The Alguhas Ridge: Connections between changing patterns of deep sea currents and volcanic -tectonic activity as well as origin of the "Dupal Anomaly" and intraplate volcanism - Cruise No. MSM19/3 - December 1st - December 23rd, 2011 - Cape Town (South Africa) - Cape Town (South Africa)

Freier Zugriff
in MARIA S. MERIAN-Berichte; MSM19/3; 1-32; MARIA S. MERIAN-Berichte

Dokumentinformationen

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

Abstract

The main purpose of R/V MARIA S. MERIAN cruise MSM19/3 was to obtain new insights into the origin and evolution of tectonic and volcanic structures in the South Atlantic (Agulhas Ridge and associated structures, Discovery Rise) using morphological, volcanological, geochemical and geochronological methods in combination with the geophysical data yielded on the previous AWI-cruise MSM19/2. The rock sampling on MSM19/3 achieved its major objectives through successful extensive dredge sampling of Richardson Seamount, the Agulhas Ridges and adjacent features, the northern Meteor Rise, and of 11 Discovery seamounts. Of the 57 dredges carried out on MSM19/3 in only 15 working days, 31 recovered magmatic rocks, 16 volcaniclastics, 7 sedimentary rock, and 23 Mn-Fe oxides. The wide range of volcanic, metamorphic, intrusive, and sedimentary rocks recovered on MSM19/3 represents the most detailed marine sampling of this area to date. SIMRAD EM120 data recorded on MSM19/2 and /3 (and previous R/V POLARSTERN cruises) were used to select sampling stations and to assess the morphology of the region. Multi-beam seafloor mapping and preliminary analyses of the recovered samples suggest among others reactivation of the Agulhas Fracture Zone, a volcanic rather than continental nature of Richardson Seamount, and a mantle plume origin of the Discovery Seamouts. Furthermore biological material was obtained successfully as macrofauna and as sediment samples containing meiofaunal organisms. Macrofaunal organisms were recovered from the rocks at 26 out of 57 stations, 43 stations yielded sediment samples in the built-in sediment traps of the dredges. Meiofauna was extracted after the cruise from sediment samples. Preliminary sorting of 1/3 of all samples reveals a total of 1,671 meiofaunal organisms.


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