<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 increasingly being applied to map tectonic architecture and mineral systems. Under the Exploring for the Future (EFTF) program, Geoscience Australia has invested significantly in the collection of new MT data. The science outputs from these data are underpinned by an open-source data analysis and visualisation software package called MTPy. MTPy started at the University of Adelaide as a means to share academic code among the MT community. Under EFTF, we have applied software engineering best practices to the code base, including adding automated documentation and unit testing, code refactoring, workshop tutorial materials and detailed installation instructions. New functionality has been developed, targeted to support EFTF-related products, and includes data analysis and visualisation. Significant development has focused on modules to work with 3D MT inversions, including capability to export to commonly used software such as Gocad and ArcGIS. This export capability has been particularly important in supporting integration of resistivity models with other EFTF datasets. The increased functionality, and improvements to code quality and usability, have directly supported the EFTF program and assisted with uptake of MTPy among the international MT community. <b>Citation:</b> Kirkby, A.L., Zhang, F., Peacock, J., Hassan, R. and Duan, J., 2020. Development of the open-source MTPy package for magnetotelluric data analysis and visualisation. 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.

We present a resistivity model of the southern Tasmanides of southeastern Australia using Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) data. Modelled lower crustal conductivity anomalies resemble concentric geometries revealed in the upper crust by potential field and passive seismic data. These geometries are a key part of the crustal architecture predicted by the Lachlan Orocline model for the evolution of the southern Tasmanides, in which the Proterozoic Selwyn Block drives oroclinal rotation against the eastern Gondwana margin during the Silurian period. For the first time, we image these structures in three dimensions (3D) and show they persist below the Moho. These include a lower crustal conductor largely following the northern Selwyn Block margin. Spatial association between lower crustal conductors and both Paleozoic to Cenozoic mafic to intermediate alkaline volcanism and gold deposits suggests a genetic association i.e. fluid flow into the lower crust resulting in the deposition of conductive phases such as hydrogen, iron, sulphides and/or graphite. The 3D model resolves a different pattern of conductors in the lithospheric mantle, including northeast trending anomalies in the northern part of the model. Three of these conductors correspond to Cenozoic leucitite volcanoes along the Cosgrove mantle hotspot track which likely map the metasomatised mantle source region of these volcanoes. The northeasterly alignment of the conductors correlates with variations in the lithosphere-asthenosphere boundary (LAB) and the direction of Australian plate movement, and may be related to movement of an irregular LAB topography over the asthenosphere. By revealing the tectonic architecture of a Phanerozoic orogen and the overprint of more recent tectono-magmatic events, our resistivity model enhances our understanding of the lithospheric architecture and geodynamic processes in southeast Australia, demonstrating the ability of magnetotelluric data to image geological processes over time.

Long-period magnetotelluric (MT) data allow geoscientists to investigate the link between mineralisation and lithospheric-scale features and processes. In particular, the highly conductive structures imaged by MT data appear to map the pathways of large-scale palaeo-fluid migration, the identification of which is an important element of several mineral system models. Given the importance of these data, governments and academia have united under the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) to collect long-period MT data across the continent on a ~55 km-spaced grid. Here, we use AusLAMP data to demonstrate the MT method as a regional-scale tool to identify and select prospective areas for mineral exploration undercover. We focus on the region between Tennant Creek in the Northern Territory and east of Mount Isa in Queensland. Our results image major conductive structures up to 150 km deep in the lithosphere, such as the Carpentaria Conductivity Anomaly east of Mount Isa. This anomaly is a significant lithospheric-scale conductivity structure that shows spatial correlations with a major suture zone and known iron oxide–copper–gold deposits. Our results also identify similar features in several under-explored areas that are now considered to be prospective for mineral discovery. These observations provide a powerful means of selecting frontier regions for mineral exploration undercover.. <b>Citation:</b> Duan, J., Kyi, D., Jiang, W. and Costelloe, M., 2020. AusLAMP: imaging the Australian lithosphere for resource potential, an example from 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.

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.

This animation shows how Magnetotelluric (MT) Surveys Work. It is part of a series of Field Activity Technique Engagement Animations. The target audience are the communities that are impacted by our data acquisition activities. There is no sound or voice over. The 2D animation includes a simplified view of what magnetotelluric (MT) stations and equipment looks like what the equipment measures and how the survey works.

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.

<div>Long-period magnetotelluric (MT) data from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), collected as part of Geoscience Australia’s Exploring for the Future program with contributions from the Northern Territory Geological Survey and the Geological Survey of Queensland, provide important first-order information for resolving large-scale lithospheric architecture and identifying the broad footprint of mineral systems in northern Australia. Large-scale crust/mantle conductivity anomalies map pathways of palaeo-fluid migration which is an important element of several mineral systems. For example, the Carpentaria conductivity anomaly east of Mount Isa and the Croydon, Georgetown to Greenvale conductivity anomaly are highly conductive lithospheric-scale structures, and show spatial correlations with major suture zones and known mineral deposits. These results provide evidence that some mineralisation occurs at the gradient of or over highly conductive structures at lower crustal and lithospheric mantle depths, which may represent fertile source regions for mineral systems. These observations provide a powerful means of highlighting prospective greenfield areas for mineral exploration in under-explored and covered regions.</div><div><br></div><div>Higher resolution scale-reduction MT surveys refine the geometry of some conductive anomalies from AusLAMP data, and investigate whether these deep conductivity anomalies link to the near surface. These links may act as conduits for crustal/mantle scale fluid migration to the upper crust, where they could form mineral deposits. For example, data reveals a favourable crustal architecture linking the deep conductivity anomaly or fertile source regions to the upper crust in the Cloncurry region. In addition, high-frequency MT data help to characterise cover and assist with selecting targets for drilling and improve the understanding of basement geology.</div><div><br></div><div>These results demonstrate that integration of multi-scale MT surveys is an effective approach for mapping lithospheric-scale features and selecting prospective areas for mineral exploration in covered terranes with limited geological knowledge.</div><div><br></div><div>Some models in this presentation were produced on the National Computational Infrastructure, which is supported by the Australian government. Abstract presented to the Australian Institute of Geoscientists – ALS Friday Seminar Series: Geophysical and Geochemical Signatures of Queensland Mineral Deposits October 2023 (https://www.aig.org.au/events/aig-als-friday-seminar-series-geophysical-and-geochemical-signatures-of-qld-mineral-deposits/)

<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>As part of Exploring for the Future (EFTF) program with contributions from the Geological Survey of Queensland, long-period magnetotelluric (MT) data for the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) were collected using Geoscience Australia's LEMI-424 instruments on a half-degree grid across northern and western Queensland from April 2021 to November 2022. This survey aims to map the electrical resistivity structures in the region. The processed data and 3D resistivity model have been released (https://dx.doi.org/10.26186/148633).&nbsp;</div><div><br></div><div>This data release contains site locations and acquired time series data at each site in two formats:</div><div>1. MTH5, a hierarchical data format. The open-source MTH5 Python package (https://github.com/kujaku11/mth5) was used to convert the recorded LEMI data into MTH5 format.</div><div>2. Text file (*.TXT). This is the original format recorded by the LEMI-424 data logger.</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.</div><div><br></div><div><strong>Data is available on request from clientservices@ga.gov.au - Quote eCat# 148978</strong></div><div><br></div>

<div>Geoscience Australia’s Exploring for the Future program (EFTF) 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>One main component of the EFTF program is the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), which is a collaborative national survey by federal government, state and territory governments, and research organizations since late 2013. The project acquires long-period magnetotelluric data on a half-degree grid spacing across Australia and provides first order electrical conductivity/resistivity structure of the Australian continental lithosphere. This reconnaissance dataset improves the understanding of lithospheric structures and tectonic evolution of Australian plate. It provides a framework and a bottom-up approach to identify newly resource potential regions for infill surveys and further study. The dataset also uses for assessment and prediction of geomagnetic storm’s nature hazards. </div><div><br></div><div>This data release contains a 3D resistivity model and site locations. The 3D model was derived from publicly available AusLAMP data in Australia (excluding western Australia). The model was projected to GDA94 MGA Zone 54 and was converted into SGrid/ASCII format and geo-referenced TIFF format.</div><div><br></div><div>We acknowledge the traditional custodians of the country where the data were collected. We also acknowledge the support provided by individuals and communities for land access and data acquisition, without whose cooperation these data could not have been collected. The 3D model was produced on the National Computational Infrastructure, which is supported by the Australian government.</div><div><br></div>