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Indian Ocean with Carlsberg Ridge area marked in grey dotted-lined box. White contours are isochron ages of the ocean floor (Muller et al. 1997). Red dots are hypocentral locations (Storchak et al. ISC-GEM catalogue) of seismicity. White bold arrows show the NE–SW oriented Carlsberg Ridge spread direction. Yellow and black triangles are active and inactive hydrothermal vents along the axis of ridge, respectively. Bold red extended line is the location of profile as explained in (c). (b) shows the detailed bathymetry of the Carlsberg Ridge mentioned in the dotted box; highlights the ridge axial valley and the offsetting fracture zones. (c) The red line shows the fall of residual geoid anomaly from the ridge axis to greater off-axis distances. The blue line depicts the reduction in ridge spreading rate since 60 Ma to present.
Source publication
The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic lithosphere with numerous intra-plate loads; whereas, contrasting elements like active Mid-Ocean ridge divergence and slow spreading ridges are present in the relatively younger (<60 Ma) Arabian Sea oceanic lithosphere. The mechanism of lithospheric cooling of young age oceanic...
Contexts in source publication
Context 1
... the northwestern Indian Ocean, the Carlsberg Ridge is an active Mid-Ocean type divergent plate boundary that separates Arabia and the Somalia plates as shown in figure 4(a). As the spreading takes place, young oceanic crusts are formed at the ridge axis. ...
Context 2
... is evident from the white con- tours of isochron ages, appeared near symmetrical at both sides of the ridge axis. The older crust was pushed away from the ridge axis to further north in the spread direction and shown as bold white arrows in the figure 4(a). Thus, in the Arabian Sea basin, the oldest oceanic lithosphere is around 90 Ma and found close to the northwestern conti- nental margin of peninsular India. ...
Context 3
... criteria that have been used for the selection of band is that anomalies are generally higher at the spreading Mid-Ocean ridge axis and hence a higher heat flux compared to the low heat flux values in the off- spread axis region. In figure 4(c), the red line explains high residual geoid anomaly close to the spread axis, which gradually gets tapered as it moves away from the ridge axis to greater dis- tances or lithosphere of older ages. Thus, the inves- tigation was mainly focussed to include the low harmonics degree geoid anomaly; such that, the slowly varying nature of heat flux anomalies of the oceanic lithosphere are retrieved effectively in the residual geoid anomaly components. ...
Context 4
... in fact, causes deepening of the sub-lithospheric mantle heat sources. The trend and fall in the thermal boundary layer from the ridge-spreading axis is correlatable with the residual geoid anomaly decay as shown earlier as red line in figure 4(c). At the ridge-spreading axis, the residual geoid anomaly is around +3 m due to the ascension of the sub-lithospheric mantle from the thin low vis- cosity layer and falls to -0.5 m as mantle descends at greater distances. ...
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Advances in Marine Geophysical Studies of the Indian Ocean ? Contributions from India (2010-2015)
