<p>Seawater intrusion (SWI) has become a serious threat to many groundwater resources in the last decades, especially in the areas of overexploitation due to population increase, or agriculture use. Significant attention was therefore brought to this complex groundwater problem in order to improve management of these affected aquifers. <p>Due to the high conductivity of seawater, SWI is a good target for many geophysical electromagnetic methods, such as airborne electromagnetic (AEM) or direct current resistivity methods. Airborne collected data are able to map extensive areas, and thus map the extent of SWI on a large scale along the coastlines. <p>However, zooming into a smaller scale, a discrepancy is often found between geophysical estimates and groundwater borehole data, due to different resolution, data sensitivity and also quality of geophysical and groundwater data. Numerous synthetic studies have shown the benefit of approaching the problem by evaluating both types of data in somewhat jointly manner. Research in combining the field geophysical and groundwater data for SWI cases is however very limited. <p>In this contribution we look at the AEM survey in Keep river, NT. It is a dense line survey with spacing of 100m, collected by SKyTEM 312 system for Geoscience Australia. Due to the character of AEM methods, the estimation of 3D (or 2D) subsurface conductivity is mathematically an ill-posed problem, giving multiple “equally good” models (here soil bulk conductivity) with the same data misfit. <p>The borehole data from this area together with geological mapping provide limited (1D) but valuable information about the seawater intrusion location and extent. We applied this “a priori” information coming from direct groundwater data to invert the selected lines of AEM data to obtain estimates that fit well the geophysical data but are also plausible with regard to geology and groundwater chemistry data.

Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the GA310 South West Margin 2D MSS were acquired for Geoscience Australia in 2008/2009 as part of the Australian Government's Offshore Energy Security Program. This survey acquired a range of pre-competitive geological and geophysical data that included seismic reflection, gravity, magnetic and swath bathymetry measurements, as well as seafloor dredge samples. A total of 26,000 line-kilometres of magnetic and gravity data were acquired during this survey.

AusLAMP is a collaborative national project to cover Australia with long-period magnetotelluric (MT) data in an approximately 55 km spaced array. Signatures from past tectonothermal events can be retained in the lithosphere for hundreds of millions of years when these events deposit conductive mineralogy that is imaged by MT as electrically conductive pathways. MT also images regions of different bulk conductivity and can help to understand the continuation of crustal domains down into the mantle, and address questions on the tectonic evolution of Australia. The AusLAMP data presented here were collected as part of three separate collaborative projects involving several organisations. Geoscience Australia (GA), the Geological Survey of South Australia, the Geological Survey of New South Wales, the Geological Survey of Victoria, and the University of Adelaide all contributed staff and/or funding to collection of AusLAMP data; GA and AuScope contributed instrumentation. The data cover the Paleo-Mesoproterozoic Curnamona Province, the Neoproterozoic Flinders Ranges, and the Cambrian Delamerian Orogen, encompassing eastern South Australia and western New South Wales and western Victoria. This project represents the first electrical resistivity model to image the entire Curnamona Province and most of the onshore extent of the Delamerian Orogen, crossing the geographical state borders between South Australia, New South Wales and Victoria.

The magnetotelluric (MT) method is increasingly being applied to map tectonic architecture and mineral systems. Under the Exploring for the Future (EFTF) program, Geoscience Australia has invested significantly in the collection of new MT data. The science outputs from these data are underpinned by an open-source data analysis and visualisation software package called MTPy. MTPy started at the University of Adelaide as a means to share academic code among the MT community. Under EFTF, we have applied software engineering best practices to the code base, including adding automated documentation and unit testing, code refactoring, workshop tutorial materials and detailed installation instructions. New functionality has been developed, targeted to support EFTF-related products, and includes data analysis and visualisation. Significant development has focused on modules to work with 3D MT inversions, including capability to export to commonly used software such as Gocad and ArcGIS. This export capability has been particularly important in supporting integration of resistivity models with other EFTF datasets. The increased functionality, and improvements to code quality and usability, have directly supported the EFTF program and assisted with uptake of MTPy among the international MT community. <b>Citation:</b> Kirkby, A.L., Zhang, F., Peacock, J., Hassan, R. and Duan, J., 2020. Development of the open-source MTPy package for magnetotelluric data analysis and visualisation. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the GA310 South West Margin 2D MSS survey were acquired for Geoscience Australia in 2008/2009 as part of the Australian Government's Offshore Energy Security Program. This survey acquired a range of pre-competitive geological and geophysical data that included seismic reflection, gravity, magnetic and swath bathymetry measurements, as well as seafloor dredge samples. A total of 26,000 line-kilometres of magnetic and gravity data were acquired during this survey.

Collection of Geoscience Australia's high-resolution elevation surveys collected using Light Detection and Ranging (LiDAR) and other instrument systems. <b>Value: </b>Describes Australia's landforms and seabed is crucial for addressing issues relating to the impacts of climate change, disaster management, water security, environmental management, urban planning and infrastructure design. <b>Scope: </b>Selected areas of interest around Australia.

The discovery of strategically located salt structures, which meet the requirements for geological storage of hydrogen, is crucial to meeting Australia’s ambitions to become a major hydrogen producer, user and exporter. The use of the AusAEM airborne electromagnetic (AEM) survey’s conductivity sections, integrated with multidisciplinary geoscientific datasets, provides an excellent tool for investigating the near-surface effects of salt-related structures, and contributes to assessment of their potential for underground geological hydrogen storage. Currently known salt in the Canning Basin includes the Mallowa and Minjoo salt units. The Mallowa Salt is 600-800 m thick over an area of 150 × 200 km, where it lies within the depth range prospective for hydrogen storage (500-1800 m below surface), whereas the underlying Minjoo Salt is generally less than 100 m thick within its much smaller prospective depth zone. The modelled AEM sections penetrate to ~500 m from the surface, however, the salt rarely reaches this level. We therefore investigate the shallow stratigraphy of the AEM sections for evidence of the presence of underlying salt or for the influence of salt movement evident by disruption of near-surface electrically conductive horizons. These horizons occur in several stratigraphic units, mainly of Carboniferous to Cretaceous age. Only a few examples of localised folding/faulting have been noted in the shallow conductive stratigraphy that have potentially formed above isolated salt domes. Distinct zones of disruption within the shallow conductive stratigraphy generally occur along the margins of the present-day salt depocentre, resulting from dissolution and movement of salt during several stages. This study demonstrates the potential AEM has to assist in mapping salt-related structures, with implications for geological storage of hydrogen. In addition, this study produces a regional near-surface multilayered chronostratigraphic interpretation, which contributes to constructing a 3D national geological architecture, in support of environmental management, hazard mapping and resource exploration. <b>Citation: </b>Connors K. A., Wong S. C. T., Vilhena J. F. M., Rees S. W. & Feitz A. J., 2022. Canning Basin AusAEM interpretation: multilayered chronostratigraphic mapping and investigating hydrogen storage potential. In: Czarnota, K (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/146376

<p>The Barkly 2D Seismic Survey was acquired during September to November 2019 and commenced near the town of Camooweal on the border of Queensland and Northern Territory. This project is a collaboration between Geoscience Australia (GA) and the Northern Territory Geological Survey (NTGS), and was funded by the Australian Government's Exploring for the Future program and the Northern Territory Geological Survey under Northern Resourcing the Territory initiative. <p>The Barkly seismic survey extends the 2017 South Nicholson seismic survey and links with the existing Beetaloo Sub-basin seismic data. The total length of acquisition was 812.6 km spread over five lines 19GA-B1 (434.6 km), 19GA-B2 (45.9 km), 19GA-B3 (66.9 km), 19GA-B4 (225.8 km) and 19GA-B5 (39.4 km). The Barkly seismic project provides better coverage and quality of fundamental geophysical data over the region from the southern McArthur Basin to northern Mt Isa western succession. The Barkly seismic data will assist in improving the understanding of basins and basement structures and also the energy, mineral and groundwater resource potential in Northern Australia. The new reflection seismic data and derivative information will reduce the risk for exploration companies in this underexplored area by providing information for industry to confidently invest in exploration activities. <p>Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 132890

<p>The accompanying data package, was released on 30 April 2020 by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA). <p>The package contains processed data from the “MinEx CRC Cobar Airborne Electromagnetic Survey” that was flown over the Cobar–Lake Cargelligo area of Central West New South Wales . The regional survey was flown at 2.5 and 5 km nominal line spacings and entails approximately 5,900 line kilometres of new geophysical data. The survey was flown in 2019 by New Resolution Geophysics Pty. Ltd. (NRG) using the XCITE® airborne electromagnetic system. NRG also processed the data. <p>The survey also included a further 800 line kilometres of infill flying that was funded by private exploration companies, in certain blocks within the survey area. The data from these infill blocks are not part of this data release due to confidentiality agreements but will be released to the public after a 12 month moratorium. <p>GSNSW commissioned the survey as part of the MinEx Cooperative Research Centre’s (MinEx CRC), the world’s largest mineral exploration collaboration. It brings together industry, government, research organisations and universities to further our understanding of geology, mineral deposits and groundwater resources in areas where rocks aren’t exposed at Earth’s surface. GSNSW is a major participant in the NDI program, committing $16 million to the program over 10 years. In NSW, the program focuses on five areas in the state’s central and far west, where metallic minerals potentially exist under a layer of younger barren geology. These areas are North Cobar, South Cobar, Broken Hill (Mundi), Forbes and Dubbo. <p>GA managed the survey data acquisition and processing contract and the quality control of the survey on behalf of GSNSW. GA also contributed by generating one of the two inversion products included in the data package. <p>The data release package comntains <p>1. A data release package summary PDF document. <p>2. The survey logistics and processing report and XCITE® system specification files <p>3. ESRI shape files for the flight lines and boundary <p>4. KML (Google Earth) files of the flight lines <p>5. Final processed point located line data in ASEG-GDF2 format -final processed dB/dt electromagnetic, magnetic and elevation data -final processed BField electromagnetic, magnetic and elevation data <p>6. Conductivity estimates generated by NRG’s inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (PDF) multiplot conductivity sections and profiles for each flight line -graphical (JPEG) conductivity sections for each line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages) -Curtain image conductivity sections (suitable 3D display in GA’s EarthSci) -Grids generated from the NRG inversion in ER Mapper® format (layer conductivities, depth slices, elevation slices) -Images generated from the grids above (layer conductivities, depth slices, elevation slices) <p>7. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (JPEG) conductivity sections for each line -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS) -GoCAD™ S-Grid 3D objects (suitable for various 3D packages) -Curtain image conductivity sections (suitable 3D display in GA’s EarthSci) -Grids generated from Geoscience Australia's inversion in ER Mapper® format (layer conductivities, depth slices, elevation slices) -Images generated from the grids above (layer conductivities, depth slices, elevation slices) <p>Directory structure <p>├── report <p>│   ├── line_data <p>│   ├── shapefiles <p>│   ├── kml <p>│   ├── contractor_inversion <p>│   │   ├── line_data <p>│   │   ├── multiplots <p>│   │   ├── sections <p>│   │   ├── georeferenced_sections <p>│   │   ├── gocad_sgrids <p>│   │   ├── earthsci <p>│   │   │   └── MinExCRC_Cobar_AEM_Contractor_Regional <p>│   │   ├── images <p>│   │   │   ├── layers <p>│   │   │   ├── depth_slice <p>│   │   │   └── elevation_slice <p>│   │   └── grids <p>│   │   ├── layers <p>│   │   ├── depth_slice <p>│   │   └── elevation_slice <p>│   └── ga_inversion <p>│   ├── line_data <p>│   ├── sections <p>│   ├── georeferenced_sections <p>│   ├── gocad_sgrids <p>│   ├── earthsci <p>│   │   └── MinExCRC_Cobar_AEM_GA-Inversion_Regional <p>│   ├── images <p>│   │   ├── layers <p>│   │   ├── depth_slice <p>│   │   └── elevation_slice <p>│   └── grids <p>│   ├── layers <p>│   ├── depth_slice <p>│   └── elevation_slice

This data collection are comprised of magnetic surveys acquired across Australia by Commonwealth, State and Northern Territory governments and the private sector with project management and quality control undertaken by Geoscience Australia. Magnetic surveying is a geophysical method for measuring the intensity (or strength) of the Earth's magnetic field, which includes the fields associated with the Earth's core and the magnetism of rocks in the Earth's crust. Measuring the magnetism of rocks, in particular, provides a means for the direct detection of several different types of mineral deposits and for geological mapping. The magnetism of rocks depends on the volume, orientation and distribution of their constituent magnetic minerals (namely magnetite, monoclinic pyrrhotite, maghaemite and ilmenite). The instrument used in magnetic surveys is a magnetometer, which can measure the intensity of the magnetic field in nanoteslas (nT). Magnetic surveys in this collection have been acquired using aircraft or ship-mounted magnetometers and are a non-invasive method for investigating subsurface geology.