Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia)


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Sebastian.Wetterich [ at ] awi.de

Abstract

Ground ice and sedimentary records of a pingo exposure reveal insights into Holocene permafrost, landscape and climate dynamics. Early to mid-Holocene thermokarst lake deposits contain rich floral and faunal paleoassemblages, which indicate lake shrinkage and decreasing summer temperatures (chironomid-based TJuly) from 10.5 to 3.5 cal kyr BP with the warmest period between 10.5 and 8 cal kyr BP. Talik refreezing and pingo growth started about 3.5 cal kyr BP after disappearance of the lake. The isotopic composition of the pingo ice (δ18O − 17.1 ± 0.6‰, δD −144.5 ± 3.4‰, slope 5.85, deuterium excess −7.7± 1.5‰) point to the initial stage of closed-system freezing captured in the record. A differing isotopic composition within the massive ice body was found (δ18O − 21.3 ± 1.4‰, δD −165 ± 11.5‰, slope 8.13, deuterium excess 4.9± 3.2‰), probably related to the infill of dilation cracks by surface water with quasi-meteoric signature. Currently inactive syngenetic ice wedges formed in the thermokarst basin after lake drainage. The pingo preserves traces of permafrost response to climate variations in terms of ground-ice degradation (thermokarst) during the early and mid-Holocene, and aggradation (wedge-ice and pingo-ice growth) during the late Holocene.



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47847
DOI https://www.doi.org/10.1002/ppp.1979

Cite as
Wetterich, S. , Schirrmeister, L. , Nazarova, L. , Palagushkina, O. , Bobrov, A. , Pogosyan, L. , Savelieva, L. , Syrykh, L. , Matthes, H. , Fritz, M. , Günther, F. , Opel, T. and Meyer, H. (2018): Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia) , Permafrost and Periglacial Processes, 29 (3), pp. 182-198 . doi: https://www.doi.org/10.1002/ppp.1979


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