HR: 0800h
AN: C51B-1030    [Abstracts]
TI: Stable-Isotope Signals Of Paleo-Winter Temperatures In Permafrost Ice Wedges Of Central Yakutia, Northeastern Siberia
AU: Popp, S
EM: spopp@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: * Diekmann, B
EM: bdiekmann@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: Syromyatnikov, I
EM: syromyatnikov@mpi.ysn.ru
AF: Melnikov Permafrost Institute, Merzlotnaya 10, Yakutsk, 677010 Russian Federation
AU: Meyer, H
EM: hmeyer@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: Siegert, C
EM: csiegert@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: Hubberten, H W
EM: hubbert@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AB: In the scope of a joint German-Russian research project, dealing with the Late Quaternary development of climate and environment in the Verkhoyansk Mountains and the lowlands of central Yakutia in eastern Siberia, the stable isotope composition of ice wedges was studied. Ice wedges are hosted in ice-rich soils and sediments of the permafrost landscape, and mainly form during spring time, when meteoric waters released by snow melt fill frost cracks that opened during the winter. Repeated frost cracking through the years leads to lateral and vertical ice-wedge growth. The stable isotope signal of meteoric waters stored in the ice wedges can therefore be used as a paleoclimatic indicator of winter temperatures. From our collected data, coldest winter temperatures occurred between approximately 40 and 30 ka BP, as indicated by very light isotope composition of oxygen around -31 permill VSMOW and hydrogen around -235 permill VSMOW in a late Pleistocene ice wedge. The isotopic composition of lower Holocene ice wedges reflect relatively warm winter temperatures around 8.5 ka BP with values of around -26 permill VSMOW for oxygen and around -199 permill VSMOW for hydrogen. Young ground ice, formed between 2.3 and 0.7 ka BP, documents climate deterioration during the late Holocene with light isotope composition of around -28 permill for oxygen and around -215 permill VSMOW for hydrogen. Using the relationship between isotope signals in Recent ground ice and modern climate data of central Yakutia, a semiquantitative estimate of paleotemperatures can be inferred. Thus, the mean winter temperature during the late Pleistocene was 2 to 5 degrees Celsius colder than today, while the lower Holocene was probably up to 3 degrees Celsius warmer than today. During the upper Holocene, the mean winter temperature fluctuated between 3 degrees Celsius colder than today and 1.5 degree Celsius warmer than today. However, the inference of absolute paleotemperatures suffers from uncertainties in regard to kinetic fractionation processes that are hardly to assess.
DE: 9315 Arctic region
DE: 9604 Cenozoic
DE: 1823 Frozen ground
DE: 1040 Isotopic composition/chemistry
DE: 1620 Climate dynamics (3309)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting