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Integrated geophysical studies over the 85°E ridge - Evaluation and interpretation

DRS at CSIR-National Institute of Oceanography

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Title Integrated geophysical studies over the 85°E ridge - Evaluation and interpretation
 
Creator Ramana, M.V.
Ramprasad, T.
Desa, M.
Subrahmanyam, V.
 
Subject Indian Ocean
gravity anomaly mosaic
 
Description Ship-borne magnetic, gravity, bathymetry and multichannel seismic reflection studies made so far on the linear subsurface ridge known as the 85°E Ridge in the northeastern Indian Ocean are reviewed. The extent and boundaries of the ridge are well reflected on the GEOSAT derived free-air gravity anomaly mosaic. It trends N 10°W between 6°N and 16°N latitudes in the Bay of Bengal. The two divergent opinions on its origin are discussed and the need to get petrological or chemical information on the rocks of the ridge is stressed to enlist support eitherway. One school favours a hotspot origin, while the other advocates that the ridge was formed due to volcanic emplacement during the major plate reorganization in the middle Cretaceous. The latter argument is primarily based on the marked geophysical anomaly signatures associated with the 85°E Ridge. Such a feature is not present in the other two-hotspot traces, namely, the Chagos-Laccadive Ridge and the Ninety east Ridge. Also the linear topographic trace of the 85°E Ridge south of equator is virtually absent unlike the long (~5000 Km) Ninety east Ridge trace. The positive magnetic and negative gravity anomalies between 5° and 16°N latitude associated with the 85°E Ridge strengthen the suggestion of emplacement origin rather than a trace of hotspot. Combined with the above, magnetic model studies on the 85°E Ridge favour a single polarity throughout the length of the ridge indicating a shorter span of time, which is unlikely if it is a trace of hotspot trace, but possible in an intrusion.
 
Date 2006-09-25T10:01:35Z
2006-09-25T10:01:35Z
2000
 
Type Journal Article
 
Identifier Visakha Science Journal, vol.4(1), 45-56p.
http://drs.nio.org/drs/handle/2264/428
 
Language en
 
Format 356132 bytes
application/pdf
 
Publisher AP Akademi of Sciences, India