b'AEGC 2023Short abstractsmineral exploration outcomes. Mapping and characterisingAEM data over the Pillara deposits show a more accurate the regolith interfaces is one of the main projects withindepth-extent of the subsurface Devonian carbonates the Mineral Exploration Cooperative Research Centrethan gravity modelling. An east-southeast dipping fault (MinEx CRC), with the objective of providing and evaluatinginterpreted in the AEM data is likely associated with a thin a range of in situ data to permit near real-time decision- interval of moderate-grade zinc mineralisation as intersected making in drilling programmes linked to the Nationalby drillholes. The observations and interpretations illustrated Drilling Initiative (NDI). Geochemical and mineralogicalabove highlight the value of AEM data for predicting the data derived from techniques such as portable XRF andstructural geometry and exploration for sulphide deposits, UV-Vis as well as hyperspectral data acquired by HyLoggerTMparticularly those hosted by resistive Devonian reef spectrometry, along with effective data processing toolscomplexes on the Lennard Shelf.using Data MosaicTM, optimised Machine Learning (ML) and other multivariate classification approaches, is being used to improve identification of significant interfacesConductivity-depth imaging in the Ord Basin, Western within regolith and basement profiles. A semi-automatedAustralia.workflow based on both data-driven and knowledge-driven approaches has been developed for cover characterisationAlex Zhan, Peter Haines, Arthur Mory and David Martinof drillholes in Cobar Basin located in western New SouthGeological Survey of Western AustraliaWales. Results demonstrate that using feature selection techniques based on data-driven classification approaches,The Ord Basin straddles the Western AustralianNorthern moderated by expert choices in determining the best suiteTerritory border in the east Kimberley region of northern of elements to retain in the modelling, can significantlyAustralia and covers 40 000 km2, of which 16 000 km2 lies boost the boundary detection and classification accuracy inin WA. The basin contains up to 2.5 km of Cambrian and cover characterisation. This workflow is being extended toDevonian strata, with the post-volcanic succession preserved include other data types, including petrophysical parameters,in the Hardman, Rosewood and Argyle Synclines to the east to further assist in classification and characterisationof the Halls Creek Fault. The basin has no seismic reflection of drill materials as part of the process of improvingdata, and the 2019 WANT airborne electromagnetic (AEM) the effectiveness of exploration in regions containingsurvey is the first dataset to resolve the basin down to a depth transported or deeply weathered cover. of 600 m. By contrast, previous geological understanding of the basin was based mostly on surface mapping and a small number of mineral and petroleum drillholes.Electromagnetic response of MVT Pb-Zn deposits on the Lennard Shelf, Canning Basin. A large portion of the Ord Basin including the Hardman Syncline and southern part of the Kalkarindji Large Igneous Province is Alex Zhan, Paul Duuring, Louisa Dent and John Brett covered by 10 westeast AEM flight lines, in which contrasts Geological Survey of Western Australia of conductivity are highly consistent with bedrock geology and the Cambrian section in Okes-Durack 1 drilled in 192324. The Canning Basin hosts known Mississippi valley-typeThe survey shows Devonian sandstone and conglomerate are (MVT) lead-zinc sulphide occurrences, including the shallowmore resistive than underlying upper Cambrian siltstone in (500 m) Pillara, Kapok and Cadjebut deposits hosted inthe western part of the syncline. The mid-Cambrian section the Devonian reef complexes on the Lennard Shelf, asshows a higher conductivity with more shale and siltstone well as deeper examples within Ordovician carbonatesin the Panton Formation and Nelson Shale. The intermediate along the Admiral Bay Fault Zone. The basin is covered byand high conductive sections appear to shallow and thicken a regional airborne electromagnetic (AEM) survey with atowards the east, indicating that the Cambrian depositional nominal spacing of 20 km, funded by the Commonwealthaxis was at least 50 km east of the Devonian outcrops. The AEM Governments Exploring for the Future (EFTF) programmes.data, in conjunction with aeromagnetic data, also indicates that Some of the flight lines were slightly deviated to fly directlymost outcrops mapped as Windoo Sandstone and previously over the shallow MVT sulphide deposits on the Lennardinterpreted to overlie the lower Cambrian Antrim Plateau Shelf. The resulting conductivity profiles help resolve theVolcanics of the Kalkarindji Large Igneous Province actually geometry of these mineralisation occurrences and structuralunderlie that unit. These outcrops are most likely a sandstone configurations. unit associated with the Neoproterozoic Timperley Shale of the Wolfe Basin.Based on existing drillholes at the Kapok West deposits, sulphide mineralisation correlates with a thick zone of highOptimising 4D signal where environmental condition conductivity, which stands out from the more resistive carbonate platform of the Devonian reef complexes. Thehinders survey repeatability, Northern Carnarvon Basin.sulfide mineralisation zone is interpreted to have beenHui Zhang and Kai Zhaodisplaced by a set of antithetic north-dipping faults, which postdate the south-dipping Cadjebut Fault. Multiple phasesCGGof faulting and fluid movement associated with the formation of the MVT deposits most likely explains the present faultTime-lapse (4D) seismic data are now being widely used for gas configuration and topography of the Emanuel Range. field reservoir development and depletion drive studies. The quality of the time-lapse analysis depends highly on the quality Sulphide occurrences at Pillara are not as prominentof acquisition repeatability between base and monitor surveys. as Kapok West, but they are still resolvable as a weaklyIn practice, it is almost impossible to perfectly replicate a base conductive feature against the more resistive platform. Thesurvey due to environmental conditions, especially for marine 155 PREVIEW FEBRUARY 2023'