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Among fine- and medium-grained eclogites, which are predominant within the Kokchetav subduction-collision zone (Kazakhstan), metasedimentary mélange in the Sulu-Tyube area bears rare porphyroblastic eclogites, which are juxtaposed with host rocks of the Zerenda series. The assemblage of garnet cores граната (X_Alm up to 0.59, X_Prp from 0.08) with epidote–clinozoisite (X_Czo=0.36–0.90), amphibole, ilmenite, titanite and rutile, prograde garnet zonation imply nearly isothermal burial of rocks down to 11.5–20.5 kbar and 535–570°С. The growth of high-Mg garnet rims (X_Prp up to 0.31) in paragenetic relations with omphacite (X_Jd up to 0.35) stem the second stage with nearly isobaric heating up to 645°С at 21.5 kbar, which, for individual samples, reach 620–690°С. Fine- and medium-grained eclogites with uniform textures and weakly zones garnet, which contains inclusions of omphacite (X_Jd=0.20÷0.40), rutile and quartz, were formed during heating and limited pressure increase (580–660°С and 16–19 kbar). Variations of equilibrium temperatures (620–730°С) indicate their different position within the structure of subducted lithosphere. MORB-like signatures of eclogites correspond to those of low-Ti tholeitic rocks, but fine-grained rocks are depleted in Nb-Ta and Eu and enriched with Th at radiogenic Sr isotope composition Sr (⁸⁷Sr/⁸⁶Sr_I 0.71181–0.72935) and moderately depleted Nd isotopes (ε_Nd(530) +0.5÷+4.2), whereas porphyroblastic rocks, rehydrated during exhumation, reveal juvenile Nd-Sr signatures (⁸⁷Sr/⁸⁶Sr_I 0.70212–0.70426, ε_Nd(530) +6.6÷+7.2). Contrasting features of eclogites result from subduction burial of rifted margin of the Kokchetav microcontinent or more ancient continental unit, which included variably contaminated N-MORB an E-MORB basites, and involvement of oceanic or eroded Cambrian island-arc rocks into the same process. Principal differences in fluid regimes of subduction and exhumation were governed by proximity of hydrated subduction channel for porphyroblastic rocks and weak fluid permeability of continental lithosphere – for their fine- and medium-grained counterparts.

The article presents the results of the detailed modern geochemical investigation of a representative (both by area and by section) collection of core material from Permian deposits of the Anabar-Khatanga petroleum province. The organic matter of Permian deposits has been firstly shown to be polygenous within all the section and have a different thermal maturation level (stages MC11-AC). It also has exhausted oil and gas generative potential in the most part of the section. The studying deposits contain paraautochthonous and allochthonous bitumoids (chloroform source rock extracts) in addition to autochthonous (syngenetic) ones, that can be the evidence of intensively occurring migration processes. There are also bitumoids with traces of biodegradation in Early Permian deposits from the Yuzhno-Tigyanskaya and Nordvikskaya wells.

We provide a brief description of the main structures in the Eastern Arctic, in the evolution of which two major stages have been distinguished and considered: the late Paleozoic–early Mesozoic and the Late Jurassic–Early Cretaceous. We have established the syn­chro­nicity of tectonic events on the Arctic margins of Northeast Asia and Arctic Alaska and within the structures of the Amerasia Basin, indicating the existence of a cause-and-effect relation between the compression (fold-and-thrust structures) and extension (rifting and spreading in the Canada Basin). We have proposed the tectonic models of the formation of fold-and-thrust structures in Chukotka and Arctic Alaska and have determined their similarities and differences. Paleotectonic reconstructions have been performed for 160 and 120 Ma. We present a critical review of the concepts about the formation of the structures in the Amerasia Basin and provide a subduction-convection geodynamic model according to the analysis of seismic tomography of the mantle and regional geology and tectonics data. This model was previously used to describe the Cretaceous and Cenozoic evolution of the Arctic lithosphere at a qualitative level. The model is based on the idea of the existence of a two-tier subduction system: a horizontally extended convection cell in the upper mantle, coupled with a conveyor mechanism of subduction of the Pacific lithosphere. As a result, there is a convergence of the “outer” Pacific subduction zone and the “inner” subduction zone located inside the South Anyui and Angayucham oceanic basins, which provides their closure and subsequent collision. Under the influence of the reverse upper mantle flow, scattered deformations of the Amerasia lithosphere occur, caused by viscous dragging with flows beneath the lithosphere, which is the reason for the diversity of the structures in the Amerasia Basin and the Canada Basin in particular. In addition, the developed geodynamic model is supplemented by a tectonic and magmatic mechanism of crustal subsidence and the formation of sedimentary basins.

In the modern concept of forest science, forest vegetation zoning is recognized as the natural-historical basis of forestry zoning, and its purpose is to reflect the natural conditions and specific features of forests that are important for their complex multi-purpose use and increased productivity. The purpose of this article is to present the concept and map of forest vegetation zoning, created over more than 60 years by a team of researchers of the Institute of Forest Siberian Branch of the Russian Academy of Sciences. The stages of work on the map and the change of concepts and notions are noted - from a natural-territorial complex to an ecosystem and geosystem, from phytogeography and geobotany to the ecological-geographical direction in forestry. The map is based on forest fund inventory data from 1973-1990; the legend indicates the percentage of coniferous and deciduous formations (larch, pine, spruce, fir, birch, aspen, dwarf pine forests, stone birch, birch sparse forests, dwarf birch brakes and other formations) within each forest growth zone and subzone. In Siberia, as a part of the entire country, three longitudinal-climatic sectors are distinguished: West Siberian, Central Siberian and East Siberian, each with its own characteristics of forest growth zones and subzones, specific typological composition and productivity of stands. The region of the Mountains of Southern Siberia is distinguished separately, in which, according to the same criteria adopted for the plains and plateaus, 4 sectors of moisture-continentality are distinguished. The internal differentiation of this mountain region on a small scale cannot be shown on the map due to its small contours, but the principle of altitudinal zonal division is observed, published and briefly discussed. The methods and new approaches to compiling the published version of the map, which is part of the zoning map of the entire territory of the forest fund of the USSR, developed at the Institute of Forestry, are described. The published map can serve as a source of information as a starting point for monitoring the forest cover of Siberia, which has been conducted since the early 2000s on a new basis, using the state forest inventory of the country and remote sensing data. This is its historical, scientific and reference value.

For the first time, the phytopathogenic fungus Heterobasidion abietinum Niemelä & Коrhonena has been detected on coniferous trees Siberian pine ( Pinus sibirica Du Tour), Siberian fir ( Abies sibirica Ledeb.), and Siberian larch ( Larix sibirica Ledeb.) in southern Siberia, far from its previously established range. It is possible that its spread to the arboretum occurred due to the movement of planting material from European botanical gardens. Among other Heterobasidion species, H. parviporum Niemelä & Коrhonena is common in the dark coniferous forests of Siberia on Siberian spruce ( Picea obovata Ledeb.), Siberian pine and Siberian fir. In terms of phytopathogenicity and ability to colonize wood with well-developed resin ducts (especially Siberian spruce), H. abietinum is significantly inferior to H. parviporum . It has been established that the Siberian strains of H. abietinum and H. parviporum are closely related. A stable difference (with the formation of separate clades) only in the glyceraldehyde 3-phosphate dehydrogenase (GPD) gene. The vast areas of Siberian fir forests (about 13 million hectares), as well as regular outbreaks of mass insect infestations: (Siberian moth ( Dendrolimus sibiricus Tschetverikov), four-eyed fir bark beetle ( Polygraphus proximus Blandford), which lead to mass weakening and drying of Siberian fir, provide optimal conditions for the development of the low-pathogenic species H. abietinum . Forests that are not subjected to various types of stress are resistant to H. abietinum . Areas of forest dieback as a result of the phytopathogenic effect of H. abietinum has been established only in the conditions of an arboretum on soils after long-term agricultural use. Global climate change, accompanied by an increase in extreme weather events (droughts, storm winds, etc.), as well as an increase in anthropogenic impact (various types of logging and industrial pollution), creates conditions for a further increase in the aggressiveness of root pathogens, particularly H. abietinum .

The effect of mycocompost (the bioadditive) - pine sawdust partially destructured by a wood-destroying fungus culture - on the forest grey soil microbiocoenosis (Krasnoyarsk forest-steppe) was studied. Mycocompost variant was compared with the two ones: soil without bioadditives (control) and soil with addition of intact sawdust. In the trial areas (1 m²), a layer of turf was removed, bioadditives were applied in the amount of 1 % by weight to the top soil layer (10 cm), then the cut turf was returned to its place. During the first year an increase of the total number of soil microorganisms by 5-10 times was observed in all variants of the experiment including the control that was mainly related to the products of degradation of dead turf. Microbial processing of the both sawdust and mycocompost began in the second year of the experiment and was accompanied by a temporary decrease in soil pH, changes in the structure of soil microbocoenosis, a rise in the proportion of fungi and oligotrophic microorganisms, as well increase of availably nitrogen deficiency. The analysis of the data on soil microorganism number, structure of microbocoenosis, microbial respiration and biomass, mineralization velocity of organic matter, enzymatic activity, etc. showed that during two years in the variants with mycocompost and intact sawdust microbial utilization of bioadditives occurred gradually and did not cause imbalance of biological processes in grey forest soil. The mycocompost variant exceeded the control and sawdust ones in terms of the total number of soil microorganisms and biomass on average 2-3 times, did not cause stable soil acidification and provided better preservation of the introduced culture of Trichoderma harzianum Rifai. In combination with additional nitrogen supplementation, mycocompost can be used as a biofertilizer for poor forest soils.

The studies were carried out in two types of spruce forests: moist bilberry spruce and bilberry-sphagnum spruce forests. They cover the quantitative characteristics of precipitation in summer period and moisture consumption through transpiration by tree canopy of the studied stands. In moist bilberry spruce forest, trees evaporate about 304 mm of water against an average rainfall of 237 mm. In bilberry-sphagnum spruce forest, the values are 305 and 181 mm, respectively. According to the data of the meteorological station situated close to the area where the research was conducted, the air temperature has increased and precipitation has decreased, compared to the long-term annual average data, since 2003. The average sum of air temperatures for these years is by 3.7 °С above the norm, but precipitation is by 30 mm under the norm, which indicates climate warming in the study area. The soils of green moss spruce forests of the middle taiga subzone are characterized by a favorable moisture regime for plants. The moisture reserves in the root zone of the soil are 60-200 mm, so the trees do not experience a lack of moisture. Due to the fact that transpiration is a physiological process and is regulated not only by external factors, but also by the plant organism itself, it can exceed the amount of precipitation that falls in the form of rain. Water consumption for transpiration in each type of forest also depends on the composition of the forest stand, in particular on the admixture of deciduous species. Thus, the ratio of deciduous and coniferous species in the wet blueberry spruce forest was 97 : 3, in the blueberry-sphagnum spruce forest 99 : 1.

The problem of the development of bypass filtration and static stability of waterworks in the permafrost zone continues to be relevant, especially in the current period of climate change on Earth. In conditions of western Yakutia, the main reason for the loss of filtration stability of hydraulic structures has been identified: the presence of ancient aeration zones in their base; these zones formed during the Holocene optimum and then were frozen under conditions of incomplete water saturation with the formation of ice jams and air cavities. Geophysical methods have been applied to study filtration processes. As a result, we have identified geocryological conditions favoring the development of bypass filtration processes and suggested a set of methods to detect and control them, which is an important challenge of permafrost engineering.

On August 23, 2025, Mikhail Nikolaevich Grigoriev, Deputy Director for Science at the Melnikov Permafrost Institute, Doctor of Geographical Sciences, Honored Scientist of the Republic of Sakha (Yakutia), celebrated his 70th birthday. This article presents his key scientific achievements and biographical information.