STRUCTURE AND TECTONICS OF THE SOUTHWESTERN CONTINENTAL-MARGIN OF INDIA

A NNW-SSE-trending graben in the inner shelf (40-60 m isobaths), a mid -shelf basement ridge (60-150 m isobaths), a shelf-margin basin (150-1 000 m isobaths) and the Prathap Ridge Complex in the slope (1000-2000 m isobaths) extend as linear features along the southwestern continent al margin of India between 12 degrees 20'N and 15 degrees 00'N. The ba sic structural framework of the margin seems to be influenced by the p re-existing Precambrian structural fabric of the continent. The mid-sh elf basement ridge and the Prathap Ridge Complex are interpreted as ma nifestation of the rift-phase volcanism when India separated from Mada gascar around 84 Ma.