Airborne electromagnetic (AEM) data measure variations in the conductivity of the ground by transmitting an electromagnetic signal from a system attached to a plane or helicopter. Depending on the AEM system used and the sub-surface conditions, AEM techniques can detect variations in the conductivity of the ground to a depth of several hundred metres. The responses recorded are commonly caused by the presence of electrically conductive materials such as salt or saline water, graphite, clays and sulphide minerals. <b>Value:</b> Data used for interpreting the geologic structure of the subsurface. This work can be used for the assessment of resource potential. <b>Scope:</b> Systematic coverage of large portions of the Australian continent.

The Capricorn 2013 AEM TEMPEST® survey, conducted as part of the Western Australia Exploration Incentive Scheme and managed by Geoscience Australia on behalf of the Geological Survey of Western Australia (GSWA), is a $2.5 million contribution to the Distal Footprints of Giant Ore Systems: UNCOVER Australia. The Capricorn 2013 AEM survey is Stage 1 of the WA Reconnaissance Airborne Electromagnetic Survey (WARAEM) 2013-20 National Geoscience Agreement project, designed to provide broad-acre, wide line-spacing, airborne electromagnetic (AEM) data over the approximately 70% of the area of Western Australia that is underlain by Precambrian rocks that occur at or within about 300 m of the surface. The Capricorn Orogen is a geologically complex area, the surface expression of which has a surface extent of approximately 240,000 square kilometres (approximately 9 per cent of the area of the State). It is prospective for potentially large discoveries of gold, copper, and other base metals. The Capricorn 2013 AEM TEMPEST data release includes the final contractor supplied (Phase 1) datasets from the TEMPEST® time domain AEM survey as well as a set of GSWA-produced imagery made from the data. The data release package includes: - Point-located, computed B-field EM time-series channel data in ASEG-GDF2 (ASCII) format (also TMI and terrain data) - Point-located computed conductivity and terrain data in ASCII format - Data multiplots (EM x- and z-component time series, CDI sections, TMI, altimeter and monitor channels) in PDF format - CDI stacked sections in PDF format - Gridded data: EM time constant (x- and z-components); selected conductivity-depth slices (in ER Mapper format, 1 km cell size) - Geo-referenced images of gridded EM data in JP2 format - Geo-referenced images of gridded TMI, Ternary Radiometrics, Bouger Gravity and DEM data in JP2 format - Flight path map in ESRI shapefile format - Survey operations report in PDF format - Metadata and License files

AusAEM (WA) 2020-21, Earaheedy & Desert Strip Airborne Electromagnetic Survey The accompanying data package, titled “AusAEM (WA) 2020-21,Earaheedy & Desert Strip Airborne Electromagnetic Survey Blocks: TEMPEST® airborne electromagnetic data and GALEI conductivity estimates”, was released on 25 March 2021 by Geoscience Australia (GA) and the Geological Survey of Western Australia. The data represents the first phase of the AusAEM2020 (WA) survey flown with a fixed-wing aircraft by CGG Aviation (Australia) Pty. Ltd. under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. The survey was flown at a 20-kilometre nominal line spacing over the most eastern part of the state and down to the southern coast of Western Australia. The total area encompasses close to 32,680 line kilometres of newly acquired airborne electromagnetic geophysical data. CGG also processed the data. This package contains 14,279 line kilometres of the survey data, which have been quality-controlled, processed and inverted. The Earaheedy Block entailed approximately 6,407 line kilometres and the Desert Strip 7,870 line kilometres. The remaining data will be released as a separate package. 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. GA 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 and TEMPEST® system specification files 3. ESRI shapefiles for the regional and infill flight lines 4. Final processed point located line data in ASEG-GDF2 format 5. Conductivity estimates generated by CGG’s EMFlow conductivity-depth transform -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -Grids generated from CGG's inversion conductivity-depth transform in ER Mapper® format (layer conductivities) 6. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages)

<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

<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.

AusAEM (WA) 2020-21, Eastern Goldfields & East Yilgarn Airborne Electromagnetic Survey The accompanying data package, titled “AusAEM (WA) 2020-21, Eastern Goldfields & East Yilgarn Airborne Electromagnetic Survey Blocks: TEMPEST® airborne electromagnetic data and GALEI conductivity estimates”, was released on 4 February 2021 by Geoscience Australia (GA) and the Geological Survey of Western Australia. The data represents the first phase of the AusAEM2020 (WA) survey flown with a fixed-wing aircraft by CGG Aviation (Australia) Pty. Ltd. under contract to Geoscience Australia, using the TEMPEST® airborne electromagnetic system. The survey was flown at a 20-kilometre nominal line spacing over the most eastern part of the state and down to the southern coast of Western Australia. The total area encompasses close to 32,680 line kilometres of newly acquired airborne electromagnetic geophysical data. CGG also processed the data. This package contains 18,482 line kilometres of the survey data, which have been quality-controlled, processed and inverted. The East Yilgarn Block entailed approximately 12,590 line kilometres and the Eastern Goldfields 5,892 line kilometres. The remaining data will be released as a separate package. 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. GA 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 and TEMPEST® system specification files 3. ESRI shapefiles for the regional and infill flight lines 4. Final processed point located line data in ASEG-GDF2 format 5. Conductivity estimates generated by CGG’s EMFlow conductivity-depth transform -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -Grids generated from CGG's inversion conductivity-depth transform in ER Mapper® format (layer conductivities) 6. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages)