanying data package, titled “AusAEM–WA, Murchison Airborne Electromagnetic Survey Blocks: SkyTEM® airborne electromagnetic data and GALEI inversion conductivity estimates”, was released on March 2022 by Geoscience Australia (GA) in collaboration with the Geological Survey of Western Australia. The data represents the first second of the AusAEM2020 (WA) survey flown with a with a rotary aircraft contracted to Geoscience Australia, using the SkyTEM® airborne electromagnetic system. The survey was flown at a 20-kilometre nominal line spacing over the most over the Murchison area and across to the west coast of Western Australia. The area encompasses over 17,600 line kilometres of newly acquired airborne electromagnetic geophysical data. This package contains (~17,600 kms) of the total of survey data which have been quality-controlled, processed, modelled and inverted both by the contractor and by GA. The survey was divided in four blocks, flown east-west. All four block’s projected grid coordinates have been supplied in GDA2020 MGA Zone 50 datum, and contain the geodetic latitude and longitude coordinate fields. Geoscience Australia and Western Australia (Department of Mines, Industry Regulation and Safety) commissioned the AusAEM 2020 survey as part of the national airborne electromagnetic acquisition program, to complete 20km line separation AEM coverage over WA. The program is designed to deliver freely available pre-competitive geophysical data to assist in the investigation and discovery of potential mineral, energy and groundwater resources within Australia. Funding for the survey came from the Western Australian government’s Exploration Incentive Scheme and additional support from the State’s COVID-19 recovery plan. Geoscience Australia managed the survey data acquisition, processing, contracts, quality control of the survey and generated the inversion products included in the data package. The data release package contains 1. A data release package summary PDF document. 2. The survey logistics and processing report. 3. KML and Shapefiles for the regional flight lines. 4. Final processed point located line data in ASEG-GDF2 format. 5. Conductivity estimates generated by SkyTEM’s Workbench. 6. Conductivity estimates and products (suitable for various 3D packages) generated by Geoscience Australia's Layered Earth Inversion algorithm.

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 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

Building on newly acquired airborne electromagnetic and seismic reflection data during the Exploring for the Future (EFTF) program, Geoscience Australia (GA) generated a cover model across the Northern Territory and Queensland, in the Tennant Creek – Mount Isa (TISA) area (Figure 1; between 13.5 and 24.5⁰ S of latitude and 131.5 and 145⁰ E of longitude) (Bonnardot et al., 2020). The cover model provides depth estimates to chronostratigraphic layers, including: Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The depth estimates are based on the interpretation, compilation and integration of borehole, solid geology, reflection seismic, and airborne electromagnetic data, as well as depth to magnetic source estimates. These depth estimates in metres below the surface (relative to the Australian Height Datum) are consistently stored as points in the Estimates of Geophysical and Geological Surfaces (EGGS) database (Matthews et al., 2020). The data points compiled in this data package were extracted from the EGGS database. Preferred depth estimates were selected to ensure regional data consistency and aid the gridding. Two sets of cover depth surfaces (Bonnardot et al., 2020) were generated using different approaches to map megasequence boundaries associated with the Era unconformities: 1) Standard interpolation using a minimum-curvature gridding algorithm that provides minimum misfit where data points exist, and 2) Machine learning approach (Uncover-ML, Wilford et al., 2020) that allows to learn about relationships between datasets and therefore can provide better depth estimates in areas of sparse data points distribution and assess uncertainties. This data package includes the depth estimates data points compiled and used for gridding each surface, for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic (Figure 1). To provide indicative trends between the depth data points, regional interpolated depth surface grids are also provided for the Base Cenozoic, Base Mesozoic, Base Paleozoic and Base Neoproterozoic. The grids were generated with a standard interpolation algorithm, i.e. minimum-curvature interpolation method. Refined gridding method will be necessary to take into account uncertainties between the various datasets and variable distances between the points. These surfaces provide a framework to assess the depth and possible spatial extent of resources, including basin-hosted mineral resources, basement-hosted mineral resources, hydrocarbons and groundwater, as well as an input to economic models of the viability of potential resource development.

<p>The AusAEM Year 1 NT/QLD Airborne Electromagnetic Survey covers the Newcastle Waters and Alice Springs 1:1 Million map sheets in the Northern Territory and the Normanton and Cloncurry 1:1 Million map sheets in Queensland. CGG Aviation (Australia) Pty. Ltd. flew the 67,700-line kilometre survey between 2017 and 2018 using the TEMPEST® airborne electromagnetic system. Flown at 20-kilometre line spacing, data were acquired and processed under contract to Geoscience Australia. <p>This data package supersedes and replaces two earlier releases: June 11, 2018, and December 2018 (eCatID 120948) with revised calibrations and processing. Along with the regionally spaced (20 km) flight lines, it now includes 1,500 line kilometres of infill flying that was funded by private exploration companies and not previously released in view of time-bounded confidentiality agreements. The survey was commissioned by Geoscience Australia as part of the Exploring for the Future (EFTF) program. The EFTF program is led by Geoscience Australia (GA), in collaboration with the Geological Surveys of the Northern Territory, Queensland, South Australia and Western Australia, and is investigating the potential mineral, energy and groundwater resources in northern Australia and South Australia. The EFTF is a four-year $100.5 million investment by the Australian Government in driving the next generation of resource discoveries in northern Australia, boosting economic development across this region. This Data Release (Phase 1) Package contains the final survey deliverables produced by the contractor CGG, including: <p>a) The operations and processing report. <p>b) Final processed electromagnetic, magnetic and elevation point located line data. <p>c) Final processed electromagnetic, magnetic and elevation grids. <p>d) Conductivity estimates generated by the EM Flow® conductivity depth-imaging algorithm. <p>e) Graphical multi-plots of line data and EM Flow® conductivity sections. <p>f) Graphical stacked EM Flow® conductivity sections. <p>g) ESRI shape-files containing the flight line locations. <p>An updated release package (Phase 2), which contains results from our in-house inversion of the EM data (from this Phase 1 release), which includes the regional and infill areas are downloadable from the link provided in the Downloads tab.