Permafrost OF THE OKA PLATEAU: KEY PARAMETRES AND THEIR VARIABILITY DUE TO CLIMATE DYNAMICS
S.V. Alexeev1, L.P. Alexeeva1, Yu.K. Vasil’chuk2, A.A. Svetlakov1, V.A. Pellinen1, E.S. Koroleva3
1Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
2Lomonosov Moscow State University, Faculty of Geography, Moscow, Russia
3Arctic Research Center of the Yamal-Nenets Autonomous District, Salekhard, Russia
Keywords: frozen unconsolidated sediments, cryogenic structures, temperature regime, frost mounds, ground ice, Sentsa River valley, Oka Plateau
Abstract
This article presents the results of the permafrost research of the Oka Plateau in the Eastern Sayan Ridge. The complex of scientific research works carried out in the Sentsa River valley involved parametric drilling, geothermal regime observations in boreholes, cryolithological analysis of unconsolidated sediments, and petrographic studies of ground ice, as well as its structural and genetic features. It was established that the geological section down to 45 m consists of clays, clayey silts, silts and sands with ice interlayers and lenses. Permafrost thickness in the Sentsa River valley does not exceed 44 m, and a mean annual ground temperature at a depth of 10 m ranges from -1.1 to -2.1 °C. The parameters of the structure of ground ice indicate its segregation and injection origin. The stable multi-year positive trend in the mean annual air temperature on the Oka Plateau contributes to a gradual increase of the frozen sediments temperature in the layer of annual heat fluctuation, the destruction of ice-mineral frost mounds and the lowering of the surface.
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