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  • Airborne electromagnetic data (AEM) are used in many and diverse applications such as mineral and energy exploration, groundwater investigations, natural hazard assessment, agriculture, city planning and defence. Unfortunately, many users do not have access to a simple workflow for assessing the quality of the data that they are using. This poster outlines the main quality assurance and quality control (QA-QC) procedures used by Geoscience Australia for our 2008-11 AEM surveys. Minor processing errors can dramatically reduce the quality of the data to the point that interpreters will be unable to use the data, or worse still, will be misled by features or characteristics produced during acquisition and processing. These scenarios not only impact the application at the time of interpretation, but can seriously impact the reputation and perceptions of the AEM industry. Every effort should be made to ensure that maximum fidelity is preserved in the data during acquisition and processing so that the best possible data are available for interpretation. Geoscience Australia is embarking on a project to upgrade the National Airborne Geophysical Database to better manage the data from major AEM surveys. This will better preserve the data and associated documentation to allow users to access and take advantage of the data well into the future. The quality of historical data included in this endeavour will unfortunately be variable and dependent on the QA-QC standards of the time. Geoscience Australia currently holds over 150 000 line kilometres of AEM data funded by the Commonwealth Government, State Governments and industry. Much of this data is available online for download, but is not available via the Geophysical Archive Data Delivery System (GADDS). Geoscience Australia is planning the expansion of GADDS to accommodate AEM data into the future. It is hoped the procedures outlined on the poster will be widely accepted by users, in particular new users, as a set of minimum requirements to help ensure that AEM data will be of a consistent quality and to a higher standard acknowledging it as the valuable resource it is. Key words: Airborne electromagnetic data; National Airborne Geophysical Database; AEM; QA-QC.

  • In 2001, the Murray Darling Basin Commission (MDBC) funded a survey to collect airborne electromagnetic (AEM) datasets for Billabong Creek (GA Project # 904) under MDBC's Strategic Investigations and Education (SI&E) Program, as part of Airborne Geophysics - SI&E Project D2018. The project was a pilot testing the relevance of airborne geophysics data for salinity management, and evolved from the National Geophysics Project originally sponsored under the National Dryland Salinity Program. The data are now being publicly released through Geoscience Australia's National Airborne Geophysics Database.

  • The Frome airborne electromagnetic (AEM) survey was designed to provide reliable pre-competitive AEM data to aid the search for energy and mineral resources around the Lake Frome region of South Australia. Flown in 2010, a total of 32,317 line kilometres of high quality airborne geophysical data were collected over an area of 95,450 km2 at a flight line spacing mostly of 2.5 km, opening to 5 km spaced lines in the Marree-Strzelecki Desert area to the north. The Lake Frome region hosts a large number of sandstone-hosted uranium deposits with known resources of ~60,000 tonnes of U3O8 including the working In Situ Recovery (ISR) operations at Beverley, Pepegoona, Pannikin and Honeymoon, and deposits at Four Mile East, Four Mile West, Yagdlin, Goulds Dam, Oban and Junction Dam. The aims of the Frome AEM Survey were to map critical elements of sandstone-hosted uranium mineral systems including basin architecture, palaeovalley morphology, sedimentary facies changes, hydrological connections between uranium sources and uranium sinks and structures that may control uranium mineralisation. Interpretations of the data show the utility of regional AEM surveying for mapping sandstone-hosted uranium mineral systems as well as for mapping geological surfaces and depth of cover over a wide area. Data from the Frome AEM Survey allow mineral explorers to put their own high-resolution AEM surveys into a regional context. Survey data were used to map a range of geological features that are associated with, or control the location of, sandstone-hosted uranium mineral systems and have been used to map and assess the prospectivity of new areas to the north of the Flinders Ranges.

  • Identification of groundwater-dependent (terrestrial) vegetation, and assessment of the relative importance of different water sources to vegetation dynamics commonly involves detailed ecophysiological studies over a number of seasons or years. However, even when groundwater dependence can be quantified, results are often difficult to upscale beyond the plot scale. Consequently, quicker, more regional mapping approaches have been developed. These new approaches utilise advances in computation geoscience, and remote sensing and airborne geophysical technologies. The Darling River Floodplain, western New South Wales, Australia, was selected as the case study area. This semi-arid landscape is subject to long periods of drought followed by extensive flooding. Despite the episodic availability of surface water resources, two native Eucalyptus species, E. camaldulensis (River Red Gum) and E. largiflorens (Black Box) continue to survive in these conditions. Both species have recognised adaptations, include the ability to utilise groundwater resources at depth. A remote sensing methodology was developed to identify those communities potentially dependent on groundwater resources during the recent millennium drought in Australia.

  • During 2008 and 2009, and under the Australian Government's Onshore Energy Security Initiative, Geoscience Australia acquired airborne electromagnetic (AEM) data over the Pine Creek Orogen of the Northern Territory. The survey area was split into three areas for acquisition. VTEM data was acquired in the Kombolgie area east of Kakadu National Park between August and November 2008. TEMPEST data was acquired west of Kakadu National Park with the area split in two to facilitate the use of two aircraft: the Woolner Granite area in the north (this data set) was acquired between October and December 2008; and the Rum Jungle area adjoining to the south, was acquired between October 2008 and May 2009. The main purpose of the surveys was to provide additional geophysical/geological context for unconformity style uranium mineral systems and thereby promote related exploration. The survey data will also provide information on depth to Proterozoic/Archean basement, which is of general interest to explorers, and will be used as an input into ground water studues in the region.

  • Airborne Electromagnetic data are being acquired by Geoscience Australia in areas considered to have potential for uranium or thorium mineralisation under the Australian Government's Onshore Energy Security Program (OESP). The surveys have been managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation project. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Frome Embayment AEM survey was acquired using the TEMPESTTM AEM system by Fugro Airborne Surveys under contract to GA. The survey covers a total of 32 300 line km and an area of 95 450 km2, the largest AEM survey by area ever flown in Australia. Phase-1 data, that is, contractor quality-controlled and quality-assessed data for the Frome survey, were released during March 2011. Phase-2 data, that is Geoscience Australia layered earth inversion (GA-LEI) data and derived products are included in this data release. The data and products described in this report are available from the GA AEM website, and are contained on the accompanying DVD.

  • The Southern Thomson Orogen VTEM-plus® Airborne Electromagnetic Survey was conducted by Geoscience Australia as part of a collaborative project with its partners the Geological Survey of New South Wales and the Geological Survey of Queensland. The Survey contributes to the Australian Academy of Science's UNCOVER Initiative and Geoscience Australia's response to this as part of the National Mineral Exploration Strategy. Geoscience Australia contracted Geotech Airborne Ltd to acquire VTEM-plus® airborne electromagnetic (AEM) data over part of the Southern Thomson Orogen in Queensland and New South Wales in April and May 2014. The data were also processed by Geotech Airborne Ltd using its FullWaveForm® processing techniques. The survey is designed to assess the under-cover geology and prospectivity of the Southern Thomson Orogen around Hungerford and Eulo and straddles the New South Wales-Queensland border. The survey comprises two parts: 1. A regular regional survey on 5000 m spaced East-West lines totalling 3352 line km and covering an area of 16 261 km2. 2. Two regional traverses adjacent various roads totalling 915 line km. The Southern Thomson Orogen is a priority area for mineral systems research. Much of the area lies underneath cover of sedimentary basins and is a poorly-understood element of Australia's geology. The Orogen contains Cambro-Ordovician rocks that have potential for Iron Oxide Copper-Gold (IOCG) resources, porphyry copper-gold and Volcanic-Hosted Massive Sulphide (VHMS) deposits. Survey data will add to knowledge of cover thickness and character and will inform future geological mapping in the region. The Southern Thomson Orogen VTEM-plus® AEM Survey data release includes the final contractor supplied (Phase 1) datasets AEM survey. The data will be available from Geoscience Australia's web site free of charge: http://www.ga.gov.au/about/what-we-do/projects/minerals/current/continental-geophysics/airborne-electromagnetics The data release package includes: 1. Point-located electromagnetic dB/dt and derived B-field data with associated position, altimeter, orientation, magnetic gradiometer, and derived ground elevation data. These data are in ASCII column format with associated README and ASEG-GDF2 header files. The dataset consists of a separate download file for the: a. Main survey block Part 1 (flight lines 1000-1171) b. Main survey block Part 2 (flight lines 1180-1360) c. Traverse lines (flight lines 3000-3006 and 4000-4007) d. Repeat lines e. High altitude lines. 2. Waveform files for every flight containing the 192 kHz sampling of the transmitter current and receiver waveforms. 3. Point-located conductivity estimates derived using the EM Flow® conductivity depth imaging (CDI) algorithm with associated position, altimeter, orientation, magnetic gradiometer, and derived ground elevation data. Data include the conductivity estimate for each 5 m interval and selected depth slices. These data are in ASCII column format with associated README and ASEG-GDF2 header files. All regular survey, traverses and repeat lines are included in a single download file. 4. Gridded data, at 1 km cell size in, for the conductivity depth slices derived from the EM Flow® CDI data, magnetics and elevation data in ER Mapper® binary raster grid format with associated header files. 5. Graphical multiplots, in PDF format, for each flight line showing EM Flow® CDI sections and profiles of Z-component dB/dt data, magnetics, powerline monitor, height and orientation data. 6. Operations Report. 7. ESRI shapefiles and KML files of flight lines. 8. Metadata and License files.

  • Airborne Electromagnetic data are being acquired by Geoscience Australia in areas considered to have potential for uranium or thorium mineralisation under the Australian Government's Onshore Energy Security Program (OESP). The surveys have been managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation project. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Frome Embayment AEM survey was acquired using the TEMPEST<sup>TM</sup> AEM system by Fugro Airborne Surveys under contract to Geoscience Australia. The survey covers a total of 32 300 line km and an area of 95 450 km<sup>2</sup>, the largest AEM survey by area ever flown in Australia. Phase-1 data, that is, contractor quality-controlled and quality-assessed data for the Frome survey, were released during March 2011. Phase-2 data, that is Geoscience Australia layered earth inversion (GA-LEI) data and derived products to 400m were released in July 2011. This data package contains GA-LEI data and derived products to 200m. Data and products described in this report are available from the GA AEM website.

  • Airborne Electromagnetic data are being acquired by Geoscience Australia in areas considered to have potential for uranium or thorium mineralisation under the Australian Government's Onshore Energy Security Program (OESP). The surveys have been managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation project. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Pine Creek airborne electromagnetic survey comprised of three survey areas Woolner Granite, Rum Jungle and Kombolgie. Tempest data were acquired for Woolner Granite and Rum Jungle survey areas and are included in this report. Woolner Granite and Rum Jungle survey areas cover a total of 21 100 line km and an area of 43 200 km2. Phase-1 data, that is, contractor quality-controlled and quality-assessed data for Woolner Granite, Rum Jungle and Kombolgie, were released during 2009. Phase-2 data, that is Geoscience Australia layered earth inversion (GA-LEI) data and derived products for Woolner Granite and Rum Jungle, are included in this data release. The data and products described in this report are contained on the accompanying DVD. The Kombolgie survey data were acquired with VTEM. The VTEM Kombolgie inversion data and report will be included in a separate data release. The main products from the AEM surveys are conductivity depth slices and sections, conductance grids and an AEM Depth of Investigation grid. The data is provided in formats which can be viewed on most computers systems. They include, JPEG (.jpg) with associated world files for easy use in geographic information system (GIS) packages, ER Mapper grids (.ers), ESRI shape files (.shp) of the flight path, and point-located ASCII data with relevant metadata for derived products.

  • Geoscience Australia (GA) is a leading promoter of airborne electromagnetic (AEM) surveying for regional mapping of cover thickness, under-cover basement geology and sedimentary basin architecture. Geoscience Australia flew three regional AEM surveys during the 2006-2011 Onshore Energy Security Program (OESP): Paterson (Western Australia, 2007-08); Pine Creek-Kombolgie (Northern Territory, 2009); and Frome (South Australia, 2010). Results from these surveys have produced a new understanding of the architecture of critical mineral system elements and mineral prospectivity (for a wide range of commodities) of these regions in the regolith, sedimentary basins and buried basement terrains. The OESP AEM survey data were processed using the National Computational Infrastructure (NCI) at the Australian National University to produce GIS-ready interpretation products and GOCADTM objects. The AEM data link scattered stratigraphic boreholes and seismic lines and allow the extrapolation of these 1D and 2D objects into 3D, often to explorable depths (~ 500 m). These data sets can then be combined with solid geology interpretations to allow researchers in government, industry and academia to build more reliable 3D models of basement geology, unconformities, the depth of weathering, structures, sedimentary facies changes and basin architecture across a wide area. The AEM data can also be used to describe the depth of weathering on unconformity surfaces that affects the geophysical signatures of underlying rocks. A number of 3D models developed at GA interpret the under-cover geology of cratons and mobile zones, the unconformity surfaces between these and the overlying sedimentary basins, and the architecture of those basins. These models are constructed primarily from AEM data using stratigraphic borehole control and show how AEM data can be used to map the cross-over area between surface geological mapping, stratigraphic drilling and seismic reflection mapping. These models can be used by minerals explorers to more confidently explore in areas of shallow to moderate sedimentary basin cover by providing more accurate cover thickness and depth to target information. The impacts of the three OESP AEM surveys are now beginning to be recognised. The success of the Paterson AEM Survey has led to the Geological Survey of Western Australia announcing a series of OESP-style regional AEM surveys for the future, the first of which (the Capricorn Orogen AEM Survey) completed acquisition in January 2014. Several new discoveries have been attributed to the OESP AEM data sets including deposits at Yeneena (copper) and Beadell (copper-lead-zinc) in the Paterson region, Thunderball (uranium) in the Pine Creek region and Farina (copper) in the Frome region. New tenements for uranium, copper and gold have also been announced on the results of these surveys. Regional AEM is now being applied in a joint State and Commonwealth Government initiative between GA, the Geological Survey of Queensland and the Geological Survey of New South Wales to assess the geology and prospectivity of the Southern Thomson Orogen around Hungerford and Eulo. These data will be used to map the depth of the unconformity between the Thomson Orogen rocks and overlying sedimentary basins, interpret the nature of covered basement rocks and provide more reliable cover thickness and depth to target information for explorers in this frontier area.