Deep sub-crustal features in the Bengal basin: Seismic signatures for plume activity

The basaltic Rajmahal Traps (117 Ma), India are believed to be due to a man tle plume. The plausible plume path on the continental side has not been tr aced probably because of the thick sedimentary cover. These Traps are locat ed close to the Bengal basin; therefore, a re-examination of the deep seism ic velocity structure should help in tracing the plume path on the continen tal side and its possible relationship to plume activity. Data obtained alo ng four seismic profiles in the Bengal basin were re-examined, which helped in identifying and modeling strong reflections from lower crust and Moho. The results indicate a 7.5 km/s velocity zone as an underplated mantle mate rial injected by the mantle plume or hotspot at the base of the continental crust. The study also indicates the probable trace of plume in the contine ntal region, a NNW-SSE trending path east of 87 degrees E with an up-warp i n Moho.