NEW SEDIMENTOLOGICAL AND MINERALOGICAL RECORDS FROM MENDELEEV RIDGE: IMPLICATIONS FOR RECONSTRUCTION OF LATE QUATERNARY HISTORY OF CIRCUM-ARCTIC ICE SHEETS AND ARCTIC OCEAN PALEOCEANOGRAPHIC CIRCULATION PATTERNS

Our research focuses on the reconstruction of past Quaternary glaciations in North America, Siberia, and Eurasia. For this research project, new sediment cores were recovered during the RV “Polarstern” ARK-XXIII/3 expedition (August-October 2008) along two transects across the Mendeleev Ridge (for background see Stein et al., 2010). Here, we mainly focus on the northern transect along 80°30’N. X-ray diffraction (XRD) method was used on bulk sediments. To get the quantification of mineral content, raw XRD data were processed using RockJock. In all studied sediment cores, Clark’s standard lithological units A to M (Clark et al, 1980) could be clearly identified, and the prominent pink-white layers and more sandy intervals are the key sedimentary characteristics used for core correlation and development of a preliminary age model (Stein et al, 2010). Additional age control is derived from new foraminiferal data and correlation with magnetic susceptibility and bulk density records. Bulk mineral assemblage and grain size distribution are used to distinguish sediment provenances. Based on previous studies, the Canadian Arctic Archipelago (CAA) is the main source area for dolomite, and the combination of plagioclase, chlorite and illite may indicate input from the East Siberian Sea (ESS) (see Stein, 2008 for review and further references). According to our age model, MIS 8, 10 and 12 are characterized by increased dolomite contents, decreased plagioclase, chlorite and illite content and high amount of sand (>63μm) indicating ice-rafted debris (IRD) input from the CAA. MIS 6 and 16, on the other hand, are characterized by low dolomite and high quartz contents, suggesting strong input from the ESS.

References

Clark, D.L., Whitman, R. R., Morgan, K. A., Mackey, S. D., 1980. Stratigraphy and glacialmarine sediments of the Amerasian Basin, central Arctic Ocean. Geol. Soc. Am. Spec. Pap. 181, 57 pp.

Stein, R., 2008. Arctic Ocean Sediments: Processes, Proxies, and Palaeoenvironment. Developments in Marine Geology, Vol. 2, Elsevier, Amsterdam, 587 pp..

Stein, R., Matthiessen, J., Niessen, F., Krylov, R., Nam, S., and Bazhenova, E., 2010. Towards a Better (Litho-) Stratigraphy and Reconstruction of Quaternary Paleoenvironment in the Amerasian Basin (Arctic Ocean). Polarforschung 79 (2), 97-121.