Engineering-geological and geochemical conditions of polygonal landscapes in the area of the Tambey River mouth (Yamal Peninsula, northern Siberia)

The paper deals with the factors determining engineering geological aspects of development of the territories adjoining the South Tambey Gas-Condensate Field in the Yamal Peninsula (including widespread development of shallow location ice wedges) by the example of a licensed site of the field in the area of the Tambey River mouth. The relief, climate, hydrological conditions, geochemical features of bottom sediments of the Gulf of Ob, soils, geocryological conditions, cryogenic processes and engineering-geological conditions of the site are characterized. Subfossil pollen spectra, spore and pollen content, chemical composition of ice wedges and surrounding sediments are investigated, that permits to clarify the formation history of ice wedges. The character of enclosing soil deformations on the contacts with ice wedges is considered especially in detail. The macro ice content of the floodplain massif to the depths of 1 and 3 m and the potential subsidence at thawing of ice wedges are calculated. Comparison of the results of geothermal measurements in boreholes of 1978 and 2013 shows that the average annual temperature increased by more than 5 °С per 35 years.