HR: 1340h
AN: A13B-0106    [Abstracts]
TI: Grey Scale Record in Lake Baikal Sediments: Climate Significance for the Last 20 ka.
AU: Fagel, N
AF: Clays and Paleoclimate Research Unit, Geology Department, University of Liege, All‚e du 6 Aout, B18, Liege, 4000 Belgium
AU: * Boes, X
EM: Xavier.Boes@ulg.ac.be
AF: Clays and Paleoclimate Research Unit, Geology Department, University of Liege, All‚e du 6 Aout, B18, Liege, 4000 Belgium
AU: Piotrovska, N
AF: Department of Radioisotopes, Institute of Physics, Silesian University of Technology, ul. Krzywoustego 2, Gliwice, 44100 Poland
AB: Three sediment cores from Lake Ba‹kal (52øN) are investigated to evidence Northern Eurasian regional climate and environmental changes. The last 20 ka are analyzed from Kasten cores (3-4 m) and short cores (60 cm) taken in turbidite free key-sites: Vydrino Shoulder, Posolsky Bank, and Continent Ridge (EU-CONTINENT project). The age-models of the cores are based on 14C AMS datings and magnetic susceptibility correlations. From the Late Glacial Maximum (LGM) to Present, sedimentation rates range around 0,05 to 0,14 mm/yr. Thus, the standard 5 mm sampling step represent a temporal resolution of no more than 100 to 30 years. The cores material was impregnated by a new polymer technique to analyze the sediments at higher resolution from continuous thin-section cover. We present continuous grey-scale record at 20 æm resolution, measured in the undisturbed part of the sediment, i.e. outside punctual burrows. The grey-scale is visually controlled by optical microscopy, and compared with magnetic susceptibility. Due to sediment properties, the grey-scale provides a high resolution record of diatom/clay ratio. For the Holocene, the grey density record shows that the biogenic productivity (diatoms) is related to the highest values (120-150 units), whereas the lowest values (80-100 units) are related to clays mixed with iron oxides and phosphates. The grey densities show an opposite trend compared to magnetic susceptibility. Our Baikal results are compared with Siberian chronozones and with global ice core record from Greenland (GISP 2).
UR: http://www.ulg.ac.be/urap/
DE: 1655 Water cycles (1836)
DE: 1823 Frozen ground
DE: 1615 Biogeochemical processes (4805)
DE: 1620 Climate dynamics (3309)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting