Geology and Geophysics pages

Geology & Geophysics Group

The Central Indian Ridge

Contact: Dr Bramley Murton

Under the hot-spot influence: TOBI imagery from the Central Indian Ridge (CIR) adjacent to the Rodriguez system

This programme involves the combined effort of several institutes: NOCS, Institute Physique du Globe, Strasbourg, The Ocean Research Institute, Tokyo and The Mauritius Oceanographic Institute. Additional material and discussion with University Brest Occidentale in France has benefited the development of the project. A current G&G PhD student, Stephen Tyler, is working on these data as part of his research.

A combined surveying/sensing/sampling programme tragetted the Central Indian mid-ocean Ridge to quantify the effects of the subjacent Rodriguez hotspot on volcanic, tectonic and hydrothermal processes. Axial sections of various distances from the intersection area were surveyed to test current hypotheses on controls on hydrothermal activity, spreading ridge geometry and its evolution.

The specific objectives of the proposed study were:

  1. To evaluate the extent of interaction between an intermediate spreading ridge (the central Indian Ridge) and a weak hot spot. The scientific interest was specifically in terms of: level and composition of MOR volcanism; spreading ridge kinematics; local and regional structural style; segmentation character: and the compositional effects of plume-MORB mantle mixing.
  2. To locate, and determine the detailed geological setting of both known and new sites of hydrothermal activity along the CIR between the Rodrigues Hot Spot and Triple Junction (19-26°S).
  3. To evaluate whether there is any statistically significant, and geologically interpretable difference in the incidence of high-temperature hydrothermal venting along the Central Indian Ridge in the vicinity of, and away from, the Rodrigues Hot Spot.

Data collected using the research vessel RRS Charles Darwin during 2001 (CD127) have been analysed. The cruise also collected 30 days of swath bathymetry, TOBI 30kHz deep tow sidescan surveying and hydrothermal plume exploration and plume sampling.