A 70 kyr record of monsoon-induced marine productivity changes, terrigenous flux and weathering variations in the southern Bay of Bengal

Abstract

The southwest (SW) and northeast (NE) monsoon winds significantly affect the oceanographic and climatic changes over the Bay of Bengal (BoB). We present here detailed geochemical and isotopic records from two sediment cores (SK157 14; 5�11? N: 90�5? E and SK157-16; 8�46? N: 90�18? E), collected from the southern BoB. In this study, we mainly focus on variations in paleoproductivity and terrigenous fluxes introduced into the BoB since last ~70 kyr: We have reconstructed biogenic barium (Babio), calcium carbonate (CaCO3) content, and total organic content (TOC) in both sediment cores to infer paleoproductivity during the period of study. The distributions of productivity proxies in both these cores indicate that the productivity may have been significantly high during MIS 1 and MIS 3 (warmer interglacial periods), when SW monsoon was intensified. The terrigenous proxies (Al%, Ti%, d(0.9)) show that the southern BoB may have received higher terrigenous input during the MIS 2 and MIS 4 (glacial periods) coinciding with the intensification of NE monsoon. The weathering proxy (K/Al), in contrast, shows no significant changes during MIS 2, 3 and 4. However; a significant shift is seen during glacial to Holocene transition