In this paper we propose the model of transformation of the Yakut Marginal Sea (YMS) into the orogenic Verkhoyansk-Kolyma mesozoid system (VKMS). The model is indicated in general terms and is undoubtedly a subject to further research. We have established similarity of the structure and formation of the YMS to the modern Japan marginal sea. In the late Mesozoic the VKMS was formed through the mini-subduction of the YMS oceanic crust beneath the island arc and microcontinent with the closure of small ocean basins, along with the collision of the YMS crustal blocks with Siberian continent. The marginal sea model allows us to claim that the major tectonic structures of the Verkhoyansk-Kolyma and Novosibirsk-Chukotka folded mesozoic systems of the Northeast Russia are in fact structural elements of different cratons: the North Asian and North American cratons. Moreover, formation of the systems occurred on different sides of the convergent boundary of the southern Proto-Arctic. Thus, the collisional (marginal sea) Verkhoyansk-Kolyma border was formed in the rear zone of the border, and the accretionary Novosibirsk-Chukotka border was formed in its frontal part.

The Tomtor massif of ultrabasic alkaline rocks and carbonatites (UAC) is located in the northeast of the Siberian Platform. The massif is one of the largest UAC in the world and is associated with the unique deposit Tomtor with colossal resources of Nb and REE. Moreover, the Ongkuchakh deposit with apatite-magnetite ores (phoscorites) is located within the massif. The deposit contains more than 1 billion tons of iron in total and about 500 million tons of P₂O₅ with high concentrations of REE. The Tomtor massif represents an important economic and strategic facility for the development of the Russian Arctic. In this paper we demostrate the contribution of phoscorites to the minerageny of the unique mineralization. We have provided geological and geochemical characteristics of the carbonatite complex and phoscorites. XFA and ICP AES methods were used to study their compositions in comparison plex and horizons of the lateritic weathering crust that form the mineralization. The generally accepted opinion that the deposit was formed during the weathering of ore carbonatites is supported by the convincing facts proving the significant participation of phoscorites in the formation of Nb-REE mineralization in the supergene complex.

We study mineralogical features of the gold-bearing hydrothermal-metasomatic formations of the Anabar region. Their main substrate is represented by fractured near-fault dolomites of the Anabar formation of the Cambrian age. We have found, for the first time, hydrothermalites developed on the slightly cemented fine-pebble quartz conglomerates of the Early Permian age in the core of exploration wells. Furthermore, we have identified two types of metasomatic rocks: quartz-potassium feldspar and jasperoid. We have revealed that the main ore minerals were galena and pyrite with different ratios by sites. The disseminated galena was the main ore mineral at the «Billyakh» and «Kurung Yuryakh» sites, and pyrite – at the «Sredny Mayat» site. At the «Sources of the Mayat» site, where sulfidized rocks were studied from a depth of more than 25 m, the main ore mineral was pyrite, which had a veinlet and continuous nature of development. Gold was identified in the form of small particles in the carbonate and siliceous substrate of hydrothermal-metasomatic formations at all sites. The lithological factor was one of the leading factors for the ore formation due to the presence of near-fault highly permeable fractured carbonate and slightly cemented terrigenous rocks. The structural control of the studied ore occurrences was determined by their localization in the Mayat-Logoy and Dogoy-Kuoy faults of the Molodo-Popigay system of discontinuous faults. We assume a two-stage formation of the gold ore occurrences. During the first stage, the ore components in the form of primary hydrothermal-sedimentary ores in the near-fault zones were formed. The second stage was related to the processes of the Mesozoic tectonic-magmatic activation when the intrusion of basite dikes initiated the mobilization of ore components. The gold-sulfide occurrences were formed in the near-fault zone as a result of silicic-potassic metasomatosis of the Cambrian carbonate and Permian terrigenous rocks.

This paper presents the study of the current dynamics of the spring flood runoff layer and the highest water discharge on the Sakhalin Island rivers. We have analyzed the changes in the amount of solid the data for the precipitation amount as reported by 13 weather stations, and the flood runoff as reported by 9 hydrological posts. We have also investigated the dynamics of other climatic parameters (the sum of the positive average daily air temperatures from the beginning of snowmelt to the end of high water, the average winter height and density of snow cover). They influenced on the spring flood runoff on the River Arkovo – Arkovo village, and were registered at the Aleksandrovsk-Sakhalinsky weather station.The analysis showed that on the territory of Sakhalin Island an increase in the amount of precipitation was detected during the cold period (November-March) at the weather stations in the northern part of the island, except for the weather station Pogibi. However, there were no significant trends in the total spring flood runoff layer on the Sakhalin rivers, except of the River Tym’, where a decrease in runoff was recorded. Thus, in Sakhalin, the increase in the amount of solid precipitation did not lead to an increase in the values of the flood runoff on its rivers.

We studied the distribution of fluorine in fresh and slightly salty surface waters, and suprapermafrost waters in Central Yakutia. The study was based on the results of hydrochemical works carried out by employees of the Melnikov Permafrost Institute SB RAS from 1984 to 2019. According to the sanitary requirements, the optimal concentration of fluorine in drinking water is 0.5–1.0 mg/L, with its maximum concentration 1.2–1.5 mg/L. Excessive intake of fluoride leads to disorders in the musculoskeletal, neuroendocrine and cardiovascular systems, while its deficiency leads to formation of dental caries. We used chemical analyzes of water samples from the surface streams and water bodies (479 samples), and underground waters of the vadoze zone (375 samples). The analyzes of water samples in the rivers and channel taliks showed that the average content of fluorine was no more than 0.3 mg/L, which did not reach the requirement for its optimal level for drinking water. The analyzes also showed a deficiency of fluorine in the waters of lakes and taliks under erosional and tukulan lakes. However, the fluorine content exceeded 1.5 mg/L in stagnant lakes, where more than 50 % of the cationic composition of water was sodium ion. Meanwhile fluorine concentration reached 3.2 mg/L in taliks under the stagnant thermokarst lakes. The saturation of suprapermafrost waters with fluorine can occur in the area of spring discharge under the influence of cryogenic disintegration of water-bearing rocks and metamorphization of the chemical composition of water during phase transitions. They lead to the precipitation of calcite from the solution, its pH increase, and accumulation of fluorine.

The changes in migration routes of the wild reindeer (Rangifer tarandus L.) have made it relevant to use pasture lands in the Avam tundra (south of the Taymyr Peninsula) for the development of domestic reindeer husbandry. The safety of forage plants is an essential condition for the reindeer husbandry. We aimed to study vegetative aboveground phytomass of the most common forage plants (lichens, cotton grass, sedge, shrubs). The ultimate composition and concentration of heavy metals were determined by pyrolysis using an atomic absorption analyzer RA-915+. We have assessed pasture safety by comparing the obtained data with the established maximum permissible level (MPL) of the chemical elements contained in feeds for the farm animals. The detected high variability of the element concentrations (υ = 21.8–96.6 %) can be attributed to the biological specifics of the species under study. We have found the maximum content of the elements of hazard class I (As, Hg, Pb) in lichen thallus (Cladonia genus). Regardless of the taxonomic status of the species, three chemical elements (Mn, Cu and Ni) account for 96.88–99.97 % of the gross content of their water-soluble forms. The concentration of nickel (except for baceous species) and chromium (except for shrubs) exceeded the maximum permissible level established for the farm animal feeds by 1.1–1.9 and 1.1–2.1 times, respectively. Taking into account the features of the regional geochemical background, the actual content of heavy metals in forage plants is not dangerous. Therefore, we conclude that the territory of the Avam tundra is suitable for developing domestic reindeer husbandry.

We investigate the temperature factors, which limit the spread and survival of plants in high mountain conditions of the Northern Urals. We aim to establish regression relationships of temperature data of four altitudinal belts in the southern part of the Northern Urals (59º30′ N, 59°15′ E) with the control data received from the Karpinsk meteorological station (Sverdlovsk region 59°46′ N, 60°00′ E). The air temperatures were recorded continuously day and night, every two hours, at a height of 1.5–2 m above the soil surface from May to October 2019 at four elevation locations: 460 m a.s.l. (in the mountain forest belt, under the canopy of Siberian stone pine stands); 640 m a.s.l. (in the mountain forest belt, under the canopy of Siberian stone pine stands); 820 m a.s.l. (in the belt of sub-alpine woodlands with elements of mountain forest-tundra);1030 m a.s.l. (on a plateau in the mountain tundra). We have established that the change in the air temperature at different elevation levels and at the meteorological station occurred relatively synchronously. The difference in average daily temperatures between the control data from the meteorological station and elevation points at 460, 640, 820 and 1030 m a.s.l. was 2.2, 3.0, 4.7 and 5.1 °С, respectively. We have established a reliable close rectilinear connection of the average daily air temperatures obtained from the station and all four elevation points. The coefficient of determination (R²) for elevation levels at 460, 640, 820 and 1030 m a.s.l. was 0.96, 0.95, 0.92 and 0.88, respectively. The relationships between the maximum and minimum temperatures, depending on the elevation level, with the control data from the meteorological station were also quite high (R² does not fall below 0.83 for maximum and 0.7 for minimum). Identified relationships and obtained regression equations allow to reconstruct, retrospectively, the dynamics of the thermal regime based on the data from the Karpinsk meteorological station for mountainous habitats of different elevation levels in the southern part of the Northern Urals over a long-term period. The results also imply the possibility of reconstruction of extreme temperatures, which act as factors limiting dispersal and survival of plants, and determine the biodiversity of ecosystems.

We investigate seasonal changes in the state of endogenous system of ethanol/acetaldehyde metabolites in the organisms of the large herbivorous mammals of the Arctic and Subarctic – reindeer (R) and Yakut breed horse (YH). We focus on the content of endogenous ethanol (EE) and endogenous acetaldehyde (EA) in the blood of the animals, along with the activity and concentration of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in their livers. We analyzed the involvement of the endogenous system in the adaptation mechanisms of the aboriginal herbivorous mammals to the extreme climate conditions at the high latitudes. The biomaterial (blood, liver) for the study was collected immediately after the slaughter in winter (December–January) and summer (June–July) in 2017– 2019. The animals led an active lifestyle throughout the year in native environment. The number of R in each season made 30, the number of YH – 40. The seasonal temperature fluctuations ranged from –50 °C (in winter) to +38 °C (in summer). We used the method of gas chromatography with mass spectrometry (GC-MS) to determine the EE and EA concentration in the animals’ whole blood. It has been shown that the levels of EE and EA in the blood of the large herbivorous mammals under study were significantly higher than those of the laboratory animals and humans. We detected seasonal dynamics in the content of metabolites, namely, a synchronous increase in their concentrations in the blood during the period of low ambient temperatures. The mechanism of the latter included seasonal changes either in isozyme forms of ADH and ALDH, which differed in their catalytic and physicochemical parameters in R, or in the concentration of enzymes in YH. These changes represent physiological and biochemical adaptive adjustments that increase resistance of the animals to the cold. An increase in the content of endogenous ethanol in the blood of YH and R prove that their reserve catabolic materials capable of generating biochemically useful energy under stressful conditions are included in the energy metabolism. Furthermore, an increase in the content of endogenous acetaldehyde represents a mechanism for reducing the overall level of bioenergetic processes with a redistribution of their intensity towards the increased generation of thermal energy. The physiological function of the system of endogenous ethanol, acetaldehyde and their metabolizing enzymes is to regulate (increase) the body’s resilience to the stressful impact of the cold.

In this paper we present a description of the forest stands in Central Yakutia. Forests of the region growing on the permafrost-taiga soils are characterized by low biological productivity, fragility and vulnerability to anthropogenic factors. Larch forests containing mixed herbs and lingonberries are the dominant forest type on the floodplain terrace and in the watershed areas due to the specific edaphic conditions. Forest stands with low productivity belong to the V-Va bonitet classes and demonstrate purity, usually without admixture of other species. We aim to analyze the structure of the main types of larch forests in the Middle Lena valley within the Namsky district of the Republic of Sakha (Yakutia). We have examined the correlation between the main taxational indicators of the larch stands within the lingonberry forest group. The analysis of their main taxational indicators has revealed their correlation with the morphometric parameters of the larch stands belonging to the mixed herb-lingonberry forest type. The analysis has proved a high degree of reliability of the established equations between a number of their indicators. The measurement data of taxational indicators demonstrated correlation between different indicators in the form of the equations of dependence. The results can lead to a comprehensive evaluation of the stands on the basis of the measurement assessment of their few taxational indicators. The revealed regularities will be used in standard tables evaluating the main structure parameters of the larch stands in the Middle Lena valley within the Namsky district. They will allow us to obtain a comprehensive characterization of the stands on the basis of evaluation of their several taxational indicators.

In this article we describe the phytocenotic characteristics of the winterfat steppes dominated by Krascheninnikovia ceratoides and Psathyrostachys caespitosa in Central and Southwestern Yakutia. The winterfat steppes under study are located in the well-warmed southern treeless steep slopes (45–50°) on the valley side of the Lena River. The communities are characterized by low diversity and include 28 species (26 genera and 15 families). Moreover, they have sparse distribution pattern. Woody and rooted herbaceous plants, representing a significant part of the life forms, are determined by an arid environment. In these conditions the leading position belongs to xerophytes. All the studied communities are located outside the borders of Specially Protected Natural Sites. Over the past decades, the habitat area of the winterfat (Krascheninnikovia ceratoides) has significantly decreased. These unique relic steppes are valid for the status of protected botanical monuments of nature. Particularly as the rare species protected in the republic (Hedysarum gmelinii, Phlojodicarpus sibiricus, Sibbaldianthe adpressa, Astragalus lenensis, Ephedra monosperma) grow together with Krascheninnikovia ceratoides in winterfat communities.

We study adaptation features of Stellaria humifusa (Caryophyllaceae) on the rocky ecotopes of the west coast of Svalbard. Stellaria humifusa, a mat-forming herb, is a monodominant plant community. In this paper we show that the mat life form is a complex structure, which is represented by a system of aboveground and underground organs, and a soil horizon. Aboveground organs are the top layer of the dead plants from the previous year. Flowering shoots of the current year plants with white flowers can be seen on the ground surface. The next layer of the mat is organogenic, which the main assimilating system. The layer is represented by the green leaves of Stellaria humifusa, which by their anatomical structures and functional indicators are adapted to the local habitat conditions in the mat. The bottom layer is the organomineral horizon. The layer represents a soil substrate, which is a source of mineral nutrition for the entire structure. The chemical composition of the soil substrate of the mat Stellaria humifusa is similar to the natural soil profile of the coastal area. The plant mat contributes to a greater accumulation of organic matter, activates humification and provides favorable conditions for the growth of Stellaria humifusa.

Intensive operation of the machinery in the natural and climatic conditions of the North often leads to premature wear of the elements of its friction units. A start-up of the equipment at low temperatures brings repeated thermal expansions of already run-in elements of friction units and changes in their geometric dimensions. An increase in the viscosity of technical lubricants in cold weather also reduces the wear resistance of friction units. The decrease in the resource of working elements and parts of the running system of earth-moving and mining equipment in the North is also due to frozen soils in the permafrost zone. Therefore, the main task of tribology for the technology of the North is the study of friction units of machines and mechanisms operated in cold conditions. The low climatic temperatures effect on the wear processes of materials of friction units, including wear-resistant powder coatings is also a task. We carried out the wear tests of modified powder coatings, profilometric and thermophysical measurements of friction surfaces on a special low-temperature stand during winter in Yakutsk (below –40 °С, December 2020, January and December 2021). We have revealed the regularities of establishing the operating temperature of the friction unit «powder coating–steel counterbody» in the cold. We have also obtained the data of mass wear of coatings and steel counterbodies, roughness parameters of contact surfaces during their sliding friction at low climatic temperatures.

Increasing the reliability and durability of sealing devices operating in cold climates mainly depends on the quality of the sealing material. Rubbers are the most common materials for sealing devices due to their high elasticity, which manifests itself in a wide temperature range, good damping ability and other important properties. As a rule, rubber seals work in contact with working hydrocarbon media, which leads to a sharp change in their composition and properties. The aim of the work was to study the combined effect of hydrocarbon media and ambient temperatures on the properties of butadiene-nitrile rubbers. Samples of commercially available rubber 98-1 and rubber RP-5, obtained under RF patent No. 2719809, were kept in hydrocarbon media (industrial hydraulic oil grade I-20A and all-season universal semi-synthetic motor oil Gazpromneft Diesel Premium 10W-40), where the main factor was the ambient temperature. We determined their resistance to hydrocarbon environments by changing characteristic indicators. The exposure of the samples was carried out in January 2022 under the following conditions: under the constant influence of ambient temperature at the climatic test site located in Yakutsk; indoors at a temperature of 20–23 °C and with a cyclic change in temperature in order to simulate the operation of seals in the units of equipment operated in the Far North in garage storage conditions. It has been established that the greatest change in indicators occurs at indoors temperature and under conditions of cyclic temperature changes. The change is associated with intense diffusion processes when rubber comes into contact with hydrocarbon media. At low-temperature exposure, the change in properties is minimal. The RP-5 rubber showed a higher level of preservation of the main indicators compared to the mass-produced rubber 98-1.