Geophysical studies over a segment of the Carlsberg Ridge, Indian Ocean

Abstract

The study of magnetic, gravity and bathymetric data over a segment of Carlsberg Ridge between 3 degrees and 4 degrees N lat., and 63 degrees 30' and 64 degrees 30'E long. revealed the presence of a prominent 57 degrees W trending rift valley. The depth of the valley varies from 3250 to 4400 m and its width varies from 15 to 19 km. Analysis of the magnetic data leads to the identification of the Brunhes/Matuyama boundary (0.73 Ma) across the ridge axis. The Jaramillo event commonly associated with the fast spreding centres is not reflected in the present study. The late Pliocene-Recent oceanic crust across part of the Carlsberg Ridge evolved with an average spreading rate of 1.25 cm yr sup(-1). The rift valley shallows in the southeast, narrows in the middle and is deeper and wider toward the northwest. The occurrence of large amplitude magnetic and gravity anomalies in association with the bathymetric deep in the northwest within the rift valley is suggested to be a zone of future segmentation of the ridge axis. A new transform fault appears to offset the trend of bathymetric and gravity contours in the northwestern part of the study area