Carbonate and organic carbon content changes over last 20 ka in the Southeastern Arabian Sea: Paleoceanographic implications

摘要

Two Gravity cores (AAS 38-4 and AAS 38-5) recovered from the eastern Arabian Sea were analyzed for calcium carbonate (CaCO_3), organic carbon, aluminium (Al) and titanium (Ti) in order to understand the calcium carbonate and terrigenous fluctuations during the Holocene and Last Glacial Period. High CaCO_3 and low Al and Ti during the Holocene, and low CaCO_3 and high Al and Ti during the Last Glacial Period suggest that CaCO_3 content in these two cores appears to be controlled by the dilution of terrigenous material. The supply of terrigenous material to the core sites was higher during the Last Glacial Period than in the Holocene. Organic carbon values were lower (<2%) during the Holocene and higher (>2%) during the Last Glacial Period in core AAS 38-4; but the opposite was found in core AAS 38-5. This inconsistent pattern of organic carbon changes in the two cores studied indicates that the distribution of organic carbon in the eastern Arabian Sea is controlled not only by the supply of organic matter from the water column but also by sediment texture and dilution of sediment components.