Publication Date

2012

Document Type

Dissertation

Committee Members

Dennis Darby (Committee Co-chair), Steve Higgins (Committee Chair), Leonid Polyak (Committee Member), Thaddeus Tarpey (Committee Member)

Degree Name

Doctor of Philosophy (PhD)

Abstract

Multiple cores from the Arctic were analyzed by XRF methods to determine the western Arctic lithostratigraphy as expressed in its geochemistry. In general, glacial and interglacial events have distinctly different chemistry. During glacial events, the sediments have elevated Ti, Fe, Rb, and Zr concentrations and depressed Sr and Mn concentrations. The opposite is true of the brown layers, where Ti, Fe, Rb and Zr are lower with higher levels of Mn and Sr. These data indicate that there are 18 chemically unique lithologic units (LUs) that exist among MIS-1 to MIS-16 age sediments. Isopach maps 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 Clark et al. (1980) SLUs F, H, J, and L. This pattern has the thickest deposits located on parts of the Northwind-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 SLUs G, I, and K. The interglacial pattern is characterized by much thinner deposits especially for the central 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 suggested. 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 between the Mendeleev-Lomonosov Ridges. Stratigraphic correlations indicate that the western Arctic, central Lomonosov Ridge, and eastern Arctic are geochemically different suggesting different sources for each area. Analysis of the coarse ice-rafted fraction (>250 μm) from strata associated with MIS-16 (LU-17) 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 existed during this period, similar to that identified by Bischof and Darby (1997).

Page Count

331

Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded

2012

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