The palaeo-bathymetry of base Aptian salt deposition and the composition of underlying basement on the northern Angolan rifted margin

PreviousNext You have accessInternational Conference and Exhibition, Barcelona, Spain, 3-6 April 2016The palaeo-bathymetry of base Aptian salt deposition and the composition of underlying basement on the northern Angolan rifted marginAuthors: Leanne CowieNick KusznirRicardo AngeloGianreto ManatschalBrian HornLeanne CowieUniversity of LiverpoolSearch for more papers by this author, Nick KusznirUniversity of LiverpoolSearch for more papers by this author, Ricardo AngeloUniversity of LiverpoolSearch for more papers by this author, Gianreto ManatschalUniversite de StrasbourgSearch for more papers by this author, and Brian HornIONSearch for more papers by this authorhttps://doi.org/10.1190/ice2016-6524491.1 SectionsAbout ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract The bathymetric datum with respect to global sea level for Aptian salt deposition on the deep-water Angolan rifted margin and the composition of underlying basement are hotly debated. Quantitative analysis of deep seismic reflection and gravity anomaly data together with reverse post-breakup subsidence modelling has been used to investigate ocean-continent transition structure, continent-ocean boundary location, crustal type and the palaeo-bathymetry of Aptian salt deposition. The analysis has been applied to the ION-GXT CS1-2400 deep long-offset seismic reflection profile and the P3 and P7+11 seismic cross sections of Moulin (2005) and Contrucci et al. (2004) offshore northern Angola. The palaeo-bathymetry of base Aptian salt deposition has been determined using reverse post-breakup subsidence modelling consisting of the sequential flexural isostatic backstripping of the post-breakup sedimentary sequences, decompaction of remaining sedimentary units and reverse modelling of post-breakup lithosphere thermal subsidence. We predict that Aptian salt was deposited between approximately 0.2km and 0.6km below global sea level, and that the inner proximal salt subsided by post-rift (post-tectonic) thermal subsidence alone, while the outer distal salt formed during syn-rift, prior to breakup, resulting in additional tectonic subsidence. Our analysis argues against Aptian salt deposition on the Angolan margin in a 2-3km deep isolated ocean basin, and supports salt deposition on hyper-extended continental crust formed by diachronous rifting migrating from east to west, culminating in the late Aptian. Gravity inversion to give Moho depth and crustal thickness, RDA analysis to identify departures from oceanic bathymetry and subsidence analysis shows that the distal Aptian salt is underlain by hyper-extended continental crust rather than exhumed mantle or oceanic crust. Keywords: crustal structure, reflection, salt, subsalt, deepwaterPermalink: https://doi.org/10.1190/ice2016-6524491.1FiguresReferencesRelatedDetails International Conference and Exhibition, Barcelona, Spain, 3-6 April 2016ISSN (online):2159-6832Copyright: 2016 Pages: 356 publication data© 2016 Published in electronic format with permission by the Society of Exploration Geophysicists and the American Association of Petroleum GeologistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 03 Apr 2016 CITATION INFORMATION Leanne Cowie, Nick Kusznir, Ricardo Angelo, Gianreto Manatschal, and Brian Horn, (2016), "The palaeo-bathymetry of base Aptian salt deposition and the composition of underlying basement on the northern Angolan rifted margin," SEG Global Meeting Abstracts : 43-43. https://doi.org/10.1190/ice2016-6524491.1 Plain-Language Summary Keywordscrustal structurereflectionsaltsubsaltdeepwaterLoading ...