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.

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.

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

Magnetotelluric survey data acquired in association with the L189 Gawler-Curnamona-Arrowie Deep Crustal Seismic Survey over the Curnamona Province. This survey was funded through the Onshore Energy Security Program. Data was acquired by Quantec Geoscience. Analysis and modelling was undertaken 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 over the Curnamona Province. This information is complementary to the reflection seismic and gravity data acquired along the 08GA-C1 traverse. Data are supplied as EDI files with support information.

The MTPy Python library is open source software that aims to facilitate processing, analysis, modelling, and inversion of magnetotelluric (MT) data. Until recently, MTpy has contained bugs and gaps in both functionality and documentation, which have limited its use to date. We are developing MTPy to rectify these problems and expand functionality. Key improvements include adding new functions and classes to the modules that handle ModEM inputs and outputs, improving data and model visualization tools, refactoring the code to improve maintainability, quality, and consistency, and developing documentation.

Several narrow, linear, highly electrically conductive zones in the crust have been detected across Australia by geomagnetic deep sounding and magnetotelluric measurements made during the previous 50 years. Three major such conductivity anomalies collectively span Australia from north to south; the Carpentaria anomaly in Queensland and the Flinders and Eyre Peninsula anomalies in South Australia. They do not appear to be electrically connected at present; whether they are related in origin is a subject of further research. Recently, new magnetotelluric data have been acquired across or near to all three zones along deep seismic reflection transects which were designed to investigate crustal architecture and mineral and energy potential. Results from the seismic and MT surveys across the Carpentaria Anomaly suggest that the data are imaging a west-dipping suture forming the eastern margin of the Mount Isa province. The suture is interpreted to be the consequence of subduction and accretion prior to 1850 Ma. The Flinders Anomaly extends in an arcuate belt to the east of Lake Frome in the Curnamona Province to transect the Willyama Supergroup and the southern Flinders Ranges in a south-westerly direction, following structural trends. New magnetotelluric data acquired along two seismic transects has further refined the position and depth of the conductive zone.

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.

This collection includes calibrated time-series data and other products from Geoscience Australia's geomagnetic observatory network in Australia and Antarctica. Data dates back to 1924. <b>Value: </b>These data are used in mathematical models of the geomagnetic field, in resource exploration and exploitation, to monitor space weather, and for scientific research. The resulting information can be used for compass-based navigation, magnetic direction finding, and to help protect communities by mitigating the potential hazards generated by magnetic storms. <b>Scope: </b>Continuous geomagnetic time series data, indices of magnetic activity and associated metadata, Data dates back to 1924.

Magnetotelluric survey data acquired in association with the L189 Gawler-Curnamona-Arrowie Deep Crustal Seismic Survey over the Gawler Craton. This survey was a collaborative project with the University of Adelaide and was funded through the Onshore Energy Security Program. The aim of the survey was to produce a two-dimensional image of electrical conductivity structure of the crust and upper mantle over the Gawler Craton. This information is complementary to the reflection seismic and gravity data acquired along the 08GA-G1 traverse. Data are supplied as EDI files with support information.

<p>The East Tennant Magnetotelluric (MT) Survey is funded under Geoscience Australia’s (GA) Exploring for the Future program. The survey is aimed to assist in regional stratigraphic drilling program to understand basement architecture and mineral potential in the east of Tennant Creek, Northern Territory, Australia. The survey covers an area of approximate 90 km x 100 km. Geoscience Australia contracted Zonge Engineering and Research Organisation (Australia) to undertake the survey from 22nd July to 19th Aug 2019. Broadband Magnetotelluric and Audio Magnetotelluric data were acquired at 131 stations with site spacing of ~2 km to ~15 km. <p>This data package includes MT data originally processed by the contractor and edited MT data by GA for modelling purpose. All the data were industry-standard EDI files. <p>Time series data are available on request from clientservices@ga.gov.au