HR: 17:15h
AN: PP24A-06    [Abstracts]
TI: A Continuous 3.6 Mio Year Record of Terrestrial Climatic Change in NE Siberia? Seismic Investigation of Impact Crater Lake El'gygytgyn
AU: * Niessen, F
EM: fniessen@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Columbusstr., Bremerhaven, D-27515 Germany
AU: Gebhardt, C
EM: cgebhardt@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Columbusstr., Bremerhaven, D-27515 Germany
AU: Kopsch, C
EM: ckopsch@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, Telegraphenberg A43, Potsdam, D-14473 Germany
AU: Wagner, B
EM: wagner@rz.uni-leipzig.de
AF: University Leipzig, Institute for Geophysics and Geology, Talstrasse 35, Leipzig, D-04103 Germany
AB: Long ($>$100ka) records of climatic change from terrestrial environments in Siberia are rare but essential to improve our understanding of the Arctic's role in global climate dynamics. North-east Siberia provides a key area to study climatic teleconnections between the North Pacific oceanic system, climatic pattern over NE Russia, the Arctic Ocean and other climate forcing areas such as the North Atlantic and the Tropics. Lake El'gygytgyn, located in central Chukotka, NE Russia, was formed 3.6 million years ago by a meteorite impact and apparently escaped continental scale glaciations during the entire Quaternary. If so a full-length sediment core would yield a complete record of Arctic climate evolution, back one million years prior to the first major glaciation of the Northern Hemisphere. A 13.0 m long sediment core retrieved from the lake in 1998 revealed a basal age of approx. 250 ka, confirmed the lack of glacial erosion, and underlined the sensitivity of this lacustrine environment to reflect high resolution climatic change on Milankovitch and sub-Milankovitch time scales. Seismic investigation carried out during two expedtions in 2000 and 2003 revealed a depth-velocity model of brecciated bedrock overlain by a suevite layer overlain by two lacustrine sedimentary units up to 350 m in thickness. The upper well-stratified sediment unit appears undisturbed apart from intercalation with debris flows near the slopes. Based on extrapolation of sedimentation rates the entire Quaternary and possibly parts of the late Tertiary record are within the 170m thick unit one and the earliest history of the lake is in unit two. There is no evidence of glacial erosion in the sedimentary record. High-resolution 3.5 kHz profiles indicate sharp termination lobes of non-erosive debris flows in distal areas. Near the centre of the lake the 250ka sediment-core record exhibit a few thin distal turbidites possibly generated by debris flows. The character of the sediment fill suggests a high potential of the record for paleoclimate studies and deep drilling would offers opportunities of impact studies of the brecciated bedrock. Our study is part of international and multi-disciplinary site-survey investigation of Lake El'gygytgyn. The lake has been recognised as potential deep drilling location by the International Continental Drilling Program (ICDP).
DE: 1630 Impact phenomena
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting