The paper presents the results of a study of epigenetic changes in technogenic-redeposited coal-bearing rocks of Irkutsk and Kuznetsk coal basin spoil heaps (Russia). Hydrocarbon products formed under high-temperature and low-temperature pyrolysis of coal-bearing rocks were studied by using a chromatography-mass spectrometer GCMS-QP2010NC Plus (made by Shimadzu Company). The average temperature of low-temperature natural pyrolysis does not exceed 120 °C, and its average speed is approximately 2 m/year. In this case, three pyrolysis zones gradually built metamorphic rock mass (from bottom to top) are clearly established: heating (focal) activated and enriched. The average temperature of high-temperature pyrolysis reaches 850 °C, and its average speed is approximately 20 m/year. Unlike low-temperature pyrolysis, high-temperature pyrolysis is accompanied by the presence of two major zones (from bottom to top): pyrogenic (focal) and enriched (coke). The chemical composition of the enriched pyrolysis zone was studied in detail. It has been established that hydrocarbon compounds in samples of the pyrolysis zone are presented by six classes: asphaltic-resinous substances; polycyclic aromatic hydrocarbons, heterocyclic compounds, organic sulphur compounds; pyrolytic hydrocarbon and heavy hydrocarbon residue. Quantitative content of hydrocarbon compounds in the analyzed samples varies from 0.35% to 41.88%.

This article is devoted to the study of the Quaternary aeolian sands of the boreal zone of north Asia. Using the example of the study reference sections of the Selenga Dauria (Western Transbaikalia), it was established that the activation of aeolian processes is determined by the complex interaction of natural and anthropogenic factors. Natural factors include neotectonic movements; wide distribution of alluvial and lacustrine-alluvial deposits; a sharply continental semi-arid climate; and forest-steppe and steppe vegetation. Among the anthropogenic factors, the leading ones are deforestation, plowing of land and construction of new settlements, roads and other line structures. The obtained radiocarbon dating of buried soils and coal from ancient fire pits indicates the activation of aeolian processes during the Holocene. The main sources for aeolian transport (winnowing) are sands located in the areas of river and lake beaches, floodplains and river terraces. Almost all aeolian sands of the boreal zone were formed as a result of short-range wind transport. They form mini-deserts unfixed by vegetation, with active aeolian processes, dunes, barkhans and deflationary basins. Aeolian swells and blowout basins characterize aeolian landscapes weakly fixed by vegetation. It is noted that aeolian deposits of the boreal zone of north Asia, in contrast to similar sands of the subtropical and tropic zones, consist of coarser-grained material. Medium- and fine-grained sands dominate their composition, which is polymineral and well-sorted. In subtropical and tropical deserts, they are predominantly monomineral, fine and fine-grained. At the same time, mainly minerals that are unstable to weathering (feldspars, plagioclases, pyroxenes and amphiboles) represent the mineralogical composition of the studied aeolian sands. Weathering-resistant minerals dominate the sands of classical deserts: quartz, leucoxene, ilmenite, epidote, zircon, garnets, tourmaline, rutile and others. Modern aeolian landscapes are a unique natural formation for the boreal zone of north Asia and can be successfully used for the development of ecotourism.

Комплексный подход к лабораторным исследованиям деформационно-прочностных свойств техногенных грунтов на примере обвально-осыпных отложений карьера «Айхал» (Якутия)

This paper presents the results of a comprehensive study of a catastrophic karst-suffosion sinkhole that occurred on September 19, 2024, in the Khadakhan-Melkhituy karst massif (Southern Angara region) and resulted in a human fatality. Using UAV‑derived data, the morphometric parameters of the sinkhole were determined (depth 9.7 m, volume 412 m³), and a comparison was made with historical monitoring data from the 1980s. Laboratory tests performed on samples collected from the sinkhole walls revealed that the 9.7‑m thick cover sequence consists of structurally unstable loess‑like loams and sandy loams, with anomalously high silt content (up to 84 %) and porosity (up to 64 %). The interaction between karst and suffosion processes plays a key role in the sinkhole formation. The long‑term (57‑year) backwater effect of the Bratsk Reservoir and its cyclic level fluctuations caused leaching of sulfate‑carbonate rocks, promoting mechanical removal of silt‑sized particles from the cover sequence by percolating water. A two-stage mechanism of karst-suffosion sinkhole development was identified: from the formation of a loosening zone above an ancient karst cavity to the instantaneous (brittle) roof collapse triggered by a technogenic factor – the weight of heavy agricultural machinery. The study of the reactivation of karst‑suffosion processes in the backwater zone of the Bratsk Reservoir contributes to the understanding of modern geodynamic processes and ground surface deformation mechanisms, including those induced by technogenesis.

The results of the study of chemical, granulometric, and mineral compositions of sapropelic bottom silts from Sagan-Nur lake are presented in four cores of the layer as thick as 45 cm that overlies sandy lacustrine deposits. The silt is used as therapeutic mud (peloids). Clay minerals in sedimentary deposits are identified using X-ray diffraction analysis and scanning electron microscopy. Finely dispersed clay minerals of peloids are considered as indicators of anaerobic conditions of lithogenetic processes in the hypergenesis zone.

The results of studying the chemical, granulometric and mineral composition of a 2.8-meter sequence of sediment layers exposed on the slope of the cinder cone of the Khurai-Khobok volcano are presented. The lower age limit of sedimentary deposits is determined by the K–Ar dating of 1.57±0.3 Ma for the volcanic cone basalts, which is consistent with the reverse magnetization of the Matuyama Epoch rocks. The lower layers are represented by clayey sands, the middle layers by layered clayey sands, and the upper layers by clayey loess-like rocks. Clay minerals of the layers are identified using X-ray diffraction analysis and scanning electron microscopy. From the results obtained, a conclusion was made about the accumulation of the lower layers in mixed subaqueous and subaerial conditions, the middle ones – in subaqueous conditions, and the upper ones – in conditions of eolian transport of material. The processing of the material was carried out in the joint laboratory of modern research methods in dynamic and engineering geology of ISU and IPC SB RAS. Studies of clay minerals were carried out using a scanning electron microscope (SEM) with an EDS spectrometer at the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences. To determine the mineral composition, samples ground in an agate mortar with alcohol were studied by powder diffraction on a DRON-3.0 X-ray diffractometer. Recording conditions: radiation – СuКα, Ni – filter, V = 30 kV, I = 20 mA, scanning step – 0.05°.