Abstract: This article examines the argumentation of the main hypothesis of disappearance of the large Pleistocene fauna. The four components of the problem are being determined and discussed – chronological, landscape-climatic, anthropogenic, and evolutionary. The author analyses the possible effect of the dating method upon the perceptions regarding the chronology of rise and fall of the populations of mammoth fauna, as well as different landscape factors of the destruction and disposal of the fossil fauna, temporal connection of the mass destruction of animals with the eras of climatic cooling and warming. The role of anthropogenic factor of mammoths’ extinction is being evaluated. Special attention is given to the loesses as a factor that forms the habitat of Pleistocene fauna. The article suggest several original hypothesis of mammoths’ extinction that are based on the principles of biospheric evolution and catastrophism. Degradation of mammoth fauna at the turn of Pleistocene and Holocene was significantly affected by the following: rapid increase of zonality of the natural environment with reduction in the area of intrazonal landscapes; disruption of the patterns of seasonal and long-term migration of Pleistocene animals, primarily most vulnerable to changes in ration of the large mammals; amalgamation of the resource-viable zoocenosis that led to degradation of grazing lands and disruption of trophic chain. The key role in disruption of the migration patterns and pasture exhausting is assigned to the thermokarst catastrophe.

Keywords: paleogeography, thermokarst, ground ice, loess, extinction mammoths, glacial cycle, paleozoology, Pleistocene faune, tundra-steppe, yedoma

Abstract: The subject of this research is the natural explosive processes into cryolithic zones. The object of this research is the Yamal Crater. The authors meticulously examine the groups of the natural explosive processes in the territory of distribution of permafrost. A new approach towards the theory of the crater of gaseous discharge is proposed. It is based on the migration mechanism of gas fluids from the zones of gas hydrates disassociation into the overlying thickness of permafrost. The dissociation zone forms in segments of the local heatup through the heat input from the top. The authors demonstrate the gradualism of processes of preparing the explosive process that formed the Yamal Crater, as well as calculate the pressure of ejection of the frozen layer in emergence of the Yamal Crater. The work provides characteristic to the four phases of preparation of the natural explosive processes, considers various scenarios of such in cryolithic zone, as well as creation of the model of the heat and mass transfer processes alongside tense and distorted situation in permafrost that contain gas hydrated in terms of temperature variation and pressure. The following conclusions were made: the explosions of hydrolaccoliths and emergence of the craters of gaseous discharge belong to the same group of processes – physical explosions of natural origin; preparation of explosive processes in permafrost passes through several stages; in preparing explosions of natural origin in permafrost, a significant role is played by the migration of gas fluids.

Keywords: plastic deformations, staging, Yamal Crater, gas discharge funnel, fluids, dissociation, gas hydrates, permafrost, physical explosion, transit zone

Abstract: This article considers the migration frost mounds (palsa) in the settlement of Yeletsky in the northeast of Bolshezemelskaya tundra. The new radiocarbon dating on the frost mounds of various size and different stages of development within the boundaries of massif explored by the authors in 2000 and 2015. The work meticulously examines the representative 3m high frost mound with no signs of destruction, covered with peat having capacity over 1m. The object of the research is defined by the goal to characterize the conditions of peat accumulation and identify the moisture sources that form the upper part of the ice core. For the radiocarbon dating was selected the thawed peat on the top or shoulder of the mound. In the shafts was minutely (at intervals of 5-10cm) selected the peat for identifying the concentration of carbon and nitrogen and isotopic composition of carbon and nitrogen. From the bottom of the shaft using the electric ice auger MORA-ICE was drilled the wellbore in frozen peat and the underlying frozen loam, as well as selected the ice lenses. The determination of isotopic composition of oxygen and hydrogen of ice were conducted using the mass spectometer Delta-V; radiocarbon dating of the peat carried out in laboratory of archeological technology of the Institute of Material Culture of the Russian Academy of Sciences. The scientific novelty consists in the comprehensive approach towards exploring the peat deposit covering the frost mound.

Keywords: hydrogen, oxygen, segregated ice, nitrogen, carbon, isotopes, radiocarbon age, peat, palsa, deuterium excess

Abstract:  This article presents and tests the method of assessment of the various geocriological threats to the developed territories of Eastern Chukotka. The research is based on the complex of field geodesic, geophysical, and geocryological measurements conducted in the core settlement of the indicated region (Lorino), as well as archival data of the engineering surveys of previous years. Based on the acquired materials using the calculation methods, the author was able to determine the current geocryological situation in subsoil of the settlement along with the development level of the negative cryogenic processes and phenomena. In the course of this war was performed the assessment of threats associated with the changes in cryogenic situation and development of the negative cryogenic processes. As a result of this research, the author allocated the sections of settlement within which is traced the low level of natural sustainability of lithocryogenic ground in terms of technogenic disturbance, as well as high level of threat pertaining to decline in the carrying capacity of refrigerated piles and increase of tangential forces of frost heaving of soil.

Keywords: Eastern Chukotka, coastal erosion, thermoerosion, frost heaving, bearing capacity of piles, natural hazards, active layer, permafrost, Lorino, geocryology

Abstract: This article concentrates on the experimental research of the heat and mass transfer properties of the technogenic soil of Yakutia that are subject to freeze-thaw cycles. Definition is given to the technogenic soils according to the GOST 25100-95. The work cites the established fact of significant difference in the coefficient of filtration of naturally located soils of seasonal layer of thaw from indexes acquired in controlled conditions. It is substantiated that there is a need to research the heat and mass transfer properties of the technogenic soils with consideration of the cyclic impact of the low temperatures and changes in the cryogenic structure for a more complete correspondence with the northern conditions. The authors analyze  the acquired data, approximate the experimental data via the methods of statistical processing and compare it with the data from other sources. The conducted research allowed determining the dependence of the thermophysical properties of the technogenic soils upon their moisture, temperature and loam content.

Keywords: freeze-thaw cycles, filtration, thermal conductivity, temperature, humidity, density, loam, frozen soils, technogenic substrates, diffusion coefficient

Abstract: This article focuses on the experimental research of the impact of additives of surface active agents upon the strength of the frozen dispersed soils. The work touches on the problem of finding new theoretical approaches towards mechanical properties of dispersed soils accounting for presence of free surface energy and impact of the physical chemistry factors upon the behavior and properties of the soils. Substantiation is made on the physical chemistry approach as the most promising one in this area. Pyotr Rebinder’s mechanism for strengthening thawed soils through the effects of the surface active agents is presented in this research. Experimental research was conducted on the strength characteristics of the frozen dispersed soils with use of surfactants and without additives. The conducted research yielded experimental curve relationship of the maximal strength from time for frozen sand and loam with surfactants and without.

Keywords: hardening, amount of unfrozen water, soil mechanics, ultimate strength, soil science, surface active agents, soils, cryolithozone, deformation, load

Abstract: This article examines the issue of numerical modeling of the soil freezing-thaw process for projection of thermal stabilization system of soil building foundations in the cryolithozone of the Sakha Republic (Yakutia). The goal of this work consists in studying the process of formation of the temperature field of the massif of the soils under the effect of thermal stabilizers. Research is conducted on the process of formation of ice wall as the result of thermal exchange of the soil with the thermal stabilizers and external cool air during clearing of the snow cover from the construction site. The main conclusions of the conducted research include the need for development of mathematical models that would account for the mass exchange processes in the zones of effect of the thermal stabilizers with consideration of the conditions of formation of the cryogenic textures in the process of forced freezing of the soils. There is also a need for mathematical explanation of the phenomena of condensation and evaporation of Freon taking place inside the thermal stabilizers.

Keywords: temperature field, heat exchange, The Stefan problem, mathematical model, termal stabilizers, soils, cryolithozone, freezing - thawing, structures, permafrost

Abstract: The subject of this research is the interaction of the seasonal thermal stabilizers with the soils, processes of thermal and mass transfer and formation of cryotextures. The thermal stabilizers found broad implementation in northern construction for strengthening foundations of buildings formed with plastic and thawed dispersed soils with installation of Anti-filtration screens and ice walls. The efficiency of the work of thermal stabilizers is assessed based on the rate of formation of the calculated temperature schedule in foundations of engineering structures. The presented data of formation of temperatures of the soil foundations cooled by the liquid-vapor thermal stabilizers reflect regularities characteristic for dispersed soils of all types with various indexes of moisture and salinization for buildings with ventilated crawl spaces.  

Keywords: thermostabilization, permafrost, northern construction, heat and mass transfer, soils, cryolithozone, season-cooling devices, temperature sensor, thermoset, piling foundation