As part of the $225 million Exploring for the Future programme, Geoscience Australia have undertaken an investigation into the resource potential of the Officer-Musgrave-Birrindudu region. Part of this project focusses on characterising palaeovalley groundwater resources within the West Musgrave region of Australia. This record presents a three-dimensional palaeovalley model and describes the method used in its generation. Understanding the 3D architecture of palaeovalleys is an important component of conceptualising the shallow groundwater system. In this region groundwater is the only significant water resource, and is critical for supporting local communities, industries and the environment. The data products released alongside this record are a base of gridded Cenozoic surface, a grid of the thickness of the Cenozoic and polygons defining the spatial extent of palaeovalleys. The study area encompasses the upper reaches of several large palaeovalleys. These valleys incised mostly crystalline rocks of the Musgrave Province and sedimentary rocks of the adjoining basin during the late Cretaceous. Subsequently, valleys were filled by Cenozoic-aged sediments, which now form the aquifers and aquitards of the modern-day groundwater system. Palaeovalley architecture has been shaped by a complex interplay of climatic, tectonic, and geological factors over geological time. In some cases, tectonic deformation has caused tilting or disruption of palaeovalleys with implications for groundwater flow. We modelled the base of Cenozoic surface across the project area and used this geological surface to identify palaeovalleys. The modelling process used airborne electromagnetic conductivity models, borehole data and geological outcrop as model inputs. Using these data, we interpreted the base of Cenozoic along AEM flightlines, at borehole locations and at the surface where Pre-Cenozoic geology was cropping out. These data were gridded to generate the base of Cenozoic surface. This surface was then used as the basis for interpreting palaeovalley extents. The resulting model is adequate for its purpose of better understanding the groundwater system. However, the model has considerable uncertainty due to uncertainty in the model inputs and data sparsity. The model performed much better within the centre of the project area within the Musgrave Province compared to the adjoining basins.

<div>AusAEM Western Resources Corridor Survey: Logistics Report, AEM Data, and GALEI conductivity estimates.</div><div><br></div><div>From&nbsp;May to October 2022, an airborne electromagnetic (AEM) survey was flown over parts of Western Australia, Northern Territory and South Australia. Geoscience Australia commissioned the survey in collaboration with the Geological Surveys of Western Australia (GSWA) and South Australia (GSSA)&nbsp;as part of the Australian Government's Exploring for the Future program and the Western Australian Government's Exploration Incentive Scheme.</div><div><br></div><div>A total of 58,858 line kilometres of new data were acquired. GA managed all aspects of the acquisition, quality control and processing of the AEM data.</div><div><br></div><div>The survey was flown by Xcalibur Aviation (Australia)&nbsp;Pty Ltd using its TEMPEST AEM system. The survey was flown in variable line directions and line spacings ranging from 20km to&nbsp;5km apart. Skytem Australia Pty Ltd also processed the data. This data package includes the acquisition and processing report, the final processed AEM data, and the results of the contractor's conductivity-depth estimates. The data package also contains the results and derived products from a 1D inversion by Geoscience Australia with its own inversion software.</div><div><br></div><div>Geoscience Australia's Exploring for the Future program provides pre-competitive information to inform decision-making by Government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. We are building a national picture of Australia's geology and resource potential by gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia's transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia's regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight-year, $225m investment by the Australian Government.</div><div><br></div><div>The survey will become part of the national AusAEM airborne electromagnetic acquisition program, which aims to provide geophysical information to support investigations of the regional geology and groundwater system and better characterise the salinity, recharge and architecture of the aquifers within the upper few hundred metres of the subsurface. It will also provide data to allow for the study of trends in regolith thickness and variability, variations in bedrock conductivity, the conductivity of key bedrock (lithology-related) conductive units under cover; and (d) the groundwater systems of the region at a reconnaissance scale.</div>

<div>As part of the Exploring for the Future (EFTF) programme, the groundwater team undertook an in-depth investigation into characterising surface water -- groundwater interaction in the Cooper Creek floodplain using airborne electromagnetics (AEM). This work is to be released as part of the Lake Eyre Basin detailed inventory and as an EFTF extended abstract. As part of Geoscience Australia's commitment to transparent science, the scientific workflows that underpinned a large component of this investigation are to be released as a jupyter notebook. This notebook contains python code, figures and explanatory text that the reader can use to understand how the AEM data were processed, visualised, integrated with other data and interpreted.</div>

<div> Airborne electromagnetic (AEM) data has been acquired at 20km line spacing across much of the Australian continent and conductivity models generated by inverting these data are freely available. Despite the wide line spacing these data are suitable for imaging the near surface and better understanding groundwater systems. Twenty-kilometre spaced AEM data acquired over the Cooper Creek floodplain using a fixed-wing towed system were inverted using deterministic and probabilistic methods. The Cooper Creek is an anabranching ephemeral river system in arid eastern central Australia. We integrated conductivity data with a range of surface and subsurface data to characterise the hydrogeology of the region and infer groundwater salinity from the shallow alluvial aquifer across a more than 14,000 km2 Cooper Creek floodplain. The conductivity data also revealed several examples of focused recharge through a river channel forming a freshwater lens within the more regional shallow saline groundwater system.</div><div>&nbsp;</div><div>This work demonstrates that regional AEM conductivity data can be a valuable tool for understanding groundwater processes at various scales with implications for how to responsibly manage water resources. This work is especially important in the Australian context where high quality borehole data is typically sparse, but high-quality geophysical and satellite data are often accessible.</div><div> </div> This presentation was given to the 8th International Airborne Electromagnetics Workshop (AEM2023) (https://www.aseg.org.au/news/aem-2023)

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.

<div>In response to the acquisition of national-scale airborne electromagnetic surveys and the development of a national depth estimates database, a new workflow has been established to interpret airborne electromagnetic conductivity sections. This workflow allows for high quantities of high quality interpretation-specific metadata to be attributed to each interpretation line or point. The conductivity sections are interpreted in 2D space, and are registered in 3D space using code developed at Geoscience Australia. This code also verifies stratigraphic unit information against the national Australian Stratigraphic Units Database, and extracts interpretation geometry and geological data, such as depth estimates compiled in the Estimates of Geological and Geophysical Surfaces database. Interpretations made using this workflow are spatially consistent and contain large amounts of useful stratigraphic unit information. These interpretations are made freely-accessible as 1) text files and 3D objects through an electronic catalogue, 2) as point data through a point database accessible via a data portal, and 3) available for 3D visualisation and interrogation through a 3D data portal. These precompetitive data support the construction of national 3D geological architecture models, including cover and basement surface models, and resource prospectivity models. These models are in turn used to inform academia, industry and governments on decision-making, land use, environmental management, hazard mapping, and resource exploration.</div>

<div>Much of Australia has been surveyed with low-flying airborne electromagnetic (AEM) instrumentation under Geoscience Australia’s AusAEM program. Acquired AEM data allow for imaging the earth's buried geology down to depths of 300-500 m. Such imaging is crucial for managing Australia’s subsurface minerals, energy and groundwater resources, by allowing geoscientists to build a 3D framework of the shallow geological architecture. However, individual AEM lines can be up to 500 km long, data are acquired every 10-12 m, and conventional electromagnetic conductivity imaging methods based on optimisation are unable to accurately characterise the subsurface imaging resolution. Bayesian probabilistic methods can do so, but at significant computational cost if naively used. Efficient Markov chain sampling strategies with parameter dimension reduction, which leverage the high-performance distributed computing capabilities inherent in the Julia language, have now made large scale Bayesian AEM imaging possible. In this work we show the results of imaging using the Julia-based, open-source, High Quality Geophysical Analysis (HiQGA) package, on continent-wide data using Bayesian probabilistic methods. We are unaware of any similar analysis at this scale, routinely using 41,600 cpu-cores for up to three hours in semi-embarrassingly parallel fashion on the National Computational Infrastructure’s Gadi cluster at the Australian National University. Consequently, deeper geology can be mapped, and subsurface 3D geology can be rapidly demarcated using posterior percentiles of conductivity, when contrasted with deterministic methods. Compared to the cost of AEM acquisition, extraction of subsurface information with computation at scale greatly increases the economic and social return on public AEM data acquisition. Abstract presented at the 2024 Supercomputing Asia Conference, Sydney NSW (SAC2024)

The product consists of 5,291 line kilometres of time-domain airborne electromagnetic (AEM) geophysical data acquired in the Fitzroy River Catchment of the West Kimberley region, the electrical conductivity models derived from the dataset, and the survey operations and processing report. The data were acquired using the heliborne SkyTEM-312 AEM system. A locality diagram for the survey is shown below. The survey was funded by the Government of Western Australia, as part of its Water for Food Initiative, through the Department of Water (WA DoW). The survey was managed by Geoscience Australia as part of a national collaborative framework project agreement with WA DoW. The aim of the survey was to map the electrical properties of the top 200-300 metres of the sub-surface geology and hydrogeology within the study area. Geoscience Australia contracted SkyTEM Australia Pty Ltd to acquire the AEM data using the SkyTEM-312 system in September and October 2015. The data were also processed by SkyTEM Australia Pty Ltd using its in-house processing and inversion techniques. The Kimberley Region in north-west Australia is a priority area for the development of irrigated agriculture. The hydrogeology of the area is poorly understood, hence the primary aim of the AEM survey was to provide geophysical data in support of groundwater investigations. Specific objectives of the AEM survey included mapping the extent of regional Canning Basin aquifers to aid assessment of groundwater resources and sustainable yield estimates for agricultural development; provide AEM data in transects to underpin studies of surface-groundwater interactions (groundwater discharge and recharge potential) associated with the major rivers, and permanent river pools in particular; detect and assess potential groundwater salinity hazards within proposed irrigation areas; and map the seawater intrusion (SWI) interface. Very specific mapping objectives were developed for each sub-area, and the survey was designed with these detailed local objectives in mind. The survey design reflects two scales of investigation: 1. Two areas (Knowsley-Mowanjum and GoGo-Fitzroy Crossing) with higher density flight line spacing (400 m) in areas with advanced plans for development of irrigated agriculture; 2. Irregular grid of regional transects and lines acquired along river tracts reflecting the reconnaissance nature of regional investigations in a frontier hydrogeological area. Much of the area lies underneath cover of sedimentary basins and is a poorly-understood element of Australia¿s geology. The Fitzroy Trough is also host to a number of mineral systems including diamonds and base metal mineralisation, as well as shale gas resources. The survey data should assist with understanding of the basin geology and neotectonics, while lamproite pipes have also been intersected in a number of flight lines. The survey data will also add to the knowledge of the thickness and character of alluvium and regolith cover and will inform future geological mapping in the region. The data will be available from Geoscience Australia¿s web site free of charge. The data release package includes: 1. Point-located electromagnetic line data with associated position, height, orientation, transmitter current, and derived ground elevation data. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey, repeat lines and high altitude lines are included in the dataset. The dataset is split into Parts 1 and 2 based on the differences in the receiver gate times for each part. 2. Point-located magnetic line data with associated position, height, orientation, and derived ground elevation data. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey, repeat lines and high altitude lines are included in the dataset. 3. Point-located line data for conductivity estimates derived by SkyTEM Australia Pty Ltd using its Automated Laterally Constrained Inversion (aLCI) algorithm with associated position, height, orientation, and derived ground elevation data. Data include the conductivity estimate for each of the 30 inversion model layers, the layer elevation, estimated depth of investigation, and data fit residuals. These data are in ASCII column format with associated ASEG-GDF2 header files. All regular survey and repeat lines are included in the dataset. 4. Gridded data for the derived ground elevations, total magnetic intensity, and the conductivity of the 30 aLCI inversion model layers. The grids are in ER Mapper® binary raster grid format with associated header files. The grids have a cell size of 100 m. For the aLCI inversion layer conductivity grids, there are versions that are masked (set to undefined) below the estimated depth of investigation and unmasked. 5. Graphical multiplots and spatial images derived from the aLCI inversion. The multiplots show the derived aLCI conductivity depth sections and selected data panels for each individual flight line in Portable Network Graphics (PNG) and Portable Document Format (PDF) formats. The spatial images show colour images of the conductivity for each aLCI model layer and are in PNG, PDF and geo-located Tagged Image Format (TIF) files suitable for use in MAPINFO. 6. The survey Operations and Processing Report, which provides the details of the AEM system, logistics, data acquisition, data processing and the aLCI inversion parameters. 7. ESRI shapefiles and KML files of flight lines. Summary Survey Name West Kimberley Airborne EM Survey, WA, 2015 (Water for Food) State Western Australia Sub Region West Kimberley Area 20,314 km2 Line km 5,291 km Survey Completed 17 October 2015 AEM system SkyTEM-312 Processing SkyTEM Australia Pty Ltd

<div>In June to September 2022 an airborne electromagnetic (AEM) survey was flown over parts of the Curnamona Province, Delamerian Orogen and Darling Region in South Australia, New South Wales and Victoria.&nbsp;Geoscience Australia commissioned the survey in collaboration with the Department of Regional New South Wales as part of the Australian Government’s Exploring for the Future program. A total of 14,509 line kilometres of new data were acquired, of which 3,407 line kilometres were funded by the Department of Regional New South Wales. GA managed all aspects of the acquisition, quality control and processing of the AEM data.</div><div><br></div><div>The survey was flown by Skytem Australia Pty Ltd using its SkyTEM312Fast AEM system. The survey was conducted on east-west lines spaced at 2,500 m and 5,000 m apart.&nbsp;Skytem Australia Pty Ltd also processed the data. 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. The data package additionally contains the results and derived products from a 1D inversion carried out by Geoscience Australia with its own inversion software.</div><div><br></div><div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government.</div><div><br></div>

These conductivity grids were generated by gridding the top 22 layers from the airborne electromagnetics (AEM) conductivity models from the Western Resource Corridor AusAEM survey (https://dx.doi.org/10.26186/147688), the Earaheedy and Desert Strip AusAEM survey (https://pid.geoscience.gov.au/dataset/ga/145265) and several industry surveys (https://dx.doi.org/10.26186/146278) from the West Musgraves. The grids resolve important subsurface features for assessing the groudnwater system including lithologial boundaires, palaeovalleys and hydrostatigraphy.