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

Wildman, M. , Gallagher, K., Chew, D. and Carter, A. (2021) From sink to source: using offshore thermochronometric data to extract onshore erosion signals in Namibia. Basin Research, 33(2), pp. 1580-1602. (doi: 10.1111/bre.12527)

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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 (‘subsample’) 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 are also presented to help track changes in provenance with 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.

Item Type:Articles
Additional Information:This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 706976. DC acknowledges support by a research grant from Science Foundation Ireland under Grant Number 13/RC/2092, which is co-funded under the European Regional Development Fund and by PIPCO RSG and its member companies.
Glasgow Author(s) Enlighten ID:Wildman, Dr Mark
Authors: Wildman, M., Gallagher, K., Chew, D., and Carter, A.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Basin Research
ISSN (Online):1365-2117
Published Online:13 November 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Basin Research 33(2): 1580-1602
Publisher Policy:Reproduced under a Creative Commons License

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