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Experimental studies modeling diamond crystallization processes in a reduced iron-bearing mantle were conducted at a pressure of 5.5 GPa under cooling conditions using BARS technique. In the Fe-C system, one of the possible scenarios of heterogeneous nucleation and growth of diamond was realized due to an increase in carbon supersaturation of the melt with decreasing temperature. The morphology of the diamonds is determined by the relative development of octahedron, tetrahexahedron, and cube faces in order of decreasing significance. Crystallized diamonds contain nitrogen impurity in the form of C-centers with concentrations of 30-60 ppm. Inclusions in the crystals are represented by cohenite, wüstite, as well as quenched melts of Fe-C and Fe-C-O compositions. Under conditions of relatively rapid temperature decrease (55-41 deg/hour) at the final stage the diamond morphology is determined only by {111} faces. With slow cooling of the melt (16.5-30 deg/hour), the stage of diamond crystallization is succeeded by a stage of dissolution due to the interaction between diamond and the melt with formation of cohenite. The evolution of diamond morphology in the Fe-C system under decreasing temperature is determined by the sequence: {111}, {hkk}, {100} → {111} → {111} with rounded vertices and edges → rounded crystals. Cracks and pseudo-secondary inclusions were found in diamond crystals with contrastingly inhomogeneous growth zones, and the mechanism of their formation was determined. It was established that the primary cause of crack formation is iron-bearing dispersed inclusions ranging in size from 60 to 600 nm. The uneven distribution of inclusions, with a maximum density of up to 1.2×10⁹ cm⁻², creates a mosaic structure in the diamond matrix and generates significant stresses. Relaxation of these stresses leads to brittle deformation and the formation of cracks under cooling conditions. All stages of the transformation of cracks into pseudo-secondary inclusions due to regeneration of crack walls and their overgrowth by growth layers were determined. The experimentally established regularities of diamond crystallization and subsequent evolution in the Fe-C system due to temperature decrease are discussed in relation to natural diamond-forming processes in the reduced iron-bearing mantle.

Against the general predominance of terrigenous and, to a lesser extent, tuff-terrigenous sedimentation, carbonate formations occasionally occur in the Ordovician of Salair basins. They were found at five different stratigraphic levels: 1) Tremadocian, 2) middle Floian, 3) late Dapingian, 4) early-middle Darriwilian, 5) Katian. In Tremadocian, carbonates are known in the Medvedkovo and Yeltsovka teсtonic blocks, and at other levels – in the East-Berd’, Guryevsk and Yeltsovka tectonic blocks. By the nature and scale of the manifestation, carbonate formations in the Ordovician of Salair are represented by shell rocks, lenses of clastic limestones, bedded, sandy and clayey limestones, small thin bioherms, small mudmounds. Paleogeomorphological control of their confinedness to the slopes of Ordovician volcanic structures was observed.

The paper examines the evolution of oil and gas exploration methodology as reflected in the seminal works of I.M. Gubkin, A.A. Trofimuk, A.A. Bakirov, S.P. Maksimov, A.E. Kontorovich, and other distinguished scholars. The paper highlights the particularly important contribution of Academician A.A. Trofimuk to the development of petroleum exploration methodology. The theoretical foundation of this methodology – the biogenic (organic) theory of petroleum origin – together with its core principles (genetic approach, regular spatial distribution of hydrocarbon accumulations and their regional nature, phased exploration activities, and integration of diverse study techniques) were incorporated into the official methodological framework governing oil and gas exploration in the USSR. These principles formed the basis of the Regulations on the Stages and Phases of Oil and Gas Exploration, adopted in 1983 by the USSR Ministry of Geology with the support of Minnefteprom (Ministry of the Petroleum Industry) and Mingazprom (Ministry of the Gas Industry). The efficiency of the Soviet exploration methodology is evidenced by the creation of an unprecedentedly extensive hydrocarbon resource base. At present, however, no comparable regulatory document exists that defines the respective competences and responsibilities of the state across the various stages and phases of exploration. The author demonstrates a critical discontinuity in the exploration cycle between regional studies conducted on unallocated subsoil funds and the subsequent prospecting phase carried out on licensed blocks, which adversely affects the replenishment of exploration scope. To address this, the author proposes that the first substage of the prospecting phase (namely, the preparation of structures for exploratory drilling) should be placed under state authority. Recommendations are also made for restoring state-funded research, development, and methodological studies in petroleum geology, which would undoubtedly enhance the overall efficiency of the exploration process.

This study propounded a numerical approach for solving a mathematical model of pollutant spread through forest resources using shifted orthogonal Bernoulli polynomials (OBPs). The model is based on a system of ordinary differential equations, which is transformed into an algebraic system using the collocation approach based on shifted OBPs. Newton's method is employed to obtain numerical solutions, and the results are compared with those obtained using the Runge-Kutta method of fourth-order (RK4) to demonstrate the efficiency of the proposed method. The results demonstrate good agreement with the RK4 method, indicating the proposed method's acceptability for modeling pollutant spread through forest resources.

The authors describe application attribute-based interpretable neural network models which allow optimization of risk management in underground mining of potassium-magnesium salts. The proposed procedure makes it possible: to classify initial natural data and manmade factors with the priority of transformation to a continuous representation, and with introduction of quality classes of sets; to build dimensionless indexes-attributes which ensure physical interpretability of models; to perform integrated selection of attributes on the basis of the single-factor linear analysis, correlation filtration, multiple regression and nonlinear analysis of a learned artificial neural network; to learn and validate neural network models with interpretation of contributions of attributes. For the transition from subsidence prediction to risk-oriented prediction, an integrated index of subsidence, inclination, curvature and accumulated damage parameter, with data mapping is proposed. The procedure is tested at Berezniki-1 Mine at the Verkhnekamsk deposit of potassium-magnesium salts.

The article describes observations over variations in deformation rates in mine roadways under changes in average annual water inflow in mines in the Torez-Snezhnoe coal province of the Donbas. The great depth of occurrence of mine roadways contributes to the peak and post-peak stress conditions even in intact rock mass, which is aggravated by water inflow from the upper levels of mined-out and closed mines. Wetting of rocks reduces greatly their strength and increases velocity of displacement of mine roadway boundaries. A direct relationship is found between the change in the overall mine water inflow and the change in the deformation rate of the mine roadway boundaries. The described observation procedure enabled the retrospective geomechanical assessment of rock mass and proved to be efficient. The differences in the displacement velocities of boundaries in different roadways are governed by geological features of their occurrence, but the factor of wetting of enclosing rock mass plays an important role in intensification of deformation process.

The study focuses on the urgent problem connected with the improvement of prediction reliability for hazardous ground surface deformations in undermined areas. Conventional geodetic surveys not always allow early detection of signs of unexpected failures. The authors propose an approach to the improvement of geodynamic diagnostic procedure using radon emanation survey. The method involves the analysis of spatial distribution of radon isotopes (²²²Rn and ²²⁰Rn) in soil air, dependent on change in the stress-strain behavior of soil. The pilot study of the procedure was carried out on a site of the Sarany deposit of chromite ore, nearby the zone of the 2013 sinkhole. In the course of areal shooting along four profile lines, the volumetric activity of radon-222 and thoron was measured. Using the compression and tension values calculated from the data of radon monitoring and normalized radon activity, the maps of deformation and geodynamic zoning were plotted. The comparison of the research findings and geodetic survey results proves informativity of the proposed method for the stress-strain analysis of rock mass, and validates its application for the enhancement of mining safety. The new approach to interpretation of emanation survey data provides information on the stress-strain characteristics of rock masses.

The article proposes a methodical approach to numerical modeling of a threshold and transition from gas-bearing coal seam to coal, rock and gas outburst. The structure of the Lee-Tarver Ignition and Growth is adapted for the description of the intact coal-damaged and gas-discharge stage transition without transfer of a chemical component of detonation process. An internal variable F is introduced, the members of the activation-growth-depletion structure are set, the dependences of coal properties on F are formulated, and the implementation is described using the SPH method for large deformations. The identifiable metrics are proposed: time to an event and length of the active zone growth. The results are correlated not with the emergency ventilation control but with gas drainage, destressing boreholes, mine support systems, monitoring, work stoppage and people evacuation upon reaching threshold indicators.

The methods of jointed rock mass investigation in open pit mining are reviewed. The modern software routines of jointing modeling are analyzed. An approach to 3D modeling of a production block is proposed and tested; the approach integrates the strength characteristics of rocks from the data on energy content of drilling and the simplified mathematical model of joints, including tectonic faults. The model is implemented in the Python language and using Surfer data visualization tool. The prospects for the further research include experimental verification of the model and development of a related program module for drill-and-blast design in open pit mining.

The authors discuss the problem of correct description of blind heading ventilation within the framework of the classical network-based approach to calculation of air distribution in mines. Voronin’s formula based on the assumed ideal agitation omits the spatial structure of air flow in a face zone and neglects the terminal time of flow circulation in large-scale vortex. A network model of blind heading ventilation is proposed with regard to air circulation in a face area owing to inertia of air flow from ventilation duct, and to its interaction with return air. In the conventional approach, a branch of a graph is collated with a heading, while in the proposed approach, it conforms with an individual air flow. The flow-oriented model is compatible with the classical network approach and can be integrated in computational modules of problem solving in mine ventilation. The model was used to obtain a theoretical explanation for the phenomenon of excess of the total circulating air flow rate in a face area of a blind heading over the air flow rate from a ventilation duct. It is found that vortex recirculation of air does not define the rate of removal of harmful impurities; however, in complicated structure flows, dynamics of a decrease in concentration of impurities is governed by the duration of air flow circulation in different circulation loops. Inhibition of ventilation in face areas is connected with the presence of low-velocity and remote areas in vortex; inclusion of these areas in consideration allows explaining deviations due to removal of impurities within the framework of the ideal displacement model.