The deep crustal structure of the c. 1080 Ma Warakurna LIP, and insights on its processes and mineralisation: Results of 3D gravity inversion

PreviousNext No AccessFifth International Conference on Engineering Geophysics, Al Ain, UAE, 21–24 October 2019The deep crustal structure of the c. 1080 Ma Warakurna LIP, and insights on its processes and mineralisation: Results of 3D gravity inversionAuthors: Abdulrhman Alghamdi*Alan AitkenMichael DentithAbdulrhman Alghamdi*Centre for Exploration Targeting, University of Western Australia M006, 35 Stirling Highway, Crawley, Western Australia 6009, AustraliaKing Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi ArabiaSearch for more papers by this author, Alan AitkenCentre for Exploration Targeting, University of Western Australia M006, 35 Stirling Highway, Crawley, Western Australia 6009, AustraliaSearch for more papers by this author, and Michael DentithCentre for Exploration Targeting, University of Western Australia M006, 35 Stirling Highway, Crawley, Western Australia 6009, AustraliaSearch for more papers by this authorhttps://doi.org/10.1190/iceg2019-070.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract Large Igneous Provinces (LIPs) of the Proterozoic era in terms of interpreting geophysical characterise of their deep crustal structure and upper mantle are still complicated due to absence of the thermal system related to the younger LIPs. However, seismically-constrained gravity inversion method can provide a reliable way of identifying magmatic underplating that characterized by a high velocity and density lower crust, a highly transitional Moho, and often by significant crustal thickness. In this study, a seismically-constrained gravity inversion method was applied to the Warakurna LIP region in central-western Australia with focusing on imaging the deep crust of this region, and defining the extent and intensity of mafic magmatism. In particular, a thick mafic underplate has been imaged in some regional seismic studies, but its regional extent is unknown. The results of 3D gravity inversions demonstrate an extensive area with very thick crust (> 45 km) and high-density materials (> 2.83 g/cm3), which are interpreted to represent a mafic underplate. The mass-excess (i.e. thickness and/or density) of this underplate is greatest beneath the magmatic centre of the LIP in the west Musgrave Province (WMP). Variations in mass excess suggest that the intensity of mafic magmatism closely followed the likely lithospheric architecture of the Australian continent at the time of emplacement, with magmatic centres concentrated adjacent to craton margins and along translithospheric shear zones. This suggests either that upwelling magma has been diverted by the roots of the Archean cratons or that melting was focused in the Proterozoic regions with thinner lithosphere. This arrangement is reflected in Ni-Cu-PGE prospectivity, with known deposits focused in the WMP, which has a thick, dense underplate. In contrast the Capricorn Orogen and Yilgarn Craton, which are not underplated, do not possess known deposits, despite extensive sill-networks in the upper crust. Our results show that this method for mapping the extent and mass-excess of lower-crustal magmatic products provides an effective indicator of the extent and intensity of magmatism during LIP events, and that this can help understand LIP processes, including ore-deposit formation. Keywords: gravity, inversion, crustal structure, sediment, densityPermalink: https://doi.org/10.1190/iceg2019-070.1FiguresReferencesRelatedDetails Fifth International Conference on Engineering Geophysics, Al Ain, UAE, 21–24 October 2019ISSN (online):2159-6832Copyright: 2020 Pages: 315 publication data© 2020 Published in electronic format with permission by the Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished: 03 Apr 2020 CITATION INFORMATION Abdulrhman Alghamdi*, Alan Aitken, and Michael Dentith, (2020), "The deep crustal structure of the c. 1080 Ma Warakurna LIP, and insights on its processes and mineralisation: Results of 3D gravity inversion," SEG Global Meeting Abstracts : 277-279. https://doi.org/10.1190/iceg2019-070.1 Plain-Language Summary Keywordsgravityinversioncrustal structuresedimentdensityPDF DownloadLoading ...