Lithosphere structure and upper mantle characteristics below the Bay of Bengal
DRS at CSIR-National Institute of Oceanography
View Archive InfoField | Value | |
Title |
Lithosphere structure and upper mantle characteristics below the Bay of Bengal
|
|
Creator |
Rao, G.S.
Radhakrishna, M. Sreejith, K.M. Krishna, K.S. Bull, J.M. |
|
Subject |
GEOLOGY AND GEOPHYSICS
GEOLOGY AND GEOPHYSICS GEOLOGY AND GEOPHYSICS |
|
Description |
The oceanic lithosphere in the Bay of Bengal (BOB) formed 80-120 Ma following the breakup of eastern Gondwanaland. Since its formation, it has been affected by the emplacement of two long N-S trending linear aseismic ridges (85°E and Ninetyeast) and by the loading of ca. 20-km of sediments of the Bengal Fan. Here, we present the results of a combined spatial and spectral domain analysis of residual geoid, bathymetry and gravity data constrained by seismic reflection and refraction data. Self-consistent geoid and gravity modelling defined by temperature-dependent mantle densities along a N-S transect in the BOB region revealed that the depth to the lithosphere–asthenosphere boundary (LAB) deepens steeply from 77 km in the south to 127 km in north, with the greater thickness being anomalously thick compared to the lithosphere of similar-age beneath the Pacific Ocean. The Geoid-Topography Ratio (GTR) analysis of the 85°E and Ninetyeast ridges indicate that they are compensated at shallow depths. Effective elastic thickness (Te) estimates obtained through admittance/coherence analysis as well as the flexural modelling along these ridges led to the conclusions: (i) 85°E Ridge was emplaced in off-ridge environment (Te = 10-15 km); (ii) the higher Te values of ~25 km over the Afanasy Nikitin Seamount (ANS) reflect the secondary emplacement of the seamount peaks in off-ridge environment, (iii) that the emplacement of the Ninetyeast Ridge north of 2°N occurred in an off-ridge environment as indicated by higher Te values (25-30 km). Furthermore, the admittance analysis of geoid and bathymetry revealed that the admittance signatures at wavelengths >800 km are compensated by processes related to upper mantle convection
|
|
Date |
2016-07-11T09:21:08Z
2016-07-11T09:21:08Z 2016 |
|
Type |
Journal Article
|
|
Identifier |
Geophysical Journal International, vol.206(1); 2016; 675-695
http://drs.nio.org/drs/handle/2264/4993 |
|
Language |
en
|
|
Rights |
This is an open access article under the CC BY-NC-ND license © Author(s) 2016.
|
|
Publisher |
The Royal Astronomical Society
|
|