Permafrost properties of the Yedoma key site at Duvanny Yar (Kolyma lowland, East Siberia)

• Main Authors: Strauss, Jens, Wetterich, Sebastian, Schirrmeister, Lutz
• Format: Conference Object
• Language: unknown
• Published: 2010
• Subjects: Arctic; Taymyr; Kolyma; Yar; Ice; IPY; Magnetic susceptibility; permafrost; Taymyr Peninsula; Thermokarst; Beringia; Siberia
• Online Access: https://epic.awi.de/id/eprint/22738/; https://epic.awi.de/id/eprint/22738/1/Str2010f.pdf; https://hdl.handle.net/10013/epic.35418; https://hdl.handle.net/10013/epic.35418.d001

In course of the IPY project № 15 Past permafrost fieldwork was undertaken at riverbank permafrost sections of Duvanny Yar (68.63190°N, 159.14200°E) in summer 2008.The Duvanny Yar section exposing the Yedoma Suite is considered as the stratotype of the East Siberian late Quaternary stratigraphy (Hopkins 1982) as well as an important key section for the palaeo-environmental history of the Late Pleistocene Beringia Land, the non-glaciated landmass between the Taymyr Peninsula and Alaska.Permafrost deposits were described and sampled for further cryolithological, sedimentological, and micro-palaeontological analyses to reconstruct landscape dynamics during several climate cycles. Sediment samples were analysed for ice contents, grain size parameters, biogeochemistry (total carbon, total organic carbon, total nitrogen, stable carbon isotopes), mineral density, mass specific magnetic susceptibility, and for radiocarbon age.Six profiles along the riverbank covering the whole section were sampled. They contain Eemian lacustrine deposits, long Ice Complex sequences of the Late Pleistocene Yedoma Suite and Holocene lacustrine and boggy deposits in thermokarst depressions.Geochronological results preliminary based on eight AMS ages revealed that the Yedoma Suite was continuously formed from the end of the Middle Weichselian (about 40 kyr BP) until the Late Glacial Maximum (about 20 kyr BP). All profiles show very bad sorted sediment of fine to coarse silt. A homogenous and polymodal grain size distribution for the ice-rich Yedoma Suite (ice content about 30 to 60 wt %) revealed a polygenetic origin and disproves the pure arctic loess hypothesis for these deposits. Measurements of bulk density, ice content and total organic carbon content (TOC) enable for a relative TOC content in Ice Complex deposits at Duvanny Yar. The mean value of TOC at Duvanny Yar was estimated as 16 ± 11 kg*m^-3.A better knowledge of the permafrost properties at the Duvanny Yar key site especially the carbon characteristics may provide a basis for more reliable predictions of future developments of the ice-rich permafrost in Siberia.