Integration of recent drill results with multichannel seismic reflection data: New inferences on the subsurface configuration and sedimentary history of the northwestern Bay of Bengal

Abstract

The study pertains to the use of two industry wells and one IODP drill site in conjunction with high quality multichannel seismic reflection data in the northwestern Bay of Bengal. The industry wells provide subsurface information from Early Cretaceous period while the IODP drill site U1444 gives information about deposition younger to Miocene. Their locations over the seismic profiles facilitated the assignment of ages to the prominent seismic horizons thereby yielding a revised seismic stratigraphy of the northwestern Bay of Bengal. The ages of the oldest seismic horizons are in agreement with the recently published ages of the underlying oceanic crust. The sediments up to Late Cretaceous time are thick west of 85E Ridge, while to its east, they are thin. The sediments up to Paleocene time thin towards offshore, implying that they are land derived (from East Coast of India). Fan sedimentation commenced in the Eocene time and was excessive since Miocene. The transparent sequence between the Late Pleistocene and Pliocene unconformities is thin over the 85E Ridge. The western extents of the Quaternary subfans above the Late Pleistocene unconformity are demarcated in the study area. Further, the study suggests that the emplacement of the 85E Ridge took place in the Middle Cretaceous period. Faulting/folding at the continental rise occurred around Miocene time and maybe linked to intraplate deformation that occurred in the Central Indian Ocean Basin. Thus, the inferences drawn from this study help to provide a reliable sedimentary history of the northwestern Bay of Bengal forming an updated base for future investigations.