Late interglacial (Eemian) records from ice wedge casts along the Dmitry Laptev Strait, NE Siberia

• Main Authors: Schirrmeister, Lutz, Wetterich, Sebastian, Andreev, Andrei, Kienast, F., Tumskoy, V., Kunitsky, V.
• Format: Conference Object
• Language: unknown
• Published: 2009
• Subjects: Arctic; East Siberian Sea; Ice; laptev; Laptev Sea; permafrost; Thermokarst; wedge*; Siberia
• Online Access: https://epic.awi.de/id/eprint/20394/; https://hdl.handle.net/10013/epic.32489

Ice wedge casts that formed due to thawing of ice wedges are significant signs of past warm periods in Arctic periglacial regions. Such permafrost degradation structures are numerous and very well exposed on both coasts of the Dmitry Laptev Strait, which connects the Laptev Sea with the East Siberian Sea between the southern island of the New Siberian Archipelago (Bolshoy Lyakhovsky Island) and the mainland (Oyogos Yar coast). Cryolithological, sedimentological and palaeo-ecological features were studied in order to obtain detailed records of interglacial permafrost, landscape and climate dynamics in the Northeast Siberian Arctic.The lithostratigraphical structure of Eemian sections on both coasts show similar patterns of two facial different horizons. The lowermost sequences of consists of thawed and subsequently refrozen (so-called taberal) deposits, accumulated in pre-Eemian times and underwent thawing in lake taliks during the Eemian Interglacial when thermokarst processes led to the formation of lakes and thawed deposits below thelakes. The sedimentological and cryolithological features of the pre-Eemian taberal horizons show single whitish laminations which are interpreted as thaw signs, numerous small dark-grey spots representing strongly decomposed organic matter, and a massive cryostructure. Pollen records reveal relatively high amounts of reworked ancient(mineralised) coniferous pollen, whereas ostracod remains are absent. The refreezing of the taberal horizons took place in post-Eemian time and the deposits remained frozen until today. Taberal deposits are covered by the Eemian lacustrine sequence that formed due to warmer conditions during the Interglacial when thermokarst lakes occurred. Under such conditions pre-Eemian ice wedges thawed; at their positions small thermokarst lake basins formed and lacustrine sediments began to accumulate. Distinctive features of the lacustrine sediments are the alternating beds of finely laminated brownish plant detritus and grey sandy silt layers. Synsedimentary ...