HR: 0800h
AN: V51B-0558    [Abstracts]
TI: New Constraints on the Evolution of the Deccan Volcanic Province, India
AU: * Mohan, G
EM: gmohan@iitb.ac.in
AF: Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 India
AU: Ravi Kumar, M
AF: National Geophysical Research Institute, Uppal Road, Hyderabad, 500007 India
AB: The evolution of the Deccan volcanic province (DVP) of India is commonly linked to the upwelling of a mantle plume beneath the Indian subcontinent in the late Cretaceous. However, the proposed mechanisms ranging from plume to non-plume models remain debatable. The pre-requisites for the plume models are a thin lithosphere and an anomalously hot upper mantle, which still remain uncertain in the case of DVP. In the present study, the mantle discontinuities beneath DVP are imaged through P-wave receiver function analysis, using about 900 seismograms from six broadband stations deployed along a 350km long profile in western DVP. We find that the move out corrected P-to-s conversion times from the standard 410 and 660 km discontinuities are normal, indicating absence of anomalous thermal anomalies in the upper mantle beneath DVP. An additional discontinuity at 200km, corresponding to the Lehmann discontinuity, possibly representing the base of the lithosphere, is delineated. These results imply that the lithosphere beneath DVP is normal and not thinned by an upwelling mantle plume. This, coupled with pervasive presence of a sub-Moho low velocity zone, raises doubts about the plume impact/incubation models suggested for volcanism in DVP, favoring rifting as a more plausible mechanism.
DE: 8450 Planetary volcanism (5480)
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere and upper mantle
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting