Home – Home – Jornals – Earth’s Cryosphere 2021 number 2

The study presents new data on the cryolithological structure of a ridge-shaped peat plateau typical for the north of Western Siberia, located in the lower reaches of the Nadym River. Two wells were drilled at the top of the ridge and in the inter-ridge depression, with subsequent core analysis. Grain size distribution, shape and surface structure of sand quartz grains, botanical composition and radiocarbon age of organogenic deposits were determined. The study revealed the presence of a three-layer peat-sand-loam ridge structure. The lower loam layer with a ~60 % volumetric ice content was affected by frost heaving. Layers of pure ice are identified below this loam layer. The ridge was formed as a result of water migration with the complementary influence of ice injection; it is of the peat-mineral type. In the ridge formation history, we identified the stages of loam and sand deposits accumulation at the end of the Late Pleistocene; bogging occurred at the beginning of the Holocene (10.6-9.8 ka BP), while active frost heaving was during the Subboreal stage (5.5-5.0 ka BP). Currently, there is a decrease in the upper organic horizon thickness and some erosion. It is proposed to consider peat-mineral and mineral frost heave landforms (mounds and ridges) as separate type of cryogenic landforms.

The work reports on new data on geochemistry of water of the Sytygan-Sylba Thermal Spring located in the permafrost zone in the northeast of Yakutia. Data on the content of rare and trace elements, elements of a rare-earth group, oxygen and hydrogen isotopes in the studied waters have been obtained for the first time. Groundwaters of the spring are classified as low-mineralized siliceous thermal waters of the deep origin, which are seasonally fed due to the inflow of more mineralized suprapermafrost waters. The year-round activity of the thermal spring in the zone of continuous permafrost 300-500 m thick is associated with the significant heat flow in the anomalous mantle uplift zone. Geochemical signs of the thermal water of the spring involve an increased concentration of sulfates, anomalous contents of Ge, Mo, W, As and other elements, which may be indicators of halo waters and proximity of ore accumulations.

The analysis of affectivity of frozen soils surface cooling methods based on the theoretical understanding of temperature shift formation with seasonal processes in the upper ground layers is provided. The surface cooling method for the building with aerated underfloor space is suggested on the base of this analysis. This method includes heat-insulation layer ground surface and free convection cooling system with its horizontal evaporator under insulation layer. Condenser of the cooling system is out of the building contour and it makes evaporator temperature near to winter air temperature. The results of mathematical modelling demonstrate that suggested method provides a significant and rapid decrease of the ground temperature as compared to other methods (up to 1.0-2.5 °С for not more than 1.5 year instead of 3-5 years). An additional temperature decrease by 1.5 °С may be obtained by connecting of the forced cooling device to the cooling system for one summer season. The calculation results allow us to propose the best sequence for connecting the cooling elements of the system at the initial stage of its operation.

A correlation analysis of long-term dynamics of sea ice extent in the Northern Hemisphere involving calculations of insolation characteristics with high spatial resolution was performed. The revealed close negative relationships between multi-year variations in sea ice extent, winter insolation and irradiance contrast were calculated in model cells with resolution of 1° x 1° for the period 1901-2018. The linkage density maps have been constructed to analyze relationships between multi-year changes in sea ice extent and insolation characteristics based on annual, semi-annual and monthly (March, September) means of sea ice extent. It is revealed that the correlation between multi-year variations in sea ice spatial distribution in the Northern Hemisphere and insolation contrast is interpreted as cause and effect relationship, while insolation contrast can be used as a predictor in statistical models for the sea ice extent dynamics. A close relationship between spatial distribution of sea ice and insolation contrast throughout the entire Northern Sea Route has been determined. This gives a perspective for long-term forecasting of the sea ice extent for the Northern Sea Route based on calculations of the intensity of insolation contrast for the Northern Hemisphere.

The features of the Late Pleistocene ice wedges in the outcrop of the Zelyony Mys Yedoma located on the right bank of the Lower Kolyma River are considered. The oxygen isotope composition of ice wedges, their radiocarbon age, hydrochemical features have been studied. Stable oxygen isotopes provide the main basis for reconstructing the mean January air temperature history of a site from ice wedges. Detailed quantitative assessments of paleogeocryological and paleoclimatic changes of the region in the Late Pleistocene 48-15 cal ka BP were performed.

It has been revealed that methodological techniques and formulas developed and widely used by Yu.K. Vasil’chuk for the reconstruction of average January temperatures (t_J = 1.5xδ¹⁸O), the sum of winter negative temperatures (∑t_w = 250xδ¹⁸O), as well as average winter temperatures (t_w = δ¹⁸O) based on the oxygen-isotopic composition of polygonal ice wedge are incorrect, and the paleoclimatic reconstructions obtained from these formulas are unreliable.

The main milestones of the history of the Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS are reflected in the light of its thirtieth anniversary, celebrated in 2021.