Late glacial to Holocene environmental dynamics of the terrestrial Arctic new records from thermokarst deposits along the Dmitry Laptev Strait (NE Siberia)
The palaeo-landscape and environmental history during the last glacial-interglacial transition was studied in a broader regional context by comparing permafrost sequences from the northern and the southern coasts of the Dmitry Laptev Strait (East Siberian Sea) on Bolshoy Lyakhovsky Island (73°17′N,...
| Main Authors: | , , , , , , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2009
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/20395/ https://hdl.handle.net/10013/epic.32490 |
| Summary: | The palaeo-landscape and environmental history during the last glacial-interglacial transition was studied in a broader regional context by comparing permafrost sequences from the northern and the southern coasts of the Dmitry Laptev Strait (East Siberian Sea) on Bolshoy Lyakhovsky Island (73°17′N, 141°20′E) and on the Oyogos Yar coast (72°36'N, 143°36'E).Both coastal exposures show the same general stratigraphy pointing to similar landscape and environmental dynamics which were reconstructed using cryolithological, sedimentological and micro-palaeontological (i.e. pollen, freshwater ostracods) methods as well as stable isotope data from ice wedges.The late Glacial and Holocene permafrost records of both coastal sections are subdivided into three horizons that are of taberal (thawed and refrozen), lacustrine, and boggy origin.In both sections, the lowermost horizons consist of taberal deposits of the former late Pleistocene Ice Complex (dated between 46.6 and 36.6 14C kyr BP) which are composed of sandy silt with peat lenses and thaw signs (whitish laminations). The ice content is generally low and the cryostructures are lens-like reticulated or layered, typical for refrozen sediments. The pollen data from the taberal horizons point to a Middle Weichselian interstadial vegetation. Ostracod shells are rare.The taberal horizon is discordantly covered by a lacustrine horizon of late Glacial age (dated between 14.8 and 12.5 14C kyr BP). Its lowermost part is composed of cryoturbated peaty palaeosols in both sections. The overlying lacustrine facies is structured by alternating beds of clayish silts and plant detritus layers which contain numerous mollusc shells, ostracods, and wood fragments. The cryostructure is lens-like or lens-like layered and epigenetic roots of ice wedges are common within the lacustrine horizons. Pollen records are in good accordance with Allerød to Younger Dryas ages indicating a grass-sedge tundra dominated vegetation. The ostracod records point to stable aquatic conditions during the late ... |
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