Geoscience Australia Magnetotellurics Program - Data, Models and Publications

<div>The Geoscience Australia magnetotellurics (MT) program collaborates with state and territory geological surveys, universities, and AuScope to acquire audio- (AMT), broadband- (BBMT), and long-period-MT (LPMT) data to help understand the electrical conductivity structure of the Australian continent.</div><div><br></div><div>This report collates the time-series and processed data, electrical conductivity models, and publications released for projects for which Geoscience Australia was the lead organisation, a collaborator, or an in-kind or financial supporter. For the most part, this report does not reference MT data, models or publications released by other parties for projects in which Geoscience Australia had no involvement. Please see Geoscience Australia’s AusLAMP, Exploring for the Future AusLAMP, and Regional Magnetotellurics webpages for more information.</div>

Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) - Western Australia data release (till Feb 2024)

<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><div>The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative national survey that acquires long-period magnetotelluric (MT) data on a half-degree grid spacing across Australia. This national scale survey aims to map the electrical conductivity/resistivity structure in the crust and mantle beneath the Australian continent, which provides significant additional information about Australia’s geodynamic framework as well as valuable pre-competitive data for resource exploration. As part of the Exploring for the Future Program, Geoscience Australia has completed AusLAMP data acquisition at 32 sites across the southwest and southeast region of Western Australia. The data were acquired using LEMI-424 instruments and were processed using the LEMI robust remote referencing process code. </div><div><br></div><div>This data release contains acquired time series data and processed data at each site. The time series data are in original format (.txt) recorded by the data logger and in MTH5 hierarchical format. The open-source MTH5 Python package (https://github.com/kujaku11/mth5) was used to convert the recorded data into MTH5 format. The processed data are in Electrical Data Interchange (EDI) format.  </div><div><br></div><div>We acknowledge the Geological Survey of Western Australia for assistance with field logistics and land access, traditional landowners, private landholders and national park authorities within the survey region, without whose cooperation these data could not have been collected.</div><div><br></div><div>Time series data is available on request from clientservices@ga.gov.au - Quote eCat# 149416.</div>

AusLAMP mapping lithospheric architecture and reducing exploration search space in central and eastern Australia

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>The Australian Lithospheric Architecture Magnetotelluric project (AusLAMP) is a collaborative, national survey that aims to acquire long period magnetotelluric (MT) data at 0.5° spacing (~55 km) across the Australian continent. AusLAMP started in 2013 and is ~51% complete to date. Over the last decade, regional-scale conductivity/resistivity AusLAMP models have been produced following data acquisition campaigns, but a levelled national model has not emerged. Here we present the largest AusLAMP conductivity model incorporating 85% of data acquired to date. The model images the conductivity structure of the Australian lithosphere across most parts of central and eastern Australia, including Tasmania. The resolved resistivity structures broadly conform with identified major geological domains and crustal boundaries but also reveal significant variations within geological provinces, orogens and cratons. There are 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 new model is a powerful bottom-up approach to inform exploration, particularly in covered and under-explored regions.</div><div><br></div><div><strong>Citation: </strong>Duan J. & Huston D., 2024. AusLAMP - mapping lithospheric architecture and reducing exploration search space in central and eastern Australia. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149675</div>

National Radioactive Waste Management Facility AEM Survey Logistics Report, AEM Data, and Laterally Constrained Inversion Results

<div>In July 2022 an airborne electromagnetic (AEM) survey was flown over and around the proposed site of the National Radioactive Waste Management Facility near the township of Kimba in South Australia. The survey was commissioned by the Australian Radioactive Waste Agency, and was project managed by Geoscience Australia. The survey has Geoscience Australia airborne survey project number P5008.</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 at 500 m spacing, with a smaller central focus area of 100 m spaced lines, acquiring a total of 2,545 line kilometres of data. Skytem Australia Pty Ltd also processed the data.</div><div><br></div><div>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.</div>

MinEx CRC Mundi Airborne Electromagnetic Survey, NSW, 2021: XCITE® AEM data and conductivity estimates

MinEx CRC Mundi Airborne Electromagnetic Survey, NSW, 2021: XCITE® AEM data and conductivity estimates The package contains processed data from the “MinEx CRC Mundi Airborne Electromagnetic Survey” that was flown over the Curnamona Orogen and overlying Eromanga and Lake Eyre basins, north of Broken Hill, in Western New South Wales. The 2,940 line regional survey was flown east-west at 2.5 km nominal line spacing in 2021 by New Resolution Geophysics Pty Ltd (NRG) using the XCITE® airborne electromagnetic system. The Geological Survey of New South Wales commissioned the survey as part of the MinEx Cooperative Research Centre’s (MinEx CRC) National Drilling Initiative (NDI), 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. The Geological Survey of New South Wales 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. Geoscience Australia is also a major participant in the NDI, committing $50 million Australia-wide over the ten years of the MinEx CRC. Geoscience Australia partly funded the survey by providing funds for an additional 940 line kilometres of data acquisition to broaden the geographical reach of the survey under the Exploring for the Future Darling-Curnamona-Delamerian Project. Additionally, Geoscience Australia provided in-kind support to the project by managing the survey data acquisition and processing, undertaking the quality control of the survey and generating one of the two inversions and associated derived products that are included in the data package. The data release package comntains 1. A data release package summary PDF document. 2. The survey logistics and processing report and XCITE® system specification files 3. ESRI shape files for the flight lines and boundary 4. KML (Google Earth) files of the flight lines 5. Final processed point located dB/dt electromagnetic, magnetic and elevation data - in ASEG-GDF2 format - in Geosoft GDB format 6. Final processed point located BField electromagnetic, magnetic and elevation data - in ASEG-GDF2 format - in Geosoft GDB format 7, Multiplots -graphical (PDF) multiplot profiles and estimated conductivity sections (NRG inversion) for each flight line 8. Conductivity estimates generated by NRG’s inversion -point located line data output from the inversion in ASEG-GDF2 format -point located line data output from the inversion in Geosoft GDB format -graphical (JPEG) multiplot conductivity sections and profiles 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) -georeferenced TIFF images generated from the grids above with accompaning world files for georegerencing (layer conductivities, depth slices, elevation slices) -images generated from the grids above (layer conductivities, depth slices, elevation slices) 9. Conductivity estimates generated by Geoscience Australia's inversion -point located line data output from the inversion in ASEG-GDF2 format -graphical (JPEG) multiplot conductivity sections and profiles 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) -georeferenced TIFF images generated from the grids above with accompaning world files for georegerencing (layer conductivities, depth slices, elevation slices) -images generated from the grids above (layer conductivities, depth slices, elevation slices) Directory structure ├── report ├── shapefiles ├── kml ├── line_data_dbdt ├── line_data_bfield ├── multiplots ├── contractor_inversion │ ├── multiplot_sections │ ├── earthsci │ │ └── Contractor-Inversion │ │ ├── jpeg │ │ ├── geometry │ │ └── MinEx_CRC_Mundi_AEM_Contractor-Inversion │ ├── georef_sections │ ├── gocad_sgrids │ ├── grids │ │ ├── layers │ │ ├── depth_slice │ │ └── elevation_slice │ ├── images │ │ ├── layers │ │ ├── layers_northwest_sunangle │ │ ├── depth_slice_northwest_sunangle │ │ ├── depth_slice │ │ ├── elevation_slice │ │ └── elevation_slice_northwest_sunangle │ ├── line_data │ │ ├── geosoft │ │ └── aseggdf2 │ └── georef_images │ ├── layers_northwest_sunangle │ ├── layers │ ├── depth_slice │ ├── depth_slice_northwest_sunangle │ ├── elevation_slice_northwest_sunangle │ └── elevation_slice ├── ga_inversion ├── georef_sections ├── gocad_sgrids ├── grids │ ├── depth_slice │ ├── layers │ └── elevation_slice ├── images │ ├── layers │ ├── layers_northwest_sunangle │ ├── depth_slice │ ├── elevation_slice_northwest_sunangle │ ├── elevation_slice │ └── depth_slice_northwest_sunangle ├── multiplot_sections ├── line_data ├── earthsci │ └── GA-Inversion │ ├── geometry │ ├── jpeg │ └── MinEx_CRC_Mundi_AEM_GA-Inversion └── georef_images ├── layers ├── layers_northwest_sunangle ├── depth_slice_northwest_sunangle ├── depth_slice ├── elevation_slice └── elevation_slice_northwest_sunangle

AusLAMP mapping lithospheric architecture and mineral potential in central and eastern Australia

<div>Geoscience Australia’s Exploring for the Future program (EFTF) 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 net zero emissions, strong, sustainable 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>One main component of the EFTF program is the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), which is a collaborative national survey by federal government, state and territory governments, and research organizations since late 2013. The project acquires long-period magnetotelluric data on a half-degree grid spacing across Australia and provides first order electrical conductivity/resistivity structure of the Australian continental lithosphere. This reconnaissance dataset improves the understanding of lithospheric structures and tectonic evolution of Australian plate. It provides a framework and a bottom-up approach to identify newly resource potential regions for infill surveys and further study. The dataset also uses for assessment and prediction of geomagnetic storm’s nature hazards. </div><div><br></div><div>This data release contains a 3D resistivity model and site locations. The 3D model was derived from publicly available AusLAMP data in Australia (excluding western Australia). The model was projected to GDA94 MGA Zone 54 and was converted into SGrid/ASCII format and geo-referenced TIFF format.</div><div><br></div><div>We acknowledge the traditional custodians of the country where the data were collected. We also acknowledge the support provided by individuals and communities for land access and data acquisition, without whose cooperation these data could not have been collected. The 3D model was produced on the National Computational Infrastructure, which is supported by the Australian government.</div><div><br></div>

LEMI-424 Magnetotelluric Station Field Operations - Geoscience Australia Standard Operating Procedure

<div>This document describes Geoscience Australia’s standard operating procedure for acquiring long-period magnetotelluric (MT) data using equipment supplied by LEMI LLC. It is current as at April 2024. Users should check periodically for updated versions.</div><div><br></div><div>The procedure is based on the use of the LEMI-424 magnetotelluric station, comprising:</div><div>·     LEMI-424 data logger</div><div>·     LEMI-039 3-component analog magnetometer and cable</div><div>·     LEMI-701 electrodes</div><div>·     GPS receiver</div><div>·     electric-line interface box</div><div><br></div><div>Geoscience Australia supplements this equipment with the addition of:</div><div>·     a Pelican equipment box to hold and transport the equipment</div><div>·     an acrylic housing to protect the LEMI-039 magnetometer</div><div>·     four 50 m electrode cables</div><div>·     a brass earth stake and cable</div><div>·     a 12 V battery</div><div>·     a solar panel</div><div><br></div>

Earaheedy, Desert Strip, Eastern Border, Goldfields, Kimberley, Murchison, SW Albany, and Yilgarn Airborne Electromagnetic Data in SEG-Y Format

<div>The dataset contained in this package and release consists of GA’s Layered-Earth-Inversion (GALEI, Brodie, 2016) conductivity-depth estimates from the AEM data, acquired over several areas of Western Australia, converted into SEG-Y format. The SEG-Y data standard was proposed by the Society of Exploration Geophysicists (SEG) standards committee (see Norris & Faichney 2002). Previously, the AEM data has been released as point located line data in conventional ascii format and is accessible through several of the following associated eCat records (<a href="https://pid.geoscience.gov.au/dataset/ga/146345">146345</a>, <a href="https://pid.geoscience.gov.au/dataset/ga/146042">146042</a>, <a href="https://pid.geoscience.gov.au/dataset/ga/144621">144621</a>, <a href="https://pid.geoscience.gov.au/dataset/ga/145265">145265</a> and <a href="https://pid.geoscience.gov.au/dataset/ga/147688">147688</a>). This SEG-Y data release is expected to benefit users who require the AEM modelled sections in SEG-Y format to assist in their interpretations, investigations and discovery of potential mineral, energy, and groundwater resources within Australia. </div>

Yathong, Forbes, Dubbo, and Coonabarabran, Airborne Electromagnetic Survey Blocks. HELITEM airborne electromagnetic data and GALEI conductivity estimates

<div><strong>Yathong, Forbes, Dubbo, and Coonabarabran Airborne Electromagnetic Survey Blocks.</strong></div><div><br></div><div>Geoscience Australia (GA), in collaboration with the Geological Survey of New South Wales (GNSW), conducted an airborne electromagnetic (AEM) survey from April to June 2023. The survey spanned from the north-eastern end of the Yathong-Ivanhoe Trough and extended across the Forbes, Dubbo, and Coonabarabran regions of New South Wales. A total of 15, 090-line kilometres of new AEM and magnetic geophysical data were acquired. This survey was entirely funded by GSNSW and GA managed acquisition, quality control, processing, modelling, and inversion of the AEM data.</div><div><br></div><div>The survey was flown by Xcalibur Aviation (Australia) Pty Ltd using a 6.25 Hz HELITEM® AEM system. The survey blocks were flown at 2500-metre nominal line spacings, with variations down to 100 metres in the Coonabarabran block. It was flown following East-West line directions. Xcalibur also processed the acquired 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>The survey will be incorporated and 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.</div><div><br></div><div><strong>The data release package contains:</strong></div><div><br></div><div>1. A data release package <strong>summary PDF document</strong></div><div>2. The <strong>survey logistics and processing report</strong> and HELITEM® system specification files</div><div>3. <strong>Final processed point located line data</strong> in ASEG-GDF2 format for the five areas</div><div> -final processed dB/dt electromagnetic, magnetic and elevation data</div><div> -final processed B field electromagnetic, magnetic and elevation data</div><div><strong> <em>Conductivity estimates generated by Xcalibur’s inversion </em></strong></div><div> -point located conductivity-depth line data output from the inversion in ASEG-GDF2 format</div><div> -graphical (PDF) multiplot conductivity stacks and section profiles for each flight line</div><div> -graphical (PNG) conductivity sections for each line</div><div> -grids generated from the Xcalibur’s inversion in ER Mapper® format (layer conductivities slices, DTM, X & Z component for each of the 25 channels, time constants, TMI)</div><div>4.<strong> ESRI shape and KML</strong> (Google Earth) files for the flight lines and boundary</div><div>5<strong>. Conductivity estimates generated by Geoscience Australia's inversion </strong></div><div> -point located line data output from the inversion in ASEG-GDF2 format</div><div> -graphical (pdf) multiplot conductivity sections for each line</div><div> -georeferenced (PNG) conductivity sections (suitable for pseudo-3D display in a 2D GIS)</div><div> -GoCAD™ S-Grid 3D objects (suitable for various 3D packages)</div><div> -Curtain image conductivity sections in log & liner colour stretch (suitable 3D display in GA’s EarthSci)</div><div><br></div><div><strong>Directory structure</strong></div><div>├── <strong>01_Report</strong></div><div>├── <strong>02_XCalibur_delivered</strong></div><div>│   ├── * survey_block_Name</div><div>│ ├── cdi</div><div>│ │ ├── sections</div><div>│ │ └── stacks</div><div>│ ├── grids</div><div>│ │ ├── cnd</div><div>│ │ ├── dtm</div><div>│ │ ├── emxbf</div><div>│ │ ├── emxdb</div><div>│ │ ├── emxff</div><div>│ │ ├── emxzbf</div><div>│ │ ├── emzdb</div><div>│ │ ├── time_constant</div><div>│ │ └── tmi</div><div>│ ├── located_data</div><div>│ ├── maps</div><div>│ └── waveform</div><div>│   </div><div>├── <strong>03_Shape&kml</strong></div><div>└── <strong>04_GA_Layer_Earth_inversion</strong></div><div> ├── * survey_block_Name</div><div> ├── GA_georef_sections</div><div> │ ├── linear-stretch</div><div> │ └── log-stretch</div><div> ├── GA_Inverted_conductivity_models</div><div> ├── GA_multiplots</div><div> └── GA_sgrids</div><div> </div> <b>Final Processed point located line data is available on request from clientservices@ga.gov.au - Quote eCat# 149118</b>

Multilayered chronostratigraphic airborne electromagnetic interpretation workflow

<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>

Electrical and electromagnetic methods in geophysics