Paleoenvironments in the Fram Strait during Marine Isotope Stages 2-6 based on planktonic paleobiological and stable-isotope proxies and ice-rafted debris

Two sediment cores from the Knipovich Ridge in the Fram Strait have been studied to examine paleoceanographic and climatic changes in the Polar North Atlantic during the late Middle and Late Pleistocene. As inferred from the data on foraminifers, nannofossils, diatoms, IRD, oxygen isotope values, and AMS 14C ages, the recovered deposits span the interval of MIS 2-6. Several beds marked by a high productivity of microplankton and often by a great IRD content are recorded in MIS 2, MIS 5a, 5c, 5e, and MIS 6 suggesting a repeated occurrence of seasonally ice-free waters and strong meridional circulation in the eastern Fram Strait. The planktonic foraminifers Globigerinoides ruber, Globorotalia scitula, G. crassaformis, and pink-colored Globigerina rubescens, exotic for this latitude, were identified in three points of the section. A hiatus in one of the cores studied was revealed from comparison of IRD variations and the occurrence of Pullenia bulloides.