HR: 1340h
AN: C13A-0258    [Abstracts]
TI: The Dynamics of permafrost and the Gas Hydrate Stability Zone in Rift Structures on the Shelf of the Seas of Eastern Eurasia
AU: * Hubberten, H W
EM: hubbert@awi-potsdam.de
AF: Alfred Wegener Institut for Polar and Marine Research, Telegrafenberg A 43, Potsdam, 14473 Germany
AU: Eliseeva, A A
AF: Geocryology Department Moscow State University, Vorobyovy Gora, Moscow, 119899 Russian Federation
AU: Romanovskii, N N
AF: Geocryology Department Moscow State University, Vorobyovy Gora, Moscow, 119899 Russian Federation
AU: Tipenko, G S
AF: Mathematics and Mechanics Department, Moscow State University, Vorobyovy Gora, Moscow, 119899 Russian Federation
AB: The Eurasian Arctic shelf areas, especially those of the Kara, Laptev and East Siberian Seas, display submarine permafrost and gas hydrate occurrences as characteristic features. In some of the shelf areas oceanic rift zones stretch to the continent, as for example in the Laptev Sea area where the Lomonossov Ridge continues on land. Great differences in geothermal heat flow values (qgt) and rock's properties in undisturbed block of the lithosphere and in fault zones in this region have to been assumed just as in continental rifts (such as Momskii and Baikal rifts, etc.). As a result, differences in the thickness of permafrost and the gas hydrate stability zone (GHSZ) within these structures are expected. For the investigation of permafrost and GHSZ evolution, and their dynamic and interaction in rift structures a two - dimensional mathematical model has been elaborated. The paleogeographic scenario used in this calculation covers the time from middle - late Pleistocene to the Holocene (c. 400 kyr), i.e. the last four climatic and glacio-eustatic cycles. Model calculations for rift structures of different sizes, and different qgt values, which are typical for different geographic situation on the shelf and as the result have different paleogeographical history have been carried out. The modeling results show that the thickness of offshore permafrost in the stages of climatic warming and transgressions essentially decrease however, rather extremely irregularly. The permafrost thickness is more reduced in fault zones, than in the consolidated blocks with lower qgt values. Similar processes take place with the thickness variation of the GHSZ as well. According to the results of the simulations, a first estimation of the regularities of permafrost and GHSZ thickness variation has been carried out. The possibilities and the boundary conditions for the occurrence of open taliks, which may result in an emission of greenhouse gases from relict sub-permafrost layers, have been estimated.
DE: 1815 Erosion and sedimentation
DE: 1823 Frozen ground
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting