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This paper presents a schematic summary of comprehensive analysis of seismic, reflection profiling, and hydroacoustic data on faults which caused sediment deformation in the central segment of the Central Baikal basin. According to the tectonophysical analysis results, the fault pattern within sediment fill has been recognized as zone-block, i.e., it represents a network of high-density fracture zones limiting weakly deformed blocks. The structure of large NE-trending fault zones (Olkhon, Beregovoy, Gydratny, and Svyatoy Nos) is controlled by main fault planes (or their segments) bounded by subsidiary faults. Geomorphic expression of NW cross faults in the sedimentary cover as broad zones of smaller-scale fractures accounts for early stages of the evolution of basement faults. In a longitudinal direction, they divide the basin into large fragments. The zone-block structure of the sedimentary strata was developed in different stress regimes: strike-slip and extension at the early and late orogenic rifting stages, respectively. At the modern stage of tectogenesis, the established network of fault zones controls the gaseous (including hydrate formation) and seismic activity expression in the subsurface. Hydrate-bearing mud volcanoes and seeps are confined to major faults, while earthquake epicenters are confined to fault zones and form clusters at junctions of large NE-trending faults with NW-oriented extension zones and E-W left-lateral strike-slip faults.

This study describes a procedure for estimating the distribution of hydrocarbon resources by fields with different amounts of reserves and by the number of pools in each field. Such estimation is important for predicting the exploration efficiency. The procedure first uses a simulation model for generating a population of hydrocarbon pool sizes. Then, the spatial distribution of pools over a petroleum basin is modeled as a nonstationary Poisson point field. When generating a field population in the basin, each field is considered a geometric object consisting of several pools according to the principle of their mutual geometric location. The proposed model was used to estimate the two-dimensional distribution of the number of fields and the amount of resources in them by the reserve sizes and by the number of pools in each field. The proposed assessment was made for oil resources in the West Siberian petroleum province.

From the viewpoint of modern knowledge, the geological structure of the Upper Jurassic-Neocomian clinoform complex, its regional seismogeological model has been constructed, and the criteria to locate oil accumulation zones (OAZ) and specific oil-promising prospects have been identified. All these factors made it possible to provide a significant increase in oil resources.

We present results of mineralogical and geochemical studies (optical and electron microscopy, probe microanalysis, and LA-ICP-MS) of accessory apatite from the rocks of four ore-bearing massifs of the Khudolaz Complex: Vostochnyi Buskun, Severnyi Buskun, Malyutka, and Tashly-Tau. Two groups of apatite are recognized by morphology and chemical composition: (1) “magmatic” unaltered apatite (Ap-1) in unaltered and slightly altered rocks and (2) “metasomatized” apatite (Ap-2) surrounded by secondary silicates that replaced primary minerals. Ap-1 is represented by euhedral and subhedral hexagonal crystals with a high content of chlorine (0.7-1.2 wt.% Cl) and an extremely low content of sulfur (<0.05 wt.% SO3). It is enriched in REE (ΣREE = 2.2-3.0 wt.%), shows a pronounced negative Eu anomaly (Eu/Eu* = 0.36-0.58), and is depleted in Co, Ni, and chalcophile trace elements (Zn, Pb, and Bi). The distribution of major and trace elements in Ap-1 made it possible to identify its two generations, early and late, in the Khudolaz Complex. The early generation, characterized by a low content of Ca ( Т ≥ 1000 °C, CaO < 54 wt.%), crystallized almost simultaneously with Ca-plagioclase (An_81-61). The late generation, characterized by a high content of Ca ( Т ≥ 700 °C, CaO > 55 wt.%), is associated with Na-plagioclase (An_28-8), amphibole, and phlogopite. Ap-2 is represented by highly cracked grains and is characterized by a low content of chlorine (0.0n-0.5 wt.% Cl) and a high content of sulfur (0.06-0.93 wt.% SO3). The content of fluorine in both groups of apatite varies in the same range (0.6-1.7 wt.% F), which determines its relative inertness during metasomatic processes. Ap-2 is less enriched in REE (ΣREE = = 1.1-2.1 wt.%) and shows a less pronounced Eu anomaly (Eu/Eu* = 0.61-0.77) but has high contents of Co, Ni, and chalcophile trace elements. The Ap-1 and Ap-2 show different variations in contents of major elements (Fe, Mg, Na, etc.), which is due to the impact of hydrothermal fluid on the mineral at the postmagmatic stage. It is shown that the low content of sulfur in apatite from unaltered rocks does not indicate a low sulfide ore potential of the Khudolaz Complex. The Cu-Ni sulfide signature of the complex is more clearly evidenced by the composition of metasomatized apatite enriched in S, Co, Ni, and chalcophile elements as a result of their hydrothermal removal from primary sulfide minerals. The high Eu/Eu* value indicates an increase in oxygen fugacity at the postmagmatic stage.

The correlation between the radon influx into the atmosphere and the formation of ions has been studied based on observations at the Fonovaya Observatory of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences. This correlation is shown to be stable in the period from October to January. In the other months, the correlation is disturbed. However, if the events of nucleation and lightning discharges are removed from the data set, then the correlation is kept throughout the year.

Density fluctuations of a clot of aerosol particles in the atmosphere are studied. A one-dimensional case is considered characteristic of the motion of particles in a narrow vertical fire column or in an aircraft trail. The effect of localization of clots is shown to be observed under certain conditions, which consists in formation of compact areas of increased density of aerosol particles surrounded by areas of low density. Knowledge of such properties of impurity density can be useful in solving inverse problems of aerosol optics.

The results of the complex study of the composition and temporal variability of urban aerosol in near-surface air in the center of Moscow during two winter seasons (2019/2020 and 2020/2021) are discussed. Daily data on PM₁₀ and PM_2.5 concentrations and the total aerosol mass concentration (by gravimetric method) and 65 chemical elements included in its composition measured for 35-40 days every season are considered. The aerosol composition is compared with the meteorological parameters in near surface air in Moscow, the direction of long-range air mass transport to the Moscow region, and the distribution of dust in near-surface air over the European Russia (according to the MERRA-2 reanalysis). The detailed study of the aerosol elemental composition in Moscow allowed us to identify the elements of global/local distribution and of natural/anthropogenic genesis. Concentrations of all aerosol components under study in Moscow in winter did not exceed the corresponding daily average MPC values for the air of residential areas. It is shown that PM₁₀ and PM_2.5 are accumulated in the near-surface air of the city in calm conditions. The maximal levels of aerosol pollution were observed in the first part of December 2020 with south-easterly winds, when long-range atmospheric transport of impurities to Moscow took place from sources located in the arid south zones of European Russia, in the Caspian Lowland and in western Kazakhstan.

The long-term temporal variability of the microstructural characteristics of aerosol in the surface air layer, measured in the monitoring mode at the aerosol station of IAO SB RAS in 2000-2020, is analyzed. Estimates are made on the basis of the concentrations of submicron ( N_f ) and coarse ( N_c ) particles and their ratio N_f / N_c . Two data arrays are considered: “full” and for the “background” aerosol weather type. The range of variations in the annual average values of the total concentration of particles N ( r > 0.2 mm) is found to be 8-50 cm^-3, and for background situations, 5-30 cm^-3. No reliable long-term trends in the characteristics under study are revealed. Spectral analysis of the monthly average concentrations for the “background” array shows the presence of a significant (with a probability of 0,95) time period of about a year for N_f / N_c and N_f and its absence for N_c .

The journal "Earth Cryosphere" is the only scientific journal in Russia aimed at comprehensive coverage of the entire spectrum of problems of Earth cryology. Currently, articles submitted to the editorial board are divided into 23 headings, reflecting the achievements of numerous scientific disciplines studying the cryosphere (geology, geography, biology, soil science, mathematics, physics, chemistry, etc.). Since 2014, an English version of the journal called "Earth’s Cryosphere" has been published in electronic form. For 25 years, the journal has published more than a thousand articles sent from 180 organizations. The journal currently has a high rating among Russian periodicals of the geological and geographical direction.

The problem of sustainable economic development is acutely manifested in the Arctic regions, which is due to the vulnerability of the Arctic infrastructure to climate change and landscape transformations. The reasons for deformations of buildings and structures in the Russian Arctic are considered. The problems and prospects for the development of the permafrost monitoring network are identified as the basis for the development of technical solutions for adapting the Arctic infrastructure to climate change. The analysis of technological solutions for control and ensuring the reliability of the bearing capacity of foundations by methods of regulating the state of permafrost soils is presented, a preliminary analysis of the economic efficiency of protective measures is carried out, the cost of which is at least an order of magnitude less than the expected damage to infrastructure by the middle of the century.