<p>The Exploring for the Future (EFTF) initiative aims to reduce the technical risk of mineral exploration by providing pre-competitive data and information to support investment and mineral exploration in northern Australia – a key part of ensuring Australia's future economic prosperity. <p>To support the EFTF initiative, the presence of hydrothermal alteration systems associated with iron oxide copper-gold (IOCG) deposits were estimated throughout the Tennant Creek -– Mt Isa Project area of northern Australia. These zones are of economic interest due to their potential to host copper, gold, uranium and rare earth element mineralisation. <p>To predict the presence of IOCG-related alteration, gravity and magnetic intensity data were used to produce 3D models of density and magnetic susceptibility, respectively. The inversion models provide an indication of the volume and distribution of these physical properties within the subsurface and were used to define volumes with relatively high densities and high magnetic susceptibilities as proxies for magnetite-rich alteration and volumes with high density, but low magnetic susceptibility, as proxies for hematite-rich alteration. <p>Contact zones between these two sets of volumes are considered to be the most favourable areas for potential IOCG mineralisation. However, the inversion modelling inevitably will have mapped a number of ‘false positives’, which will require more detailed inversion modelling and/or other data sets to discriminate these from true IOCG-related alteration.

<div>This document defines the technical standards set by Geoscience Australia for the acquisition, processing and supply of airborne magnetic, horizontal magnetic gradient and radiometric (gamma-ray spectrometric) data. The technical standards cover the requirements for equipment, calibrations, quality control checks, reporting and data formats for airborne surveys.</div><div><br></div><div><br></div><div><strong>Table of Contents</strong></div><div><br></div><div>Attachment 1A – Data Acquisition and Processing</div><div><br></div><div>1 Aircraft</div><div>2 Flight and Tie Lines</div><div>3 Global Navigation Satellite System (GNSS)</div><div>4 Parallax Correction</div><div>5 Altimeter</div><div>6 Barometer</div><div>7 Digital Elevation Model</div><div>8 Magnetic System Equipment</div><div>9 Magnetic Gradient System Equipment</div><div>10 Magnetic / Gradient Calibration and Quality Tolerances</div><div>11 Magnetic Base Station (Diurnal Monitoring)</div><div>12 Magnetic Data Reduction</div><div>13 Magnetic Gradient Data Reduction</div><div>14 Radiometric System Equipment</div><div>15 Radiometric Calibration and Quality Tolerances</div><div>16 Radiometric Data Reduction</div><div><br></div><div>Attachment 1B – Reporting and Data Supply</div><div><br></div><div>1 General</div><div>2 Calibration Report</div><div>3 Daily Acquisition Report</div><div>4 Weekly Acquisition Report</div><div>5 Operations and Processing Summary Report</div><div>6 Supply Schedule</div><div><br></div><div>Attachment 1C – Data Formats</div><div><br></div><div>1 General</div><div>2 Point-Located Data Files</div><div>3 Definition Files</div><div>4 Description Files</div><div>5 Raw-Edited Magnetic Data File</div><div>6 Reduced Magnetic Data File</div><div>7 Diurnal Magnetic Data File</div><div>8 Raw-Edited Magnetic Gradient Data File</div><div>9 Reduced Magnetic Gradiometry Data File</div><div>10 Raw-Edited Radiometric Data File</div><div>11 Reduced Radiometric Data File</div><div>12 Gridded Data Files</div><div>13 Image Enhanced GeoTIFF Files

<div>This report contains information about the operation of Geoscience Australia’s ten permanent geomagnetic observatories, repeat stations and other relevant information covering the period from 2017 to 2021.</div><div>Information regarding the activities and services of Geoscience Australia’s Geomagnetism program, distribution of geomagnetic data, geomagnetic instrumentation and data processing procedures is also provided.</div><div><br></div>

Survey Name: East Tasmania Datasets Acquired: Magnetics, Radiometrics and Elevation Geoscience Australia Project Number: P5020 Acquisition Start Date: 20/03/2022 Acquisition End Date: 23/06/2022 Flight line spacing: 200 m Flight line direction: East-West (090-270) Total distance flown: 57,709 line-km's Nominal terrain clearance: 80 m Data Acquisition: Magspec Airborne Surveys Pty Ltd Project Management: Geoscience Australia Quality Control: Geoscience Australia Dataset Ownership: Geoscience Australia and Mineral Resources Tasmania Datum: Geocentric Datum of Australia 2020 (GDA2020) Projection: Map Grid of Australia 55 (MGA55) Included in this release: 1. Point-located Data - ASCII-column (.dat) or NetCDF (.nc) format. • Magnetic diurnal; • Magnetics raw-edited; • Magnetics reduced; • Radiometrics raw-edited; • Radiometrics reduced. 2. Gridded data - ERMapper (.ers) format. • Total magnetic intensity (TMI); • TMI reduced to pole (RTP); • TMI RTP with first vertical derivative (1VD) applied; • Dose rate (with NASVD and standard processing); • Potassium concentration (with NASVD, standard processing); • Thorium concentration (with NASVD, standard processing); • Uranium concentration (with NASVD, standard processing); • Radar-derived digital elevation model (geoidal). 3. Reports. • Calibration report; • Operations and processing summary report. © Commonwealth of Australia (Geoscience Australia) and Mineral Resources Tasmania, Government of Tasmania 2022. With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International Licence (http://creativecommons.org/licenses/by/4.0/legalcode).

<div>Near-surface magnetizations are ubiquitous across many areas of Australia and complicate reliable estimation of depth to deeper magnetizations. We have selected four test areas in which we use equivalent source dipoles to represent and quantify the near-surface magnetizations. We present a synthetic modelling study that demonstrates that field variations from the near-surface magnetizations substantially degrade estimation of depth to a magnetization 500 metres below the modelled sensor elevation and that these problems persist even for anomalies with significantly higher amplitudes. However, preferential attenuation of the fields from near surface magnetizations by upward continuation proved quite effective in improving estimation of depth to those magnetizations.</div> This Abstract was submitted/presented at the 2023 Australasian Exploration Geoscience Conference (AEGC) 13-18 March (https://2023.aegc.com.au/)

Survey Name: Cobar magnetic and radiometric survey, 2021 Datasets Acquired: Magnetics, Radiometrics and Elevation Geoscience Australia Project Number: P5009 Acquisition Start Date: 8/06/2021 Acquisition End Date: 10/08/2021 Flight line spacing: 200 m Flight line direction: East-West (090-270) Total distance flown: 53,617 line-km Nominal terrain clearance: 60 m Blocks: 7 Data Acquisition: Magspec Airborne Surveys Project Management: Geoscience Australia Quality Control: Baigent Geosciences P.L. on behalf of Geoscience Australia Dataset Ownership: Geological Survey of NSW and Geoscience Australia Included in this release: 1. Point-located Data ASCII-column data with accompanying description and definition files. • Magnetics corrected i. Magnetic data with corrections for diurnal, IGRF, tie-levelling, micro-levelling. ii. Elevation data converted to geoidal values and a digital elevation model. • Radiometrics corrected i. Equivalent ground concentrations of radioelements with and without NASVD spectral filtering and standard IAEA processing, pressure, temperature and survey altitude. 2. Grids Gridded data in ERMapper (.ers) format (GDA94, MGA55). • Total magnetic intensity (TMI). • TMI reduced to pole (RTP). • TMI RTP with first vertical derivative applied. • Dose rate (with NASVD and standard processing). • Potassium concentration (%, with NASVD, standard processing). • Thorium concentration (ppm, with NASVD, standard processing). • Uranium concentration (ppm, with NASVD, standard processing). • Radar-derived digital elevation model (geoidal). 3. Images Data in tagged image format (TIF), (GDA94, MGA55). • Total magnetic intensity (TMI). • TMI reduced to pole (RTP). • TMI RTP with first vertical derivative applied. • Dose rate (with NASVD and standard processing). • Potassium concentration (% with NASVD, standard processing). • Thorium concentration (ppm, with NASVD, standard processing). • Uranium concentration (ppm, with NASVD, standard processing). • Radar-derived digital elevation model (geoidal). 4. Reports • P5009_2585_V3_GA_Cobar_Logistics_Report • P5009_BGS_GA_CobarQCReport © Geological Survey of New South Wales and Commonwealth of Australia (Geoscience Australia) 2021. With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International License. (http://creativecommons.org/licenses/by/4.0/legalcode).

<div>In July 2022 an airborne electromagnetic (AEM) survey was flown over and around the proposed site of the National Radioactive Waste Management Facility near the township of Kimba in South Australia.&nbsp;The survey was commissioned by the Australian Radioactive Waste Agency, and was project managed by Geoscience Australia. The survey has Geoscience Australia airborne survey project number P5008.</div><div><br></div><div>The survey was flown by Skytem Australia Pty Ltd using its SkyTEM312Fast AEM system.&nbsp;The survey was conducted on east-west lines at 500 m spacing, with a smaller central focus area of 100 m spaced lines, acquiring a total of 2,545 line kilometres of data. Skytem Australia Pty Ltd also processed the data.</div><div><br></div><div>This data package includes the acquisition and processing report, the final processed AEM data and the results of the 1D laterally constrained inversion of the data to conductivity-depth estimates that was carried out by the contractor.</div>

<div>Geoscience Australia (GA), in collaboration with the New South Wales (NSW) Government’s Geological Survey of NSW, undertook a horizontal magnetic gradient and radiometric survey in the Yathong area of NSW. This survey was fully funded by the NSW Government as part of a project to find deep groundwater for use in times of drought.</div><div><br></div><div>Survey Name: Yathong</div><div>Datasets Acquired: Horizontal Magnetic Gradient, Radiometrics, and Elevation</div><div>Geoscience Australia Project Number: P5023</div><div>Acquisition Start Date: 21/05/2023</div><div>Acquisition End Date: 14/09/2023</div><div>Flight line spacing: 200 m</div><div>Flight line direction: East-West (090-270 degrees)</div><div>Total distance flown: 65,503.75 line-km's</div><div>Nominal terrain clearance: 80 m</div><div>Data Acquisition: Magspec Airborne Surveys Pty Ltd</div><div>Project Management: Geoscience Australia</div><div>Quality Control: Geoscience Australia</div><div>Dataset Ownership: Geological Survey of New South Wales</div><div>Datum: Geocentric Datum of Australia 2020 (GDA2020)</div><div>Projection: Map Grid of Australia Zone 55 (MGA55)</div><div><br></div><div>Included in this release:</div><div><br></div><div>1. Point-located Data - ASCII-column (.dat) and NetCDF (.nc) format.</div><div>• Magnetic diurnal;</div><div>• Magnetic gradient raw-edited;</div><div>• Magnetic gradient reduced;</div><div>• Radiometrics raw-edited;</div><div>• Radiometrics reduced.</div><div><br></div><div>2. Gridded data - ERMapper (.ers) format.</div><div>• Gradient enhanced Total Magnetic Intensity (TMI);</div><div>• Gradient enhanced TMI Reduced to Pole (RTP);</div><div>• Gradient enhanced TMI RTP with First Vertical Derivative (1VD);</div><div>• Dose rate (with NASVD and standard processing);</div><div>• Potassium concentration (with NASVD, standard processing);</div><div>• Thorium concentration (with NASVD, standard processing);</div><div>• Uranium concentration (with NASVD, standard processing);</div><div>• Radar-derived digital elevation model (geoidal).</div><div><br></div><div>3. Reports.</div><div>• Calibration report;</div><div>• Operations and processing summary report.</div>

Geoscience Australia is the custodian of the most comprehensive publicly available Australian airborne magnetic, gamma-ray, seismic, electromagnetic and gravity data sets. The airborne geophysics data set contains approximately 34 million line kilometres of data, which, at current prices, would cost approximately $197 million to acquire. The gravity data set contains more than 1.57 million reliable onshore stations gathered during more than 1800 surveys. The collection also includes a large number of seismic surveys from Australia's offshore basins. The onshore component of this data set was previously approved for RDSI for 8 TB. This proposal extends the collection to 150TB. The data types and access methods for the Offshore and Onshore data are identical Certain holdings are additionally hosted at the NCI (see downloads)

Several products were produced from the Total Magnetic Intensity (TMI) Grid of Australia 2019, seventh edition (eCat ID 131505). The grid was found to include 3 extreme, high-amplitude cultural data spikes from current and historical aluminium smelters in Victoria and Tasmania. Also, 3 data spikes of unknown origin were located in the Hunter region of NSW. These 6 data spikes were removed from the gridded data. The following products were produced from the grid with the data spikes removed: 1. Total Magnetic Intensity (TMI) edited grid (.ers) 2. Variable Reduction to Pole (VRTP) grid (.ers) 3. First Vertical Derivative (1VD) grid (.ers) 4. Half Vertical Derivative (05VD) grid (.ers) 5. Pseudo-Gravity (PGrav) grid (.ers) 6. Pseudo-Gravity, Total Horizontal Derivative (THD) grid (.ers) 7. Susceptibility (Sus) grid (.ers) 8. Variable Vertical Gradient (VBzz) grid (.ers) 9. Analytic Signal (AS; Total Gradient) grid (.ers) 10. Tilt Angle (Tilt; Phase Map) grid (.ers) 11. Tilt Angle (Tilt; Phase Map), Total Horizontal Derivative (THD) grid (.ers) 12. Upward Continuation (UC) Residual (Res) Filters (0 to 100 km; 12 grids) 13. Mutliscale Edge Detection Polygons (for each MGA zone; .shp) 14. Analytic Signal Phase Polygons (.shp) 15. GeoTiff Images (of all grids; .tif)