Evidence for change in depositional environment in the Arabian Sea

Abstract

Sediments of late Pleistocene and Holocene periods, from a 12 m long core collected at a depth of 3627 m from the Arabian Sea, have been studied in order to understand the depositional environment. Sub-samples selected at 5 cm and occasionally at 10 cm interval were analyzed for calcium carbonate, organic carbon and reduced sulfur contents. Sedimentological analysis indicates that the core contains hemipelagic Globigerina ooze of Holocene age at the top, underlain by sediments depositEd. by turbidity currents and sediment gravity flows during the Late Pleistocene. Correlation between organic carbon (C) and sulfur (S) varied significantly and the sediments are enriched in sulfur compared to normal marine sediments. The C-S relationship in the top 50 cm of the core suggest that the sediments were deposited under normal marine conditions, whereas the relationship in the rest of the core is similar to that of anoxic sediments