The Solongo boron-magnetite skarn deposit (Western Transbaikalia, Russia) features industrial reserves of rare kurchatovite-sakhaite ores. The purpose of the work is to study the oxygen isotopic composition of boron-bearing minerals from the kurchatovite-sakhaite ores of the deposit. The samples were studied using modern methods of electron microscopy, mass spectrometry. The original photographs of transparent thin sections and images of the samples in backscattered electrons show mineral associations of sakhaite and kurchatovite icluding polymineral szaibeliite-sibirskite-calcite aggregate, roweite, fedorovskite, ludwigite, forsterite, serpentine, titanite, sphalerite, magnetite, jacobsite, apatite, turneaureite. The evolution of the Solongo deposit boron minerals is described. The following indicators of the oxygen isotopic composition δ18О v-SMOW in minerals have been obtained: sakhaite – +1 ‰, roweite – +2.7 ‰, kurchatovite – +1.9 ‰, magnetite – -0.3 ‰. The comparison of isotopic data on sakhaite with the available literature data has shown that the sakhaite of Solongo boron ores has a relatively light oxygen composition. The indicators obtained are attributed to the participation of meteoric waters including melt waters of firn basins and permafrost, in the formation process of the deposit, as well as reduced index of the oxygen isotope composition δ18O of the dolomites of the Ozerninsky ore cluster, whose transformation is associated with the sakhaite formation.

The purpose of the article is to consider the issues of geological and geophysical interpretation of the data of balloon and satellite magnetic measurements along the regional profile crossing the territory of the Angara-Baikal region. In order to conduct scientific research along the regional Trans-Siberian geological and geophysical profile A-B the author used various geological and geophysical materials including the magnetic field digital data measured by the MAGSAT artificial Earth satellite and a balloon; data on the values of the electrical resistivity in the mantle of this region; geothermal data; seismic data on the location of earthquake hypocenters in the area of the profile under investigation. The research methods involved multilevel measurements of satellite and balloon magnetic fields, which significantly expanded the possibilities of geological and geophysical interpretation of the data obtained. The conducted study revealed that the geological and geophysical interpretation of multilevel aeromagnetic data allows for a reasonably accurate determination of the location coordinates and lithospheric penetration depth of tectonic faults associated with the Angara and Trans-Baikal mantle  plumes, which are of significant interest in terms of exploration of coal and uranium deposits. The spatial and depth characteristics of tectonic faults obtained from balloon and satellite data are confirmed by a set of analyzed independent geophysical data: magnetotelluric sounding, geothermy, seismology and other geophysical methods. In conclusion it should be noted that the author has demonstrated the application possibility of satellite and balloon magnetic surveys for the study of the deep structure of the Angara and Trans-Baikal mantle plumes. In addition, it was found out that according to balloon and satellite magnetic data, large deep tectonic faults in the lithosphere (Barguzinsky, Ikatsky, Tukolamsky, Tungirsky) can be identified, which also allow marking various subhorizontal boundaries of lithospheric layers in the location area of the Angara and Trans-Baikal mantle plumes using special points of the magnetically active zones of these faults. The practical significance of the conducted research is in the identification of the spatial relationship between the location of the Angara mantle plume and coal deposits of the Irkutsk basin, as well as uranium deposits in the zone of the Trans-Baikal mantle plume.

The data of near-field transient electromagnetic sounding, which are widely used for the purposes of oil and gas exploration within the Nepa-Botuoba anteclise, are typically interpreted in terms of quasi-horizontally-layered models of media. The purpose of this study is to develop an approach to the inversion of transient electromagnetic sounding curves obtained via high-density 3D observation networks. The study was based on mathematical modeling, whose results allowed to estimate the lateral spatial parameters of a non-stationary electromagnetic field as well as to understand the differences between the results of one-dimensional inversion of the transient electromagnetic sounding data and the true parameters of the target horizon. As a result, the characteristic of the electromagnetic field described by an exponential function and used in the lateral-constraint inversion of high-density electromagnetic sounding was obtained. The proposed approach was tested on the practical data within the site under investigation located on the slope of the Nepa-Botuobа anteclise. It is shown that the use of spatial discrepancy under TEM sounding data inversion makes it possible to obtain geoelectric models characterized by lateral consistency of section geoelectric parameters. The application of the spatial stacking-based approach in the inversion process allows to increase the solution stability of the inverse problem of the near-field TEM sounding data.

The purpose of the research is to analyze the lithological and facies conditions of formation and the causes of lithological composition variability of the Yarakta horizon deposits as well as formation and distribution features of reservoir rocks in the horizon. The paper uses the data on drilling and geophysical work results and research materials from the public sources. The Yarakta horizon is commercially productive in the deposits of the southeastern slope and the central part of the Nepa-Botuoba anteclise: Dulisminskoe, Yaraktinskoe, Ayanskoe, Danilovskoe deposits, etc. The deposits of the Yarakta horizon were formed during the initial transgressive stage of the Vendian sedimentation cycle and are characterized by extreme lithological irregularity of rock composition and thickness. Investigations of a number of scientists testify that in the early formation of the Yarakta horizon its territory in geomorphological terms was predominantly presented by a coastal plain, which was occasionally flooded by the sea. The rocks in the area are represented by the facies of temporary proluvial-deluvial flows of the coastal plain replaced by coastal shallow sediments. The change in the lithological composition of rocks and thicknesses of the Yarakta horizon is a result of changes in the nature of oscillatory movements, while its structural and textural features are determined mainly by the dynamics of water flows of the sedimentation medium and the paleorelief nature of the underlying surface. The conducted research allows to conclude that lithological heterogeneity of the Yarakta horizon in sections (vertically) and along the strike (laterally) is determined by the frequent alternation of various lithotypes, the formation of which is determined by the complex nature of tectonic movements and irregularity features of sedimentary layer facies.

The article deals with the studies of gold-bearing ore benefication by flotation methods. The object of the study is a low-sulfide gold-quartz type of ores with the following petrographic composition: quartz – 90 %, quartz-chlorite schists – 10 %. The ore from this deposit consists of the weathering crust rocks including iron-mica rocks with veins and spots of granoblastic quartz. The purpose of the research is to develop an optimal flotation regime for obtaining sulfide gold-bearing concentrate. The influence of ore size, reagent mode, flotation redistribution structure, and flotation time on operations was recorded during the experiment. The paper presents the results of studying the chemical composition of the ore by the method of silicate and optical emission analysis. The flotation process used butyl potassium xanthate as a collector and a combination of pine essential oils as a foaming agent. The Hancock concentration efficiency criterion was determined based on a series of experiments. The following technological indicators of ore processing were identified: gravity concentrate with the gold grade of 1165 g/t with the yield of 0.3 % and the recovery of 73.74 %; flotation concentrate (after purification II) with the gold grade of 68.9 g/t with the yield of 1.52 % and a recovery of 22.05 %. Its silver content was 15.9 g/t. The total gold recovery was 95.79 %, with the yield of 1.82 % and the gold grade of 249.9 g/t. The gold grade in the flotation tailings was 0.19 g/t.

The purpose of this investigation is to develop an analytical model for predicting the groundwater level rise due to the barrage effect. Processing of a significant volume of production decisions for multiple objects has resulted an analytical model that allows predicting the dynamics of groundwater rise due to the barrage effect when building deep foundation structures. The study has been conducted for the downtown areas of Irkutsk and other cities of Eastern Siberia. Prediction schemes for the groundwater level formation have been made, and an assessment of the study areas by their underflooding conditions has been carried out. Being adequately simple and multi-purpose. The analysis of the research results shows that the hydraulic gradient of the underground water flow and the project structure width have the biggest effect on the groundwater rise. Vertical planning of the territory and the use of pile foundations play a significant role in the formation of the groundwater level. Besides, when evaluating the depth of the underground water formation level and developing the prevention and protection measures, it is necessary to take into account the seasonal rise of the underground waters. The developed model can be applied in the corresponding geological and hydrogeological conditions.

The purpose of the research is to refine a geological model of the Verkhnechonsk field of technical groundwater (Eastern Siberia, Russia), reassess groundwater reserves by the industrial category and form a geofiltration model. The article deals with the main approaches used in conducting of field and desk researches. It also introduces the organization experience of large-scale pilot filtration work under time- and personnel-limited conditions at a large operating field. The work is based on the results of long-term regime observations, field experimental and filtration works carried out in 2019- 2020. It uses the information of a geological database on the water and oil intake facility of wells, including a complex of borehole studies, as well as the data on the geological and hydrogeological structure of the field according to archival and published sources. Visual ModFlow Flex software was used to create a geofiltration model. Having conducted and interpreted the works, the justification of a natural hydrogeological model different from the one adopted earlier was performed. Thus, the relationship of two water-bearing complexes – the Verkholensky-Ilginsky complex of the Upper-Middle Cambrian age and the Litvintsevsky complex of the Lower-Middle Cambrian age was proved. The works in the Visual ModFlow Flex resulted in the creation of a geofiltration model, which correlates well with the actual data, allows to identify impenetrable barriers, as well as predicts the geomigration of hydrogen sulfide. It is the first time that the underground water reserves of the field were included in the State balance sheet in full-scale according to the industrial category B. The reassessment was performed for three sites of the field, well loads were adjusted for optimal operation of water intakes. The obtained results of the conducted research imply that the use of geofiltration model is reasonable in the fields of complex geological structure and this model can be used on a permanent basis for monitoring and adjusting of the development mode. The organization experience of works at a large operating oil field can also be useful under the reserve reassessment at analogous fields.

The article deals with the engineering-geological assessment of the rocky soils of the Albazinskoye deposit located in the north of the Khabarovsk Territory, Russia conducted on the example of the analysis of the collection of samples of various petrographic types of certain geological formations. The purpose of the research is to implement a specially developed complex methodological scheme including an optical method (analysis of thin rock sections), measurement of seismic (surface and through sounding of samples to determine longitudinal seismic wave velocity), strength (vertical compression and tension) and physical (density and water absorption) properties. Using the obtained data, a comparative analysis of samples is performed based on the results of seismic, strength and physical properties taking into account petrographic information. Anisotropy in terms of seismic and strength properties is established. Using a cluster analysis program, the correlation coefficients between property indicators are determined. On example of the materials of the collection, it is shown that the differences in the velocity of longitudinal seismic waves and strength are determined by the textural-structural features and composition of rocky soils, which are studied at the micro level.