The GEOPHYS_SURV database describes geophysical surveys (air, land, and marine), the datasets derived from those surveys, and the methods used for delivery of those datasets. The database includes metadata for all surveys conducted or managed by Geoscience Australia and its predecessor agencies, as well as data and surveys from State and Territory geological survey agencies.

Drilling in the Geoscience Australia Exploring for the Future East Tennant project was conducted as part of the MinEx CRC National Drilling Initiative. Ten stratigraphic boreholes were drilled for scientific purposes in the region around the Barkly Roadhouse in the Northern Territory. Where possible, the boreholes were comprehensively wireline logged to obtain petrophysical data on the cover and basement rocks to help improve knowledge and geophysical models of the region. Formation density data obtained by wireline logging were validated using laboratory-based bulk density data obtained by Archimedes method on diamond drill core samples at Geoscience Australia. Results of the validation show that wireline-logged formation density data and Archimedes wet bulk density data are in good general agreement in the first five boreholes drilled (NDIBK01, NDIBK02, NDIBK03, NDIBK04 and NDIBK05). Difficult drilling and some lost drilling equipment meant that boreholes NDIBK06, NDIBK07 and NDIBK09 could not be cased properly, or could not be re-entered, and thus formation density wireline logs could not be obtained in these holes. Boreholes NDIBK08 and NDIBK10 were wireline logged, however formation density results from these last two holes were problematic. Wireline formation density results for borehole NDIBK08 are shown to be too high due to miscalibration of the wireline formation density tool, and results from borehole NDIBK10 cannot be robustly assessed because of a lack of sufficient Archimedes bulk density data needed to provide statistical relevance and validate the wireline formation density data.

Geoscience Australia commissioned reprocessing of selected legacy onshore 2D reflection seismic data in the Kidson Sub-basin of the Canning Basin, Cobb Embayment in the SE Canning Basin, NW Canning Basin, and Southern Carnarvon, Western Australia. This reprocessing is a collaboration between the Geoscience Australia Exploring for the Future (EFTF) program and The Government of Western Australia, Department of Mines, Industry Regulation and Safety, Exploration Incentive Scheme (EIS). Reprocessing was carried out by Ion (Cairo) between January 2018 and September 2018. The Canning project comprised 30 lines from 5 vintages of data totalling 1412 km. The Carnarvon project comprised 36 lines from 6 vintages of data totalling 1440 km. This reprocessing is intended to produce an improved quality seismic dataset that will increase confidence in the mapping of the structure and stratigraphy of the onshore sedimentary basins of Western Australia. The new seismic reprocessed data is being made available as pre-competitive information to assist industry to better target areas likely to contain the next major oil, gas and mineral deposits. <b>Processed data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 144258</b>

Modern magnetotellurics (MT) offers a multiscale capability to image the electrical properties of Earth’s crust and upper mantle. The data it provides and the models derived from it are important geophysical contributions to understanding Earth’s geology and resource potential. In Australia, MT data is acquired by the resource exploration industry, university-based research groups, and Federal, State and Territory geological surveys. To ensure this data can be used to its full potential, including by groups and individuals who may not have been responsible for its acquisition, it is important that community-agreed standards be adopted for the acquired data and its associated metadata. <b>Citation: </b>Jingming Duan, Alison Kirkby, Darren Kyi, Wenping Jiang, Marina Costelloe & Adrian Hitchman (2021) Metadata standards for magnetotelluric time-series data, <i>Preview</i>, 2021:215, 61-63. DOI: 10.1080/14432471.2021.2012035

<p>This image is a ternary image of the radiometric grid of Australia, 2019. The radiometric grid of Australia is derived by merging over 600 airborne gamma-ray spectrometric surveys by the Commonwealth, State and Territory Governments and held in the national radioelement database of Australia. The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The original survey grids are levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS). The grids were then re-sampled to generate the Radiometric Map of Australia grids with a cell size of about 100m (0.001 degrees). Since the AWAGS traverses are consistent with the International Atomic Energy Agency’s (IAEA) radioelement datum, the new continental merges are levelled to this datum as well. The data quality varies depending on the survey. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The final grid is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. <p>The ternary image was generated by combining filtered K, Th and U grids. The grids were assigned the three usual hues of red (for potassium), green (for Thorium) and blue (for Uranium). This ternary image is very useful for both mineral exploration and environmental mapping.

Survey Name: Tasmanian Tiers Datasets Acquired: Magnetics, Radiometrics and Elevation Geoscience Australia Project Number: P5003 Acquisition Start Date: 10/02/2021 Acquisition End Date: 02/04/2021 Flight line spacing: 200 m Flight line direction: East-West (090-270) Total distance flown: 33,019 line-km Nominal terrain clearance: 80 m Blocks: 5 Data Acquisition: Magspec Airborne Surveys Project Management: Geoscience Australia Quality Control: Geoscience Australia Dataset Ownership: Mineral Resources Tasmanian and Geoscience Australia Included in this release: 1. Point-located Data ASCII-column data with accompanying description and definition files. • Magnetics corrected i. Magnetic data with corrections for diurnal, IGRF, tie-levelling, micro-levelling. ii. Elevation data converted to geoidal values and a digital elevation model. • Radiometrics corrected i. Equivalent ground concentrations of radioelements with NASVD spectral filtering and standard IAEA processing. 2. Grids Gridded data in ERMapper (.ers) format (GDA2020, MGA55). • Total magnetic intensity (TMI). • TMI reduced to pole (RTP). • TMI RTP with first vertical derivative applied. • Dose rate (with NASVD and standard processing). • Potassium concentration (with NASVD, standard processing, 3D topographic correction). • Thorium concentration (with NASVD, standard processing, 3D topographic correction). • Uranium concentration (with NASVD, standard processing, 3D topographic correction). • Laser-derived digital elevation model (geoidal). • Radar-derived digital elevation model (geoidal). 3. Outlines (survey extents) • Polygon outlines showing the extent of each block and the entire survey in ArcGIS shapefile format (GDA2020, MGA55). 4. Reports • P5003_3D_topographic_correction_of_gamma_ray_data.pdf i. Details of the 3D topographic corrections applied to the radiometric data. • P5003_calibration_report_fixed_wing.pdf i. Details of the calibration performed on the fixed wing aircraft (block 1). • P5003_calibration_report_helicopter.pdf i. Details of the calibration performed on the helicopter (blocks 2-5). • P5003_operations_and_processing_report.pdf i. Summary of the data acquisition and processing. © Mineral Resources Tasmania, Government of Tasmania and Commonwealth of Australia (Geoscience Australia) 2021. With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International Licence. (http://creativecommons.org/licenses/by/4.0/legalcode).

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.

For the AusAEM Year 1 survey an inertial measurement unit (IMU) was installed for the first time on the TEMPEST receiver bird to measure its orientation and to augment GPS derived positioning of the receiver. This has given us the opportunity to develop better quality control and calibration procedures, which would otherwise not be possible. Theoretical modelling of the primary field on high altitude zero-lines, using the full position/orientation information, revealed discrepancies between observed and modelled data. It alerted us to time-lag parallaxes between EM and bird position/orientation data, some spurious IMU data on many pre-flight zero-lines, and a coordinate system sign convention inconsistency. The modelling also revealed systematic differences that we could attribute to the calibration of the receiver pitch and EM data scaling. We developed an inversion algorithm to solve for a receiver pitch offset and an EM scaling calibration parameter, for each zero-line, which minimised the systematic discrepancies. It eventuated that the calibration parameters fell into five distinct populations explicable by significant equipment changes. This gave us the confidence to use the medians of these populations as parameters to calibrate the data. The work shows the value of the new receiver bird orientation data and the importance of accurate IMU calibration after any modification. It shows the practical utility of quantitative modelling in the quality control workflow. It also demonstrates how modelling and inversion procedure can be used to successfully diagnose calibration issues in fixed-wing AEM data. Presented at the 2019 Australasian Exploration Geoscience Conference

Instrumentally observed earthquakes sequences typically show clusters of earthquakes interspersed with periods of quiescence. These ‘bursty’ sequences also have correlated inter-event times (‘long-term memory’). In contrast, elastic rebound theory forms the basis of the standard earthquake cycle model, and predicts large earthquakes to occur regularly through cycles of strain accumulation and release (periodicity). In this model the conditional probability of future large earthquakes is reduced immediately following fault rupture, and inter-event times are independent. Here we use the burstiness and memory coefficient metrics to characterize more than 100 long-term earthquake records. We find that large earthquake occurrence on the majority of Earth’s faults is weakly periodic and does not exhibit long-term memory; earthquakes occur more regularly than a random Poisson process although inter-event times are variable. In contrast, clustering occurs in slowly deforming regions (annual rates < 2 x 10-4), and is not explained by elastic rebound theory. <b>Citation:</b> Griffin, J. D., Stirling, M. W., & Wang, T. (2020). Periodicity and clustering in the long‐term earthquake record. <i>Geophysical Research Letters</i>, 47, e2020GL089272. https://doi.org/10.1029/2020GL089272

<p>Eight hundred and seventy two km of gravity and deep crustal reflection data were collected for the Kidson Sub-Basin 2D seismic survey along a single transect: 18GA-KB1 during June to August 2018. <p>The purpose of the survey was to image basin and basement structures of the Kidson Sub-Basin of the onshore Canning Basin, and extending across the Paterson Orogen and on to the eastern margin of the Pilbara Craton. <p>The new data will help geological interpretations to determine the stratigraphy, lateral extent and stratigraphic relationships of the basin and adjoining terranes, and an assessment of the region for its oil and gas and mineral potential. <p>The project is a collaboration between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) and was funded by the Australian Government's Exploring for the Future program and the Western Australian Government's Exploration Incentive Scheme (EIS). <p>Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 128284