Last glacial-interglacial productivity and associated changes in the eastern Arabian Sea

Article history: Received 8 February 2016 Received in revised form 5 July 2016 Accepted 9 July 2016 Available online xxxx Wereconstruct paleo-productivity and bottomwater oxygenation changes during thepast 32 ka, from the southeastern Arabian Sea, using absolute abundance of planktic foraminifera, relative abundance of Globigerina bulloides, angular asymmetrical benthic foraminifera (AABF), measurements of total organic carbon (Corg), %CaCO3, and Globigerinoides ruber δO and δC. The faunal and geochemical proxies suggest that productivity in the southeastern Arabian Sea was high during MIS 3. A distinct decrease in productivity is inferred during the last glacial maximum (19–23 ka) (LGM). Bottom water was well oxygenated during MIS3, only to become oxygen-depleted during the LGM. Productivity decreased abruptly during Heinrich Stadial 1 (HS-1), but the response to Heinrich Stadial 2 (HS-2) was different. Low productivity during the early deglaciation is also synchronouswith an increase in ice-volume corrected δO (δOsw-ivc), a salinity proxy, between 18.9 (18.3–18.9) ka BP and 15.9 (15.0–16.3) ka BP, and a concomitant decrease in δC between 18.2 (17.5–18.7) ka BP and 16.4 (15.3– 16.7) ka BP. These patterns suggest that the global δC minimum event during the last deglaciation was associated with the weak monsoon interval during HS-1 and a drop in productivity in tropical regions. A progressive increase in productivity is observed throughout the Holocene, with a distinct jump at 5.4 (3.8–6.3) ka BP. We infer that although productivity was higher in the eastern Arabian Sea during most of the last glacial interval, the overall resultant carbon sequestration was confined only to a restricted zone and not large enough to substantially alter atmospheric CO2. © 2016 Published by Elsevier B.V.