The Ninetyeast Ridge in and around the Andaman Trench - an appraisal from marine magnetics

Marine magnetic data acquired in a part of the Bay of Bengal between latitudes 12 degrees 30 'N to 14 degreesN and longitudes 90 degrees 54 'E to 92 degrees 54 'E were transformed to frequency domain. These data were used to prepare a sediment isopach map of the study area. The results are in excellent agreement with sediment thicknesses reported in an earlier study for a single seismic reflection profile along 13 degreesN. In addition, the reconstruction of the configuration of the Ninetyeast Ridge up to the Andaman Trench has been completed. The ridge has been found to be discontinuous, with enechelon faulting and a dextral shift of 95 km within the study area. A Curie depth profile prepared from the longest observed magnetic line near the subduction complex indicates that heat flow over the subduction zone was lower than values recorded on either side of the zone.