Pleiades - Cruise No. MSM17/2 - December 31, 2010 - January 27, 2011 - Walvis Bay (Namibia) - Walvis Bay (Namibia)

Freier Zugriff
in MARIA S. MERIAN-Berichte; MSM17/2; 1-48; MARIA S. MERIAN-Berichte

Dokumentinformationen

  • Format / Umfang:
    48 pages
  • ISSN:
  • DOI:
  • Medientyp:
    Aufsatz (Zeitschrift)
  • Format:
    Elektronische Ressource
  • Sprache:
    Englisch
  • Klassifikation:
    DDC:    550 Earth sciences and geology

Abstract

Continental break-up is closely related to the question regarding the driving forces behind processes related to such an incisive geological event. A common explanation calls on mantle plumes as the most important triggers for the separation of continents. Around the head of a plume, the upper mantle temperatures strongly increase. After weakening of the continental crust by horizontal extension, the high temperatures cause extensive volcanism, thus forming continental flood basalts as parts of so-called Large Igneous Provinces (LIP) and also in some cases in the newly formed oceanic basins. Some of the best examples of such relationships found on Earth are the Parana/Etendeka flood basalts and the Rio Grande Rise/Walvis Ridges, located on both margins of the South Atlantic. Expeditions MSM17/2_1+2 were designed to investigate critical parameters, such as crustal thickness and structure of the subjacent Earth's mantle, in this region offshore northern Namibia with regards to a globally important plate tectonic process. The operations during both legs were extremely efficient between scientists and crew, and so successful that they led to the possibility of acquiring an additional deep seismic sounding profile, as originally proposed, further westward off the Namibian coast. All deployed instruments were recovered with the exception of a single OBS, which was probably caught in a fishing net close to the coast. The seismic data quality acquired both on- and offshore turned out to be excellent. They also show, however, that the prevailing assumptions about the structure and eruption style of the Walvis Ridge differ from previous models.


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