Geophysical study of the easternmost Walvis Ridge, South Atlantic: Deep structure

Abstract

Research Article| December 01, 1975 Geophysical study of the easternmost Walvis Ridge, South Atlantic: Deep structure J. GOSLIN; J. GOSLIN 1Institut de Physique du Globe de Paris, Laboratoire de Géophysique Marine, 4 Avenue de Neptune, 94100, St. Maurdes-Fossés, France Search for other works by this author on: GSW Google Scholar J. C. SIBUET J. C. SIBUET 2Centre Océanologique de Bretagne, B.P. 337, 29273, Brest, France Search for other works by this author on: GSW Google Scholar Author and Article Information J. GOSLIN 1Institut de Physique du Globe de Paris, Laboratoire de Géophysique Marine, 4 Avenue de Neptune, 94100, St. Maurdes-Fossés, France J. C. SIBUET 2Centre Océanologique de Bretagne, B.P. 337, 29273, Brest, France Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1975) 86 (12): 1713–1724. https://doi.org/10.1130/0016-7606(1975)86<1713:GSOTEW>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J. GOSLIN, J. C. SIBUET; Geophysical study of the easternmost Walvis Ridge, South Atlantic: Deep structure. GSA Bulletin 1975;; 86 (12): 1713–1724. doi: https://doi.org/10.1130/0016-7606(1975)86<1713:GSOTEW>2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract A seismic-refraction study of the sedimentary structure of the South West African continental shelf was carried out between lat 17°S and 24°S using expendable sonobuoys. Striking differences exist both in the topography and sedimentary structure between the shelf north and south of the Walvis Ridge. South of the ridge, as far as lat 23°S, the shelf consists of a prograded series, whereas north of the ridge, at least as far as lat 17°S, east-trending canyons cut the shelf sedimentary cover. The steep northern scarp of Walvis Ridge can be traced eastward under the sediment of the continental margin. The southern flank of the ridge is buried under a thicker sedimentary cover and could only be traced eastward to long. 10°E on seismic-reflection records. This flank probably parallels the northern scarp under the continental margin. Two-dimensional structural models, built with the help of seismic-reflection and seismic-refraction results and based on the hypothesis of local isostatic equilibrium, account for the observed gravity profiles. A compensating root consists of light material (density 2.95 g/cm3) and reaches a depth of about 25 km. Gravity results also suggest that the Walvis Ridge does not constitute a superimposed load on the lithosphere; rather, the ridge and its underlying compensating mass were created at approximately the same time as the adjacent ocean basins.The creation of the two aseismic ridges of the South Atlantic — the Rio Grande Rise and Walvis Ridge — by a mantle hot spot and plume is accepted; this theory seems to explain most of the peculiar features of the Walvis Ridge. However, it is probable that the surface expression of the mantle hot spot was controlled by the presence of weak zones in the lithosphere such as transform faults. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.