. Compositions of gneisses from the Early Precambrian crystalline complexes of the Aldan shield and of mantle xenoliths from kimberlites plot along the magmatic fractionation trends. Their isotope age and crystallization temperature decrease in accord with the sequence of their formation during fractionation. This indicates that the crystalline crust and mantle formed as a result of crystallization and fractionation of a layered magma ocean. Evidence of chemical disequilibrium between the mantle rocks and metallic iron suggests that accretion of the Earth’s core occurred before that of the silicate mantle under the effect of magnetic forces. In the silicate magma ocean, which originated through impact melting, there occurred processes of compressional crystallization and fractionation of its near-bottom parts. Due to a very low pressure in the incipient magma ocean, the early formed residual melts varied in composition from granites to tholeiites. This provided very early formation of the acid crystalline crust. An increase in temperature during the accretion process resulted in the higher temperature of the upper mantle as compared to the lower one. For this reason the lower mantle plumes did not ascend in the Early Precambrian, and magmas in ancient platforms were forming mainly from residual melts of compositionally varying layers of the magma ocean. In the Phanerozoic, the temperature of the lower mantle became higher than that of the upper one. As a result, lower mantle plumes and oceans came into existence. In the ascending mantle plumes, basic eclogites were subject to decompression melting. Fractionation of the formed magma chambers led to the formation of acid magmas under low pressure conditions and of various alkali-basic magmas under high pressures.

The article concentrates on geology, petrology, crystallization conditions and geochemical features of granitoids and dykes of the Ukachilkani ore field with a complex cassiterite-silicate-sulfide mineralization. The ore field is localized on the border of Polousnyi synclinorium and buried structures of Primoskyi lowlands. The main ore bodies are confined to areas of intensive development of dikes and significantly divorced in time from the formation of granitoids of Ukachilkan massif. Geochemical specialization of all magmatic rocks on Bi, Sb, As, Ag is identified, that corresponds to the fact that crystalline basement rocks are enriched with these elements, while terrigenous strata are depleted in these elements and tin. The Sn content in granitoids of the massif is closey to clarke and its redistribution during differentiation of the melt and autometasomatism is not registered. Crystallization of granitoids took place in conditions of low activity of fluoride and high activity of oxygen, unfavorable for the generation of tin mineralization. Maximum concentrations of tin and associated elements characterize the rocks of the dikes crystallized from water-saturated melts at high activity of water, chlorine and sulfur, i.e. they could be sources of ore-bearing solutions. Dikes trachyandesite and trachydolerite are maximally enriched with ore and volatile elements; parental meltsof these dikes fre formed in metasomatized mantle. It is suggested that, melts that formed complexes of dikes, primarily of basic composition, were one of the main sources of tin and associated elements. It is shown that the main features of potential tin content – presence of minerals-concentrators of tin and associated elements and fluid regime of crystallization. Geochemical specialization of dikes on Au and high activity of chlorine with their crystallization resulted in formation of the related gold mineralization.

Manifestations with Fe-oxide-Cu-Au±REE ores is a new direction in mining geology of Russian North-East. One of unexplored genetic varieties of the Fe-oxide Cu-Au (IOCG) ores, associated with basalt covers was discovered during field works 2013-2015, Sette-Daban ridge. The sole of basaltic cover (manifestation Hurat) include a bedded deposit of hematite breccia with sparse sulfide mineralization. Ores are complex and economically attractive the content of FeOtot – 15.11–43.29 %; Cu – 0.023–0.083 %; Au – 0.1–17.5 g/t and the main mineral-concentrator of gold is hematite. It has been established that clusters of Fe-oxide ores were formed by the decomposition of ilmenite into hematite, ulvospinel, pseudorutile and rutile. Native gold in ores contain admixture of iron and palladium and does not contain any silver at all. One of the important genetic characteristics of ores are constant presence of monazite-Ce, the chemical composition of which is not constant and is determined by the amount of Ce, La, Pr, Nd, Sm, Eu, Gd, Tb. Its origin is closely connected with the formation of Fe-oxide ores, where monazite is found everywhere in intergrowths with Ti-hematite and pseudorutile.

This study examined historical data sets from DC vertical electrical soundings performed for trunk gas pipeline projects in Central Yakutia and obtained characteristic values for salinity and resistivity of the active-layer soils. The results suggest that the correlation between these two parameters increases significantly and becomes stable in the metric of average median values. This makes it possible to derive, with different levels of generalization, direct and reverse petrophysical models both for theoretical understanding of the relationship between the two parameters and for practical calculation of average salinities from resistivity values. The absolute accuracy of salinity calculations is less than 0.1 % in 70 % of the cases, when resistivities averaged over 11 sounding points are introduced into the power function equations. The question of an optimal number of data points is left open and requires a special study for each case. It seems right to solve this problem at key sites of the terrain. The accuracy of salinity prediction with the regression equations is sufficient for rapid, cost-effective and environmentally safe solution to the problems of regional characterization and classification of permafrost terrain by active-layer salinity in the Central Yakutian lowland. Solving such problems before reconnaissance drilling is always important for engineering site investigations, as well as for soil salinity control and prediction in the agriculture.

This article discusses the thermal response of upper permafrost to anthropogenic disturbances. It presents the results of experimental geocryological investigations conducted in support of geotechnical exploration and construction of linear engineering projects.

The geocryological conditions in the study area, as well as the methods of permafrost thermal monitoring are described. The research focuses on the upper permafrost within the depth of annual temperature fluctuations. Field observations involve repeated surveys of the disturbed landscapes, including measurements of snow depth, snow density, soil properties, thaw depth, and ground temperature in the cold and warm seasons. The study aims to explore active layer thickness and near-surface permafrost temperatures, the variables which indicate changes to the ground thermal regime in the pipeline, railway, road and powerline corridors. The observation results demonstrate significant increases in mean annual temperature of the upper permafrost layers, as well as in seasonal thaw depth following tree removal, ground surface stripping and post-fire clearing. Soil thaw depths along the linear corridors show a distinct increase from year to year, in places reaching the top of ice wedges and causing permafrost degradation. The development of hazardous cryogenic processes is reported. Quantitative estimates have been obtained for the thermal dynamics of the ground on selective, gradual and clear cuts, as well as on old and recent burns in relation to plant succession stages.

The results of the study have been used in the design and construction of linear structures. Observational data can be further used in predicting the thermal dynamics of disturbed landscapes and in developing guidelines for rational land management.

Vickers micro hardness measurement was done on nine hard probes of welded samples of lowalloyed 14H2GMR steel and on one sample of low-carbon St3sp steel using the PMT-5 equipment. An investigation was carried out to see the thermal cycling influence on the HAZ. It was discovered that, welding at 40°C does not lead to a significant increase of its micro hardness as compare welding at +20°C despite the large difference in cooling rates. It was also discovered that, the crack grows mainly along the grain boundaries of martensite and bainite (as overchilled austenite), but in some places passes through the body of grain and cuts across it for 14H2GMR steel. For St2sp steel the intergranular cracks are revealed both in weld metal and in the heat affected zone nevertheless of milder test conditions against hard technological probes.

Combined treatment of low-carbon steel St3sp by means of equal-channel angular pressing and extrusion is presented. The increase in the strength of steel as a result of combined treatment is shown. At the same time, the low temperature (213 K) of testing hardened steel specimens for uniaxial stretching practically does not affect the change in its strength, whereas for steel in the initial state, a decrease in temperature affects the growth of the values of these characteristics. A description of the mechanisms of failure based on the analysis of fractograms of fissures of specimens is performed. A qualitative difference in the mechanism of the destruction of steel before and after the combined treatment has not been established. Destruction of samples from steel St3sp in the initial and reinforced by ECAP and extrusion conditions is viscous with the formation of pits by merging micropores.

The paper considers some specific features of application of nonlocal criterion, based on the concept of finite fracture mechanics, in the strength problem of a solid body containing a stress raiser under tension or compression. The criterion is pertained to energy-based methods. The approach of finite fracture mechanics consists in modification of the traditional energy balance as used in linear elastic fracture mechanics (LEFM). The modification involves the using of a finite amount of crack extension instead of an infinitesimal extension when calculating the energy release rate in LEFM. This makes LEFM to be suitable for predictions in situations of blunt notches in which it is normally invalid. Advantages and restrictions of the using of the finite fracture criterion are shown. The expressions for the failure stress in the problems of tension or compression of the plate with a circumferential hole are obtained. The reductions in strength of the plates with a circumferential hole predicted by the finite fracture criterion are compared with known experimental data on composite plates in tension, and own experimental data on gypsum plates in compression. In reference to some materials, the finite fracture criterion similar to other non-local criteria (the criteria of average stress, point stress, and fictitious crack) can be successfully applied to describe the hole-size effect on tensile fracture initiation and assess the critical size of the flaw under compression. However, its application to other materials allows us to obtain only a qualitative assessment of the failure stress.

The results of a study of the structure and mechanical properties of low carbon and low alloyed steel of a pipe from a reserve stock and after long operation as a part of the Republics Sakha (Yakutia) main gas pipeline are presented. It is shown, that proceeding on nanometer scale level structurally degradation processes lead to degradation of structure and properties on micro-and macro-levels. It is shown, that АFМ is a unique method of quantitative definition of a roughness of phase components, characteristics of borders of grains and structure regularities of pearlit of ferritic-pearlitic steels which can be used for estimation of life of gas main pipes having operated for a long time. The calculation and experimental estimation of the strength properties of steels based on representations of physical metallurgy and on experimental data of structural researches is performed. The influence of structural factors on the strength properties of pipeline steel at long operation was analysed.

Methods of gas-thermal dusting are effective ways of drawing powder protective coatings on a surface of details of cars and mechanisms. In the course of gas-thermal dusting the coating is formed of the separate melted and melted-off particles of powder material. Particles with a high speed collide with a surface, are cooled and stiffen, forming a protective coating. Numerous physicomechanical processes at blow, deformation, cooling, hardening of particles, their interaction with the gas environment define structure and properties of a coating. One of important characteristics of the received powder coatings is their porosity with sizes of a time in rather wide range of 10^-4 – 10^-8 m.

Research objects in work are the wearproof coatings received by arc metallization of a powder wire with refractory additives of corundum Al2O3, a wires with additives of tungsten W and tantalum Ta and also the flowed gas-flame coatings with the ultradisperse modifying additives of spinels of cobalt and copper.

Dependences of open porosity of the wearproof modified coatings on technical characteristics on their receiving are studied. For this purpose the method of hydrostatic weighing has determined levels of open porosity of samples of the modified coatings on substrates. It is shown that the open porosity significantly depends on a look and the maintenance of modifiers of powder material, the modes of dusting and the subsequent heat treatment of a gas-thermal coating.

The content of main iones, biogenic elements and microelements – heavy metals (HM) in surface waters of Neryungri coal-mining region of Southern Yakutia have been studied. The complex of analytical and instrumental chemical methods of analysis has been applied. It was found that coal of Neryungi coal mine is characterized by average ash content of 12-20 %. The ash consisted predominantly of silicon (40-60 %) and aluminum oxides (16-22 %), and also contained Fe, Ca and Mg oxides of 8-14, 4-10, 2-4 % respectively. The aqueous suspension of oxidized coals had pH value of 7,1-7,2, they contained approximately 1 % of сommon N and about 0,01% of both total K and P, and 0,15-0,45 % of S, thus these coals were classified as low-phosphorus and low-sulfur. Also, these coals did not contain considerable amount of heavy metals such as As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb and Zn. It is evident that during the past 40-years period of coal mine operation the chemical composition of the Chulman River and its tributaries within the mining area has changed significantly.

Thus pH value has increased by 0,5, the total mineralization and hardness of water increased more than 3 fold, while the water type has not changed and remains of hydrocarbonate-calcium type. The content of nitrates and total P increased 5 and 3 times respectively. The content of Cr has changed from 1,0 to 1,7 mg/L, Cu – from 0,7 to 4,0 mg/L, Mnfrom 10,0 to 50,0 mg/L, Mo – from 0,5 to 0,8 mg/L and Zn – from 5,0 to 18,0 mg/L. The content of other heavy metals estimated by the atomic emission spectrometry method was below the detection limit. It should be also noted that the content of all studied heavy metals did not exceed the maximum permissible concentration determined by State Standard Specifications and Sanitary and epidemiological regulations and guidelines. Therefore, at present as well as before, the water of the Chulman River satisfies the sanitary requirements and regulations for water quality, and may be used for drinking water supply.

The article presents the results of the study of nonspecific adaptation reactions (NAR) of the body by the method of LH Garkavi et al. in pregnant women, depending on the age in the following samples: the “control” group is practically healthy, the “risk” group is women at risk of pregnancy, the “threat” group are women with the threat of abortion who are on inpatient treatment. The study involved 100 pregnant women in the first trimester of pregnancy, aged 18 to 42 years. The most unfavorable course of pregnancy is observed in women 18-24 years in the group “Threat”, and in pregnant women 35 years and older in all study groups. As a result of the study, the presence of differences in the state of nonspecific adaptation reactions in the study groups, depending on age, was revealed. The most unfavorable nonspecific adaptive reactions of the body are observed in the group “Threat” among women aged 18-24 years and in the “Risk” group older than 35 years. Decreasing the adaptive potential in these groups of pregnant women suggests the need for preventive measures aimed at restoring the reserves of adaptation of the organism.

This article presents the silvicultural and geobotanical characteristics of forests from Chosenia arbutifolia of the Central Verkhoyansk region, especially on the basin of the Arkachan River. Chosenia arbutifolia is a relic of the Far East, is a pioneer on pure pebbly alluviums of mountain rivers. When characterizing the diversity of cenoses formed by this tree species, the uniformity of forest composition is revealed. Based on the analysis of the ages of trees the main stages of the development of vegetation have been identified, starting with the primary colonization of this rock by pure pebbly alluvium. The accumulation of silt fractions, the change in microclimatic conditions under the canopy of the Chosenia stand, precludes the possibility of the emergence of a young generation of Chosenia. In the article, the indicators of the dynamics of the morphologic characteristics of forest stands are given. It is shown that the values of the closeness of the tree canopy and, accordingly, the number of tree stems per hectare, having reached its maximum by 30-40 years of the existence of the Chosenia stand, are gradually decreasing. This indicates the early beginning of the processes of differentiation of Chosenia according to the vitality of trees and the disintegration of the mother's canopy in the absence of replacement by the younger generation. The maximum age of Chosenia in the study area does not exceed 60-80 years. It is established that the development of mature Chosenia stands goes in the direction of the gradual replacement of the dominant forest-forming species by larch. The existence of stable Chosenia forests that function for more than one generation is impossible.

Object of researches in 2016 is cattail, collected by E.V. Chemeris on reservoirs of Viljujsky and Pokrovsk paths of the Central Yakutia. On acting on a surface pistillate a spadix to insignificant white hairs gynophore and to absence bracteole plants have been carried to section Typha of subsection Komaroviae [5, 6, 7]. Plants differed habit from the Northeast specified for terrain рогоза east T. orientalis also conceded in the age attitude to the previous kind. Possibly, could arise owing to hybridization migrating in paleogene to the north of active populations T. orientalis from Southern China where the greatest quantity of representatives of ancient flora, including hydrophilic, and East Siberian (beringiya) populations penetrate in these areas on «land bridges» from the North America.

During 2013-2014 winter seasons, in the territory of Yakut ‘Orto-Doydu’ Zoo, 50 km the south of Yakutsk, Salamandrella keyserlingii wintering conditions were studied. The DS 19221-F5 thermograph, programmed to measure the temperature every 3 hours, was placed in a typical wintering den of a Siberian salamander. On September 16, 2013, the den was found in the forest, 70 m from a lake under a dead stump at a depth of about 10 cm with three Siberian salamanders inside. Next year on May 5, at the opening of the wintering den there were discovered all three hardly active Siberian salamanders. To the end of the third decade of December, in the wintering den of the Siberian salamanders, under the snow cover up to 40 cm deep, the temperature was at minus 10 15°C. From the late December to early March, the temperature in the den fluctuated from minus17°C to minus 26°C, and then it started to rise. In the second half of March the temperature increased up to above minus 10°C. In late April, the rate of temperature rise has increased dramatically reaching nearly zero values. In the middle of the third decade of April the rate was positive. And in early May, awakening of Siberian salamanders from hibernation began. The achieved data state that in Central Yakutia a relatively deep snow cover plays a significant role in thermal protection for animals wintering at ground surface and at shallow depths in the surface soil and subsoil layer. This is most clear in the coldest months from November to February, when the temperature difference reaches up to 20° or more degrees. One of the conditions favouring successful wintering of Siberian salamander in Central Yakutia, unlike in other regions, including the Magadan region, is that cold snaps and warmings stop alternating after October, and once frozen animals don’t wake up. The remarkable cold resistance of Siberian salamander was also confirmed by the fact that they successfully wintered in a frozen condition for a long seven-month Yakutian winter at temperatures from minus 5° to minus 26°C.