On the basis of material collected from deepwater drilling of the World Ocean floors (programs DSDP, 1963–1984 and the ODP, 1985–2003) and generalizations of new data of stratigraphy, paleogeography, and paleobiogeography on the propagation of marine fauna, it is shown, in the Late Triassic lithosphere was not broken into tectonic plates, and the ocean basins of Paleotethys and Paleo-Pacific (=Panthalassa) were absent. We present a new model for the paleogeography of the Earth in the Late Triassic, which provides for the existence of three supercontinents – Afalia, Pacifida, Arasia and two continents – Antarctida and Hyperborea, which divided the inland shelf sea basins and their geodynamics is examined. Based on the study of the differentiation and geographical distribution of the families and subfamilies of the late Triassic (Rhaetian) brachiopods: the Boreal, Tethyan and Notal biogeographical realms, are distinguished. In the Tethyan Realm there are the AlpineChinese, Melanesian, West-North American and West-South American subrealms. The interlinking of the initial stage of the Upper Triassic (Rhaetian) – Upper Jurassic (Volgian) megacyclite and phase in the development of marine fauna makes it possible to distinguish the Byrandian Stage in the Boreal Standard of the Upper Triassic. It is shown, the terrigenous and terrigenous-sedimentary (Northern Priokhotie) types of sedimentation prevailed in the Boreal epicontinental marine basin.

During its formation, Tungus syneclise basits, according to the physical and geological laws of formation, generated in bodies (sills, dikes, etc.) petromagnetic taxa (PMT) which are characterized by the certain statistical values of density and magnetic parameters. According to the nature of their distribution, PMT are subdivided on petromagnetic groups (PMG) and petromagnetic heterogeneities (PMHs). In its turn, PMT is composed of petromagnetic complexes (PMC), conforming to the magmatic phases of the basits intrusion. PMT allows more securely zoning of the Yakut diamondiferous province closed by the trap areas in order to develop a methodology of prospecting for primary diamond deposits, as well as isolating structural and tubular types of anomalies over kimberlite pipes based on gravity-magnetic exploration materials.

The study of the material composition of Middle Paleozoic basites from the Tenkelyakh area, located within the Vilyui-Markha dike belt in the eastern part of the Siberian platform was made. The basites of the region are characterized by an increased content of titanium, potassium, phosphorus, and incompatible elements and by a significant differentiation of REE (La / Yb) n = 5.5-7.0, which are typical features of Devonian basites. Comparing them with the dominant type of even-aged basites of the Vilyui- Markha dyke belt, adjacent to the territory of the object under study, showed the identity of their petrographic, chemical and trace element compositions. High-Ti basites (> 4.5% TiO₂ ) are locally found within the Tenkelyakh area are established, which, according to previous studies [12, 13], are usually adjacent to kimberlite pipes and can be used as indicators of search of promising areas for indigenous diamond sources.

It was shown that modern evidence of global magma ocean fractionation during Earth accretion allow to explain discussion problems of Early Precambrian. Due to a relatively low pressure during fractionation early magma ocean its mainly residual melts have acid composition. This provided acid composition mainly Early Precambrian rocks. Origin from melts explain high temperature crystallization these rocks. Dipping of cold rocks and sediments caused origin of heterogeneous complexes. Raising of deep migmas caused presence of high-baric rocks and very ancient age of basic crystalline schists. Emanation and magmatic differentiation of magma ocean caused origin of unique deposits.

Dam safety is one of the most critical issues in permafrost regions. At present, the existing dams are reaching their design life limit. Geocryological processes, such as thermokarst, thermal erosion, frost heaving, suffosion, and concentrated seepage through meltout voids have intensified at the damsites due to climate warming. Global warming which began in the second half of the twentieth century is continuing. However, the rates of warming have significantly slowed down in some parts of the permafrost zone, with some areas beginning to show a cooling trend and permafrost aggradation. Unsteady thermodynamic conditions have developed in the lithosphere, in the layer of annual ground temperature fluctuations which hosts engineering structures. This paper discusses the current concepts of dam design and construction in permafrost regions. Based on several case studies, it is demonstrated that embankment dams often change their state from frozen to thawed and back during the operation period. It is shown that these transitions are not always attributable to observed climate warming. Where geotechnical, hydrogeological, and permafrost conditions are complicated, proper performance of embankment dams can only be provided by adhering to a selected thermal design, for example, to a frozen type. There is a need for radical revision of the existing standards for dam design in permafrost areas.

In this article we presented the results of forestry and geobotanical studies in the upper reaches of the Amga River, which belongs to the Southern region of Yakutia. Materials are collected in 2006 in the riverheads of Amga – from the mouth of its right inflow Khatyrhai to the Amginsky Ridge, almost not studied site of South Yakutia. The study area is unique from the geobotanical point of view, since it is located at the junction of the three floristic districts, two geomorphological provinces, bordered by Olekminsky reserve in Yakutia. On the investigated site the entire area is covered with forest vegetation, where pure and mixed forests are formed. A distinctive feature of the region is the spread of forest communities rare for Yakutia with the presence at the basic evergreen coniferous species. Many communities include rare, endangered and endemic plant species listed in the Red Books of different levels. Materials of article will be a basis for creation of the database of infrequent vegetable communities for the organization of protection actions and also will add not numerous data on a vegetable cover of upper courses of the Amga River.

In this arcticle anomalies of prolification and «ramification» in the inflorescence of genus Typha are examined. It is noted that during all periods of the Cenozoic era the type of the genus was a complex ear (of different sexes) in the common inflorescence axis. Appearance in the inflorescence Typhaceae of the anomalies of prolification and «ramification» is connected with strengthening of anthropogenic factor. These processes can be interpreted as the tendencies of the extinction of the initial «parental» form of inflorescence, in connection with the formation of new structure.

It was studied the soils of abandoned 30 years ago arable land within the Central Yakutia Plain. The area is located on the grounds with ice complex. During the global climate change the ice complex degradation occurs on the abandoned arable lands. The melting of the underground ice on the arable lands over the vast areas causes the formation of young thermokarst landforms on the surface of abandoned arable lands bylars. Bylars represent a combination of remnants in the form of mounds (up to 5–6 m in diameter) with subsidence between them and a polygonal network of hollows over the ices (0.3–1.5 m deep), formed as a result of thawing the upper part of the ice complex. The formation of a thermokarst microrelief leads to the transformation of a previously homogeneous soil cover of abandoned arable lands into a complex of polygonal character.

A short-term (2007–2017) and long-term (1965, 1967–2017) monitoring of chemical composition of surface waters in the development zone of the Amur-Yakutsk Mainline (AYAM) in the territory of southern Yakutia were conducted. According to the results of the short-term monitoring, the chemical composition of most of the rivers studied in southern Yakutia varied insignificantly. All recorded changes in the chemical composition of these waters were within the seasonal variation of their contents and values caused primarily by natural factors. In our opinion, significant anthropogenic and technogenic influence over the observation period was recorded only on 3 small rivers, including the Sylgylyr, Mundruchuch and the Lyutenga rivers. As the result of the long-term monitoring conducted in the coal and gold mining areas in the territory of southern Yakutia, we have identified significant changes in chemical composition of the Chulman and Aldan rivers, as the result of technogenic influence during the 30–40-year period of industrial development of southern Yakutia. At the same time, changes in all chemical indicators in waters of the Chulman and Aldan rivers do not exceed their maximum allowable values and meet the standards for drinking water supplies. Changes in chemical indicators in waters of the Chulman and Aldan rivers during the period of 2007–2017 indicate that technogenic stress on the Chulman River is gradually decreasing, and remains at the same level on the Aldan River.

The article presents the results of laboratory studies of the fatty acid composition of the subcutaneous fat of ringed seal (Phoca hispida), harvested in the Arctic regions of Yakutia. Identification and determination of the concentration of fatty acids in the samples was carried out using the method of gas-liquid chromatography with a mass spectrometric detector, methyl esters of fatty acids were obtained by acid hydrolysis with sulfuric acid in methanol. A comparison of the subcutaneous fat of two types of seals (Phoca (PUSA) Sibirica Gmel and Phoca hispida) and fish oil, as sources of omega-3 polyunsaturated fatty acids. The adipose tissue of the ringed ringed seal (Phoca Hispida) contains up to 40 % of the polyunsaturated fatty acids of the total number of fatty acids in the fatty tissue, which is 25 % more than that of the Baikal seal (Phoca (PUSA) Sibirica Gmel), and 56 % more than in fish oil. The data obtained in this work indicate the uniqueness of the fat of the ringed seal as a raw material for the creation of drugs aimed at the treatment and prevention of diseases of the cardiovascular system.

Wild plants are a valuable bioactive factor to produce bioactive drugs. The initial assessment of biological products is the study of their biological activity and toxicity with respect to biological objects. A rapid assessment was made of the biological activity and toxicity of aqueous-alcoholic extracts obtained from six types of plant materials in Central Yakutia, using two methods of biotechnological processing. For the biological activity and toxicological properties of aqueous-alcoholic extracts obtained from several plant species in Central Yakutia, a test object is used the single-celled organism Paramecium caudate. Our data allowed us to identify some of the natural relationships between biological activity and toxicity at the cell level (for example, caudate paramecium), which are the initial target of the complex of biologically active substances contained in the extracts that have passed two studies. Further study of the effect of biologically active substances on cellular organisms. It has been established that there are some regular relationships between biological activity and toxicity at the cell level, which are the primary target of the action of the complex of biologically active substances required in the extracts obtained by the two products.

The modified model for dynamic crack growth in viscoelastic material has been proposed. The model based on the structural approach that includes Zhurkov thermokinetical concept and Neiber-Novozhilov criterion of brittle fracture. The structural approach describes the microstructure inhomogeneity of material and staging of crack propagation revealing by fractography as changing the scale of damage accumulation and fracture. The main parameters of the physical model approved on experimental data on pulse hit action of the striker to a notch of the previously hardly loaded single edge-notched specimen in wide range of environment temperatures has been analyzed in the paper.

Today, working elements of hard tungsten-cobalt alloys are widely used in drilling equipment. However, the friability and low plasticity of hard alloys often lead to insufficient working capacity of the working elements under conditions of intensive operational loads of the North drilling equipment (frozen soil, rocks, etc.). One of the ways to improve the structure and properties of hard alloys is to control the grain size of their carbide phase by injection growth inhibitors from ultradispersed powders. Ultradispersed powder additives introduced into tungsten-cobalt alloys, contribute to reducing the size of tungsten carbide grains in the alloy structure. This leads to the improvement of the physicomechanical and operational properties of the working elements of the drilling equipment. The paper presents the results of research on the use of ultrafine magnesium spinel powder MgAl₂O₄ and silicon carbide SiC to improve the structural condition and physicomechanical properties of the VK8 tungsten-cobalt alloy. The technological operations for the preparation of powder

mixtures and the manufacture of drilling plates with ultradispersed additives were reasonably and selected. The physicomechanical properties and structure of experimental drilling plates are investigated. For this purpose, traditional methods of studying mechanical properties added with metallographic analysis were used. The results of experimental studies show the potential use of ultradispersed magnesium spinel powder MgAl₂O₄ and silicon carbide SiC additives to improve the physicomechanical and operational properties of drilling plates made of VK8 tungsten-cobalt alloy.