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New insights into the tectonic evolution of the Andaman basin, northeast Indian Ocean

DRS at CSIR-National Institute of Oceanography

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Title New insights into the tectonic evolution of the Andaman basin, northeast Indian Ocean
 
Creator KameshRaju, K.A.
Ramprasad, T.
Rao, P.S.
Rao, B.R.
Varghese, J.
 
Subject magnetic anomalies
tectonics
seafloor spreading
swaths
bathymetry
seismic data
data analysis
magnetic data
 
Description Multibeam swath bathymetry data acquired over an area of about 30 000 km 2 ,together with magnetic and single channel seismic data, have been analyzed to understand the tectonic evolution of the Andaman basin,northeast Indian Ocean. Swath bathymetry data revealed several morphotectonic features that divide the basin into a complex western part comprising arc-parallel seamount chains and N-S-trending fault systems and a relatively smooth eastern part. A SW-NE-trending spreading ridge bisects the basin.An offset of about 11.8 km at 94 degrees 21 minutes E longitude divides the spreading ridge into SW and NE segments. High-resolution bathymetry and magnetic data enabled us to identify two finer-scale segments over the SW part of the ridge that display distinct topographic fabric compared to the NE segment. Thin sediment cover and presence of axial seamounts characterize SW segments of the ridge whereas the NE segment has thick sediment cover and well-maintained rift valley. Kinematics of basin evolution, derived from the identification of the seafloor spreading magnetic anomalies, suggest very slow initial opening rates of about 1.6 cm/yr and an increase in the spreading rate to about 3.8 cm/yr from anomaly 2 to present, although this interpretation relies only on magnetic anomalies in the two westernmost segments.It is suggested that the true seafloor spreading started about 4 Ma in the Andaman backarc basin, rather than the 11 Ma postulated previously. Based on the integrated analysis of swath bathymetry, magnetic and seismological data that the basin has evolved as a consequence of extrusive tectonics that prompted extension and rifting along the plane joining the Sagaing and Semengko fault systems are infered. Extension by seafloor spreading during the past 4 Myr resulted in the formation of the deep Andaman backarc basin. This phase has also experienced westward propagation of the spreading center.
 
Date 2008-07-02T05:06:18Z
2008-07-02T05:06:18Z
2004
 
Type Journal Article
 
Identifier Earth and planetary science letters, Vol.221; 145-162p.
http://drs.nio.org/drs/handle/2264/1155
 
Language en
 
Rights Copyright [2004]. It is tried to respect the rights of the copyright holders to the best of the knowledge. If it is brought to our notice that the rights are violated then the item would be withdrawn.
 
Publisher Elsevier