University of Wollongong
Browse

Strong rocks sustain ancient postorogenic topography in southern Africa

Download (1.67 MB)
journal contribution
posted on 2024-11-14, 23:04 authored by Taryn E Scharf, Alexandru CodileanAlexandru Codilean, Maarten De Wit, John Jansen, Peter W Kubik
The Cape Mountains of southern Africa exhibit an alpine-like topography in conjunction with some of the lowest denudation rates in the world. This presents an exception to the often-cited coupling of topography and denudation rates and suggests that steep slopes alone are not sufficient to incite the high denudation rates with which they are commonly associated. Within the Cape Mountains, slope angles are often in excess of 30° and relief frequently exceeds 1 km, yet 10Be-based catchment-averaged denudation rates vary between 2.32 ± 0.29 m/m.y. and 7.95 ± 0.90 m/m.y. We attribute the maintenance of rugged topography and suppression of denudation rates primarily to the presence of physically robust and chemically inert quartzites that constitute the backbone of the mountains. 10Be-based bedrock denudation rates on the interfluves of the mountains vary between 1.98 ± 0.23 m/m.y. and 4.61 ± 0.53 m/m.y. The close agreement between the rates of catchment-averaged and interfluve denudation indicates topography in steady state. These low denudation rates, in conjunction with the suggestion of geomorphic stability, are in agreement with the low denudation rates (/m.y.) estimated for southern Africa during the late Cenozoic by means of cosmogenic nuclide, thermochronology, and offshore sedimentation analyses. Accumulatively, these data suggest that the coastal hinterland of the subcontinent may have experienced relative tectonic stability throughout the Cenozoic.

History

Citation

Scharf, T. E., Codilean, A. T., De Wit, M., Jansen, J. D. & Kubik, P. W. (2013). Strong rocks sustain ancient postorogenic topography in southern Africa. Geology, 41 (3), 331-334.

Journal title

Geology

Volume

41

Issue

3

Pagination

331-334

Language

English

RIS ID

76345

Usage metrics

    Categories

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC