Strong rocks sustain ancient postorogenic topography in southern Africa

Abstract

Research Article| March 01, 2013 Strong rocks sustain ancient postorogenic topography in southern Africa Taryn E. Scharf; Taryn E. Scharf * 1Earth Surface Geochemistry, Deutsches GeoForschungsZentrum (GFZ), Potsdam D-14478, Germany2Africa Earth Observatory Network (AEON), Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa *E-mail: taryn@shango.co.za. Search for other works by this author on: GSW Google Scholar Alexandru T. Codilean; Alexandru T. Codilean 1Earth Surface Geochemistry, Deutsches GeoForschungsZentrum (GFZ), Potsdam D-14478, Germany Search for other works by this author on: GSW Google Scholar Maarten de Wit; Maarten de Wit 2Africa Earth Observatory Network (AEON), Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa Search for other works by this author on: GSW Google Scholar John D. Jansen; John D. Jansen 3Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm SE 10691, Sweden Search for other works by this author on: GSW Google Scholar Peter W. Kubik Peter W. Kubik 4Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich, Switzerland Search for other works by this author on: GSW Google Scholar Geology (2013) 41 (3): 331–334. https://doi.org/10.1130/G33806.1 Article history received: 29 Jun 2012 rev-recd: 20 Sep 2012 accepted: 08 Oct 2012 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Taryn E. Scharf, Alexandru T. Codilean, Maarten de Wit, John D. Jansen, Peter W. Kubik; Strong rocks sustain ancient postorogenic topography in southern Africa. Geology 2013;; 41 (3): 331–334. doi: https://doi.org/10.1130/G33806.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract 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 (<20 m/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. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.