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    Contrasting Mesozoic evolution across the boundary between on and off craton regions of the South African plateau inferred from apatite fission track and (U-Th-Sm)/He thermochronology

    Wildman, M. and Brown, R. and Persano, C. and Beucher, R. and Stuart, F.M. and Mackintosh, V. and Gallagher, K. and Schwanethal, James and Carter, Andrew (2017) Contrasting Mesozoic evolution across the boundary between on and off craton regions of the South African plateau inferred from apatite fission track and (U-Th-Sm)/He thermochronology. Journal of Geophysical Research: Solid Earth 122 (2), pp. 1517-1547. ISSN 0148-0227.

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    Abstract

    The timing and mechanisms involved in creating the elevated, low-relief topography of the South African plateau remains unresolved. Here we constrain the thermal history of the southwest African plateau since 300 Ma using apatite fission track (AFT) and (U-Th-Sm)/He (AHe) thermochronology. Archaean rocks from the centre of the Kaapvaal Craton yield AFT ages of 331.0 ± 11.0 and 379.0 ± 23.0 Ma and mean track lengths (MTL) of 11.9 ± 0.2 and 12.5 ± 0.3 µm. Towards the southwest margin of the craton and in the adjacent Palaeozoic mobile belt, AFT ages are significantly younger and range from 58.9 ± 5.9 to 128.7 ± 6.3 Ma, and have longer MTLs (>13 µm). The range of sampleAHe ages complements the AFT ages and single grain AHe ages for most samples are highly dispersed. Results from joint inverse modelling of these data reveal that the centre of the craton has resided at near surface temperatures (<60 °C) since 300 Ma, whereas the margins of the craton and the off-craton mobile belt experienced two discrete episodes of cooling during the Cretaceous. An Early Cretaceous cooling episode is ascribed to regional denudation following continental break up. Late Cretaceous cooling occurs regionally but is locally variable and may be a result of a complex interaction between mantle driven uplift the tectonic setting of the craton margin. Across the entire plateau, samples are predicted to have remained at near surface temperatures throughout the Cenozoic suggesting minimal denudation (<1 km) and relative tectonic stability of the plateau.

    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.
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Professor Andrew Carter
    Date Deposited: 15 Feb 2017 11:04
    Last Modified: 10 Nov 2017 14:31
    URI: http://eprints.bbk.ac.uk/id/eprint/18126

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