b'AEGC 2023Short abstractsparameter-sweeps on selected subsets of the data to deriveundertaken anywhere in the world. Funded by the Government calibration parameters that best represent the knownof Western Australia and run by the Geological Survey of unknowns in a dataset. A new bunch-by-bunch inversionWestern Australia, WA-ARRAY is designed to investigate algorithm, which allows along-line system geometry constraintsthe crustal and lithospheric mantle structure with the aim to be applied, is also used in the procedure. The methodologyof identifying prospective regions for mineral exploration, shows promise of remedying the issues for some datasets andespecially in areas undercover. The programme will deploy a lays the groundwork for further work aimed at increasing theseries of temporary arrays array of 165 seismometers in a grid utilisation of historical AEM data. pattern at 40 km intervals. Each seismometer will be left in place for one year before being rolled over into the next area, with the entire State being mapped over a 10-year period between nine Informing groundwater resource potential for miningregional areas.a magnetite resource using regional scale exploration datathe Braemar Corridor in South Australia. The results of this high resolution programme will create a step change in our understanding of Western Australias Timothy Munday, Shane Mul, Tania Ibrahimi and Kevin Cahill lithospheric architecture by imaging Earth structure down to the lithosphere-asthenosphere boundary. This knowledge CSIRO will provide a sound scientific basis for mineral and energy The South Australian Government has identified water as aexploration, but also for evaluating crucial land use decisions critical resource and a limiting factor in the development ofover the coming decades, at a time when large areas of the some of the most prospective areas in the State. The BraemarState are expected to accommodate renewable energy projects, Corridor is one of these regions, being highly prospectiveincluding those required to support a future hydrogen energy not only for magnetite, but also for other commodities. A keyindustry.recommendation in the Governments Magnetite Strategy wasIn addition, WA-ARRAY data will contribute to the National for the determination of priority areas for future groundwaterSeismic Hazard Assessment of seismic risk for industrial exploration and mapping to support the development ofinfrastructure such as pipelines and hydrogen generation and magnetite resources in the region. storage installations as well as building codes for residential They initiated a study of existing regional and finer-scalehousing and commercial buildings.geophysical, particularly airborne electromagnetic (AEM) data, that cover the Braemar Corridor, to help better define the groundwater resource potential of the region. HistoricalComparison between downhole and core gamma AEM data sets (fixed-wing and heliborne) were combined andmeasurements for lithology logging and stratigraphic inverted, to generate an enhanced understanding of the aquifercorrelation.systems present, their spatial continuity and character (including groundwater quality). A critical output from this work was theSekelo Mutelekeshadefinition of a product defined as a Regolith-Sediment Aquifer Thickness map, which defined the distribution of palaeovalleyFQMsystems and the importance of fault systems in the NNWDrilling is one of the best ways of acquiring reliable margin of the Murray Basin in generating thicker sequences ofgeological, geophysical and geochemical information of an sediments. These systems were then assessed for their potentialarea. Geoscientists are unable to get enough information against an extensive drillhole/stratigraphic data base developedfrom the drill core with their naked eyes, and as a result through mineral exploration activities in the Braemar Corridor. they resort to using tools that can measure the physical Their analysis coupled with those from existing hydrogeologicalproperties and the chemical compositions of core to get investigations, determined that higher yielding bores awaya clear understanding of the geology. Natural gamma is a from sedimentary basin cover sequences to the south andgeophysical dataset that is acquired because of its usefulness north of the Corridor intersect groundwater in fractures/faults/ for lithological logging and stratigraphic correlation. The bedding planes in Neoproterozoic rocks. Yields were oftenREFLEX EZ-GAMMA survey tool from IMDEX was used to airlift yields with only local limited supply. The palaeovalleysacquire downhole gamma data on a select few boreholes defined on southern margins of Corridor were thin, andat First Quantum Minerals Kasempa and EROI projects only partially saturated; of limited value for groundwaterin Zambia. Core gamma measurements using handheld supply. The best options for a more sustainable groundwaterscintillometers were also acquired for comparison and to supply near existing magnetite resources were along faultcomplement the downhole data. High quality downhole systems, including the Anabama Fault. Recent groundwatergamma data were taken every 10 cm in the boreholes, investigations support this. with data being made available in real time for lithological logging and correlation. The downhole gamma dataset was exceptional at picking subtle geological features and was WA_ARRAY: a State-wide passive seismic imagingthus used for stratigraphic correlation of deeper boreholes. campaign in Western Australia. Stratigraphic correlation was only done on the deep EROI boreholes because of the multiple stratigraphic sequences Ruth Murdie, Huaiyu Yuan and John ODonnell they intersect, unlike the Kasempa boreholes which are short Geological Survey of Western Australia and all drilled in the same basin. Gamma logs work well at complementing the geologists lithology logs by fine tuning WA-ARRAY is the extension of AusARRAY into Western Australiathe contacts and picking thin beds which could not be seen and will be of the largest passive seismic programmesby the geologist.FEBRUARY 2023 PREVIEW 122'