The magnetotelluric (MT) data were acquired along a total of 690 km of the Youanmi deep seismic reflection traverses 10GA-YU1, 10GA-YU2 and 10GA-YU3-in Western Australia. This was a collaborative project between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), which provided the funding. The aim of the MT survey was to produce information of the electrical conductivity structure of the crust and upper mantle. This information is complementary to that obtained from deep seismic reflection, gravity, magnetic and geological data, which together provide new knowledge of the crustal architecture, rock properties and geodynamics of the region, important for helping to determine the potential for both mineral and energy resources. Data are supplied as EDI files with support information.

Magnetotelluric (MT) measures the natural variations of the Earth' magnetic and electrical (telluric) fields. The Audio-Magnetotelluric method (AMT) samples signal frequencies in the range of 20k Hz down to ~1Hz and provides data pertaining to the upper few kilometres of the Earth' crust. Broadband MT (BBMT) measures frequencies ranging from ~400 Hz down to periods of ~5000 s, providing measures of the conductivity of the crust. AMT and BBMT data were acquired at 138 stations with an interval of 2.5-5.0 km along a 690 km transect extending from Four Ways to Longreach in the South-eastern Mount Isa region. Full-waveform time series data were acquired and processed into frequency-domain transfer functions. Remote reference was applied to eliminate uncorrelated noise. After quality assurance, processed data were exported to industry-standard EDI files containing site info, impedance tensor, apparent resistivity, phase and vertical transfer function.

Magnetotelluric survey data acquired in association with the L184 Isa-Georgetown Deep Crustal Seismic Survey and L185 Charters Towers Deep Crustal Seismic Survey. These surveys were funded through the Geoscience Australia's Onshore Energy Security Program and the Queensland Governments Smart Mining - Future Prosperity Program. Quantec Geoscience were contracted to acquire and process these data. The aim of the surveys was to produce a two-dimensional image of electrical conductivity structure of the crust and upper mantle over the Isa and Georgetown blocks. This information is complementary to the reflection seismic and gravity data acquired along lines 07GA-IG1, 07GA-IG2 and 07GA-GC1. Data are supplied as EDI files with support information and models.

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.

Geoscience Australia (GA) and the Geological Survey of Queensland (GSQ) conducted the Cloncurry Magnetotelluric (MT) survey. MT data (0.001 s to 1000 s in period) at 476 sites with a grid spacing of 2km were acquired over an approximate 40km x 60km area in the Cloncurry region from July to November 2016. The survey area covers the eastern margin of the Mount Isa Block situated to the west of the Eromanga Basin. The MT data can image the thickness of cover, the basement architecture and the crustal architecture in this area that has high resource exploration potential. Data QA/QC were performed during the data acquisition stage of the survey. This release includes processed MT data and a data acquisiton report written by the contractor. Details on the data processing, data analysis, and modelling/inversion of the data will be released as a comprehensive report at a later date.

Geoscience Australia in partnership with State and Territory Geological Surveys has applied the magnetotelluric (MT) technique to image Australia’s resistivity structure over the last decade. As part of the Mount Isa Geophysics Initiative program, MT data were collected at 138 sites along a 690 km transect in the South-Eastern Mount Isa. Geoscience Australia undertook data analysis and data inversion to create the most plausible resistivity model. 2D and 3D data modelling were undertaken using well-verified algorithms. The 2D and 3D resistivity models derived from the MT data show some consistent features that are likely to be the real subsurface geology. The near-surface conductive layer resolved by the MT models represents the Carpentaria and Eromanga sedimentary basins reasonably well, in terms of resistivity and thickness. The MT models reveal a predominant crustal-scale conductor, which is interpreted to be part of the Carpentaria Conductivity Anomaly. A number of localised zones of enhanced conductivity are also detected within the crust. These conductors correspond to known major faults identified by seismic and geological data. One of the faults, i.e. the Cork Fault, marks the tectonic boundary between the Mount Isa terrane and the Thomson Orogen. The geometries of these conductive bodies suggest that the enhanced conductivity may be caused by deformation or mineralisation associated with faulting. Some of these faults linking into the middle and lower crust are considered as the primary factors in the partitioning of mineralisation in the region. Results from the magnetotelluric data provide new insights into the understanding of the complex crustal structure where little geological history is known.

Magnetotelluric survey data acquired in association with the L190 Gawler-Officer-Musgrave-Amadeus Deep Crustal Seismic Survey. This survey was co-funded through AuScope, Primary Industry and Resources South Australia and Geoscience Australia's Onshore Energy Security Program. Data was acquired, processed and modelled by Geoscience Australia. The aim of the survey was to produce a two-dimensional image of electrical conductivity structure of the crust and upper mantle. This information is complementary to the reflection seismic and gravity data acquired along the 08GA-OM1 traverse. Data are supplied as EDI files with support information.

Magnetotellurics (MT) is a passive geophysical method which uses natural time variations of the Earth's magnetic and electric fields to measure the electrical resistivity of the sub-surface. Electrical resistivity is a bulk property of a volume of Earth material and is associated with factors such as rock composition, porosity and permeability as well as temperature and pressure. The Magnetotelurics (MT) Data Collection includes datasets from The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) and regional-scale MT surveys across the Australian continent. These data were collected by Geoscience Australia in collaboration with the State and Territory Geological Surveys and other partners. <b>Value: </b>Magnetotelluric data to expand the geoscientific understanding of the earth's lithospheric structure and provide new insights into Australia's onshore energy and mineral potential. <b>Scope: </b>AusLAMP is being conducted over multiple years to create a national MT dataset and map lithospheric structure of the Australian continent. MT data have also been acquired for mapping crustal structure and resource potential at regional scale. These data provide valuable information for multi-disciplinary interpretations. To view the magnetotellurics data via the Geoscience Australia internet page click on the following URL: <a href="https://www.ga.gov.au/about/projects/resources/regional-mt-program">https://www.ga.gov.au/about/projects/resources/regional-mt-program</a> For further information about the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) click on the following URL: <a href="https://www.ga.gov.au/about/projects/resources/auslamp">https://www.ga.gov.au/about/projects/resources/auslamp</a>

The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP): New South Wales (NSW) magnetotelluric survey is a collaborative project between the Geological Survey of New South Wales (GSNSW) and Geoscience Australia. Long period magnetotelluric data are being acquired at around 305 sites on a half degree grid spacing across the state of NSW. <u>Phase one</u> This record outlines the field acquisition, data QA/QC, and data processing methodologies relating to the 224 sites released in phase one. The data are released in EDI format containing impedance estimates and transfer functions for each processed site. <u>Phase two</u> A further 73 EDI format data are released as part of phase two. These data were collected and processed using the same methodology as described in the GA record released as part of phase one.

Magnetotelluric (MT) measures the natural variations of the Earth’ magnetic and electrical (telluric) fields. In 2018, MT data including broadband and audio-magnetotelluric data were collected across the Olympic Domain in South Australia. MT data at 327 sites with spacings from ~1.5km to ~10km were collected by contractor Zonge Engineering and Research Organisation Australia, on behalf of Geological Survey of South Australia and Geoscience Australia. The survey was funded by the Geological Survey of South Australia's PaceCopper Initiative. Six extra MT stations (MASLIN1-6) were collected and funded by Investigator Resources Ltd. They were provided by Geological Survey of South Australia. This data package contains 333 processed edi files across the Olympic Domain in South Australia.