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    From sink to source: using thermochronometric data from offshore Namibia to extract onshore erosion signals

    Wildman, M. and Gallagher, K. and Chew, D. and Carter, Andrew (2020) From sink to source: using thermochronometric data from offshore Namibia to extract onshore erosion signals. Basin Research , ISSN 0950-091X. (In Press)

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    Abstract

    Products of onshore passive continental margin erosion are best preserved in offshore sedimentary basins. Therefore, these basins potentially hold a recoverable record of the onshore erosion history. Here, we present apatite fission track (AFT) data for 13 samples from a borehole in the southern Walvis basin, offshore Namibia. All samples show AFT central ages older or similar to their respective stratigraphic ages, while many single grain ages are older, implying none of the samples has been totally annealed post-deposition. Furthermore, large dispersion in single grain ages in some samples suggests multiple age components related to separate source regions. Using Bayesian mixture modelling we classify single grain ages from a given sample to particular age components to create ‘subsamples’ and then jointly invert the entire dataset to obtain a thermal history. For each sample, the post-depositional thermal history is required to be the same for all age components, but each component has an independent pre-depositional thermal history. With this approach we can resolve pre- and post-depositional thermal events and identify changes in sediment provenance in response to the syn- and post-rift tectonic evolution of Namibia and southern Africa. Apatite U-Pb and compositional data obtained during the acquisition of LA-ICP-MS FT data is also presented to help track changes in provenance and source material over time. We constrain multiple thermal events linked to the exhumation and burial history of the continental and offshore sectors of the margin over a longer timescale than has been possible using only onshore AFT thermochronological data.

    Metadata

    Item Type: Article
    Additional Information: This is the peer reviewed version of the article, which has been published in final form at the link above. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
    Keyword(s) / Subject(s): Namibian passive margin, Numerical modelling, tectonics and sedimentation, thermochronology
    School: School of Science > Earth and Planetary Sciences
    Research Centres and Institutes: Earth and Planetary Sciences, Institute of
    Depositing User: Andy Carter
    Date Deposited: 20 Nov 2020 16:34
    Last Modified: 14 Jun 2021 10:03
    URI: https://eprints.bbk.ac.uk/id/eprint/41564

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