Marine magnetic anomalies as a link between the granulite belts of east coast of India and enderby land of Antarctica

Abstract

Magnetic data of the eastern continental margin of India (ECMI) helped in demarcating the offshore extension of the granulite belts of east coast of India and their possible link to those of the East Aantarctica. Short wavelength and high amplitude negative magnetic anomalies (200 to 1600 nT) are observed over the northern part of ECMI between Kakinada and Chilka Lake and also off Madras shelf, the coastal regions of which are associated with granulite facies rocks. This part of the shelf is associated with structural lineaments with predominant NE-SW trends. In contrast, the offshore basins off Cauvery, Krishna-Godavari (K-G) and Mahanadi rivers are associated with subdued possitive anomalies (less than 200 nT) indicating subsidence off these basins by heavy load of Phanerozoic/younger shelf sediments. Structural lineaments with NW-SE or W-E trends delineated over these basins are related to the offshore extension of these rift related Gondwana grabens. Similarity in the trends of the magnetic anomalies and the granulite facies on the east coast of India and their correlation with the granulite belt of Enderby Land of Antarctica supports the view that the entire region comprised of a single and stable block of granulite rocks prior to the fragmentation of the Gondwanaland. The study also suggests probable continuation of Mahanadi and Godavari grabens into East Antarctica.