The surface electric field induced by external geomagnetic source fields is modeled for a continental-scale 3-D electrical conductivity model of Australia at periods of a few minutes to a few hours. The amplitude and orientation of the induced electric field at periods of 360 s and 1800 s are presented and compared to those derived from a simplified ocean-continent (OC) electrical conductivity model. It is found that the induced electric field in the Australian region is distorted by the heterogeneous continental electrical conductivity structures and surrounding oceans. On the northern coastlines, the induced electric field is decreased relative to the simple OC model due to a reduced conductivity contrast between the seas and the enhanced conductivity structures inland. In central Australia, the induced electric field is less distorted with respect to the OC model as the location is remote from the oceans, but inland crustal high-conductivity anomalies are the major source of distortion of the induced electric field. In the west of the continent, the lower conductivity of the Western Australia Craton increases the conductivity contrast between the deeper oceans and land and significantly enhances the induced electric field. Generally, the induced electric field in southern Australia, south of latitude −20°, is higher compared to northern Australia. This paper provides a regional indicator of geomagnetic induction hazards across Australia. <b>Citation:</b> Wang, L., A. M. Lewis, Y. Ogawa, W. V. Jones, and M. T. Costelloe (2016), Modeling geomagnetic induction hazards using a 3-D electrical conductivity model of Australia, <i>Space Weather</i>, 14, 1125–1135, doi:10.1002/2016SW001436

The Geoscience Australia Rock Properties database stores the results measurements of scalar and vector petrophysical properties of rock and regolith specimens. Many are sourced from Geoscience Australia's mapping and research programs, but some are are compiled from published literature, university studies, the resources industry and State/Territory geological surveys. Measured properties include mass density, magnetic susceptibility, magnetic remanence, gamma, electrical conductivity and sonic velocity. The database also records analytical process information such as methods and instrument details wherever possible.

<div>Defining and characterising groundwater aquifers usually depends on the availability of data necessary to represent its spatial extent and hydrogeological properties, such as lithological information and aquifer pump test data.&nbsp;In regions where such data is of limited availability and/or variable quality, the characterisation of aquifers for the purposes of water resource assessment and management can be problematic.&nbsp;The Upper Darling River Floodplain region of western New South Wales, Australia, is an area where communities, natural ecosystems and cultural values are dependent on both surface and groundwater resources.&nbsp;Owing to a relative paucity of detailed geological and hydrogeological data across the region we apply two non-invasive geophysical techniques—airborne electromagnetics and surface magnetic resonance—to assist in mapping and characterising the regional alluvial aquifer system.&nbsp;The combination of these techniques in conjunction with limited groundwater quality data helps define an approximate extent for the low salinity alluvial aquifer in a key part of the Darling River valley system and provides insights into the relative water content and its variation within the aquifer materials.&nbsp;This work demonstrates the utility of these key geophysical data in developing a preliminary understanding of aquifer geometry and heterogeneity, thereby helping to prioritise targets for follow-up hydrogeological investigation. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium

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>The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative national survey between federal government, state/territory governments and research organisations. The project aims to acquire long-period magnetotelluric (MT) data at half-degree spacing (~55&nbsp;km) across the Australian continent. AusLAMP started in 2013 and has completed about 1500 stations (~50% of total planned stations) to date. Over the last decade, regional-scale AusLAMP resistivity/conductivity models have been produced following data acquisition campaigns, but there is a strong demand for a single model. We produced a resistivity model from 1260 AusLAMP stations incorporating 85% of data acquired to date. The new AusLAMP resistivity model shows significant variations of resistivity at varying depths from a few kilometres to a couple of hundred kilometres in the crust and upper mantle. The model resolves the first-order resistivity structure of the Australian lithosphere across most parts of central and eastern Australia, including Tasmania. The resolved resistivity structures allow seamless interpretation across states and regions, broadly conform with identified major geological domains and crustal boundaries, and reveal significant variations within geological provinces, orogens and cratons. There are also strong spatial associations between crustal/mantle conductors and copper and gold deposits and carbonatites, which provide further evidence that major lithospheric conductors control the distributions of a range of mineral systems. This evidence aligns well with the conceptual model of mineral systems, that convecting mantle fluid and metal-rich magma can migrate into the crust through weak zones to form some ore deposits in the lithosphere. This new AusLAMP model demonstrates that long-period MT data are an important first-order reconnaissance dataset to resolve large-scale lithospheric architecture and provides a powerful tool with a bottom-up approach to highlight potential exploration areas, particularly in covered and under-explored regions. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium