Mesozoic anomalies in the Bay of Bengal

Abstract

The analysis of 8200 line km of total magnetic intensity data in the Bay of Bengal, northeastern Indian Ocean, revealed the presence of approximately N30~'E-trending seafloor spreading type magnetic anomalies. These anomalies resemble the Mesozoic anomaly series (M11-M0) reported elsewhere. The oldest anomaly (M11, 132.5 Ma) identified close to the east coast of India is followed by the younger series of Mesozoic anomalies towards the offshore. Some of the anomalies are offset by 60-80 km. The configuration of the offsets of the isochrons allowed us to propose approximately N120~'E-trending oceanic fracture zones. The Mesozoic crust of 132.5-118 Ma is estimated to evolve with an average half-spreading rate of 3.5 cm/yr, except for the ocean floor between the M9 and M4 magnetic isochrons. This part of the crust appears to be affected by the buried subsurface 85~'E Ridge