<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>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;LEMI-424 data logger</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;LEMI-039 3-component analog magnetometer and cable</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;LEMI-701 electrodes</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;GPS receiver</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;electric-line interface box</div><div><br></div><div>Geoscience Australia supplements this equipment with the addition of:</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a Pelican equipment box to hold and transport the equipment</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;an acrylic housing to protect the LEMI-039 magnetometer</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;four 50&nbsp;m electrode cables</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a brass earth stake and cable</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a 12&nbsp;V battery</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;a solar panel</div><div><br></div>

The AusLAMP-Victoria magnetotelluric survey was a collaborative project between the Geological Survey of Victoria and Geoscience Australia. Long period magnetotelluric data were acquired at 100 sites on a half degree grid spacing across Victoria in the south-east of Australia between December 2013 and September 2014. Some repeated sites were acquired in December 2017. Geoscience Australia managed the project and performed data acquisition, data processing, and data QA/QC. In this record, the field acquisition, data QA/QC, and data processing methodologies are discussed. A separate report will provide information on data analysis, data modelling/inversion, and data interpretation.

<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

The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) aims to collect long period magnetotelluric data on a half degree grid across the Australian continent. Data were collected in northern Australia under Geoscience Australia’s Exploring for the Future (EFTF) program from 2016 to 2019. This survey covers the area in south parts of Northern Territory and north western region of Queensland. The project aims to improve understanding of the lithospheric structure in northern Australia. It also provide pre-competitive data and knowledge for selecting mineral prospective areas in the under-explored and covered regions. This data package contains the preferred resistivity model and associated information for the project. The report provides details for data acquisition, data process and data inversion. The results provide new insights on the lithospheric architecture and mineral potential in the region.

<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>

This OGC compliant service provides access to magnetotelluric data and associated products, which have been produced by Geoscience Australia’s Magnetotelluric Program. This program includes regional magnetotelluric projects and the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), a collaborative project between Geoscience Australia, the State and Northern Territory geological surveys, universities, and other research organisations. The data provided in this service comprise resistivity model depth sections and the locations of sites used in these studies.

This OGC compliant service provides access to magnetotelluric data and associated products, which have been produced by Geoscience Australia’s Magnetotelluric Program. This program includes regional magnetotelluric projects and the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), a collaborative project between Geoscience Australia, the State and Northern Territory geological surveys, universities, and other research organisations. The data provided in this service comprise resistivity model depth sections and the locations of sites used in these studies.

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 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. As part of Exploring for the Future (EFTF) program with contributions from the Geological Survey of Queensland, long-period magnetotelluric (MT) data for the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) were collected using Geoscience Australia's LEMI-424 instruments on a half-degree grid across Queensland from April 2021 to November 2022. This survey aims to map the electrical resistivity structures in the region. These results provide additional information about the lithospheric architecture and geodynamic processes, as well as valuable precompetitive data for resource exploration in this region. This data release package includes processed MT data, a preferred 3D resistivity model projected to GDA94 MGA Zone 54 and associated information for this project. The processed MT data were stored in EDI format, which is the industry standard format defined by the Society of Exploration Geophysicists. The preferred 3D resistivity model was derived from previous EFTF AusLAMP data acquired from 2016-2019 and recently acquired AusLAMP data in Queensland. The model is in SGrid format and geo-referenced TIFF format.

This OGC compliant service provides access to magnetotelluric data and associated products, which have been produced by Geoscience Australia’s Magnetotelluric Program. This program includes regional magnetotelluric projects and the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), a collaborative project between Geoscience Australia, the State and Northern Territory geological surveys, universities, and other research organisations. The data provided in this service comprise resistivity model depth sections and the locations of sites used in these studies.

Magnetotelluric (MT) data allow geoscientists to investigate the link between mineralisation and lithospheric-scale features and processes. In particular, the highly conductive structures imaged by MT data appear to map the pathways of large-scale palaeo-fluid migration, which is an important element of several mineral systems. New data were collected as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) under Geoscience Australia Exploring for the Future (EFTF) program in northern Australian. We use this dataset to demonstrate that the MT method is a valuable tool for mapping lithospheric-scale features and for selecting prospective areas for mineral exploration. Our results image a number of major conductive structures at depths up to ~200 km or deeper in the survey region, for example, the Carpentaria Conductivity Anomaly in east of Mount Isa; and the Tanami Conductive Anomaly along the Willowra Suture Zone. These significant anomalies are lithospheric- scale highly conductive structures, and show spatial correlations with major suture zones and known mineral deposits. These results provide important first-order information for lithospheric architecture and possible large footprint of mineral systems. Large-scale crustal/mantle conductivity anomalies mapping fluid pathways associated with major sutures/faults may have implications for mineral potential. These results provide evidence that some mineralisation occurs at the gradient of or over highly conductive structures at lower crustal and lithospheric mantle depths. These observations provide a powerful means of highlighting greenfields for mineral exploration in under-explored and covered regions.