Record of the Cretaceous magnetic quiet zone in the distal Bengal fan and its significance in understanding the evolutionary history of the northeastern Indian Ocean
Date
1996Author
Ramana, M.V.
Subrahmanyam, V.
Sarma, K.V.L.N.S.
Desa, M.
Rao, M.M.M.
Subrahmanyam, C.
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The Bengal Fan was one of the thickest sedimentary basins of the World. Many were of the view that the magnetic anomalies will be hard to find off East Coast of India due to this huge sediment accumulation. Though extensive underway geophysical data was collected during the International Indian Ocean Expedition Programme and subsequent expeditions to unravel the evolutionary history of Indian Ocean, not much was known about the age and nature of the ocean floor of the Bengal Fan but for few speculations. Various plate reconstruction models show the stage by stage evolution of the eastern Indian Ocean since late Cretaceous (84 Myr) to present. However, refined plate reconstruction models for the early opening prior to late Cretaceous are poorly constrained due to the inadequate geophysical data particularly in the Bay of Bengal, Northern Indian Ocean. Recent geophysical studies in the northern Bay of Bengal revealed the presence of N 30 degrees E trending Mesozoic magnetic anomaly sequences M11 to M0 (corresponding to 132.5 to 118 Myr age old crust) and N 120 degrees (equal to NW-SE) trending fracture zones. The direction of these fracture zones indicate the initial Indian plate motion from Antarctica-Australia immediately after the early Creatceous breakup
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