Dating and correlation of Neogene coastal deposits in the Western Cape (South Africa): Implications for Neotectonism

Abstract

Research Article| December 01, 2002 Dating and correlation of Neogene coastal deposits in the Western Cape (South Africa): Implications for Neotectonism David L. Roberts; David L. Roberts Council for Geoscience, PO Box 572, Bellville 7535, Republic of South Africa, e-mail: dave@geobell.org.za Search for other works by this author on: GSW Google Scholar James S. Brink James S. Brink National Museum, P.O. Box 266, Bloemfontein 9300 Republic of South Africa, e-mail: florisbad@na5mus.co.za Search for other works by this author on: GSW Google Scholar Author and Article Information David L. Roberts Council for Geoscience, PO Box 572, Bellville 7535, Republic of South Africa, e-mail: dave@geobell.org.za James S. Brink National Museum, P.O. Box 266, Bloemfontein 9300 Republic of South Africa, e-mail: florisbad@na5mus.co.za Publisher: Geological Society of South Africa First Online: 07 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2003 Geological Society of South Africa South African Journal of Geology (2002) 105 (4): 337–352. https://doi.org/10.2113/1050337 Article history First Online: 07 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 David L. Roberts, James S. Brink; Dating and correlation of Neogene coastal deposits in the Western Cape (South Africa): Implications for Neotectonism. South African Journal of Geology 2002;; 105 (4): 337–352. doi: https://doi.org/10.2113/1050337 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 SocietySouth African Journal of Geology Search Advanced Search Abstract A northward trending, fossil dune system (Prospect Hill Formation) extends for ~20 km parallel to the coast north of Saldanha. Fossil eggshell fragments of the giant struthious bird Diamantornis wardi were recovered from three palaeosols in the Prospect Hill Formation. D. wardi has been assigned to the late Middle Miocene (12 to 10 Ma) in Namibia, making this one of the oldest coastal dune systems in South Africa. The aeolianites rest conformably on a +40m boulder beach, equated with the global Middle Miocene high sea level cycle (HSLC) and the latter stages of the +90m HSLC of Namaqualand. The presence of struthious birds and the dune snail Trigonephrus globulus suggests a relatively dry, Mediterranean climate. A younger +25m beach and associated aeolianites are banked up unconformably on the seaward aspect of the Prospect Hill Formation. The zone fossil (bivalve) Donax rogersi relates these deposits to the +30m HSLC in Namaqualand and probably to a Plio-Pleistocene (~2Ma) global highstand. Altimetric discrepancies between the global Mio-Pliocene HSLC in the Western Cape (Varswater and De Hoop Vlei Formations) and Namaqualand suggest crustal subsidence of some 50m along the northern west coast. Comparison of global Middle Miocene sea levels (up to +140m) and the Middle Miocene HSLC in Namaqualand (maximum +90m) yields a similar result. Terrestrial deposits at ~50m below sea level at Noordhoek on the Cape Peninsula are attributed to eustacy rather than tectonism. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.