HR: 0800h
AN: C31A-1112    [Abstracts]
TI: The Submarine Permafrost in the Laptev Sea Imaged With High-Resolution Multi-Channel Seismic
AU: * Schwenk, T
EM: tschwenk@uni-bremen.de
AF: University of Bremen Dept. of Geosciences, P.O. Box 330440, Bremen, 28334 Germany
AU: Spiess, V
EM: vspiess@uni-bremen.de
AF: University of Bremen Dept. of Geosciences, P.O. Box 330440, Bremen, 28334 Germany
AU: Kassens, H
C31A-1112 AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 241177 Germany
AU: Rekant, P
C31A-1112 AF: Otto Schmidt Laboratory for Polar and Marine Sciences, UI Beringa 38, St. Petersburg, 199397 Russian Federation
AU: Gusev, E
C31A-1112 AF: VNIIOkeangeologia, Anglyisky pr. 1, St. Petersburg, 190121 Russian Federation
AB: A thick permafrost layer has developed below the Laptev Sea during the last glacials as the now flooded shelf was exposed and not glaciated. The permafrost still exists today in a submarine environment after the last transgression, but global warming with increasing arctic water temperatures may lead to degradation. Since organic carbon and gas hydrates are expected within und beneath the submarine permafrost, the degradation of permafrost could release considerable amounts of greenhouse gases into the atmosphere. Even though this importance of the submarine permafrost for the global climate system, the knowledge of its distribution and possible degradation in the Laptev Sea is still limited. In September 2004, high-resolution multi-channel seismic data as well as sediment echosounder and sidescan data were collected during the Expedition Transdrift X. This expedition was carried out in a Russian-German cooperation between the GEOMAR (Kiel, Germany), the VNIIO (St. Petersburg, Russia) and the University of Bremen (Germany). As seismic source, a Mini GI Gun was used; the seismic signals were received with a 48-channel streamer especially designed for shallow water. The main goal of the expedition was to image the distribution and character of the top of the permafrost. The seismic data show different seismic facies and features in the Laptev Sea. A central target of the cruise was a prominent reflector imaged with a dense grid of seismic and acoustic data. Shape and scale of the reflector seems to be similar to the thermokarst terrain of the Sibirian coastlands today including ice-complexes and filled thermokarst lakes. The strong reflection of the interface indicates the presence of permafrost. To the west, this reflector change from distinct to prolonged, which may interpreted as the degradation of the permafrost. A large number of gas seeps, mostly located in the depression of the prominent reflector, could be identified, underlining the possible potential of the submarine permafrost as greenhouse gas releaser.
DE: 0702 Permafrost (0475)
DE: 0708 Thermokarst
DE: 0935 Seismic methods (3025, 7294)
SC: Cryosphere [C]
MN: Fall Meeting 2005