Geology & Geophysics Group
The Mid Atlantic Ridge: Ascension Island
Contact: Dr Lindsay Parson
As part of a NOCS survey programme commissioned by the UK Government for the purposes of delimitation of maritime space around UK overseas territories, the Royal Research Ship James Clarke Ross carried out a swath multibeam survey on ridge sections north and south of Ascension Island (Cruise JCR 65).
The first and second order segmentation of the MAR was observed to be of a complex geometry, involving locally broad, non-transform discontinuities, non-offset transforms and major fracture zones (such as the Boca Verde FZ in the S). Additional survey work carried out within 200 nautical miles of the Island provided both data to add to the uncertainties surrounding the existence of ridge propagators re-orienting the MAR between 7 and 9°S, and evidence of some high temperature hydrothermal venting on the ridge, approximately on a flow line from the Island.
Left: Cruise JR65 track location over the MAR, north and south of Ascension Island between 2 and 14° S. Simrad EM120 multibeam bathymetry, three-component magnetics, TOPAS high resolution seismic collected throughout. CTD stations occupied at ridge segment centres used to locate high temperature vent products both proximal and distal to the influence of the Ascension hotspot. Bathymetric background is adapted from predicted bathymetry of Sandwell and Smith.
