Holocene environmental history recorded in the Lake Lyadhej-To sediments, Polar Urals, Russia


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aandreev [ at ] awi-potsdam.de

Abstract

An 1180-cm long core recovered in Lake Lyadhej-To (68°15'N, 65°45'E, 150 m a.s.l.) at the NW rim of the Polar Urals Mountains reflects the Holocene environmental history from c. 11,000 cal. yr BP. Pollen assemblages from the diamicton (c. 11,000-10,700 cal. yr BP) are dominated by Pre-Quaternary spores and redeposited Pinaceae pollen, pointing to a high terrestrial input. Turbid and nutrient-poor lake conditions existed in the lake c. 10,700-10,550 cal. yr BP. The chironomid-inferred reconstructions suggest that mean July temperature increased rapidly from 10.0 to 11.8°C during this period. Sparse, treeless vegetation dominated on the disturbed and denudated soils in the catchment area. The period c. 10,550-8800 cal. yr BP is noticeable for the lowest lake-ice coverage and the highest bioproductivity during the lake history. Birch forest with some shrub alder grew around the lake reflecting the warmest environmental conditions during the Holocene. Mean July temperature was likely 11-13°C and annual precipitation - 400-500 mm. The period c. 8800-5500 cal. yr BP is characterised by gradual deterioration of environmental conditions in the lake and lake vicinity. The pollen- and chironomid-inferred temperatures reflect a warm period (c. 6500-6000 cal. BP) with mean July temperature at least 1-2°C higher than today. Birch forests disappeared from the lake vicinity after 6000 cal. yr BP. The vegetation in the Lyadhej-To region became similar to the modern. Shrub (Betula nana, Salix) and herb tundra dominated around the lake since c. 5500 cal. yr BP. All proxies are pointing to rather harsh environmental conditions. Diatom assemblages reflect relatively short growing seasons and longer persistence of ice on the lake c. 5500-2500 cal. yr BP. Pollen-based reconstruction suggest significant cooling between c. 5500 and 3500 cal. yr BP with mean July temperature 7-10°C and annual precipitation - 100-300 mm. The bioproductivity in the lake remained low after 2500 cal. yr BP, but biogeochemical proxies reflect a higher terrestrial influx. Changes in diatom content may indicate warmer water temperatures and reduced ice cover on the lake; however, chironomid-based reconstructions reflect a period with minimal temperatures during the lake history



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Scopus/ISI peer-reviewed
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Published
Eprint ID
11054
DOI 10.1016/j.palaeo.2005.04.004

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Andreev, A. , Tarasov, P. E. , Ilyashuk, B. P. , Ilyashuk, E. A. , Cremer, H. , Hermichen, W. D. , Hubberten, H. W. and Wischer, F. (2005): Holocene environmental history recorded in the Lake Lyadhej-To sediments, Polar Urals, Russia , Palaeogeography palaeoclimatology palaeoecology 223, pp. 181-203 . doi: 10.1016/j.palaeo.2005.04.004


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