STABLE ISOTOPE ANALYSIS OF POLAR FORAMINIFERA AND SEDIMENTOLOGICAL EVIDENCE OF DEEP PALEOCURRENT EXCHANGE WITHIN FRAM STRAIT SINCE THE LAST GLACIAL MAXIMUM

Fram Strait, the only deep-water channel between the North Atlantic and the Arctic Ocean, acts as a major conduit for interbasin deep-water exchange. Sediments deposited within Fram Strait may record deep-water paleocurrent activity reflecting the history of this exchange. Understanding oceanic processes and deep-water transport between the Arctic Ocean and North Atlantic Ocean following the Last Glacial Maximum (LGM) is essential for the advancement of climate and atmospheric science, as the history of Arctic climatic response has the potential to inform predictions of future variations in Northern hemisphere climate. Here we present sediment grain size records of paleocurrent variation in two sediment cores (75º10’N, 10º 52’W at 2,459 m depth and 76º25.4’N, 10º48’E at 2,113 m depth) from the eastern and western boundaries of Fram Strait, lying within the deep Atlantic-to-Arctic flow and Arctic-to-Atlantic flow respectively. Radiocarbon dating and oxygen isotope stratigraphy were used to establish chronologies for the cores, and grain size analyses were conducted using a Retsch Camsizer. Preliminary δ¹⁸O values obtained from planktic foraminifera Neogloboquadrina pachyderma (left) are in good agreement with previously established isotope and temperature record data. δ¹⁸O values from core V28-24 on the Greenland slope show a trend from enriched to depleted values over the course of the deglaciation, with transient enrichments likely corresponding to Heinrich Event 1 and the Younger Dryas stadials, and a depletion event which may represent the Bolling-Allerod interstadial. Grain size analyses will provide insight into deep paleocurrent strength based on sortable silt size, and surface climatic events based on coarse fraction/ice-rafted debris (IRD) analysis. Preliminary grain size results suggest three main end members contribute to Fram Strait sediment deposition: a primarily clay dominated end member, a mixed clay and silt end member, and a poorly sorted end member with coarse content which we suggest represents IRD. Existing records from eastern Fram Strait imply glacial, deglacial and Holocene bottom water variability; our paired eastern and western margin records will give new insight into the history of interbasin exchange variability at the sill depth of Fram Strait during the past 24 kyr.