Volume 522, Nº 1 (2025)

The series of pits describes lake deposits on the southeastern edge of the Chui basin (Gorny Altai). For the first time, we made four OSL dating as 22 thousand years. It clearly showed the age of the last ice-dammed lake lake of the Chui basin. We conclude that the age of the glaciers blocking the exit from the basin corresponds to the last glacial maximum of the Upper Pleistocene.

The paper presents isotopic U–Pb zircon data (LA-ICP-MS method) on the intrusive rocks from the Aktau and Koitash massifs, which the Lyangar and Koitash tungsten-molybdenum skarn deposits are spatially and genetically associated with. These deposits, together with the other W and Au deposits (Muruntau, Zarmitan, etc.), are part of the largest Au (Au–W) metallogenic belt of Tien Shan. The deposits are represented by zones of hydrothermally-altered skarn with scheelite and molybdenite, and later (overprinting) near- and within-intrusive stockworks of veins and veinlets of late metasomatites (propylitic and phyllic alteration) with scheelite-gold mineralization. The concordant isotopic zircon U–Pb data (269.3±2.4 Ma for quartz diorite of the Aktau massif, 268.9±1.9 Ma for granite of the Aktau massif, 278.6±2.7 Ma for granodiorite of the Koitash massif, 276.4±3.6 Ma and 270.0±2.3 Ma for granites of the Koitash massif) were obtained. A greater scatter of the isotopic U–Pb dates was obtained for granodiorite of the Aktau massif, with the two maxima decoupled, 269.1±2.8 Ma and 278.4±3.4 Ma, corresponding to zircon “autocrysts” and “antecrysts”, respectively. All this indicates essentially younger age of the intrusive rocks studied, compared to the rocks of the other tungsten and gold deposits of the Tien Shan that corresponds to the late (Early-Middle Permian) stage of the Late Carboniferous-Permian epoch of formation of these deposits, which occurred under the conditions of a mature post-collisional development of the region. The data obtained highlight the long-lasting emplacement and crystallization of the intrusive massifs studied that occurred under periodic replenishment of magmatic chambers and resulted in a protracted magmatic differentiation, with the fluid and metal accumulation in residual melts.

Isotope effects accompanying decarbonation process during the redox interaction of carbonate with metallic Fe and Ni at high PT parameters (1200°C, 6.3 GPa) were assessed. Under these conditions, carbonate decomposition proceeds with the formation of reduced carbon (ΣC: graphite, carbides, carbon dissolved in metal) and metal oxides (wustite, Mg-wustite). The isotope effect calculated using the models of batch and Rayleigh decarbonation for carbon isotopes in the ΣC-carbonate system ranged from 1.2 to 0.5‰, for oxygen isotopes in the Mg-wustite-carbonate system from 1.1 to 0.46‰. The obtained estimates show that during redox-induced decarbonation, isotopic shifts of oxygen and carbon in the residual carbonate are directed towards its enrichment in heavy isotopes ¹⁸O and ¹³C. This direction of the isotopic shift is opposite in sign to the isotopic effects that arise during decarbonation with the separation of CO₂ at low pressures.

The paper presents the results of studying the chemical composition of “depleted” garnets from lherzolite xenoliths of the highly diamondiferous Mir and V. Grib kimberlite pipes. Garnets from the Mir pipe xenoliths are distinguished by their rather large sizes, up to 15 mm; the shape of the grains is often complicated by hooked and elongated formations. Garnets from the V. Grib pipe have a more rounded shape and range in size from 1 to 4 mm. Based on the content of CaO and Cr₂O₃, the garnets belong to the lherzolite paragenesis. Garnets from the studied xenoliths have low contents of incompatible elements and have fractionated REE distributions with a sharp decrease from heavy to light. The LREE concentrations are 10 or more times lower than in the composition of chondrite. Variations in Y and Zr contents form a trend from “depleted” peridotites to “metasomatized” lherzolites, which can be observed both within a single xenolith and within a single grain. While metasomatized garnets show an increase in Y and Zr contents from the cneter to the edge, in depleted garnets the peripheral regions of garnet grains are depleted in Y, Zr, Ti and LREE, in contrast to their central parts. These features of the chemical composition and morphology of garnets indicate their restite origin as a result of partial melting. For the first time, it has been shown that restitic lherzolites have been preserved in the upper horizons of the lithospheric mantle, the garnets in which have not been subjected to metasomatic changes.

The first occurrence of glendonite (calcite pseudomorph after cold-water mineral ikaite) was described from the Aptian Stage (Tanopcha Formation) of Western Siberia. The review of Aptian-Albian glendonite record in other regions of the world is provided, and the significance of these occurrences for clarifying the climate of the terminal part of the Early Cretaceous is discussed. Aptian glendonites from the North-East of Russia are figured.

The U–Pb dating of carbonate rocks using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has enabled precise age determinations of vein calcite, which has found wide application in tectonic studies to obtain the age of displacements along faults and the corresponding stress fields. The aim of the study is to apply this approach to the fold-and-thrust structures of the southern part of the Verkhoyansk fold-thrust belt (VFTB) in the Belaya River basin within the Gornostakh Anticline. Based on structural analysis and paleostress reconstruction, three stages of deformations with approximately E-W compression, WNW-ESE extension with a dextral strike-slip component, and a sinistral strike-slip faulting correspondently were identified the first time. For the first time for the South Verkhoyansk sector, U–Pb dating of the calcite vein established the age of the extension stage at about 63 Ma, which turns out to be younger than the compression stages documented in the same region (~160–70 Ma).

At present, the bending of the lithosphere is studied on the basis of Kirchhoffʼs (1845) thin plate bending equations. However, they give an error of ~15% in the bending of thick blocks, when the thickness to length ratio is h/L = 1/4. More accurate equations of bending of thick plates by Timoshenko (1922) and Reisner (1945) are used in engineering. But even they still contain inaccuracy, because they do not take into account transverse compression in bending. The authors have obtained new more accurate equations of bending of thick plates of the second approximation, taking into account all deformations at bending, which makes them, unlike the Timoshenko–Reisner equations, mathematically completely correct. By refining the Timoshenko and Reisner equations, the new second approximation equations are not complicated, since only the numerical coefficient in the ordinary differential equation for the bending function is changed and explicit additive terms in the algebraic expressions for longitudinal stress and longitudinal and transverse displacements are added. Compared to the more complex general partial elasticity equations, the resulting bending equations neglect only small fourth-order terms (h/L)⁴, which, even for thick plates with a thickness equal to one-quarter of the length, are only about one percent. A universal analytical solution of the new equations, which gives a more accurate stress and strain field, has been obtained as an application to oceanic plate bending.

We analyzed the nature of the relationship between the induction of the Earth's magnetic field and the speed of its rotation. We used data from mid-latitude magnetic observations at the Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences and the BEL, HAD, MMB and LYC observatories of the international INTERMAGNET network and data on the unevenness of the Earth's rotation. It is shown that the induction of the geomagnetic field increases with increasing speed of rotation of the Earth and vice versa decreases with its fall. We obtained a quantitative relationship has been between the absolute magnitude of the geomagnetic field induction vector and the LOD value equal to the difference between the observed and ephemeris day duration.

Radar images from the Sentinel-1A satellite have been used to determine the displacement field in the focal area of the January 7, 2025 earthquake in the south of the Tibetan Plateau. A rupture surface model has been constructed, revealing that the earthquake occurred along one of the branches of the rift zone – Dinggye-Xainza Rift (DXR), on a fault with a strike of 187° and a dip of 55° towards the west. The maximum displacement reaches 5.1 m, with an average of 3.5 m. The rift zone is located within a sublatitudinal extension zone, north of the Main Himalayan Thrust. Modeling of the January 7, 2025 event is of great interest as it allows for a detailed examination of the focal zone's position, its relationship with regional structures, and the comparison of instrumental and geological estimates of fault displacement rates. In particular, the findings suggest that geological estimates of extension rates along faults, as well as the seismic potential of southern Tibet rift zones, may be underestimated.

On the basis of numerical modeling and natural data, the restructuring of water circulation in the western part of the South China Sea under the influence of typhoons formed in different areas of this region is shown.

Tropopause-level jet streams are an integral part of the atmospheric general circulation and play a role in the formation of the Earth's weather and climate, and are also an object of continuous monitoring for aviation weather services of all countries. The initial and important stage of exploration jet streams includes reliable determination of their characteristics, the main ones being the latitudinal position and intensity. A simple and universal method for identifying the jet stream core in three-dimensional space containing wind data at nodes with a regular grid is proposed. The searching algorithm of wind speed maxima related to the core of the jet stream takes into account areas with a jet deviation from the west-east direction through the ratio of the zonal component of the wind speed to its absolute value. Using reanalysis fields, the position of the Northern Hemisphere jet stream cores is given at one of the synoptic hour with estimates of the intensity of individual sections of the jet. To analyze and identify differences in jet stream regimes, latitude-longitude and latitude-altitude frequency distributions were constructed for December 2010 and 2020. It is shown that three-dimensional analysis, in particular, identifying cores in highly curved sections of jet streams, allows for a more detailed determination of characteristics such as branching, merging, degree of meandering, and intensity.

The scientific basis for the quantitative assessment of climate change adaptation measures for critically and strategically important objects of socio-natural and man-made systems is formulated. A risk-based approach developed for climate change conditions is used as an assessment tool. An example is considered using the example of a strategically important object of the technosphere, the result of which indicates the importance of substantiating and improving the safety and security of objects of socio-natural and man-made systems from accidents and catastrophes under changed climatic conditions. At the same time, within the framework of a risk-based approach, it becomes mandatory to calculate the necessary costs to reduce risks to acceptable levels.

It is known from the literature that the rheological behavior of soils is largely determined by the water content in pastes and soil organic matter, which is the basis of organomineral soil gels. With an increase in soil moisture, gels can swell. As a result, the viscosity of soil pastes should change. The aim of the work was to assess the effect of soil moisture on the viscosity of soil pastes. Arable horizons of soils were used in the work: sod-podzolic, gray forest, leached chernozem and chestnut. During the experiments, soil moisture was changed, but the water content in the pastes for each type of soil remained unchanged. The viscosity of soil pastes was determined by vibrational viscometry, and the size of organomineral particles in pastes was determined by laser diffractometry. For all the studied samples, the existence of two peaks in the viscosity of pastes was found, depending on soil moisture. An explanation of viscosity peaks in pastes is proposed from the perspective of changes in the structure of humic substances in organomineral gels upon reaching critical concentrations: micelles – supramolecular formations – fractal clusters. Apparently, the transition between the structural forms of humic substances under mechanical action on pastes is accompanied by the disintegration of large gel particles and the formation of a more balanced form of existence of humic substances at a given water content.

Local anthropogenic sources of coarse aerosol (dust) in cities may cause a “dusty haze” effect in the territory adjacent to the source sites of such aerosol (construction objects, areas of reconstruction of roads and buildings), due to a sharp increase in the concentration of PM₁₀ particles in the near-surface air. The paper analyzes two such episodes recorded in the center of Moscow in the summertime of 2021 and 2024. The variability of mass concentration and particle size distribution of dust aerosols under abnormally high atmospheric pollution (PM₁₀ concentration above the maximum permissible concentration) have been studied. A comparison of the characteristics of urban construction dust and arid aerosol in the atmosphere of the desolate zones of Kalmykia showed similarities between them in the increased content of lithophilic elements (of natural origin). However, in the city, the concentrations of potentially toxic elements (heavy metals, metalloids, etc.) typical for urban dust are higher in aerosols from construction sources. The dusting of megalopolis atmosphere under the influence of intensive construction sources not only worsens visibility and creates uncomfortable conditions for population, but also creates great risks for the environment of the city and human health.