The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U-Th-Sm)/He thermochronology

Wildman, M., Brown, R., Beucher, R., Persano, C., Stuart, F. , Gallagher, K., Schwanethal, J. and Carter, A. (2016) The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U-Th-Sm)/He thermochronology. Tectonics, 35(3), pp. 511-545. (doi:10.1002/2015TC004042)

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Abstract

Atlantic-type continental margins have long been considered “passive” tectonic settings throughout the entire postrift phase. Recent studies question the long-term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin's evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U-Th-Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6 Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 µm, and mean (U-Th-Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4 Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150–130 Ma and 110–90 Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1–3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle-driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.

Item Type:Articles
Additional Information:12/02/16 GM - Additional award to SUERC associated with publication - NE/H008454/1
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wildman, Mr Mark and Persano, Dr Cristina and Stuart, Professor Finlay and Brown, Professor Roderick
Authors: Wildman, M., Brown, R., Beucher, R., Persano, C., Stuart, F., Gallagher, K., Schwanethal, J., and Carter, A.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Tectonics
Publisher:Wiley
ISSN:0278-7407
ISSN (Online):1944-9194
Copyright Holders:Copyright © 2016 Wiley
First Published:First published in Tectonics 35(3):511-545
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
586271NERC DTG 2011-15Mary Beth KneafseyNatural Environment Research Council (NERC)NE/J500252/1RSI - RESEARCH STRATEGY & INNOVATION
525621Resolving the age of the first-order topography of AfricaRoderick BrownNatural Environment Research Council (NERC)NE/H008276/1SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES