SEDIMENT CHEMISTRY AND LITHIC COUNTS FROM ARCTIC OCEAN CORES DISTINGUISH DIFFERENT SEDIMENT FLUXES FROM CIRCUM-ARCTIC SOURCES BETWEEN GLACIAL AND INTERGLACIAL CONDITIONS

Fifteen cores from across the Arctic were analyzed by X-Ray Fluorescence methods for several glacial and interglacial intervals. In general glacial and interglacial events have distinctly different chemistry. During glacial events, the sediments have elevated Ti, Fe, Rb, and Zr concentrations at the same time they have depressed Sr and Mn concentrations. The opposite is true of the brown interglacial layers, where Ti, Fe, Rb and Zr are lower and there is higher levels of Mn and Sr. Isopach maps based on the thickness of these intervals indicate two general depositional patterns appear to have existed during the late Quaternary. The first pattern is defined as a glacial depositional pattern based on sediment thicknesses present in four recent coarse-grained and foraminifera-poor layers. This pattern has the thickest deposits located on parts of the Northwind and Alpha Ridges as well as within the Makarov Basin. The second pattern is associated with interglacial deposits and is based on sediment thicknesses present in three intervening units. The interglacial pattern is characterized by much thinner deposits especially for those existing in the central western Arctic region. Based on the isopach sediment patterns, the potential source areas of the sediments deposited during the glacial and interglacial periods are slightly different. During glacial stages, a strong Canadian source area is indicated. During interglacial stages a Canadian source area exists for deposits in the Canadian Basin, and a potential mixture of Canadian and Russian source areas for sediments located along the Trans-Polar Drift from the Mendeleev to Lomonosov Ridges. Stratigraphic correlations indicate that the western Arctic, central Lomonosov Ridge, and eastern Arctic are geochemically different suggesting a different source area for each ridge. Analysis of the coarse ice-rafted fraction (>250 μm) from strata associated with marine isotope stage 12 indicates a Canadian source for the carbonate grains in this unit. However, statistical analysis of these grains in four cores supports the existence of a modified Beaufort Gyre circulation system during this deglacial event.