Академическое издательство «Гео»

Pingo, oxygen isotope, deuterium, radiocarbon age, North-West Siberia, intrusive ice

KRIOSFERA ZEMLI, 2014, Vol. XVIII, № 4, p. 47-58

Isotope composition of pingo ice core in the Evoyakha river valley, North-West Siberia

Yu.K. Vasilchuk, N.A. Budantseva, A.C. Vasilchuk, K. Yoshikawa*,
Ye.Ye. Podborny**, Ju.N. Chizhova

Lomonosov Moscow State University, Department of Geography and Geology,
119991, Moscow, Leninskie Gory, 1, Russia; vasilch@geol.msu.ru, vasilch_geo@mail.ru
*Water and Environmental Research Center of the Institute of Northern Engineering
of the University of Alaska, Fairbanks, Alaska, USA; kyoshikawa@alaska.edu
**Center Hydroecological Research, 199406, Saint-Petersburg, Nalichnaya str., 16a, Russia; epodbornyy@yandex.ru

Ice core of Pestsovoye pingo in the Evoyakha River valley in north-west Siberia has been studied. Thickness of the pingo ice is more than 15 m. The δ18О value of the pingo ice varies from –11.6 to –15.8 ‰, δD from –93.2 to –123.0 ‰. Comparison with isotope data of ice core of Weather pingo (Alaska) has been carried out. In Weather pingo ice δ18О values range from –15.5 to –22.0 ‰, δD values change from –132 to –170 ‰. Both isotope profiles of pingo ice are contrasting and arcuate-shaped as a result of isotope fractionation during freezing of sub-pingo waters in closed system. Fractionation leads to isotopic contrast of ice: by 4–6 ‰ of δ18О and by 20–25 ‰ of δD values. Radiocarbon dating of the covering peat at Pestsovoye pingo evidences that the heaving occurred in two stages. At the first stage the heaving began at about 5 kyr BP in the distal part of the mound. At the second stage about 2.5 kyr BP the heaving recommenced actively in the central part of the pingo. The heaving rate was very high – more than 2–3 cm per year. As a result a pingo of 17 m high has been formed.

Pingo, oxygen isotope, deuterium, radiocarbon age, North-West Siberia, intrusive ice