The very high ore content of carbonatites determines the relevance of ascertaining the origin of these rocks. However, to date, this problem has not had a convincing solution. The obtained evidence of the hot heterogeneous accretion of the Earth allows us to explain all the features of their formation. With such accretion at the early stage of the Earths evolution, there was a layered global magmatic ocean. The accumulation of carbon dioxide during fractionation of its largest picrite layer led to the appearance of the most common residual ultrabasic carbonatites. Its very deep fractionation and the huge volume of this layer caused a substantial accumulation of rare and rare-earth elements in carbonatite residual melts. The expansion of the products of crystallization of the magmatic ocean by the spreading substance of the lower mantle superplumes during the formation of oceanic regions led to the absence of carbonatites in these regions and to their distribution mainly on ancient platforms. Fractionation of the basic layer of the magmatic ocean led to the emergence of the most ancient residual-basic carbonatites that formed the Seligdar apatite deposits on the Aldan shield. An example of residual-frictional carbonatites formed by fractionation of the products of frictional melting of differentiates of the magmatic ocean are the carbonatites of the Mesozoic Murunsky alkaline massif. In the areas of kimberlite magmatism, small intrusions of residual kimberlite carbonatites are widespread.

Basite magmatism has been manifested repeatedly for a long time in various geodynamic structures within the eastern part of the Siberian platform. In the Late Precambrian and Middle Paleozoic, it was related to rifting processes, and in the Late Paleozoic-Early Mesozoic – to the initiation and development of trap syneclises. Differences of the geodynamic regime of magma formation are displayed in the material composition of rocks. This article presents a generalizing study of the petro-geochemical features of the tholeiitic basaltic melts formed in different geodynamic settings. The composition of initial magmas changes significantly at different stages of the development of magmatic system. Using multicomponent analysis, we reviewed the influence of fractionation processes of the basal melt, which occurred under various PT conditions, on its chemical composition. A significant change of the composition occurs during the intra-chamber differentiation of the melt in a sequence of rock strata varied from the basic magnesian to felsic alkaline rocks. In the resulting series of rocks, the content of rare elements included in the lattice of the early femic phases decreases, as well as the accumulation of almost all incompatible elements. The evolution of melts of normal alkalinity occurs with an increase in REE content and their insignificant separation. Intrusions that have undergone the stage of high-pressure fractionation in the deep transitional chamber are of particular importance. As a result of such differentiation, a peculiar group of rocks is formed in the cross section of bodies, such as monzonite-porphyries in one case and anorthosite gabbrodolerites in the other. It is established that the monzoitoid type of differentiation is characterized by accumulation of LREE, LITE and the elements of zirconium group Nb, Ta, Hf and Y. Isolation of anorthosite gabbro-dolerites in the cross-section of bodies, as well as an increase in the content of aluminum, calcium, and strontium in them, is an indication of the anorthositic tendency of magmatic melt differentiation.

Oncolites are widely distributed in the Neoproterozoic (Riphean and Vendian) deposits of Eastern Siberia. Their nature remained insufficiently substantiated by the factual material. Oncolites are also widely distributed in the Neoproterozoic sedimentary carbonate rocks of the Urinsk Uplift; they have been proved suitable for the identification of their nature. Many of these rocks (such as osagia tenuilamellata) are similar to oolites and other carbonate grains of chemogenic origin and are often difficult to distinguish without detailed studies of their nature. In the Neoproterozoic oncolites of the Urinsk Uplift, spherical and filamentous unquestionable microorganisms were found, which are presumably photosynthesizing iron bacteria, cyanobacteria and algae. They are represented by calcified cells, colonies and filamentous forms, and provide the first indication of the organogenic-sedimentary nature of the Neoproterozoic oncolites, rather than chemogenic, as accepted in some publications. The results obtained can be used to clarify the environmental conditions of sedimentation, which are associated with the prediction of potential carbonate reservoirs of oil and gas in the Neoproterozoic section of the Predpatomsk depression.

The data on the body sizes of the woolly mammoth Mammuthus primigenius (Blumenbach) of the second half of Late Pleistocene in the north of Eastern Siberia (Yakutia, Taimyr Peninsula, western Chukotka) are analyzed. The data presented in the article are based on the original data of the author who took part in the study of the morphological features of frozen remains of mummies and skeletons of mammoths found on the territory of Yakutia over the past 30 years: Churapchinsky, Maksunuokhsky, Yukagirsky mammoths; part of the skeleton of a mammoth from the Zimovye River (Bolshoy Lyakhovsky Island). The skeleton of the Tirekhtyakh mammoth was measured separately. In addition, the literature data on the body size of the woolly mammoth of the second half of Late Pleistocene in Eastern Siberia and other regions were analyzed. Previous researchers noted that the height at the withers of adult males of M. primigenius from the territory of Yakutia and the Taimyr Peninsula is close to that of the male Asian (Indian) elephant Elephas maximus L. It was concluded from this fact that the overall body size of the woolly mammoth was similar to that of the Asian elephant. It is demonstrated in this article on the basis of more representative material that, although the woolly mammoth was indeed very similar in height at the withers to modern E. maximus, at the same time, its body was on average longer, the head was larger, i.e. body proportions of these species were different. Apparently, the peculiarities of the proportions of the body of the woolly mammoth contributed to its better survival under the conditions of the Ice Age.

The results of assessing the possibility of hydrate formation in the bottomhole zone of gas wells and modeling of gas flow in wells taking into account the possible hydrate formation are presented. The obtained results are especially relevant for regions where gas production is complicated by the presence of permafrost, i.e. by low reservoir temperatures. Due to inevitable gas cooling during its production, the formation of gas hydrates is possible both in bottomhole zones and in wellbores. A reliable forecast of hydrate formation in the bottomhole zone is possible only within the framework of a non-isothermal model of real gas filtration. In the mathematical model of hydrate formation in pipes, account of the dependence of convective heat transfer coefficients and hydraulic resistance on the pipe flow area varying with time leads to an increase in the duration of complete blockage with hydrates. The influence of mineralization of various genetic types of stratum waters on the formation of natural gas hydrates in the volume and in a porous medium was studied. It was established that C₂–C₄ hydrocarbons get concentrated in the hydrate phase, which leads to an increase in the fat coefficient and the calorific value of initial gas. The thermodynamic conditions of hydrate formation in dispersed rocks are determined taking into account the salinity of stratum waters.

Technogenic impacts inevitably transform natural conditions in the areas of permafrost distribution and deep seasonal freezing. In particular, technogenic impact on cryolithozone leads to changes in surface runoff and groundwater discharge. As a result, icing appears on the roads in the sites where it was not observed previously. Morphometric parameters, the regimes of formation and thawing of the existing natural icings are also transformed. The Lena Highway stretches over 1157 km from the village of Never to Yakutsk. Only an icing-prone region of the highway from Never to Tommot was considered within the framework of this study. Remote sensing was applied as the main method of investigation. Multispectral satellite images Sentinel-2 with atmospheric correction were used. Satellite imageries were processed with a semiautomatic algorithm using QGIS 3.16 software. Icings were identified in satellite images with the help of the Normalised Difference Snow Index (NDSI). Totally, 107 icings were detected to be forming within 712 km of the road. On the basis of icing areas, the majority of roadside icings are related to the III (1000– 10000 m² ) and IV (10000–100000 m² ) categories. The major amounts of the icings are formed within the altitude range 500-900 m. In the geological respect, the majority of icings are confined to the Quaternary and Proterozoic deposits, as well as to Cretaceous intrusive rocks. It was established that the total area of icings formed on the Lena Highway on the region from Never to Tommot increased almost by a factor of 6 during the years 2018–2019 in comparison with the data related to the years 1927–1928.

A significant problem for non-explosive development of a deposit is an increase in resistance to digging when rocks and coal freeze. With an increase in the strength properties of rocks, the performance of combines may sharply decrease, especially when operating in winter.
The degree to which the physical and mechanical properties of different lithological compositions of rocks in the Elga deposit affect the productivity of KSM-2000R combine was determined through calculation. For the compression strength of rocks up to 40 MPa, which includes coals and carbonaceous siltstones, the productivity of KSM-2000R will be 1400 m³ /h. With an increase in the content of hard components in rocks from 40 to 60 MPa to 40 % (mainly siltstones), the expected decrease in productivity will be up to 1000 m³ /h, and for the content of hard rocks from 60 to 80 MPa to 33 % – 650 m³ /h. It is proposed to use a surfactant – NaCl solution for preliminary softening of the rocks. After processing these rocks with surfactants under negative temperatures down to –20 degrees, σ decreased by 30–50 %, and σ r decreased by about 50 % for all types and layers of constituent rocks, which will ensure the necessary conditions for their explosive-free development using KSM 2000R type combines.

For the first time, the volume magnetic susceptibility (VMS) was determined for technogenically polluted soils of Yakutsk formed on permafrost and functioning in the cryoarid climate of Central Yakutia. Magnetometric survey was carried out over the territory of the modern city of Yakutsk using an arbitrary observation network, and 444 measurements of soil VMS were made using a small-sized KM-7 kappameter. The values of soil VMS in Yakutsk vary significantly, with the average value equal to 163,5·10^–5 Si units. This parameter varies within the range 13,2-1220,0·10^–5 Si units, that is, almost three orders of magnitude (10³ ), which points to its high variability while the variation coefficient is V = 64 %. The average values of VMS obtained for the soils of individual streets and districts of the city vary significantly, too: from 80,3 to 314,6·10^–5 Si units, which is almost 4 times. A histogram of the VMS of soils in Yakutsk was compiled, when the entire data array was divided into 7 ranks or classes with a step equal to 50·10^{– 5} Si units. As a result, the majority of all values (84 %) fit within the range up to 250·10^–5 Si units, while only 16 % of the total number of measurements were above 250·10^–5 Si units. According to the results of the study, it was also found that the total indicator of contamination of the studied soils with heavy metals (Zc) is associated with the VMS indicator with a strong positive (r = 0,937) statistically significant (n = 8, r_st = 0,707, p = 0,95) correlation, almost approaching a linear relationship. The average VMS of the Yakutsk soils is comparable with the values determined for the industrial districts of Moscow (160–180·10^–5 Si units), Perm (183·10^–5 units Si), Mednogorsk (158·10^–5 Si units), but at the same time it is much larger than the values obtained for large industrial cities in China, such as Hangzhou and Luoyang (128·10^–5 Si units).

The new information on the outbreak of the Siberian moth population in the vicinity of Yakutsk in 2020 is presented. The outbreak occurred at the site of an extinct focus that operated in 1999–2001. The seasonal dynamics of population, the activity of entomophages and preliminary forecasts for the next year are discussed.
The June surveys showed that both even and odd pest generations developed in the outbreak locus in the same way. The average number of larvae per tree reached 126.5 specimens. The largest number of larvae (214.4 spec./tree) was recorded in the forb-lingonberry larch forest, where the larvae of older instars dominated (64 %). An increase in the number of Calliteara abietis Den.&Schiff. larvae was also observed in the locus. In July, the average number of the pest was 73.2 spec./tree with predomination of wintering caterpillars of the fourth instar of the odd generation. Siberian moth cocoons were found on larch trees since the third decade of June, while the emergence of butterflies of the new generation and oviposition were recorded since the first decade of July.
The high activity of entomophages was observed in the locus, in particular tachinid flies parasitizing on larvae (57.1 %) and egg-eating parasitic wasps (up to 77.1 %, with dominating Telenomus tetratomus Kieffer). The density of wintering larvae in the forest litter was estimated to be of medium level (55.8 spec./m² ); among them, the younger instars larvae (II–III) accounted for only 24.2 %.

The influence of different temperature conditions on the germination of seeds of 20 species of perennial herbaceous plants in Central Yakutia was studied. The seeds of 8 species of Aconitum kusnezoffii Reichb., Actaea erythrocarpa Fisch., Adonis sibirica Patrin, Anemonidium dichotomum (L.) Holub., Heracleum dissectum Ledeb., Iris laevigata Fisch. et C.A. Mey., Trollius sibiricus Schipcz., Thalictrum minus L. do not germinate in the temperature range from 5 to 35 °C; among them, there are the species of forest and meadow vegetation belonging to Ranunculaceae family. The species were divided into 2 groups according to the demand for heat at the time of germination: plant seeds starting to germinate at 5 °C, and plant seeds starting to germinate at 10 °C. The temperature range of seed germination for the studied species is wide. For the majority of steppe and meadow species, it ranges from 5 to 35 °C, while for forest and coastalwater species – from 10 to 35 °С. The ranges of optimal temperatures for seed germination are diverse. The narrowest optimum range is typical for the seeds of forest plants; in each of them, the optimum temperature regime is specific. The widest range of optimum temperatures is characteristic of the seeds of meadow Acetosa thyrsiflora – from 10 to 25 °С. For the seeds of all the studied steppe species, the optimum lies within the range of 20–25 °С, while there are two optimal temperature points for the coastal-water Rumex aquaticus: 20 and 35 °С. At low (5 °С) and high (35 °С) temperatures, the germination of the seeds of the studied species becomes difficult; the delay in germination under these conditions is a tool protecting the seeds of Yakut plants from untimely germination in late autumn before the harsh winter or in dry summer months, during the period of acute moisture deficit, which is typical for Central Yakutia.

The results of studying the abundance and spatial distribution of stray dogs over the territory of Yakutsk in 2011–2019 are presented. The distribution of dogs over the territory of two types of environment (residential multistorey area and residential 1–2-storey area) is discussed. Considerable differences in population density values are registered, depending both on area type and on census sites located in different city blocks. In multistorey areas, the density varies from 4 to 42 individuals per km² , while in 1–2-storey areas, it varies from 23 to 120 individuals/km² . These parameters depend not only on area type but also on other factors: season, availability of food sources, etc. The number of stray dogs obtained by extrapolation of the obtained results for two major types of environment (49,41 km² ) over the whole city territory (122 km² ) was about 6500 individuals in 2019. Migratory habits of stray dogs at the territory of Yakutsk were also analyzed. Residence is more characteristic of 1–2-storey areas (32 % of individuals), because in this type of environment the conditions are more favorable for stray dogs (regular feeding by local people and significant amount of local garbage dumps and suitable places for breeding), while in multistorey areas permanently migrating dogs are observed more frequently (74% of individuals).

Hemerocallis minor – is included in the Red Book of the Republic of Sakha (Yakutia), in category 2b, a species whose numbers are decreasing as a result of excessive human use. In 2019, in the vicinity of the village Zhemkon of the Khangalassky ulus of the Sakha Republic (Yakutia) on a floodplain cereal-forb meadow, next to the roadway, a new location of a species rare for Yakutia was discovered. The study was carried out according to the generally accepted research method for plant cenopopulations, on 20 sites with a size of 1 m² . The studied coenopopulation of H. minor is small, occupying about 20 m² . The total number of the population is 103 individuals, the density of growth of the species is 5.1 ind./m² . The cenopopulation is young, normal, incomplete, the age spectrum is left-sided with a maximum for virginal individuals. Self-maintenance of cenopopulation is only seed. The anthropogenic factor is the limiting aspect of the number and self-maintenance of the cenopopulation. This coenopopulation of H. minor is endangered and needs special protection measures. The creation of an introduction population can serve as a reserve fund for the restoration of the H. minor cenopopulation in the Central Yakutia.

The biological activity and toxicity of aqueous-alcoholic extracts of four species of coniferous plants in Yakutia have been studied. The biological test object was Paramecium caudatum in the stationary growth phase. The exposure time to the test object was carried out for 30 minutes and 48 hours. The extracts of larch and juniper have high biological activity and toxicity. Extracts of larch and juniper with an increase in the duration of exposure expanded the range of toxic effects. On the contrary, extracts of fir and dwarf pine, with an increase in the duration of exposure, narrowed the breadth of the toxic effect on Paramecia. The study carried out on the effect of coniferous extracts at the cellular level made it possible to characterize the degree of their safety and toxicity. It made possible to further use them for the production of biological products.

Currently, basalt-plastic composite materials are widely used in various branches of industry. As practice shows, during the operation of products made of basalt-plastic composite materials, their reliability and durability are significantly influenced by the natural and climatic conditions of the external environment. The problem of ensuring high service properties of basalt-plastic composite materials is especially clearly manifested during the operation of products in the areas with extreme climatic conditions. This determines the urgency of carrying out full-scale climatic tests of basalt-plastic composite materials under the climatic conditions of the North and the Arctic. In this work, the formation of porosity during climatic tests of basalt-plastic composite materials was investigated by means of hydrostatic weighing. It is shown that during climatic degradation of a composite material in the North, there is a significant increase in its open porosity. On the basis of the theory of Markov chains, a statistical model of the formation of porosity during climatic tests of basalt-plastic composite materials with cylindrical and planar symmetry is developed. Calculations of the porosity of the layers of a basalt-plastic composite material with uniform degradation from the outer surface were carried out. As the number of tests increases, porosity spreads to the inner layers. With a long test duration, the distribution of the porosity of the layers approaches the limiting linear or uniform laws, depending on the shape of the basalt-plastic composite material.