Comparison of interglacial stages in the South Atlantic sector of the southern ocean for the past 450 kyr: implifications for Marine Isotope Stage (MIS) 11

Oxygen and carbon isotopic gradients in surface waters were reconstructed f or the past 450 kyr by analysis of the planktic foraminifer Neogloboquadrin a pachyderma in cores located at approximately 43 degrees, 47 degrees, and 54 degrees S across the Polar Frontal Zone in the South Atlantic sector of the Southern Ocean. Comparison of the oxygen isotopic records for peak inte rglacial conditions during the past 450 kyr reveals that Marine Isotope Sta ge (MIS) ii was not substantially warmer than other interglacials at high s outhern latitudes, although the period of warmth lasted longer. The carbona te and carbon isotope chemistry of surface and deep water represent the tru ly distinctive aspects of Stage 11 in the Southern Ocean. Peak carbonate pr oduction occurred at high southern latitudes during MIS 11, resulting in li ght-colored, high-carbonate sediments deposited throughout the Southern Oce an above the lysocline. Carbon isotopic values of benthic foraminifera in c ores bathed by Circumpolar Deep Water (CPDW) were highest during MIS11, sug gesting strong input of North Atlantic Deep Water (NADW) to the Southern Oc ean. Planktic delta(13)C values at high southern latitudes were also highes t during MIS Il, which may reflect upwelling of CPDW with a greater contrib ution of NADW, lower whole-ocean nutrient inventories, higher gas exchange rates, and/or lowered alkalinity of Antarctic surface waters (resulting fro m carbonate precipitation south of the Polar Front). (C) 2000 Elsevier Scie nce B.V. All rights reserved.