Marine Geology, 95 (1990) 147-153 147 Elsevier Science Publishers B.V., Amsterdam Letter Section Magnetic and bathymetric studies in the vicinity of the 73 ° E fracture zone, Central Indian Basin K.A. Kamesh Raju National Institute of Oceanography, Dona Paula-403 004, Goa, India (ReceivedJanuary 25, 1990; revision acceptedAugust 20, 1990) ABSTRACT Kamesh Raju, K.A., 1990. Magnetic and bathymetric studies in the vicinity of the 73°E fracture zone, Central Indian Basin. Mar. Geol., 95: 147-153. Studies of magnetic data and bathymetryin the Central Indian Basin coveringabout 8000 line km between water depths from 2600 m to 5500 m have been evaluated in the light of the new data over a profile along 71°E. The identification of the Cenozoicmagnetic anomalies 21 to 24 on the N-S profile along 71 °E confirmsthe presenceof the 73°E fracture zone and suggeststhat the crust in this part of the Central Indian Basin was generated at the Southeast Indian Ridge spreading centre. Introduction Southeast and Central Indian Ridges. The re- construction studies of Patriat and Segoufin The Central Indian Basin, located between (1988) provided a synthesis of the magnetic the Central Indian Ridge and the Ninety East data from these three ridges. In addition, de- Ridge and bounded in the south by the South- tailed studies were carried out in the Central east Indian Ridge, represents a relatively un- Indian Basin in order to delineate the finer disturbed ocean basin with no major top.- scale features (Kamesh Raju and Ramprasad, graphic features. The area is of considerable 1989). The present study evaluates the de- interest as it contains the evidence for the tailed studies carried out in the Central Indian northward movement of India during Creta- Basin in the light of the additional data col- ceous and and Tertiary times. Studies by lected along 71 *E. McKenzie and Sclater (1971) and Schlich (1982) have revealed most of the regional tee- Data tonic features in the Central Indian Basin, and detailed studies in the vicinity of the Indian Bathymetry and magnetic data were col- Ocean Triple Junction by Tapscott et al. lected along fourteen proffles spaced 0.5 ° apart (1980)andSclateretal. (1981) and the stud- between 73°E and 79"30'E and 9°S and ies on the Southeast Indian Ridge by Royer and 16" 30' S; a profile recently collected along 71 *E Schlich (1988) have enhanced our under- was also studied. Figure 1 shows the study area standing of the evolution of the Indian Ocean and the major tectonic features in the Central and highlighted the importance of a synthesis Indian Basin. The positions were obtained with of magnetic anomaly data from the Southwest, the Satellite Navigation System, total mag- 0025-3227/90/$03.50 © 1990 - - Elsevier Science Publishers B.V.