Subsurface Geology off Bombay with Paleoclimatic Inferences Interpreted from Shallow Seismic Profiles

Abstract

High resolution seismic reflection profiles of nearshore areas off Bombay provide information on subsurface geology and permit certain paleoclimatic inferences. Three sedimentary units overlie the acoustic basement: late Pleistocene consolidated sediment, early Holocene layered sediment (about 7 m thick) and Modern Clay (2.5 - 3m thick). An unconformity probably due to subaerial erosion during the Pleistocene lowered sea level stand separates the consolidated sediments from the over-lying layered sediments. The latter were probably deposited during the early Holocene marine transgression, when the precipitation pattern was different from the present (wetter). The Modern Clay conformably overlies them and was deposited during the last 600-700 years, during which the climate was similar to that of the present day. The bedrock appears to be fractured, tilted and eroded but no evidence was observed for any Holocene disturbance.