<p>This dataset contains magnetotelluric data and a 3D inversion model from the 09GA-GA1 deep magnetotelluric transect, collected in Central Australia in 2009. The transect is 350 km long, with data acquired from 18 stations with both broadband and long period instrumentation, and 21 stations with broadband instrumentation only (a total of 39 sites). The resulting station spacing is 10km for the broadband stations, and 20km for stations with both broadband and long period instrumentation. We have reprocessed the broadband data using the Bounded Influence, Remote Reference Processing software (BIRRP), yielding an extended bandwidth of 0.003 to 1300 s and merged these data with the long period data. We have inverted the data using the ModEM 3D inversion code. <p>More details on the data processing, analysis, modelling, and interpretation can be found in the following paper: Kirkby, A. and Duan, J., 2019. Crustal Structure of the Eastern Arunta Region, Central Australia, From Magnetotelluric, Seismic, and Magnetic Data. Journal of Geophysical Research: Solid Earth, 124. <a href="https://doi.org/10.1029/2018JB016223">https://doi.org/10.1029/2018JB016223</a>

The magnetotelluric (MT) method is becoming more widely used in the geoscience community as it becomes increasingly recognised as a useful exploration tool. However, while the analysis and inversion tools available to the MT community have increased over recent years, the software available to work with these tools is still somewhat limited and often costly in comparison to some of the more mature techniques like gravity, magnetics and seismic. The MTpy python library is open source software that aims to assist MT practitioners in carrying out the processing and analysis steps that need to be carried out with MT data and in working with the various inversion codes that are available. However, MTpy still contains coding issues, bugs and gaps in functionality, which have limited its use to date. We are currently developing MTpy to rectify these problems and expand the functionality, and thus facilitate the use of MT as an exploration technique. Key improvements include adding new functions and modules, refactoring the code to give better quality and consistency, fixing bugs and adding new Graphic User Interfaces. Abstract prepared for the Australian Exploration Geoscience Conference (AEGC) 18 -21 February 2018, Sydney, NSW. (https://www.aig.org.au/events/first-australian-exploration-geoscience-conference/)

The footprint of a mineral system is potentially detectable at a range of scales and lithospheric depths, reflecting the size and distribution of its components. Magnetotellurics is one of a few techniques that can provide multiscale datasets to understand mineral systems. The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative national survey that acquires long-period magnetotelluric data on a half-degree grid spacing (about 55 km) across Australia. This project aims to map the electrical conductivity/resistivity structure in the crust and mantle beneath the Australian continent. We have used AusLAMP as a first-order reconnaissance survey to resolve large-scale lithospheric architecture for mapping areas of mineral potential in Australia. AusLAMP results show a remarkable connection between conductive anomalies and giant mineral deposits in known highly endowed mineral provinces. Similar conductive features are mapped in greenfield areas where mineralisation has not been previously recognised. In these areas we can then undertake higher-resolution infill magnetotelluric surveys to refine the geometry of major structures, and to investigate if deep conductive structures are connected to the near surface by crustal-scale fluid-flow pathways. This presentation summarises the results from a 3D resistivity model derived from AusLAMP data in Northern Australia (Figure 1). This model reveals a broad conductivity anomaly in the lower crust and upper mantle that extends beneath an undercover exploration frontier between the producing Tennant Creek region and the prospective Murphy Province to the northeast. This anomaly potentially represents a fertile source region for mineral systems. A subsequent higher-resolution infill magnetotelluric survey revealed two prominent conductors within the crust (Figure 2) whose combined responses produced the lithospheric-scale conductivity anomaly mapped in the AusLAMP model. Integration of the conductivity structure with deep seismic reflection data revealed a favourable crustal architecture linking the lower, fertile source regions with potential depositional sites in the upper crust. Integration with other geophysical and geochronological datasets suggests high prospectivity for major mineral deposits in the vicinity of major faults. In addition to these insights, interpretation of high-frequency magnetotelluric data helps to characterise cover and assist with selecting targets for stratigraphic drilling. This study demonstrates that the integration of geophysical data from multiscale surveys is an effective approach to scale reduction during mineral exploration in covered terranes. The success of this data integration and scale reduction approach is demonstrated by the uptake of over 11,000 square kilometres of new exploration tenements in the previously under-explored East Tennant region of northern Australia. This abstract was submitted to and presented at the 26th World Mining Congress (WMC) 2023 (https://wmc2023.org/)

Geoscience Australia’s geomagnetic observatory network covers one-eighth of the Earth. The first Australian geomagnetic observatory was established in Hobart in 1840. This almost continuous 180-year period of magnetic-field monitoring provides an invaluable dataset for scientific research. Geomagnetic storms induce electric currents in the Earth that feed into power lines through substation neutral earthing, causing instabilities and sometimes blackouts in electricity transmission systems. Power outages to business, financial and industrial centres cause major disruption and potentially billions of dollars of economic losses. The intensity of geomagnetically induced currents is closely associated with geological structure. We modelled peak geoelectric field values induced by the 1989 Québec storm for south-eastern Australian states using a scenario analysis. Modelling shows the 3D subsurface geology had a significant impact on the magnitude of induced geoelectric fields, with more than three orders of magnitude difference across conductive basins to resistive cratonic regions in south-eastern Australia. We also estimated geoelectrically induced voltages in the Australian high-voltage power transmission lines by using the scenario analysis results. The geoelectrically induced voltages may exhibit local maxima in the transmission lines at differing times during the course of a magnetic storm depending on the line’s spatial orientation and length with respect to the time-varying inducing field. Real-time forecasting of geomagnetic hazards using Geoscience Australia’s geomagnetic observatory network and magnetotelluric data from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) helps develop national strategies and risk assessment procedures to mitigate space weather hazard. This Abstract was submitted/presented to the 2023 Australian Exploration Geoscience Conference 13-18 Mar (https://2023.aegc.com.au/)

We present a 3‐D inversion of magnetotelluric data acquired along a 340‐km transect in Central Australia. The results are interpreted with a coincident deep crustal seismic reflection survey and magnetic inversion. The profile crosses three Paleoproterozoic to Mesoproterozoic basement provinces, the Davenport, Aileron, and Warumpi Provinces, which are overlain by remnants of the Neoproterozoic to Cambrian Centralian Surperbasin, the Georgina and Amadeus Basins, and the Irindina Province. The inversion shows conductors near the base of the Irindina Province that connect to moderately conductive pathways from 50‐km depth and to off‐profile conductors at shallower depths. The shallow conductors may reflect anisotropic resistivity and are interpreted as sulfide minerals in fractures and faults near the base of the Irindina Province. Beneath the Amadeus Basin, and in the Aileron Province, there are two conductors associated strong magnetic susceptibilities from inversions, suggesting they are caused by magnetic, conductive minerals such as magnetite or pyrrhotite. Beneath the Davenport Province, the inversion images a conductive layer from ∼15‐ to 40‐km depth that is associated with elevated magnetic susceptibility and high seismic reflectivity. The margins between the different basement provinces from previous seismic interpretations are evident in the resistivity model. The positioning and geometry of the southern margin of the crustal conductor beneath the Davenport Province supports the positioning of the south dipping Atuckera Fault as interpreted on the seismic data. Likewise, the interpreted north dipping margin between the Warumpi and Aileron Province is imaged as a transition from resistive to conductive crust, with a steeply north dipping geometry.

The magnetotellurics (MT) method maps the electrical conductivity/resistivity structure of the subsurface, which provides crucial information for mineral exploration. Geoscience Australia has actively applied the method to provide multiscale world-leading datasets to improve the understanding of geology and resource potential. We demonstrate the value of scaled MT data acquisition starting from mapping large-scale conductivity structures in the lithosphere utilising long-period MT datasets through to the resolution of finer scale structures in the crust suitable for camp scale targeting. Integration of data from multiscale surveys provides an effective way to narrow the search space and to identify ‘targets’ of mineral potential in covered terranes. Our work has helped to increase explorers’ investment confidence for new mineral discoveries in greenfield regions.

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 data have recently been collected in New South Wales under a National Collaborative Framework agreement between Geoscience Australia and the Geological Survey of New South Wales. This data release contains a preferred resistivity model and associated inversion files for southeast Australia using data from AusLAMP Victoria (Duan & Kyi, 2018), far west NSW (Robertson et al. 2016) and from the rest of New South Wales up to August 2019 (Kyi et al 2020). The original work behind this model can be cited through the following paper which contains discussion on model development and its significance for tectonic evolution and metallogenic potential: Kirkby, A., Musgrave, R.J., Czarnota, K., Doublier, M.P., Duan, J., Cayley, R.A., Kyi, D., 2020. Lithospheric architecture of a Phanerozoic orogen from magnetotellurics: AusLAMP in the Tasmanides, southeast Australia. Tectonophysics, v. 793, 228560.

<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 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>During February and March in 2023, Geoscience Australia undertook the Curnamona Cube Extension Magnetotelluric (MT) Survey in western New South Wales and eastern South Australia. The survey complements the University of Adelaide/AuScope Curnamona Cube MT survey by extending the coverage from the Curnamona Province into the Delamerian Orogen. Geoscience Australia contracted Quantec Geoscience Ltd. and its subcontractor Australian Geophysical Services to conduct the data acquisition and processing.&nbsp;Audio and broadband MT data was acquired at 99 sites on an approximately 12.5-25&nbsp;km grid with denser sites across known geological structures and along seismic lines acquired by Geoscience Australia in 2022 (L213 Darling-Curnamona-Delamerian (DCD) 2D Seismic Survey, eCAT # 147423). Instruments were set up to record five channels (three magnetic and two electric fields) for a minimum of 24 hours with a target bandwidth of 0.0001 – 1000 s. Processed data show good quality at a majority of the survey sites, except a few sites affected by environmental and cultural noise. The acquired data will be used to derive resistivity models, and to enhance the understanding of the geodynamics and mineral potential in the Curnamona Province and Delamerian Orogen.&nbsp;</div><div><br></div><div>This data release contains a field logistic report; processed data in EDI format containing spectra and site locations in shape file and .txt format. Time series data in ASCII format is available on request from clientservices@ga.gov.au - Quote eCAT#147904.</div><div><br></div><div>Geoscience Australia acknowledges the 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>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>

<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.&nbsp;</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.&nbsp;&nbsp;</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#&nbsp;149416.</div>