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We report results of geostructural, mineralogical, petrographic, geochemical and geochronological (⁴⁰Ar/³⁹Ar) investigations of ophiolites from the northern and southeastern fragments of the Tatarka-Ishimba suture zone of the Yenisei Ridge combined into the Rybnaya-Panimba belt. The ophiolites consist of massive and pillow-lava metabasalt, massive and layered metagabbro and metadolerite, and represent fragments of the upper part of the oceanic crust. They formed in a mid-ocean ridge or marginal sea setting from depleted mantle sources corresponding to components of the N-MORB and E-MORB geochemical types. We propose a model for the tectonic history of emplacement of the ophiolites in the Meso-Neoproterozoic time. At the Meso-Neoproterozoic boundary (Stenian-Tonian), 1051-916 Ma, a thrust system was formed and the oceanic crust fragments (ophiolites) were accreted to the passive margin of the Central Angara terrane (microcontinent). The subsequent convergence and collision of this microcontinent with the Siberian Craton (786-749 Ma) caused the formation of strike-slip/thrust deformation in the rocks of the Tatarka-Ishimba suture zone including the ophiolites. In the Cryogenian time (708-700 Ma), strike-slip and reverse fault deformations occurred in these rocks due to a new episode of tectonic activity caused by the transition between convergent settings - end of the collision and start of the active continental margin.

We analyzed composition of monzonite-syenite intrusive rocks within the Bilikan-Khulamri magmatic zone of the central segment of the Yana-Kolyma Orogenic Belt. These rocks compose small intrusions cutting terrigenous strata of the Inyali-Debin turbidite terrane. The monzonitoids under consideration contain moderate amount of silica and Al₂O₃, relatively high contents of K₂O, Na₂O, MgO; by chemical composition they are similar to latite and very close to alkaline-salic intrusive rocks of the Aldan Igneous Province. Concentrations of major and rare elements indicate that these rocks belong to granitoids of convergent continental margins, including syncollisional and those of volcanic arcs. According to U-Pb dating (SIMS), the age of zircon from quartz syenite is 84.0 Ma. It corresponds to the secondary pulse of magmatic activity of the Okhotsk-Chukotka Volcanic Belt. The specific chemical composition of the monzonitoids close to the shoshonite-latite series is due to their location deep in the back arc of the volcanic belt, at more than 200 km from its axial zone, on the sialic bedrock composed by turbidite terrigenous complexes.

This paper deals with new geological, mineralogical, isotopic-geochemical (major, trace, and rare earth elements, Sm-Nd isotopic data) characteristics of the unique Kalevian (1926-1923 Ma) komatiite-tholeiitic magmatic manifestation for the first time identified in the supracrustal Kaskama Formation from the Inari terrane of the Kola-Norwegian region Fennoscandian Shield. In the massive and porphyritic komatiites, the primary (magmatic) mineral paragenesis represented by olivine 20-40%, orthopyroxene up to 5%, hornblende up to 10%, clinopyroxene 20-40% and plagioclase 20-30% was identified. Liquidus temperatures for olivine and pyroxenes calculated in the COMAGMAT3.73 software suite are in the range of ~ 1500-1200 °C. The komatiites of the Kaskama Formation belong to the Al-nondepleted type and are characterized by low REE _N content (1-2 relative to C1 chondrite), a total concentration ∑REE_avr = 0.15-0.36 ppm, and an unfractionated distribution of REEs, which is a consequence of the generation and evolution of their primary melts outside the field of thermodynamic conditions of garnet stability. The Zr-Y-Nb and Sm-Nd isotopic systematics of the rocks of the komatiite-tholeiitic association indicates the origin of their high-temperature primary melts from a plume source in depleted mantle (ε_Nd( T ) = +3.2 ± 0.3), which is different from the mantle sources of the Jatulian-Ludicovian picrite-komatiite association of the Central Lapland greenstone belt of Finland and the Pechenga intracratonic structure. Considering the amphibolite facies metamorphic conditions of the Kaskama Formation, it can be assumed that the komatiite-tholeiitic association is a deeply eroded (at least 10 km) section of a supracrustal volcan.

The purpose of this study is to substantiate the existence and prevalence of the phenomenon of dynamic equilibrium in the development of morphological patterns of permafrost landscapes, the related regularities, and the possibilities of their application for forecasting and analyzing processes. The state of dynamic equilibrium in the development of morphological patterns is quite common for certain permafrost landscapes, such as abrasion and thermo-erosional shores, thermokarst plains with fluvial erosion, and floodplains. It is characterized by a combination of constant changes in the elements of the morphological pattern with the constancy of its characteristics (first of all, quantitative) for the landscape as a whole. A promising way to substantiate the existence of dynamic equilibrium of the morphological pattern of a given landscape is to analyze its mathematical model. It is argued that the state of dynamic equilibrium is reflected in a number of specific statistical characteristics. Thus, for thermokarst plains with fluvial erosion, a consistent statistical (integral-exponential) distribution of thermokarst lake areas and a correlation between the average area of thermokarst lakes and the average area of alas depressions (khasyreys) are observed. The obtained information on the state of dynamic equilibrium can be used for planning landscape monitoring, as well as for determining the quantitative parameters of dynamic landscape processes on the basis of the analysis of the quantitative characteristics of its morphological pattern without stationary observations.

An increase in air temperature entails an increase in soil temperature, which is dangerous for buildings and structures constructed with the foundation soils preserved in a frozen state. One of the most common methods of maintaining the frozen state of foundation soils is the construction of a ventilated basement. This system cools the soil by circulating cold atmospheric air. However, with the rise in the mean monthly temperature, the efficiency of the ventilated basement decreases. In a number of regions, the construction of buildings with a ventilated basement without additional measures to cool the foundation soils is already insufficient and may lead to the instability of buildings during their operation. In this paper, analytical calculations are carried out to determine the critical year for the loss of efficiency of ventilated basements according to data from weather stations in the north of European Russia and Western Siberia, as well as in the Central and Eastern Siberia. These calculations are based on representative values of the maximum soil temperature at the base of the pier foundation at the edge of the building with ventilated basement for the beginning of operation in 2025, 2075, and 2125.

The article discusses issues related to the stability of bases and foundations of buildings in the town of Tiksi, Bulunsky district, Sakha Republic (Yakutia). In August 2023 and July 2024, the authors conducted a complete visual survey and selective instrumental inspection of foundations of buildings and measured temperatures in operating thermometric boreholes in Tiksi; scientific and technical literature on research conducted in Tiksi and its environs was analyzed. This study made it possible to identify the main factors currently affecting the stability of foundations: improper maintenance and leaks of utility networks, excessive snow accumulation, and snow drift. In addition to the development of taliks in the bases of buildings and temporary structures, these factors lead to cryogenic weathering of concrete foundation structures.

The problem of railway operation in permafrost areas is associated with the degradation of permafrost at the subgrade base. A concept of the combined thermal stabilization of the subgrade base soils through their rapid cooling with liquid nitrogen with long-term maintenance of subzero temperatures using a vapor-liquid seasonal cooling device is suggested for the conditions that require immediate response to eliminate possible frost heaving. The results of a large-scale laboratory experiment allowing us to compare the efficiency of the combined thermal stabilization device with the widely used vapor-liquid seasonal cooling devices are presented. The experiment provided qualitative and quantitative empirical data for further substantiation and verification of analytical or numerical methods of thermal stabilization calculations in the chosen direction. Additionally, heat losses during the operation of the combined device in the rapid cooling mode with liquid nitrogen have been estimated.

This study presents a comprehensive analysis of regional climate dynamics - specifically, solid precipitation - and its impact on mountain geosystems in the Kuznetsk Alatau. The research integrates long-term field observations with ERA5-Land reanalysis data, focusing on snowpack measurements across the Kanym Highlands (2011-2025). We detail the spatial distribution, parameters, and temporal variability of snow cover, including avalanche hazards and maximum snow redistribution volumes. Additionally, we provide new UAV-based monitoring results (2024) for the Iyus-Tersa glacier group, alongside a detailed assessment of six major glaciers’ retreat since the 1980s. The surface temperatures in the different landscapes (900-1500 m a.s.l.) were investigated. The well-documented snowpack dynamics of the Kanym Highlands and Iyus-Tersa glaciers enable a comparative analysis, shedding light on local geosystem responses to climate warming and associated physiographic changes. Our validation shows that while ERA5-Land reliably estimates ten-day mean snow depth at the foothills, it underestimates snowpack thickness in high-altitude cryosphere zones, underscoring the critical role of in situ measurements.

A key feature of the upper part of geological sections in the Arctic is the presence of permafrost, with which a number of cryogenic phenomena - thermokarst, frost mounds, gas-emission craters, etc. - are associated. These phenomena represent significant geohazards potentially causing large-scale negative consequences in the context of the actively developing oil and gas infrastructure. of the region. In this paper, some results from the interpretation of high-density shallow (up to 500 m) transient electromagnetic method data obtained in the eastern part of the Yamal Peninsula to identify fluid migration channels, which may be associated with the formation of frost mounds. It has been established that the distribution of frost mounds in the study area correlates with anomalies in polarizability and electrical resistivity. The layer of rocks, above which pingo-like landforms are found, is associated with the manifestation of inductively induced polarization likely characteristic of sediments with the low ice content, In the underlying strata, anomalies of reduced resistivity are noted, which may be associated with fluid migration channels and accumulations of gaseous hydrocarbons in the permafrost.

This article presents the results of a GPR study at groundwater discharge sites located in the Makhatta and Kysyl-Syr tukulans (Republic of Sakha (Yakutia)). GPR profiles were obtained using 50 and 150 MHz antenna systems, characterizing the structure of sandy sediments and the boundaries of suprapermafrost subaerial taliks. In the southeastern margin of the Makhatta Tukulan, groundwater boundaries with a depth of 4.5-10 m in different lithological conditions were identified. In the Kysyl-Syr Tukulan, watered horizons with a width of 550 m and a depth of 13-32 m forming complex channels of groundwater migration and discharge were detected.