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.

Geoscience Australia is the custodian of the most comprehensive publicly available Australian airborne magnetic, gamma-ray, seismic, electromagnetic and gravity data sets. The airborne geophysics data set contains approximately 34 million line kilometres of data, which, at current prices, would cost approximately $197 million to acquire. The gravity data set contains more than 1.57 million reliable onshore stations gathered during more than 1800 surveys. The collection also includes a large number of seismic surveys from Australia's offshore basins. The onshore component of this data set was previously approved for RDSI for 8 TB. This proposal extends the collection to 150TB. The data types and access methods for the Offshore and Onshore data are identical Certain holdings are additionally hosted at the NCI (see downloads)

Over the last decade there has been an exponential growth in MT data acquisition over the Australian Continent through collaboration between Geoscience Australia, state and territory governments and academics. This data is resulting in a step change in our understanding of the lithosphere and basin architecture. Abstract submitted/presented at 2017 Target Conference (https://www.aig.org.au/events/target-2017/)

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.

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.

<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

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.

<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 upper mantle beneath the Australian continent, which provides significant additional information about Australia’s lithospheric architecture and geodynamic framework as well as valuable pre-competitive data for resource exploration.</div><div><br></div><div>Geoscience Australia (GA) in collaboration with the Geological Survey of Queensland acquired AusLAMP data in Queensland from May 2023 to July 2024. The funding of the survey was provided as part of the Queensland Government's Queensland Resource Industry Development Plan. The data were acquired using GA's LEMI-424 instruments and were processed using the Lemigraph software. The processed data contain transfer functions for each site in Electrical Data Interchange (EDI) format. </div><div><br></div><div>This data release includes site locations, processed data in EDI format, and time series data in the format of the LEMI-424 data logger and a hierarchical data format MTH5 (Peacock. J, et al. 2022, https://doi.org/10.1016/j.cageo.2022.105102). Time series data is available on request from clientservices@ga.gov.au - quote eCat#150000.</div><div><br></div><div>We acknowledge the traditional landowners, private landholders and national park authorities within the survey region, without whose cooperation these data could not have been collected.&nbsp;</div><div><br></div>

As part of Geoscience Australia’s Exploring for the Future Program, Broadband and Audio Magnetotelluric (MT) data were acquired at 131 stations in the East Tennant region, Northern Territory, in 2019. This survey aimed to characterise major crustal structures, to map cover thickness to assist in stratigraphic drill targeting, and to help understand mineral potential in the region. The data package was released in December 2019 (http://dx.doi.org/10.26186/5df80d8615367) and the 3D resistivity model was released in March 2020 (https://pid.geoscience.gov.au/dataset/ga/135011). We applied a probabilistic approach to inverting high-frequency MT data for cover thickness estimation using the 1D Rj-McMCMT code, newly developed in Geoscience Australia. The inversion employs multiple Markov chains in parallel to generate an ensemble of millions of resistivity models that adequately fit the data given the assigned noise levels. The algorithm uses trans-dimensional Markov chain Monte Carlo techniques to solve for a probabilistic resistivity-depth model. Once the ensemble of models is generated, its statistics are analysed to assess the posterior probability distribution of the resistivity at any particular depth, as well as the number of layers and the depths of the interfaces. This stochastic approach gives a thorough exploration of the model space and a more robust estimation of uncertainty than deterministic methods allow. This release package includes the results of probabilistic inversion of Audio Magnetotelluric data at the 131 stations. They can be used to estimate cover thickness for drill site planning, and to map the base of geological basins in the region. Model data files are large, but can be made available on request to clientservices@ga.gov.au.