HR: 0800h
AN: PP51A-0186    [Abstracts]
TI: Variability in Sediment Supply to the Pleistocene Eastern Arctic Ocean: A Mineralogical Perspective
AU: Mildner, T
EM: Tanja.Mildner@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, Bremerhaven, D-27568, Germany
AU: Matthiessen, J
EM: Jens.Matthiessen@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, Bremerhaven, D-27568, Germany
AU: * Vogt, C
EM: cvogt@uni-bremen.de
AF: University Bremen, Klagenfurther St., Bremen, D-28359, Germany
AB: ODP Leg 151 Hole 910A is located on the Yermak Plateau which is a crucial area for monitoring the Pleistocene variability of Atlantic Water inflow to the Arctic Ocean and the history of glaciations at the Eurasian continental margin. In contrast to other Arctic Ocean records, a well-constrained chronostratigraphy based on stable isotopes, biostratigraphy and magnetostratigraphy allows the identification of glacial-interglacial cycles and a detailed reconstruction of paleoenvironmental conditions in the past 800,000 years. Thus, stable isotope studies revealed that the glacial-interglacial cycles are superimposed by short-term freshwater supply to the Eastern Arctic Ocean on sub-Milankovitch time-scales (Knies et al. in press, Effects of Arctic freshwater forcing on thermohaline circulation during the Pleistocene, Geology). The sources of freshwater and the history of glaciations in the Brunhes Chron prior to the late Pleistocene are virtually unknown. Previous studies on clay mineral assemblages revealed a pronounced variability on various time-scales in the past 150,000 years, reflecting shifts in sediment input between different source areas in response to freshwater input and waxing and waning of ice sheets. Based on these results, the middle to late Pleistocene of Hole 910A has been studied at sub-Milankovitch time-scales to decipher a possible relationship between climate cycles and input of fine sediments from various source areas during the Brunhes Chron. Despite of a strong imprint of local sources on clay mineral sedimentation on the southern Yermak Plateau, a distinct variability has been recognized in the past 800,000 years. The strongest supply from northern Spitsbergen occurred only during the LGM associated with a maximum input of coarse sediments. Previous reconstructions that suggest a pronounced advance of the northern Barents Sea Ice Sheet across the southern Yermak Plateau are refuted since sediments of Hole 910A are normally consolidated in the Middle and Late Pleistocene. The supply of coarse sediments prior to the LGM is moderate indicating that the location was somewhat protected from massive deposition of ice-rafted debris from melting icebergs. Therefore, the clay mineral record of Hole 910A reflects not only supply from local sources but also long-distance transport of fine sediments from source regions located at the Eurasian continental margin. There is apparently a distinct link between climate cycles and the supply from specific source areas. Sequences of sedimentological and clay mineral events are recurrently recorded in Hole 910A indicating that cryosphere variability followed a characteristic pattern at the Northern Barents Sea margin, in particular during deglaciations. Pleistocene clay mineral records are compared along a transect from Yermak Plateau to Lomonosov Ridge to identify events that were of basinwide significance in the Eurasian Arctic.
DE: 0726 Ice sheets
DE: 0750 Sea ice (4540)
DE: 3022 Marine sediments: processes and transport
DE: 3036 Ocean drilling
DE: 3675 Sedimentary petrology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting