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Marine Geophysical Researches

, Volume 25, Issue 3–4, pp 305–319 | Cite as

The Agulhas Ridge, South Atlantic: The Peculiar Structure of a Fracture Zone

  • Gabriele Uenzelmann-Neben
  • Karsten Gohl
Article

Abstract

The Agulhas Ridge is a prominent topographic feature that parallels the Agulhas-Falkland Fracture Zone (AFFZ). Seismic reflection and wide angle/refraction data have led to the classification of this feature as a transverse ridge. Changes in spreading rate and direction associated with ridge jumps, combined with asymmetric spreading within the Agulhas Basin, modified the stress field across the fracture zone. Moreover, passing the Agulhas Ridge’s location between 80 and 69 Ma, the Bouvet and Shona Hotspots may have supplied excess material to this part of the AFFZ thus altering the ridge’s structure. The low crustal velocities and overthickened crust of the northern Agulhas Ridge segment indicate a possible continental affinity that suggests it may be formed by a small continental sliver, which was severed off the Maurice Ewing Bank during the opening of the South Atlantic. In early Oligocene times the Agulhas Ridge was tectono-magmatically reactivated, as documented by the presence of basement highs disturbing and disrupting the sedimentary column in the Cape Basin. We consider the Discovery Hotspot, which distributes plume material southwards across the AAFZ, as a source for the magmatic material.

Keywords

Agulhas-Falkland Fracture Zone transverse ridge Agulhas Ridge South Atlantic seismic reflection and refraction data Discovery Hotspot Shona Hotspot Bouvet Hotspot ODP Leg 177 

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Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Alfred Wegener Institute for Polar and Marine ResearchBremerhavenGermany

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