Environmental records in permafrost of East Siberian Arctic during the MIS2 Stadial and the MIS3 Interstadial

• Main Authors: Rudaya, Natalia, Andreev, Andreev, Wetterich, Sebastian, Tumskoy, Vladimir, Schirrmeister, Lutz
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Arctic; Ice; laptev; permafrost; Tundra; Beringia
• Online Access: https://epic.awi.de/id/eprint/32519/; https://hdl.handle.net/10013/epic.41123

In East Siberian Arctic permafrost deposits is increasingly employed as an archive that preserves records of regional environmental history. Pollen records play a leading role among bioindicators because of the common presence of fossil pollen in Quaternary terrestrial periglacial and lacustrine sediments. One of the most promising study areas for collecting information that can be used to highlight the environmental history of West Beringia is Bol’shoy Lyakhovsky Island, located between the Laptev and the East Siberian seas. The southern coast of B.Lyakhovsky Island exposes permafrost outcrops that feature frozen sediments, ground ice, and fossil remains dating from the mid-Pleistocene. During the MIS3 Interstadial, continuous Ice Complex development took place on B.Lyakhovsky Island. Pollen records of Kargin Interstadial reflect some amelioration of the harsh environmental conditions predominant during the previous interval. The studied record of a continuous permafrost sequence dated between > 55 and 27 kyr BP reflects the palaeoenvironmental history from the end of the MIS4 to the end of the MIS3. The combined data sets allow to differentiate the late Zyryan Stadial (>55 to 52 kyr BP) with a quickly developing polygon tundra; harsh cold and dry summers are reflected by sparse grass-sedge tundra-steppe and high amounts of redeposited conifers. During the early Kargin Interstadial (52-48.5 kyr BP) pollen record shows higher Artemisia percentages within a grass-sedge tundra-steppe vegetation that support dry conditions. The Kargin Interstadial optimum between 48.5 and 37 kyr BP promoted low-centered polygon tundra with shallow water in polygon centers. Moister conditions in the landscape than during the previous Zyryan Stadial are assumed while the general summer climate conditions likely remained dry, but slightly warmer as reflected by higher Salix abundances. Warmer summer air temperatures and moister condition on landscape scale during the MIS3 optimum are revealed mainly by Salix and green algae findings in the palynological tundra-steppe records. A cooling trend in summer air temperatures between 37 and 27 kyr BP can be deduced from disappearing Salix pollen. Changes in the accumulation conditions are indicated at the end of the MIS3 in transition to the MIS2. The palynological complex (L7-07) dated to the early Sartan stadial reflects the existence of an impoverished variant of tundra steppe or cryophyte steppe vegetation. The dominance of graminoids, together with abundant Artemisia, and low percentages of Ericales (indicator of wet plant communities) in the pollen spectra point to rather dry climatic conditions. Evidence of an extremely cold climate is given by the dominance of Poaceae over Cyperaceae. The large amount of Caryophyllaceae, Brassicaceae, and Papaveraceae, which are arctic pioneer taxa characteristic of northernmost vascular plant communities in polar deserts, confirms this interpretation.The temporal appearance of LGM conditions in East Siberian permafrost as represented by pollen and ground ice data differs somewhat within the region, but delineates a general trend to coldest and driest climate conditions between about 24 and 18 ka BP. Herb- and shrubdominated Lateglacial vegetation is reflected in pollen data from Bol’shoy Lyakhovsky after the Sartan stadial. Betula sect. Nanae, B. sect. Albae, and Duschekia fruticosa pollen mirror warming climate conditions.