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Curstal evolution and sedimentation history of the Bay of Bengal since the cretaceous

DRS at CSIR-National Institute of Oceanography

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Title Curstal evolution and sedimentation history of the Bay of Bengal since the cretaceous
 
Creator Rao, D.G.
Krishna, K.S.
Sar, D.
 
Subject geophysical data
continental shelves
fracture zones
plate tectonics
anomalies
crustal accretion
cretaceous
sedimentation
 
Description Multichannel seismic reflection, gravity, magnetic, and bathymetric investigations were made along five latitudinal profiles from the eastern shelf of India of the Andaman shelf and four NW-SE profiles in the Western Basin off Madras (seismics on three latitudinal profiles) in the Bay of Bengal. The trend of the fracture zones, the locations of the magnetic chron 34, and the Cretaceous Magnetic Quiet Zone suggest that Greater India separated from Antarctica after a period of transform motion in the early Cretaceous, that is, about polarity chron MO (120 Ma) and drifted northwestward. Negative gravity annomalies are associated with basement rises including the 85 degrees E Ridge between the continental margin of India and the Ninetyeast Ridge. magnetic rever-sals and northweard trend of the 85 degrees E Ridge support a hotspot origin of the ridge and its emplacement most likely after the Cretaceous quiet period. Juxtaposition of high - amplitude hyperbolic reflections, down-faulted continental blocks buried under thick sediments, and associated gravity and magnetic anomalies mark the bounday between continental and oceanic rocks at the foot of continental slope, about 80 km seaward of the present continental shelf edge. Eight seismic sequences, as thick as 8.5 km, overlie the early Cretaceous oceanic basement and include four unconformities (lower Eocene, upper Oligocene, upper Miocene, and upper Pleistocene) which have been correlated to the major geologic/tectonic events. We also interpret the late Cretaceous/early Tertiary features on the eastern flank of the buried 85 degrees E Ridge as carbonate reefs. The observation of steep subduction of older (cold) Indian plate beneath the Burmese plate near the Andaman Islands suggests the Sunda Arc in this region as low to intermediate stress subduction zone
 
Date 2009-01-12T09:18:24Z
2009-01-12T09:18:24Z
1997
 
Type Journal Article
 
Identifier Journal of Geophysical Research (B: Solid Earth), Vol.102; 17747-17768p.
http://drs.nio.org/drs/handle/2264/2055
 
Language en
 
Rights Copyright [1997]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher American Geophysical Union