The article considers the origin and peculiarities of geographical location of deposits of the Pleistocene loess formation. Being a goal of researchers for over two hundred years, this problem is still debatable. Based on the analysis and generalizations of paleogeographical and geological materials of the natural conditions of Pleistocene reconstruction, it is shown that the loess formation areas are con ned to the water areas of transgressive basins. It was established that regardless of geographical location of transgressive basin, its speci c type of climate, glaciation, permafrost and another regional features of territorie, loess and loess-like sediments were always the product of sedimentogenesis. Loess of Europe, born in humid and cool climate of glacial expansions; loess of China, born in extremely arid and hot conditions of ice-free south-east of Asia; and loess of Yakutia, accumulated in extremely cold region of planet in permafrost zone - all of them are united by common subaquatic sedimentation conditions, generated by Pleistocene transgressions. It is the shallow basins ( lagoons, bays, lake and estuarine systems, and etc.), which occupied vast areas of land in the Pleistocene, that served as the main loess “incubator”. As all obtained and studied by us paleogeographical and geological evidence composition, structure, porosity and distribution features of the loess deposits) showed, this fact determined the ( current spatial and chronological position of all known horizons of the loess formation.Aconnection of periodicity of loess formation cycles with one of the leading Pleistocene rhythms - the 40700-year Milankovitch rhythm - was established. According to radiocarbon and OSL dates of the Quaternary deposits, the development of the last cycle of loess formation covers the interval from 26,000-28,000 years BP (end of the Late Neopleistocene) to 1 0,000-11,000 years BP (beginning of the Holocene). This cycle, judging by the materials obtained, was preceded by earlier loess-formation cycles, associated with periodic rhythm of the Pleistocene oods.

The main purpose of the conducted research was to determine the prospects of the ore areas of the Aldan-Stanovoy Shield for identifying new gold ore objects in the zones of development of products of regressive metamorphism. The materials obtained during prospecting and exploration works in different years were used. The processes of diaphoresis manifested on the territory of theAldan-Stanovoy Shield, composed of metamorphic complex-dislocated complexes, were considered, the types of dia uorites and their features were established. A review of the results of previously conducted geological studies to identify the manifestations of gold of different ranks associated with the zones of dia uorites was made. The extremely insuf cient study of the territory of the Aldan-Stanovoy Shield for ore gold in Precambrian formations was established. The main areas of the Aldan- Stanovoy Shield have been identi ed, where zones of dia uorites have been identi ed and contoured in different years. The tectonic and geochemical factors of control over the manifestation of regressive metamorphism and associated ore formation were revealed. The connection of dia uorosis with ore formation and metallogemc special ization of dia uorites of promising ore areas of the shield was established. Based on the available data, including the results of geochemical searches conducted in different years, a forecast was made for the detection of new gold ore occurrences in the ore-bearing and gold-bearing areas of the Aldan-Stanovoy Shield. Promising areas were identi ed for conducting priority prospecting and exploration work for gold and determining their metallogeny.

To date, the main deposits of oil and gas in the Cambrian and Precambrian section of the southern SiberianPlatform are con ned to the terrigenous part of the Precambrian sedimentary cover, while in the much more powerful halogen-carbonate complex of the Vendian-Cambrian and Lower Cambrian, few industrial hydrocarbon accumulations have been found [9]. Therefore, the carbonate complex is associated with the prospects of the largest reserve for the growth of oil and gas reserves. Along with the relevance of identifying the causes of the existing disproportion in the discovery of deposits, there is a need to assess the feasibility of the prospects for the carbonate complex on the basis of a discussion of the nature and mechanism of formation of deposits. Research methods: correlation and cross-correlation analyzes of maps of geological benchmarks and seismic re ecting horizons, as well as maps of hydrodynamic indicators based on well test data, the results of which were linked to the results of lineament analysis based on data from space surveys and potential elds. It is argued that deposits in productive strata of the Precambrian terrigenous complex were formed due to subvertical uid ows from sub-basement sources under the in uence of activation of faults of early northeastern generations, and in productive carbonate horizons of the Vendian-Cambrian and Lower Cambrian - due to the reformation of deposits in terrigenous deposits faults of the late northwestern generation. The deposits were formed at the same time in the zones of overlap with faults of the earlier generation, which determines the linear-zonal character of their distribution. This means that in carbonate reservoirs it is impossible to achieve advanced discovery of deposits and when determining the sequence of prospecting, terrigenous horizons should be considered as the main or priority ones. The research results are consistent with the distribution of deposits in 35 elds in the south of the Siberian platform.

The article presents data on the foundation of higher geological education inYakutia, contribution of the graduates of the Faculty of Geology and Survey of the Yakutsk State University (now known as the M. K. Ammosov North-Eastern Federal University) to the geological study of the territory and development of the mineral resource base of the Sakha Republic (Yakutia). The Faculty of Engineering and Technology (now the Faculty of Geology and Survey) was established within the university in 1956. At the faculty, the training of geologists in the Department of Geology and Exploration of Mineral Deposits began 65 years ago. In 2021, the rst graduating class of geologists in Yakutia celebrates its 60th anniversary, with more than 2,130 specialists trained during this period. The graduates of the YSU and NEFU have been working in the geological enterprises of Yakutia, scienti c organizations, and public and executive agencies. At present, graduates of the YSU and NEFU are the members of DPMGI SB RAS research team and academic staff of the Faculty of Geology and Survey. Among the YSU/NEFU graduates, there are 2 winners of the USSR State Prize, 2 Honoured Geologists of the Russian Federation, 23 Honoured Geologists of the Sakha Republic (Yakutia), and 2 Honoured Miners of the Sakha Republic (Yakutia); 25 geologists were awarded with the badges of the Honoured Prospector and Honourable Worker of Mineral Exploration. There are there over 25 discoverers of mineral deposits, 2 corresponding members of the Russian Academy of Sciences, 4 full members of the Academy of Sciences of the Sakha Republic (Yakutia), 7 Honoured Science Workers, and winners of the State Prize. They have participated in the development of the mineral and hydrocarbon base of the region, and contributed to the study of the geology of mineral deposits and their distribution patterns, geological structure and history of the geological evolution of the territory of Yakutia.

The article deals with the problem of recoverable gas reserves. The analysis of the development of gas and gas condensate elds of the Predverkhoyansk and Vilyui oil and gas bearing regions is made. For the Ust-Vilyui gas eld, a signi cant overestimation of the initial gas reserves approved by the USSR State Reserves Committee was shown. The nal gas recovery factor for the main reservoir III-A of the Ust-Vilyui gas eld was 0.56. For the Sobo-Khainsky gas eld, an assumption was made about insuf cient knowledge due to the location in the water area of the river. Vilyui and the existing negative experience in the development of the Ust-Vilyui eld. For the Mastakhskoye gas condensate eld, revaluations are given with a decrease in the initial balance reserves. It is shown that the high rate of gas production has become the most signi cant factor behind the low development ef ciency. The total nal gas recovery ratio for the depleted deposits of the Mastakhskoye gas condensate eld did not exceed 0.34 of the initial reserves calculated by the volumetric method and 0.55 of the reserves estimated by the pressure drop method. It was concluded that the most reliable in the conditions of a complex geological structure of deposits is the assessment of gas reserves by the pressure drop method. The idea is formulated that for the elds of the Vilyui syneclise, which have productive horizons with an initial low gas saturation of the reservoirs, the nal gas recovery coef cients can be estimated in the range of 0.55.

The relevance of the paper topic is justi ed by the reduction of mathematical calculations when interpreting gravitational and magnetic anomalies by applying a well-known method to the initial anomalies. The author designates the purpose of the scienti c research - the development of the application of the methodology for the interpretation of gravimagnetic anomalies, considered in [1-6], under the conditions of some initial gravitational and magnetic anomalies. The article describes the developed two-dimensional methods for interpreting the sensitivity to the shape of eld sources. The technique of mentioned methods is based on the use of the values of the mutually inverse functions of the initial gravimagnetic anomalies. When expressing a gravitational or magnetic anomaly by a direct function y = f (x), the function x = f (y) will be mutually inverse. In the developed methods, the values of the relations c = x/x' are used, where x' is a mutually inverse function of the horizontal rst-order derivative of f (x). 1 It is possible to use the methods when interpreting gravimagnetic anomalies from various geological structures by the method of approximating structures with bodies of regular shape. The result of the research performed is the developed methods of interpreting gravimagnetic anomalies through the solids most often used in practice [7]: an in nite horizontal physical line or a horizontal circular cylinder (magnetic unipolar line), an in nite horizontal physical band (horizontal charged band), an in nite vertical physical band (vertical charged band).

We discuss the modeling of gas ow in the reservoir, described by the equations of Darcy and Darcy- Forchheimer. Mathematical modeling of uid ow in porous media is the most crucial element in understanding the processes in oil and gas production; it is used when choosing the optimal option for developing oil and gas elds. The primary ltration law is the linear Darcy equation. However, it is known that this equation is not ful lled at high ltration velocities due to the manifestation of inertial forces. In problems of nonlinear ltration, the motion of liquid and gas is most accurately described by the two-term Darcy-Forchheimer law. The work aimed at studying the nonlinear law of Darcy-Forchheimer ltration in the bottom-hole zone of a gas well. In the course of the research, we performed a comparative analysis of the application of Darcy and Darcy-Forchheimer equations. To achieve this goal, we formulated the following tasks: to study the ltration process’s mathematical models, simulate the bottom-hole zone of a gas well, and compare the laws of Darcy and Darcy-Forchheimer. To obtain visual results, we used mathematical modeling. For the numerical solution of differential equations, we used the nite element method. The software implementation was carried out on the FEniCS computational package, which simpli es the solution of equations by the nite element method. We conclude that we got overestimated ow rates of gas wells when using the Darcy law, and using the Darcy- Forchheimer law, we were able to get data close to the actual ow rates. The simulations showed that the use of the Darcy-Forchheimer law is applicable for modeling gas ltration in actual conditions.

The paper presents a method for solving the problem of freezing of the formed core to the inner walls of the core pipe during drilling of exploration wells by the core method with compressed air purging in the winter conditions of the Sakha Republic (Yakutia). In the process of doing this work, we studied the long-term experience of the engineering and survey company “ Arctic-Bur” LLC, which operates on the basis of the Department of Subsurface Use, Geological Exploration Faculty, North-Eastern Federal University, and is engaged in drilling operations all year round in the territory of the North-East of Russia. To solve the above problem, we proposed to improve the standard geological exploration equipment for core drilling by installing an additional core receiver made of a polymer material with low adhesion to moisture- saturated frozen and thawed soils inside the core pipe. As a result of the research and design, we developed an effective and practical way to solve the problem of core freezing to the inner walls of the core pipe, which does not require serious upgrades of existing equipment and large nancial investments. Our next step is to conduct full-scale tests of the proposed method of solving the problem on the basis of the company “Arctic-Bur” LLC.

The bioeffects of detergents under bioassay conditions were studied. The test objects were: Lepidium sativum L. (watercress), Lens culinaris M. (lentils), Phaseolus vulgaris L. (white beans), and Vigna radiata L. (mung bean). The experiment consisted of 19,200 seeds. The concentration of detergents used in the work were: 0 g/l control; 0.05 g/l; 0.3 g/l; 3.1 g / l. Observations were made on the 6th day. Incubation of organisms occurred at 19 ± 1°C. The plants showed different tolerance to contamination. The toxic effect affected all plants. The detergents suppressed plant seedlings in growth and development. The average length of seedlings was calculated and then the results were processed using statistical methods. Plants P. vulgaris, L. culinaris and L. sativum were suitable as organisms for assessing the toxicity of chemicals. The information about the high tolerance of V. radiata is of interest in connection with the development of technologies for bioremediation of polluted areas of the environment. Researches of the toxic effects of detergents provide new material for the study of environmental pollution. They increase attention to the problem of contamination with this class of substances.