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.

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.

As part of the Australian Government's Onshore Energy Security Program (2006-2011) Geoscience Australia in collaboration with Geological Survey of Western Australia acquired magnetotelluric (MT) data along the deep crustal seismic reflection transect across the Yilgarn Craton, Officer Basin and Musgrave Province in Central Western Australia. The aim of the MT survey is to map the electrical resistivity distribution and improve scientific understanding of the crustal and upper mantle structure in this region. This information is complementary to that obtained from deep crustal seismic reflection, seismic refraction, potential field and geological data, which together provide new knowledge of the crustal architecture and geodynamics of the region. It is 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. MT data were collected at forty-three sites in the Coompana region in Apr 2016 and Feb 2017. The instruments used were Phoenix Geophysics equipment including MTU-5A receiver, MTC-150L coils and PE5 electrodes. Time series data were processed into frequency domain using remote reference and Robust Processing scheme. After quality assurance, processed data were exported to industry-standard EDI files. Time series data are available on request from clientservices@ga.gov.au.

As global metal demands are increasing whilst new discoveries are declining, the magnetotelluric (MT) technique has shown promise as an effective technique to aid mineral systems mapping. Several case studies have shown a spatial correlation between mineral deposits and conductors, with some showing that resistivity models derived from MT are capable of mapping mineral systems from the lithosphere to deposit scale. However, until now, the statistical significance of such correlations has not been demonstrated and therefore hindered robust utilization of MT data in mineral potential assessments. Here we quantitatively analyze resistivity models from Australia, the United States of America (USA), South America and China and demonstrate that there is a statistically-significant correlation between upper mantle conductors and porphyry copper deposits, and between mid-crustal conductors and orogenic gold deposits. Volcanic hosted massive sulfide deposits show significant correlation with upper mantle conductors in Australia. Differences in the correlation pattern between these deposit types likely relate to differences in the chemistry, redox state and location of source mineralizing fluids and magmas, and indicate signatures of mineral system processes can be preserved in the crust and mantle lithosphere for hundreds of millions of years. Appeared in Scientific Reports volume 12, Article number: 8190 (2022), 17 May 2022

Calibrated time-series data are acquired from Geoscience Australia's geomagnetic observatory network in Australia and Antarctica. Indices of geomagnetic activity are derived from these time series. These primary and derived data are provided to international data centres and agencies, space weather analysts, the resource exploration sector, and research institutions. They are used in navigation, magnetic-field modelling, resource exploration and exploitation, space weather monitoring and geoscience research.

Geoscience Australia (GA), in partnership with State (SA, NSW, VIC, QLD, WA and TAS) and Northern Territory Geological Surveys, has applied the magnetotelluric (MT) technique to image the resistivity structure of the Australian continent over the last decade. Data have been acquired at nearly 5000 stations across Australia through a national MT survey program and regional MT surveys. Most of the data are available at GA’s website. These data provided valuable information for multi-disciplinary interpretations that incorporate various datasets. This release package includes ArcGIS shape files and Excel files of MT station locations for the completed AusLAMP and regional surveys up to December 2017.

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.

The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) aims to collect long period magnetotelluric data on a half degree (~55 km) grid across the Australian continent. New datasets have been collected in Northern Australia, as part of Geoscience Australia’s Exploring for the Future (EFTF) program with in-kind contributions from the Northern Territory Geological Survey and the Geological Survey of Queensland. This web service depicts the location of the 155 sites which were used in this study.

The footprint of a mineral system is potentially detectable at a variety of scales, from ore deposits to the Earth’s crust and lithosphere. To map these systems, Geoscience Australia has undertaken a series of integrated studies to identify key regions of mineral potential using new data from the Exploring for the Future program, together with legacy datasets. The conductivity anomaly mapped from long-period magnetotellurics (AusLAMP) data with a half-degree resolution has highlighted a structural corridor to the east of Tennant Creek, representing a potential source region for iron oxide copper–gold mineral systems. To refine the geometry of this anomaly, we used a higher-resolution magnetotellurics survey to investigate if the deep conductivity anomaly is linked to the near surface by crustal-scale fluid pathways. The 3D conductivity model revealed two prominent conductors in the resistive host, whose combined responses result in the lithospheric-scale conductivity anomaly mapped in the AusLAMP model. The resistivity contrasts coincide with major structures preliminarily interpreted from seismic reflection and potential field data. Most importantly, the conductive structures extend from the lower crust to the near surface. This observation strongly suggests that the major faults in this region are deep-penetrating structures that potentially acted as pathways for transporting metalliferous fluids to the upper crust where they could form mineral deposits. This result indicates high mineral prospectivity for iron oxide copper–gold deposits in the vicinity of these major faults. This study demonstrates that integration of geophysical data from multiscale surveys is an effective approach to scale reduction during mineral exploration in covered terranes with limited geological knowledge. <b>Citation:</b> Jiang, W., Duan, J., Schofield, A. and Clark, A., 2020. Mapping crustal structures through scale reduction magnetotelluric survey in the East Tennant region, northern Australia. 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.