Abstract: The object of the study is the isotope composition of three aufeis (icing) in the Viluy River basin. Two of the three tested icing were located in the wide valleys of the streams-tributaries of the Viluy River, one on the flat bottom of the thermosuffusion sinkholes. The areas of studied icings did not exceed 30 sq. m., their thickness ranges from 45 to 100 cm. Stratification is recorded in the icings. The co-isotope diagram δ2H-δ18O shows that icing ice was formed from spring water and generally is isotopically “lighter” compared to the water of Kysyl-Yurekh stream and Viluy River. The isotope composition of the icing ice varies in a very narrow range: a) for icing 1 δ18O values vary from –19.3 to –20.9‰, δ2H values vary from –156.5 to –162.9‰; b) for icing 2 δ18O values vary from –19.7 to –22.4‰, δ2H values vary from –153.2 to –173.1‰; c) for icing 3 δ18O values vary from –19.8 to –22.7‰, δ2H values vary from –162.9 to –181.3‰. The similarity of the isotope profiles of icing 2 on Viluy and icing IB93-5 on Baylot Island and isotope profiles of icing 3 on Viluy and icing F192-6 on Baylot Island was noted, however, the scale of isotopic variations for icings on Baylot Island are 5-6 times greater than that of Viluy icings.

Keywords: cryolithozone, Yakutia, Viluy, deuterium excess, deuterium, oxygen isotopes, river water, snow, permafrost, aufeis

Abstract: The results of long-term observation of the foundations temperature regime and dangerous cryogenic processes development near exploited well pads on the Yamburg field are presented. Temperature observations (1992-2020) includes data on four well pads. Influence of the natural and anthropogenic factors on the permafrost temperature regime was investigated. Based on a great experience of dangerous cryogenic processes field observations, a thermoerosion near gas well pads were characterized. Some well pads are considered, where the increasing of riverbed and ravine thermoerosion required the development of anti-erosion measures. According to observations, well pads frozen foundations temperature increases by an average of 0,039 °C per year. The results of observations show the absence of a pronounced technogenic temperature increase in the frozen well pads foundations, which Cenomanian gas produces. Taliks with a radius of 5-10 m around the wells are observed at the well pads foundations, which Valanginian gas produces. On the slopes and adjacent depressions, the temperature of frozen rocks is high, sandy soils of the dumps are subject to erosion. The development of thermoerosion processes threatens to the well pads foundations near the eroded riversides, in the areas of ice-wedge polygonal tundra.

Keywords: gas temperature, production well, well pad, temperature observations, temperature regime of foundations, thermerosion, ravine, ice-wedge, Taz Peninsula, Yamburg field

Abstract: The article is devoted to the consideration of surface and deep factors that trigger the mechanisms for the preparation of explosive processes that form gas emission craters. The study object is local zones of gas-saturated soils with abnormally high gas pressure and gas craters. The main method used in this article is the bibliography review. The synthesis of the analyzed materials was carried out based on the geosystem approach. In the proposed work, an analysis was made of the main hypotheses of the formation of gas-saturated zones with increased gas pressure in frozen soils: 1) due to the comprehensive freezing of taliks (completely dependent on surface conditions; 2) due to the inflow of warm gas from underlying rocks into the surface layers (depending on deep sources); 3) due to the decomposition of gas hydrates contained in the permafrost (the reasons can be both surface and deep); 4) due to the joint interaction of the freezing talik and the associated deep gas inflow channel. Possibilities of realization of these or those hypotheses in real conditions are revealed. The relevance of the topic is due to the reassessment of the role of frozen soils as a screen that protects the atmosphere from the emission of greenhouse gases from the lithosphere. Evidence has appeared that this role of the cryolithozone is significantly weakened with an increase in temperature, while the frozen soils themselves can be a source of gas release.

Keywords: permafrost, plastic deformations, heat flux, dissociation of gas hydrates, gas filtration, gas fluids, fluid geodynamics, ice ground saturated geosystems, stage of development, paragenetic relationships

Abstract: When studying landslide processes, researchers pay great attention not only to the geometric dimensions of landslide bodies, displacement mechanisms, geomorphological features and reasons for their activation, but also to the time of their activation. The data obtained by radiocarbon dating of organic material selected from various geomorphological elements of landslides in the upper reaches of the Mzymta river basin (Western Caucasus) with a large sample of samples allow us to confidently say about the age of the event, or several episodes of landslide formation, the frequency of repetition of the process, as well as to establish the trigger causes that triggered the landslide. To obtain more reliable definitions of the age of the landslide, a method for performing serial selection of organic matter has been developed. Organic material was selected from various elements of the landslide : a) from sections of depressions in the rear part of the landslide, b) from sections of depressions on the main body of the landslide, c) from the humus horizon buried under the lingual part of the landslide. More than 40 new dates of samples of organic material have been obtained. The chronology of late- and Mid-Holocene landslides in the valley of the Mzymta river has been performed: 1. Landslides located on the northern slope of the Aibga ridge were formed during two major stages of landslide formation; 2. The older stage of landslide formation dates from the Middle Holocene from 6310 to 5380 cal. 3. The relatively younger stage of landslide formation dates from the Middle Holocene from 2930 to 2820 cal. years ago.

Keywords: lake-marsh depressions, Western Caucasus, Mzymta River Valley, Aibga Ridge, radiocarbon dating, landslides, holocene, Aibginsky fault, trigger reasons for activation, reconstruction of landslide history

Abstract: The subject of research is the earthwork of the railway track and artificial structures on hazy weak-draining areas in the areas of permafrost distribution on the bypass of the Bureyskaya HPP reservoir within the Verkhnebureinskaya depression. The purpose is to identify the conditions and causes of adverse processes and phenomena that have arisen during operation. The objectives of the research are to identify the main causes and conditions for the manifestation of unfavorable geocryological processes and phenomena – waterlogging, flooding, stagnation of water, degradation of permafrost, sediment of the roadbed. Design errors are analyzed and recommendations are given for the application of design solutions in accordance with the state and dynamics of geocryological conditions and the requirements of the current regulatory documents for the areas of distribution of low-level marys and high-temperature permafrost. For the first time, a comprehensive analysis of the conditions and causes causing adverse processes and phenomena was carried out for the described territory. Inefficient constructions and design solutions have been identified. Optimal design solutions and measures are recommended to ensure the stable and safe operation of transport facilities in the region in conditions of low-drainpipe and high-temperature permafrost. For the studied area, the characteristic features are the significant swampiness of the territory, and the wide distribution of low– and high-temperature permafrost soils of the merging type. There are cases of irrational and inefficient design. It is not uncommon to use unsuitable soils for filling the roadbed and its elements. Also, the excess of the volume of earthworks during construction. Under these conditions, it is recommended: When designing a railway track plan, trace the line through local elevated terrain areas, in order to ensure the necessary slope of the design profile of drainage ditches of at least 4 ppm. Drainage ditches along the path should be located at a distance that excludes the inflow of water into the base of the roadbed.

Keywords: design solutions, precipitation of the roadbed, degradation of permafrost rocks, silting of drainage ditches, stagnation of water, flooding, waterlogging, slabostochnaya mary, permafrost, the roadbed