Dispersed organic matter from Neogene and Pleistocene sediments of Site 218 of Deep Sea Drilling Project Leg 22, Bengal Fan, Indian Ocean

Abstract

Dispersed organic matter has been recorded from the Neogene-Pleistocene sediments of site 218 of the Deep Sea Drilling Project Leg 22, Bengal Fan and depositional environment of the studied sequences has been deduced. An attempt has been made to calibrate frequency abundance of organic matter in order to identify variation at various depth levels. Based on the occurrence and frequency of various types of organic matter the borehole section has been divided into lower, middle and upper zones. The lower zone is rich in biodegraded terrestrial organic matter, whereas the upper zone exhibits abundance of structured terrestrial and black debris. Spores and pollen are poorly represented. Recycled Cretaceous palynofossils have been recorded throughout the sequence. The analysis of lithologic and organic matter data indicates that these sediments were deposited in deltaic environment. The behaviour pattern of biodegraded, structured and black debris indicates reducing condition in the lower zone and oxidizing condition in the upper zone.