b'AEGC 2021Short abstractsimproved constraints on the shear velocity structures andprovide opportunity to investigate the uplift history of the sub-builds a new basis for the next-generation crustal model of thebasin. In this project, we use seismic and well data to calculate Australian continent. a detailed uplift history of the Kidson Sub-Basin. Seismic data reveal two major unconformities, namely pre-Mesozoic and pre-Devonian unconformities and these are interpreted as erosional 258: Lithospheric-scale magnetotellurics over theperiods resulting from uplift. Using well data, the decompaction Eastern Goldfields Superterrane, Yilgarn Craton method is used to restore sedimentary units (including source/Dr Kate Selway, Prof Mike Dentith and Dr Klaus Gessner reservoir rocks) to their maximum burial depths and the difference between the maximum burial depths and present The Eastern Goldfields Superterrane, in the Yilgarn Craton,depths is used to estimate the amount of uplift. Results indicate Western Australia, is one of the most highly mineralised regionsthat, up to 200 m of uplift occurred during the Middle Silurian on Earth, hosting world-class orogenic gold and nickel-sulfide(the Prices Creek Movement). Up to 350 m of uplift occurred deposits. Mineral systems models for both of these depositduring the Middle Carboniferous (the Meda Transpression). Up types suggest that lithospheric-scale processes are involvedto 600 m of uplift occurred during the Early Jurassic (the Fitzroy in their formation. Therefore, lithospheric-scale geophysicalTranspression). In general, the Kidson-Sub-Basin appears to imaging is a promising tool to improve understanding of thehave undergone relatively less uplift compared to other regions formation of the deposits and to aid future exploration. within the Canning Basin.Long-period magnetotelluric (MT) data were collected over260: Inversion-based automatic processing of AEM datathe western Eastern Goldfields Superterrane and the eastern Youanmi Terrane. The survey region covers the Kalgoorlie andA/Prof Gianluca Fiandaca 1St Ives gold camps and the Kambalda nickel camp, as well as the isotopic boundary between the older Nd model ages of the1 University of MilanoYouanmi Terrane and the younger Nd model ages of the EasternData processing is a mandatory step before inversion for any Goldfields Superterrane. A 3D conductivity model of the datageophysical inversion, because data outliers significantly affect has good resolution to 150 to 200 km depth the inversion process, often forbidding to reach reasonable Results show that the lithospheric mantle is more conductiveinversion models and misfits. In the processing of Airborne beneath the Youanmi Terrane than the Eastern GoldfieldsElectromagnetic (AEM) data, the specificity consists in the Superterrane. Crustal conductivity is more heterogeneous butnecessity to cull out capacitive and galvanic coupled data, with most of the strongly conductive regions (100 ohm m) arethe latter more difficult to recognize in data space alone.located in the Eastern Goldfields Superterrane. AnomalouslyIn this study I propose to use a generalization of the conductive zones in tectonically stable mantle often indicateminimum support norm, namely the asymmetric generalized past metasomatism, either through the hydration of nominallyminimum support (AGMS) norm, for defining the data misfit anhydrous minerals or the growth of conductive mineral phasesin the objective function of an iterative reweighted least such as amphibole or phlogopite. squared (IRLS) gauss-newton inversion. The AGMS norm Quantitative interpretation of the MT model shows that thein the data misfit puts a cap on the weight of non-fitting mantle conductors in the Youanmi Terrane are too conductivedata points, allowing for the inversion to focus on the data to be explained purely by hydrated peridotite and imply thepoints that can be fitted. Outliers can be identified after the presence of hydrous metasomatic minerals. The observedAGMS inversion computing a classic L2 misfit from the final patterns of lithospheric conductivity suggest a more complexinversion model.relationship between mantle metasomatism and gold andInversions on AEM data with and without manual processing nickel mineral systems than expected from previous studies,are compared, with the AGMS inversion able to recognize which may inform future exploration. outliers in the same areas in which data are manually culled out because of coupling, with comparable final inversion models. 259: The uplift history of the Kidson Sub-Basin Moreover, the processing scheme can recognize not only data which are affected by noise, but also data that are not modelled Mr George Marfo 1, Dr Stuart Clark2 and Ms Tehani Palu3 correctly, for instance because of the dimensionality of the forward response: in this case, it can be used for identifying the 1 University of New South Wales (UNSW), Sydney. appropriateness of the modelling within the inversion area.2 UNSW3 Geoscience Australia This inversion-based automatic processing scheme is very robust and works well also with a significant number of outliers; The Canning Basin, offshore Western Australia, is highlyfurthermore, it is fully general and can be applied not only to prospective for conventional and non-conventionalAEM data, but to any geophysical problem simply using the hydrocarbons as well as Uranium and Zinc-Lead mineralappropriate forward modelling.deposits. The Basin has evolved since Early Ordovician undergoing both extensional and transpressional tectonic261: Inversion of Airborne IP data with a multi-mesh regimes since then. The transpression events have beenapproach for parameter definitionassociated with significant uplift and has impacted heatflow and fluid migration pathways in the basin. Although the KidsonA/Prof Gianluca Fiandaca 1 and Dr Andrea Viezzoli2sub-basin is the largest block in the Canning Basin, the uplift history is not as well understood due to sparse data collection1 Department of Earth Sciences Ardito Desio, University of in that region. The recent acquisition of seismic line 18GA-KB1Milano (Italy)in 2018 across the Kidson Sub-basin in addition to existing wells2 Aarhus Geophysics107 PREVIEW AUGUST 2021'