Aeromagnetic anomalies in the Bengal fan

Abstract

Aeromagnetic data recorded by the 'Project Magnet' have been analysed along 4 profiles in the Bengal fan. Some of the anomalies found are large and distinct and have shown good correlation in different profiles. From detailed studies of these anomalies the major trends in the basement layer can be delineated. These anomalies include an arcute trench over the continental margins of India and Sri Lanka, the deep valleys in the central Bengal fan, northward extension of the Ninetyeast ridge up to 8° N and the continuation of the Java-Sumatra trench to the west of Andaman-Nicobar Islands. Some of the anomalies recorded at about 84° to 86° E and 2° to 4° N suggest that the Indira and Indrani fracture zones extend northward. Large thick sedimentary layers present in the central Bengal fan suggest a depressed oceanic crust in this area.