Studies have been made of the carbon and strontium isotope composition in carbonate sediments of the Khorbusuonka group and Kessyusa formation corresponding to the Upper Vendian in deep Khastakhskaya-930 and Burskaya-341-0 boreholes at the northeastern margin of the Siberian Platform. The maximum δ¹³С values in carbonates of the Turkut and Kessyusa formations in the Khastakhskaya-930 borehole are +7.0...+7.4 %, while the minimum ⁸⁷Sr/⁸⁶Sr ratios are as low as 0.7079. Such isotope-geochemical characteristics suggest that these formations are younger (Tommotian) or older (early Vendian) than it was supposed and allow for the possibility of alternatives to their regional correlation with the Burskaya-341-0 borehole and Olenek uplift sections. The deposition of sediments of the age considered, more intensive than in the adjacent regions, may be indicative of rift-related extension settings.

⁴⁰Ar/³⁹Ar analyses were made on maruyamaite (potassium-dominant tourmaline) from tourmaline-quartz-feldspar rocks discovered within the Kumdy-Kol microdiamond deposit (Kokchetav massif, North Kazakhstan). Turmaline yielded well-defined ⁴⁰Ar/³⁹Ar plateau age spectra whose values coincide within the error - ages of 502.3±8.0, 502.2±8.0, 506.0±8.0 Ma. These ages are much younger than the age of 530±2 Ma determined for high-pressure metamorphism by different methods. Thus, the formation of tourmaline-rich rocks of the Kumdy-Kol deposit cannot be associated with the high-pressure metamorphic events, and, therefore, testifies in favor of the low-pressure nature of maruyamaite. Based on the coincidence of age data for tourmaline crystals with different potassium contents, it can be concluded that the K/Ar system in tourmaline can be used for dating metasomatic and metamorphic processes.

The Precambrian to Cambrian strata at the southwestern margin of the Siberian Platform are ubiquitously characterized by a gradual transition from red-colored alluvial and deltaic deposits to shallow-marine carbonates, reflecting a transgressive infill of the accommodation space of the foreland basin. However, a supposed synchronicity of the Early Precambrian marine transgressive events calls for verification by geochronological and bio- and chemostratigraphic dating. The herein-presented data on small skeletal fossils, trace fossils and variations in the carbon isotope composition of carbonates from the mixed carbonate-terrigenous succession (Redkolesnaya and Ostrovnoy formations) in the southern Yenisei ridge show that the base of the Cambrian Fortunian stage is placed within the Redkolesnaya formation. Age distribution of detrital zircons in the studied succession suggests the Siberian craton to be a major source of the clastic material in the foreland basin during the development of the Redkolesnaya formation. An increase in the amount of zircons derived from "non-Siberian" sources, located at the southwestern periphery of the paleocontinent at that time, in the coeval strata of the northern part of the southern Yenisei ridge, indicates a complex morphology of the paleobasin and considerable differentiation among the sources of clastic material therein.

The physics of earthquakes was contriubuted to by the concept of proper time of the source of a strong earthquake, which is different from universal (calendar) time. The earlier idea of proper time was implicit and has been considered only in relation to the physics of aftershocks. The present paper extends the applicability of the concept of proper time, proposes a possible way of its measuring, and provides an example to illustrate the procedure for sequential ordering of earthquakes by proper time. The object of this study is a global activity of strong (M≥7) earthquakes. We consider the sequence of earthquakes as a Poisson-type random process. Comparatively weak earthquakes are used as the "underground clock", the tick of which marks the proper time. The Poisson distribution is compared with the distributions for two sequences of strong earthquakes. One of the sequences is ordered by universal time, and another - by proper time. The studies indicate the distribution of events ordered by proper time is closer to the Poisson distribution than that of events ordered by universal time. We attribute this to the non-stationarity of the geological medium, which is an immanent property of the Earth's lithosphere.

Giant aufeis fields are the indicators of water exchange processes in the permafrost zone. The study of aufeis dynamics is relevant to assessing the state of the cryosphere in a changing climate. The Anmangynda aufeis which forms upstream of the Kolyma River basin, was as large as 6.8 km² in the last century and is considered representative of the mountainous territories in the northeast Russia. In recent decades, there have been significant changes in the aufeis formation regime that require updating the understanding of the cryosphere processes. The historical observational data obtained in 1962-1990 for the Anmangynda aufeis allows using it as the present-day object of research.

The main goal of geophysical research in 2021-2022 was to study the structure of the Anmangynda aufeis and aufeis glade to determine its genesis and development processes. The main tasks were to identify the boundary between frozen and unfrozen rocks, to reveal groundwater discharge channels, and to assess the aufeis thickness distribution. There were carried out georadar survey using an antenna unit with central frequency of 250 MHz and ground-based capacitively coupled electrical resistivity tomography. It was found that by April 5, 2021, the maximum ice thickness was 4.35 m with an average value of 1.35 m, and the volume of aufeis was 3.56 million m³. By means of georadar, there were performed identification and drilling verification of the groundwater discharge channels from alluvium to aufeis surface, located in the stream beds. There is geophysical evidence of deep bedrock groundwater sources. Based on the electrical resistivity tomography data, there were identified large and locally freezing river taliks, from which the water is squeezed onto the ice surface. It is recommended to conduct further interdisciplinary research to clarify the geophysical results obtained.

An interdisciplinary research in the Late Quaternary loess-like cover deposits in the valley of the Kuytunka River (Western Transbaikalia) was aimed at reconstructing the conditions and dynamics of regional sedimentation. Particular attention is paid to assessing the information capacity of the methods involved therein: lithofacies analysis, grain-size analysis, and petromagnetic and lithochemical analyses. It is shown that the results of each method independently provide additional information on the processes of sedimentation, are not duplicated, and make it possible to obtain a full characterization of the factors and features of sedimentogenesis. It was found that the valley sedimentation was of cyclic character: warm (soil formation) periods changed to the periods of cooling-(accumulation of sandy-loamy strata); all processes occurred predominantly in semi-arid climate with slight fluctuations in humidity. The mode of the normal formation of a blanket of sedimentary material manifests itself in the structure and properties of deposits exposed on the southern slope of the valley (Kuytun-1 section). Intensive slope processes, and reworking and remixing of sediments on the gentle valley north-exposure slope by catastrophic flows (slope mudflows) and cryogenesis are reflected in the structure and properties of the deposits exposed in the Kuytun-2 section. There are shown the advantages of an integrated approach for detailing the structure of the sections, explaining the genesis of sediments, determining the most probable source areas for the sediment and modes of sediment transport, and reconstructing sedimentary environments.

The paper presents the results of an analysis of faults of different ranks near the Okhotnichya Cave in Pribaikalye, aimed at identifying their role in the formation and evolution of the cave and its adjacent areas. This was done using rank-wise structural-paragenetic analysis of faults, which forms the basis of a specialized mapping tool for fault zones. Factual evidence was obtained through several methods. The speleoinitiating fracture network was studied based on the results of the cave digital topographic survey performed using Leica DistoX 310 laser rangefinder. The therewith-generated 3D-model of the cave allowed making up a detailed plan of the passages for linking to the local geological-structural observations with mass fracture measurements and studying dip directions and strike orientations of the cave fractures. The results stated that the passages in the cave network correspond to the paragenesis of the right-lateral NNE trending strike-slip fault. Local analysis of rock fracturing within the cave made it possible to determine the type of kinematics of speleoinitiating fractures and to verify the reconstruction of the fault zone of the supra-local level. It has been stated that narrow tunnels follow the local NNE- and WNW-oriented strike-slip faults, and large chambers and grottoes follow the extension structures - ENE- and NE-striking normal faults. The lineament analysis of the cave-adjacent area revealed that the strike-slip fault network of the cave is an element of paragenesis of the regional normal fault, typical of the late-orogenic Baikal rift system. Thus, the conducted research showed that the genesis of the Okhotnichya Cave has a mixed character and provided the possibility of analyzing the karst caves' spatial patterns to reconstruct kinematic types of faults at different hierarchic levels - local, supra-local, and regional.

Fault structures in folded areas are an important element of the geological structure. Their age and history of development affect seismicity, distribution of minerals, and engineering and geological characteristics of the area. The geological structure of the Altai-Sayan folded area was mainly formed during the Paleozoic and transformed during the Cenozoic activation. Geoinformation methods and technologies were used to compare between the Paleozoic and Cenozoic fault networks. It is shown that the degree of reactivation of the Paleozoic faults varies greatly within the territory.

Conjugate analysis of the orientation and spatial distribution of faults of different ages in the study area does not confirm that the Cenozoic fault system was formed by reactivation or inherited development of the Paleozoic fault system. These two systems arose at different compression orientations. The left-lateral strike-slip ensemble was formed under sublatitudinal compression in the Paleozoic, and the right-lateral strike-slip ensemble - under submeridional compression in the Cenozoic. A significant coincidence between the directions of the main faults of different ages is due to their dominant strike along the boundaries of the accretionary complexes in the region.

The article considers the geological framework of a large orogenic structure in northeastern Eurasia - the Verkhoyansk fold-and-thrust belt (VFTB), formed in the Late Mesozoic on the eastern margin of the Siberian craton. Zoning of geopotential fields and the authors' interpretation of frequency-energetic characteristics along the 3-DV reference geo-physical profile provided the basis for modeling the deep structure of the VFTB and adjacent structures of the Siberian craton. There were identified structural zones of different geodynamic nature: the outer zone of the fold belt, underlain by the dropped margin of the craton; the inner zone of the VFTB with the oceanic crust at the base; the rear-zone structures formed by the Verkhoyansk complex in the subduction zone of the Uyandina-Yasachnaya island arc. In the Earth's crust of the VFTB there are distinguished two layers of approximately equal thickness: the lower one comprises a duplex system of complexes of the oceanic crust, and the upper one is built up by formations of the Verkhoyansk terrigenous complex, which have also undergone folding and duplexing. In parallel with thrusting of the upper terrigenous layer over the craton in the zone of collision between the VFTB structures and the Siberian craton margin there also occurred subduction of the lower layer of the VFTB under its margin. This led to an increase in thickness of the craton's crust by 5-10 km from below. The development of the Uyandina-Yasachnaya island arc system comprises two stages associated with blocking of the subduction zone and its transition towards the Oimyakon Ocean, which increased its area and complicated the structure. The paleosubduction zones and blocking structures are well-traced on the deep sections of reference seismic profiles.