Under the Community Stream Sampling and Salinity Mapping Project, the Australian Government through the Department of Agriculture, Fisheries and Forestry and the Department of Environment and Heritage, acting through Bureau of Rural Sciences, funded an airborne electromagnetic (AEM) survey to provide information in relation to land use questions in selected areas along the River Murray Corridor (RMC). The proposed study areas and major land use issues were identified by the RMC Reference Group at its inception meeting on 26th July, 2006. This report has been prepared to facilitate recommendations on the Lindsay-Wallpolla study area. The work was developed in consultation with the RMC Technical Working Group (TWG) to provide a basis for the RMC Reference Group and other stake holders to understand the value and application of AEM data to the study area. This understanding, combined with the Reference Group's assessment of the final results and taking in account policy and land management issues, will enable the Reference Group to make recommendations to the Australian Government.

Predictive maps of the subsurface can be generated when geophysical datasets are modelled in 2D and 3D using available geological knowledge. Inversion is a process that identifies candidate models which explain an observed dataset. Gravity, magnetic, and electromagnetic datasets can now be inverted routinely to derive plausible density, magnetic susceptibility, or conductivity models of the subsurface. The biggest challenge for such modelling is that any geophysical dataset may result from an infinite number of mathematically-plausible models, however, only a very small number of those models are also geologically plausible. It is critical to include all available geological knowledge in the inversion process to ensure only geologically plausible physical property models are recovered. Once a set of reasonable physical property models are obtained, knowledge of the physical properties of the expected rocks and minerals can be used to classify the recovered physical models into predictive lithological and mineralogical models. These predicted 2D and 3D maps can be generated at any scale, for Government-funded precompetitive mapping or drilling targets delineation for explorers.

The Pine Creek AEM survey was flown over the Pine Creek Orogen in the Northern Territory during 2008 and 2009 as part of the Australian Government's Onshore Energy Security Program at Geoscience Australia (GA). The survey covers an area of 74,000 km2 from Darwin to Katherine in the Northern Territory which hosts several world class deposits, including the Ranger Uranium Mine, Nabarlek, Mt Todd, Moline and Cosmo Howley. Aimed at regional mapping, uranium exploration, reducing exploration risk and promoting exploration activity, the program worked closely with industry partners to infill wide regional line spacing (5km) with deposit scale line spacing (less than 1km). The survey results are relevant in exploration for a variety of commodities and resources, including uranium, copper, lead, zinc, gold, nickel and groundwater. Geoscience Australia's interpretation products include sample-by-sample layered earth inversion products comprising located data, geo-located conductivity depth sections, depth slice grids, elevation slice grids, inversion report and an interpretation report. All data and products are available from GA as well as the Northern Territory Geological Survey Geophysical Image Web Server.

The Frome airborne electromagnetic (AEM) survey is the largest of three regional AEM surveys flown under the 5-year Onshore Energy Security Program (OESP) by Geoscience Australia (GA). The aim of the survey is to reduce risk and stimulate exploration investment for uranium by providing reliable pre-competitive data. The Frome AEM survey was flown between 22 May and 2 November 2010, is approximately 95 450 km2 in area and collected 32 317 line km of new data at an average flying height of 100 m. The Frome AEM survey covers the Marree (pt), Callabonna (pt), Copley (pt), Frome (pt), Parachilna (pt), Curnamona, Olary and Chowilla (pt) 1:250 000 standard map sheets in South Australia and was flown largely at 2.5 km line spacing, with the northern portion flown at 5 km line spacing. GA partnered with, the Department of Primary Industries and Resources South Australia and an industry consortium. The survey results indicate a depth of investigation (DOI - depth of reliable signal penetration) of up to 400 m in areas of thin cover and resistive basement (e.g., Adelaidean rocks in the Olary Ranges). In Cenozoic - Mesozoic sediments in the Frome Embayment and the Murray Basin the DOI is up to 100-150 m. A range of under-cover features are revealed, including (but not limited to): extensions to known palaeovalley networks in the Frome Embayment; the under-cover extent of the Benagerie Ridge; regional faults in the Frome Embayment and Murray Basin; folded and faulted Neoproterozoic rocks in the Adelaide Fold Belt; Cenozoic - Mesozoic stratigraphy in the Frome Embayment; neotectonic offsets in the Lake Eyre Basin; conductive Neoproterozoic rocks associated with copper-gold mineralisation; and, coal-bearing structures in the Leigh Creek area, as well as groundwater features.

The product consists of 8,800 line kilometres of time‐domain airborne electromagnetic (AEM) geophysical data acquired over the far north part of South Australia known as the Musgrave Province. This product release includes: a) the measured AEM point located data, b) electrical conductivity depth images derived from the dataset, and c) the acquisition and processing report. The data were acquired using the airborne SkyTEM312 Dual Moment 275Hz/25Hz electromagnetic and magnetic system, which covered a survey area of ~14,000 km2, which includes the standard 1:250 000 map sheets of SG52-12 (Woodroffe), SG52-16 (Lindsay), SG53-09 (Alberga) and SG53-13 (Everard). The survey lines where oriented N-S and flown at 2km, 500m and 250m line spacing. A locality diagram for the survey is shown in Figure 1. This survey was funded by the Government of South Australia, as part of the Plan for Accelerating Exploration (PACE) Copper Initiative, through the Department of the Premier and Cabinet, (DPC) and the Goyder Institute of Water Research. Geoscience Australia managed the survey as part of a National Collaborative Framework project agreement with SA. The principal objective of this project was to capture a baseline geoscientific dataset to provide further information on the geological context and setting of the area for mineral systems as well as potential for groundwater resources, of the central part of the South Australian Musgrave Province. Geoscience Australia contracted SkyTEM (Australia) Pty. Ltd. to acquire SkyTEM312 electromagnetic data, between September and October 2016. The data were processed and inverted by SkyTEM using the AarhusInv inversion program (Auken et al., 2015) and the Aarhus Workbench Laterally Constrained Inversion (LCI) algorithm (Auken et al. 2005; Auken et al. 2002). The LCI code was run in multi-layer, smooth-model mode. In this mode the layer thicknesses are kept fixed and the data are inverted only for the resistivity of each layer. For this survey a 30 layer model was used. The thickness of the topmost layer was set to 2 m and the depth to the top of the bottommost (half-space) layer was set to 600 m. The layer thicknesses increase logarithmically with depth. The thicknesses and depths to the top of each layer are given in Table 1. The regional AEM survey data can be used to inform the distribution of cover sequences, and at a reconnaissance scale, trends in regolith thickness and variability, variations in bedrock conductivity, and conductivity values of key bedrock (lithology related) conductive units under cover. The data will also assist in assessing groundwater resource potential and the extent of palaeovalley systems known to exist in the Musgrave Province. A considerable area of the survey data has a small amplitude response due to resistive ground. It very soon becomes evident that lack of signal translates to erratic non-monotonic decays, quite opposite to the smooth transitional exponential decays that occur in conductive ground. Some sections of the data have been flown over what appears to be chargeable ground, hence contain what potentially can be identified as an Induced Polarization effect (airborne IP—AIP). For decades these decay sign changes, which characterize AIP, have not been accounted for in conventional AEM data processing and modelling (Viezzoli et al., 2017). Instead they have mostly been regarded as noise, calibration or levelling issues and are dealt with by smoothing, culling or applying DC shifts to the data. Not accounting for these effects is notable on the contractor’s conductivity-depth sections, where data can’t be modelled to fit the data hence large areas of blank-space have been used to substitute the conductivity structure. The selection of the survey area was undertaken through a consultative process involving the CSIRO, GOYDER Institute, Geological Survey of South Australia and the exploration companies currently active in the region (including industry survey partner PepinNini Minerals Ltd). The data will be available from Geoscience Australia’s web site free of charge. It will also be available through the South Australian Government’s SARIG website at https://map.sarig.sa.gov.au. The data will feed into the precompetitive exploration workflow developed and executed by the Geological Survey of South Australia (GSSA) and inform a new suite of value-added products directed at the exploration community.

Presentation to minerals industry representatives at the Geological Survey of Western Australia, 4 May 2010.

Airborne Electromagnetic data were 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. Government of South Australia Department for Manufacturing, Innovation, Trade, Resources and Energy (DMITRE), formerly the Department of Primary Industries and Resources South Australia (PIRSA), which changed name in October 2011 purchased infill. Three survey areas were recognised in the Frome AEM survey area and Cariewerloo traverses. Industry paid for infill - all of this data has now been released to the public domain and is available at the GA website. In contrast to industry style deposit scale investigations, these surveys are designed to reveal new geological information at regional scale. The Frome airborne electromagnetic data were acquired at line spacing's of between one and five kilometres, a total of 32 317 line km and covers an area of 95 450 km squared. The outcomes of the Frome AEM survey include mapping of subsurface geological features that are associated with unconformity-related, sandstone-hosted and palaeovalley-hosted uranium mineralisation. The data are also capable of interpretation for other commodities including metals and potable water as well as for landscape evolution studies. The improved understanding of the regional geology resulting from the Pine Creek survey results will be of considerable benefit to mining and mineral exploration companies. This Data Package is for Archive to the internal area of the CDS and contains all data, grids, images, mxd, shape files, documentation, licenses, agreements, interpretations and scripts used to create the Frome deliverables. At the projects completion (2012) all directories are required to be moved off the NAS. The reason to keep all the files is that more work is to be done on this data in the 2012-2015 period and these files may be needed in this future work.

Presentation to minerals industry representatives at the Geological Survey of Western Australia, 4 May 2010.

Under the Community Stream Sampling and Salinity Mapping Project, the Australian Government through the Department of Agriculture, Fisheries and Forestry and the Department of Environment and Heritage, acting through Bureau of Rural Sciences, funded an airborne electromagnetic (AEM) survey to provide information in relation to land use questions in selected areas along the River Murray Corridor (RMC). The proposed study areas and major land use issues were identified by the RMC Reference Group at its inception meeting on 26th July, 2006. This report has been prepared to facilitate recommendations on the Nangiloc - Colignan study area. The work was developed in consultation with the RMC Technical Working Group (TWG) to provide a basis for the RMC Reference Group and other stake holders to understand the value and application of AEM data to the study area. This understanding, combined with the Reference Group's assessment of the final results and taking in account policy and land management issues, will enable the Reference Group to make recommendations to the Australian Government.

This report presents key results from hydrogeological investigations at Alice Springs, completed as part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. The Southern Stuart Corridor (SSC) project area within the Northern Territory extends in a north–south corridor from Tennant Creek to Alice Springs, encompassing four water control districts and a number of remote communities. Water allocation planning and agricultural expansion in the SSC is currently limited by a paucity of data and information regarding the volume and extent of groundwater resources and groundwater systems more generally. This includes recharge rates, surface water –groundwater connectivity, and the dependency of ecosystems on groundwater. Outside the proposed agricultural areas, the project includes numerous remote communities where there is a need to secure water supplies. Geoscience Australia, in partnership with the Northern Territory Department of Environment and Natural Resources and the Power and Water Corporation, undertook an extensive program of hydrogeological investigations between 2017 and 2019. Data acquisition included helicopter airborne electromagnetic (AEM) and magnetic data, investigative groundwater bore drilling, ground-based and downhole geophysical data (including nuclear magnetic resonance for mapping water content and induction conductivity/gamma for defining geological formations), and hydrochemistry for characterising groundwater systems. This report investigates the hydrogeology across the Alice Springs focus area, which includes the Roe Creek and proposed Rocky Hill borefields, where five hydrostratigraphic units were mapped based on AEM interpretation and borehole geophysical information. The mapping supports the presence of a syncline, with a gentle parabolic fold axis that plunges westward, and demonstrates that the main Siluro-Devonian Mereenie Sandstone and Ordovician Pacoota Sandstone aquifers are continuous from Roe Creek borefield to the Rocky Hill area. Areas with the highest potential for recharge to the Paleozoic strata are where Roe Creek or the Todd River directly overlie shallow subcrop of the aquifer units. Three potential recharge areas are identified: (1) Roe Creek borefield, (2) a 3 km stretch of Roe Creek immediately west of the proposed Rocky Hill borefield, and (3) the viticulture block to the east of Rocky Hill. Analysis of groundwater chemistry and regional hydrology suggests that the rainfall threshold for recharge of the Paleozoic aquifers is ~125 mm/month, and groundwater isotope data indicate that recharge occurs rapidly. The groundwaters have similar major ion chemistry, reflecting similar geology and suggesting that all of the Paleozoic aquifers in the focus area are connected to some degree. Groundwater extraction at Roe Creek borefield since the 1960s has led to the development of a cone of depression and a groundwater divide, which has gradually moved eastward and is now east of the proposed Rocky Hill borefield. The majority of the groundwater within the focus area is of good quality, with <1000 mg/L total dissolved salts (TDS). The brackish water (7000 mg/L TDS) further to the east of the proposed Rocky Hill borefield warrants further investigation to determine the potential risk of it being captured by the cone of depression following the development of this borefield. This study provides new insight to the hydrogeological understanding of the Alice Springs focus area. Specifically, this investigation demonstrates that the Roe Creek and proposed Rocky Hill borefields, and a nearby viticulture area are all extracting from the same aquifer system. This finding will inform the future management and security of the Alice Springs community water supply. New groundwater resource estimates and a water level monitoring scheme can be developed to support the management of this vital groundwater resource.