BIROn - Birkbeck Institutional Research Online

    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.R. and Brown, R. and Beucher, R. and Persano, C. and Stuart, F. and Gallagher, K. and Schwanethal, J. and Carter, Andrew (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 , ISSN 0278-7407.

    [img]
    Preview
    Text
    Wildman_et_al-2016-Tectonics.pdf - Published Version of Record

    Download (7MB) | Preview

    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 ± 3.6Ma, 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 ± 31.4Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150–130Ma and 110–90Ma 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.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): apatite fission track, (U-Th Sm)/He, Africa, thermochronology, passive continental margin, landscape evolution
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Professor Andrew Carter
    Date Deposited: 07 Apr 2016 13:56
    Last Modified: 05 Sep 2016 23:11
    URI: http://eprints.bbk.ac.uk/id/eprint/14772

    Statistics

    Downloads
    Activity Overview
    48Downloads
    102Hits

    Additional statistics are available via IRStats2.

    Archive Staff Only (login required)

    Edit/View Item Edit/View Item