Consideration of the main stratigraphic and paleogeographic features of the Lower Dulgalakhian deposits of the Capitanian stage of the Permian system of Yakutia is accompanied by a structural-facial zoning scheme and a lithofacial map. The Early Dulgalakhian time is characterized by the last major transgression in the Permian history and the wide distribution of marine sediments in the continental part of Angaraland. At the same time, a wide range of sediments of the Verkhoyansk terrigenous complex accumulated in the territory of Yakutia, having a distinct zonality from the accumulative plains of the continent to the areas of accumulation of silts from the outer shelf. The Verkhoyansk-Cisokhotsk and Kolyma-Omolonsk water areas were probably delimited by the length of the Moma-Selennyakh land. The presence of bioherms in the Barajy subzone suggests a significant warming in the Early Dulgalakhian time, and the fact that the formation of aleuropelitic sediments of the Mol Formation and its analogs occurred at insignificant depths of the sea, but away from the frontal deltas of large rivers that were sources of terrigenous material. A common factor in the occurrence of the Dulgalakhian (Gizhigian) diamictites of the Verkhoyansk and Cisokhotsk regions was a sharp rise in the level of the world ocean (Early Dulgalakhian transgression), associated with the significant climate warming. However, the nature of the formation of the diamictites in some parts of the Verkhoyansk-Cisokhotsk water area was associated with different processes: volcanism, transfer of detrital material of coastal beaches by sea ice, movement of diamictites by mudflows and landslides.

Detailed scientific enquiry and description of remains of the Neoproterozoic microworld of Siberia with biologic interpretation and systematic identification are very actual, they are important for development of evolutional biology. In the Byukskaya suite of the Vendian (Ediacaran) of the Southern Siberian platform, well preserved microfossils are found in silicified columnar stromatolite for the first time. They are interpreted as microscopic fronds of lower nonseptate aquatic fungi, incrusted with calcium-siliceous and calcium-phosphate material. The fronds are composed of abundant very thin thread-like hyphae, densely interlaced with each other. They occur in algal (Chlorophyta) medium.

The appearance of the late Pleistocene landscapes of the Northern Hemisphere is still a debated issue. The existing reconstructions of the Late Pleistocene plant cover of Yakutia, which are based on the treelessness of vast territories, rather contradictoryly explain the variegated composition of the faunistic complex, where forest species of animals occupied quite noticeable positions, as well as paleobotanical finds of larches, made to the north of their modern range. Most likely, Dahurian larch in the Late Pleistocene was more widespread than it is now, which is explained by its adaptation to the long-term permafrost and frequent fires. Based on the late Pleistocene finds of pollen and macroscopic remains of larch and tree-like birch trees in the north of Yakutia, we assume a rather wide participation of forest communities in the composition of the vegetation cover. A steady analysis of the fauna allows to draw a conclusion about the savanna appearance of Late Pleistocene landscapes. At the same time, pasture grazing of large and giant representatives of the mammoth fauna made it possible to support the wide distribution of meadow phytocenoses, often a post-pyrogenic search. Post-pyrogenic succession processes in the Late Pleistocene and at present are quite similar, with one exception. Now there is no zoogenic stabilization in the process of reforestation at the stage of development of grassy formations, which in the late Pleistocene led to the widest development of meadow phytocenoses. In the Holocene, the vegetation of Yakutia acquired a modern taiga shape, with which enrichment of the fauna with strictly forest species (squirrels, chipmunks, flying squirrels) is connected. The deep transformation of the vegetation cover of Yakutia occurred at the border of the Holocene and Pleistocene, which led to the gradual extinction of representatives of the mammoth fauna as the area of pastures decreased.

The Siberian platform is known for numerous placers of platinum-group minerals (PGM), covering vast areas in river basins of Vilyui, Lena, Aldan, Anabar, and Olenek. However, bedrock sources for the deposits are still unknown. These placers have different mineralogical-geochemical characteristics, which is due to their varying PGM associations and specific typochemical features of the minerals. It is obvious that these Pt placers of large areal extent are associated with different productive platiniferous primary rocks forming within large igneous provinces (LIPs) of mafic-ultramafic formations. In an attempt to determine likely parent rocks for the placers we compared their mineralogical-geochemical compositions with those of basic-ultrabasic rock complexes. Correlation was also made between the Re-Os and ¹⁹⁰Pt–⁴He ages of minerals of the Ir-Os-Ru composition, ferroan platinum, isoferroplatinum, and sperrylite from the placers and times of major magmatic events that occurred in the Siberian platform. The results obtained suggest that the sources for the studied Pt placers might be buried mafic-ultramafic rocks which are manifestations of major Precambrian magmatic events occurred 1900, 1865, 1750, 1700, 1640, 1500, 1350, 1258, 725 million years ago. The Phanerozoic productive Pt deposits were formed in relation to Riphean and Middle Paleozoic rift, a Paleozoic-Mesozoic episode of the manifestation of the Siberian mantle plume in the form of giant eruptions of basic and alkali-ultrabasic magmatic rocks as well as active Mesozoic tectonomagmatic transformations in the southern margin of the Siberian platform.

The article deals with specificity of compositions of Cretaceous granitoids of South-Eastern spurs of the Polousnyi range, localized in the zone of joint (articulation) of the Polousnyi, Selennyakh and Tuostakh anticlinoriums, characterized by a wide development of long-lived tectonic disorders. It is shown that in the Cretaceous time this territory was a scene of intensive manifestation of granitoid magmatism – supersubduction of early orogenic M-type, late orogenic active continental margin of I-type, post-orogenic or riftogenic A-type. It is established that all granitoids are geochemically specialized in As and Ag, and in the majority also in Au, and conditions of their crystallization were favorable for formation of gold-rare-metal and/or silver-arsenic mineralization. Generality of the geochemical specialization of granitoids, high concentrations of Th, U, HREE, Cr, V and Co in them indicate the presence of an external (deep) source constantly acting here in the Cretaceous era, contributing to the provision of further heat and fluids, in all probability, associated with the rise of alkaline-basic diapirs.

Specificity of features and characteristics of soils from two forest international ecological monitoring network stations located within the Central Yakutia plain were studied. The studied areas differ in moisture and genesis of parent materials. The Spasskaya Pad station is located in the area with a moderately warm, arid climate with a sum of active temperatures of 1400–1500 °C and a humidification module <0.20 according to D.I. Shashko. The Elgeeii station is located in the area with the moderately warm but slightly arid climate with the humidification module of 0.20–0.30. The parent materials of the Spasskaya Pad station are represented by sandy-loamy carbonate deposits. Whereas in the Elgeeii station, the eluvial-deluvial loamy carbonate deposits on bedrock play a role of the parent material. It has been revealed that under the low-productive larch forests (bonitet V–Va) of the Spasskaya Pad station permafrost sod-pale solodic coarsehumused soils with a structure of a profile O-AYaoe-BPLhi-BPLcr-BCAg,cr are dominant. The sod-pale typical soils with the profile O1/O3-AY-BPL-BCA-BCca have developed under the medium-productive larch forests (bonitet III–IV) of the Elgeeii station. Differences in composition of granulometric fractions and absorbed bases as well as some parameters of a humus state of the soils were revealed. The present studies confirm a previously proposed need to identify a type of sod-pale soils in the Classification of Soils of Russia, which are characterized by pH values in a weakly acidic range in upper horizons and alkaline in the lower horizons; a low humus content in the mineral horizons and a high proportion of weakly decomposed organic matter in the organogenic ones, with a sequence of the horizons: AY-BPL-BCA-Cca.

We studied natural pyrological properties of the main forest types in Central Yakutia. The forests of this region have a common high fire danger due to a sharply continental climate and absolute prevalence of light coniferous forests (larch and pine) of a cowberry group. The fire danger of forests depends on the amount and types of vegetable flammable materials. The main conductors of burning in larch forests are dense litter and dry mosses, in pine forests – loose litter and lichens. Regional fire danger scales are plotted according to the types of larch and pine forests. The lichen pine forests and lichen larch forests burn well. They reach maturity fire within 2–3 days after rainfall. We also studied the dynamics of post-fire communities in the forests of Central Yakutia. It is established that significant changes in the vegetation, occurring after the fires, stabilized during successional time as the vegetation overgrew the burnt area. The time changes occur in the direction of formation of the native forest type – the cranberry larch forest.

The paper provides information on the population and fauna of birds of the least studied in this respect territory mountains of the eastern part of Southern Siberia. According to the results of modern information and literary sources, 193 species of birds were recorded in the territory of the Aldan Upland, of which 166 species were recorded as nesting species, the remaining species were encountered during the migration, it should be noted that during the study, random bird encounters were recorded, which were transferred to the list as migratory. As a result of research, the current composition of avifauna of the surveyed region is increased by 14 species, and nesting – by 19 species. During the research in the territory of the Aldan Upland, five new bird species were discovered (Pale-legged Leaf-warbler, Radde’s Warbler, Asian Brown Flycatcher, Grey-streaked Flycatcher, Barn Swallow). Probably, new information on the findings of these species of birds for the study area is due to the insufficient knowledge of the territory of the Aldan Upland in the past. The following rare species of birds are listed in the Red Data Book of the Russian Federation: Black Stork, Siberian Crane, Hooded Crane, Golden Eagle, Osprey, Peregrine Falcone, White-tailed Sea-eagle, Siberian Grouse, Far Eastern Curlew, Eurasian Eagle-owl and Great Grey Shrike.

The species composition and structure of algae of reservoirs of the Endybal river basin are studied. The research results revealed 81 taxa of algae from 5 divisions. In the studied reservoirs, 5 species new to the reservoirs of Yakutia were found: Bicoeca borealis Hill., Epipyxis deformans Aver., Pinnularia divergens var. elliptica (Grun.) Cl., Eunotia robusta var. tetraedon (Ehr.), Pediastrum brauni Wartmann, Cosmoastrum fristichum (Elfv.) Pal.-Mordv. The species of the Chrysophyta – Hydrurus foetidus; Cyanophyta – Oscillatoria geminata, Stigonema mamillosum, St. ocellatum and Siphononema polonicum; Xanthophyta – Tribonema viridis; Chlorophyta – Ulothrix zonata and Bacillariophyta – Tabellaria flocculosa, Hannaea arcus, Meridion circulare, Achnanthes lanceolata, Cyclotella bodanica, Cymbella cistula, Gomphonema angustatum, Hantzschia amphioxys, etc. dominate in the numbers and biomass. In eco-geographical characteristics, there were present in all the studied water bodies freshwater, benthonic-planktonic, rheophylic and widespread species developing mainly in the interior, phytoperiphyton and benthos of cold flowing water and springs. Among them, the typical cryophilic species of the water column Cyclotella bodanica, Hannaea arcus, Meridion circulare, Hydrurus foetidus take the leading position in the phytoplankton. Along with the freshwater species, there were identified the freshwater-brackish and brackish-water species of the genera Cymbella and Epithemia. The Pantle-Buck saprobity index (S) at different sites was 1,0–1,45. The water in the reservoirs can be attributed to the II class of purity

The article presents results of studies of initial breeding material of agricultural crops in the Yakut Scientific Research Institute of agriculture for 2015–2017 for creation of new varieties adapted to soil and climatic conditions of Central Yakutia. The studies were conducted in the climatic conditions of two major agricultural landscapes: Lena in floodplain areas of the middle course of the Lena River for potatoes, grain, forage and berry crops; the Churapchinsky agrolandscape of the Lena-Amga interfluve in an alas ecosystem with perennial grasses. There were studied a total of 484 variety samples of potatoes, grain (soft spring wheat, spring barley and winter rye), forage crops (peas, siberian wildrye, thin-flowered alkali grass, short-awned barley), black currant from the world collection of the N.I. Vavilov Research Institute of Plant Industry (VIR), hybrids and varieties of local breeding and other scientific institutions, local wild specimens. As a result of the study of the initial breeding material of agricultural crops, sources of economically valuable characteristics and properties are selected for the breeding in Yakutia: for the 17 – potato variety samples, spring wheat – 8, spring barley – 7, winter rye – 7, black currant – 22, peas – 5, siberian wildrye – 2, thin-flowered alkali grass – 2, short-awned barley – 3.

The main pipelines in permafrost areas are exposed to various exogenous processes, for example, frost heaving. In the work, values of frost heaving of various types are shown by mathematical modeling. Numerical realization of the problem of heat and moisture transfer process is carried out by a scheme with directed differences considering the sign of the speed of groundwater infiltration. For the computational experiment, initial parameters for heat and moisture transfer at a base of the pipeline are defined in relation to natural and climatic conditions of Central Yakutia. In the presence of groundwater, the heaving of an injection type is formed. Over time, frost injection of the injection type increases, which leads to a change in the value of the coefficient of unevenness. It is shown that the stress state of the pipeline as a result of frost heaving gradually transforms into plastic deformation. With the help of the pipeline fold equation, the stress-deformed state of the pipeline is estimated from the amount of migration heaving. The heaves are associated with a multi-year «seasonal loosening», which can lead to low-cycle fatigue failures.

Studies were carried out to assess the state and determine the permissible period of safe operation of the main gas pipeline («MG») «Pavlovsk-Mayya» of the JSC «Sakhatransneftegaz» at its most loaded nodes and elements operating under the most unfavorable conditions. A comparison of the standard estimate of the residual life of main gas pipelines with the developed methodology for estimating the residual life of pipelines and reservoirs operating in the Far North is presented. For the studies, the main metal sites were chosen at different sites of the MG. Standard methods for measuring and controlling technical characteristics used in the examination of industrial safety of technical devices were used in the work. The thickness of gas pipeline walls was measured by an ultrasonic thickness gauge «TUZ-2», and the determination of the hardness of the gas pipeline material by a portable hardness tester «TEMP-4» in pits, in open sections and crane assemblies along sections in four planes clockwise along the product. The actual value of the thickness and hardness of the wall is the average result of at least 3 measurements at each point. The MG «Pavlovsk– Mayya» was built and operates in the zone of permafrost spreading. For 12 years, the stable operation of gas pipeline systems provides the main fuel for the village of Mayya, the localities of Chuyya, Khara and Beke and other rural villages and settlements of the Republic of Sakha (Yakutia). The results of the industrial safety examination carried out by the expert organization LLC «ELTEK» were used in the work.