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Date submitted2024-05-15
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Date accepted2024-11-07
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Date published2025-04-14
Metacarbonate rocks of the Paleoproterozoic Khapchan series (southeastern part of the Anabar Shield): mineral and chemical composition, metamorphic conditions
The mineral composition of metacarbonate rocks (silicate marbles and carbonate-silicate rocks) of the Khapchan series (southeastern part of the Anabar Shield) was studied, and the PT (pressure and temperature)-parameters of their formation were established. Silicate marbles contain calcite, dolomite, forsterite, clinohumite, spinel, enstatite, diopside, pargasite, meionite, phlogopite, and feldspars. Carbonate-silicate rocks are composed of calcite, quartz, feldspars, diopside, grossular, marialite, and vesuvianite. Carbonate-silicate rocks are significantly enriched in SiO 2 , Al 2 O 3 , FeO, Na 2 O, K 2 O, TiO 2 and contain less MgO, CaO than silicate marbles. A difference was revealed in PT-parameters determined for silicate marbles (temperatures 700-900 °C and pressure no more than 8 kbar) and for carbonate-silicate rocks (temperatures 680-820 °C, pressures 8-15 kbar). Silicate marbles have a primary sedimentary nature, as evidenced by their rare-element composition and the presence of fragments of host terrigenous rocks. There is no doubt about the primary sedimentary nature of carbonate-silicate rocks, which are very similar in REE distribution spectra and in rare-element composition to silicate marbles. A number of features indicate that metacarbonate rocks have undergone metasomatic alteration. Thus, in silicate marbles, reaction rims are observed around orthopyroxene, forsterite, potassium feldspar, as well as quartz veins bordered by accumulations of phlogopite, feldspars, and diopside. In carbonate-silicate rocks, the development of secondary marialite on potassium feldspar has been established; the rare-element composition of garnet may indicate its metasomatic origin.
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Date submitted2023-12-07
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Date accepted2024-11-07
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Date published2025-04-07
Determination of the tangential component of cutting resistance during frozen sedimentary rock cutting using blocked, deeply blocked and cell cutting methods
Due to the insufficient accuracy of existing studies of frozen sedimentary rock cutting process for practical calculations, the article solves the problem of determining the tangential component cutting resistance for blocked, deep blocked and cell cutting, which are currently the most commonly used methods in earthmoving equipment. The cutting tool and rock mass force interaction is considered from the point of view of the emerging stresses, which act on the separated chip element. The analytical dependences for determining the tangential component of cutting resistance were obtained. The numerical explanation of the choice of cell cutting in relation to blocked and deeply blocked cutting is given. For all three methods of cutting, under equal geometrical parameters of the cutting tool and the physical and mechanical properties of the frozen rock, the numerical value of the tangential component of cutting resistance is obtained. The comparison of the cutting resistance estimated values has shown that cell cutting requires relatively less energy and is preferred during the process of frozen sedimentary rock excavation. During field and laboratory investigations with the use of a multi-purpose cutting stand, a sufficient convergence of the analytical statements with the physics of frozen sedimentary rock cutting process was established. The results of the research allow a more reasonable approach to the adjustment of existing methods for determining the required tractive force and power for the drive of an excavation machine, and, therefore, to the actual efficiency and profitability of work.
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Date submitted2024-05-17
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Date accepted2025-03-27
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Date published2025-03-27
Determination of impact hazard potential of rocks in the Norilsk Industrial Region
The deeper the mineral deposits developments are, the worse the mining and geological conditions become. Significant growth of stress level in the rock mass contributes to possible manifestation of rock pressure in dynamic form. The resulting task of assessment of rock impact hazard is closely related to the task of obtaining more accurate results of compression tests of samples in rigid or servohydraulic test presses using graphs of their full deformation. This approach requires special expensive equipment, considerable time resources, and sufficient core material. Therefore, it is important to have an approach that allows to assess the propensity of rocks to brittle fracture with research methods simple enough not to result in the loss of quality and reliability of the obtained results. This paper presents the results of laboratory tests of rocks from the Norilsk Industrial Region to determine their tensile and compressive strengths. Test methods involved both domestic and foreign standards for determining the value of the brittleness coefficient. The impact hazard potential of rocks was determined using the Kaiser criterion. It is found that the tested lithological types (rich sulfide ores, hornblende, disseminated ores, and gabbro-dolerite rocks), with the exception of anhydrite, have a low impact hazard potential.
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Date submitted2023-10-02
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Date accepted2024-11-07
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Date published2025-03-20
Laboratory studies of hydraulic fracturing of intersecting boreholes in a non-uniform stress field
This study focuses on the features of hydraulic fracture propagation in intersecting boreholes in polymethyl methacrylate blocks in a non-uniform stress field. Glycerol aqueous solution and plasticine were used as the working fluids. According to linear fracture mechanics, a stress concentrator at the borehole intersection contributes to the beginning of crack formation, with further crack propagation occurring in the plane containing their axes. The relevance of this study is due to the search for innovative approaches and the development of technological solutions to address the issue of effective longitudinal crack formation and its further propagation in a rock mass under unfavourable stress field conditions. This paper provides a scheme of laboratory stand operation and a general view of the sealing packers used to isolate a specified interval when performing tests. The graphs of glycerol pressure versus injection time are presented, and the breakdown pressure in the blocks is specified. The shape of fractures formed during the indentation of plasticine into the borehole system was investigated. The findings of physical modelling indicate that longitudinal cracks are predominantly formed in the boreholes. The deviation of the crack trajectory from the vertical plane containing the borehole axes is primarily affected by the magnitude of the horizontal compressive stress field rather than the increase in the angle between them. In addition, the angles of inclination of the longitudinal crack plane measured at its intersection with the side face of the block are specified.
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Date submitted2024-03-20
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Date accepted2024-11-07
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Date published2025-02-27
Analysis of the stress state of rocks transformation near a horizontal well during acid treatment based on numerical simulation
The article presents an overview of the assessment and modelling of the stress state of rocks in the near-wellbore zone of horizontal wells during acid stimulation of the formation for improving the efficiency of oil and gas field development. A numerical finite element model of near-wellbore zone of the reservoir drilled by a horizontal section was compiled using one of oil fields in the Perm Territory as an example. The distribution of physical and mechanical properties of the terrigenous reservoir near the well was determined considering transformation under the action of mud acid for different time periods of its injection. Multivariate numerical simulation was performed and the distribution of horizontal and vertical stresses in near-wellbore zone was determined with regard for different values of pressure drawdown and changes in stress-strain properties depending on the area of mud acid infiltration. It was found that a change in elastic modulus and Poisson's ratio under the influence of acid led to a decrease in stresses in near-wellbore zone. Analysis of the stress distribution field based on the Coulomb – Mohr criterion showed that the minimum safety factor of rock even after the effect of mud acid was 1.5; thus, under the considered conditions of horizontal well modelling, the reservoir rock remained stable, and no zones of rock destruction appeared.
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Date submitted2023-07-31
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Date accepted2024-11-07
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Date published2025-02-25
Environmental assessment of biochar application for remediation of oil-contaminated soils under various economic uses
- Authors:
- Tatiana V. Minnikova
- Sergey I. Kolesnikov
Remediation is an important area of oil-contaminated soil restoration in Russia, since oil refining industry is the major one for Russia and neighbouring countries, and the issues of environmentally effective and economically profitable remediation of oil contamination have not yet been solved. Soils under various economic uses have different surface areas and degrees of soil particles envelopment with oil due to the presence or absence of cultivation, the amount of precipitation and plant litter. The introduction of various substances for remediation into oil-contaminated soils of steppes (arable land), forests, and semi-deserts, considering their differences, gives different results. Biochar is coal obtained by pyrolysis at high temperatures and in the absence of oxygen. The uniqueness of this coal lies in the combination of biostimulating and adsorbing properties. The purpose of the study is to conduct an environmental assessment of biochar application for remediation of oil-contaminated soils under various economic uses. The article compares the environmental assessments of biochar application in oil-contaminated soils with different particle size fraction. The following indicators of soil bioactivity were determined: enzymes, indicators of initial growth and development intensity of radish, microbiological indicators. We found that the most informative bioindicator correlating with residual oil content is the total bacteria count, and the most sensitive ones are the roots length (ordinary chernozem and brown forest soil) and the shoots length (brown semi-desert soil). The use of biochar on arable land and in forest soil (ordinary chernozem and brown forest soil) is less environmentally efficient than in semi-desert soil (brown semi-desert soil). The study results can serve to develop measures and managerial and technical solutions for remediation of oil-contaminated soils under various economic uses.
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Date submitted2023-08-31
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Date accepted2023-12-27
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Date published2024-11-12
Geochemical studies of rocks of the Siberian igneous province and their role in the formation theory of unique platinum-copper-nickel deposits
- Authors:
- Nadezhda А. Krivolutskaya
The Norilsk deposits, unique both in their geological structure and reserves of nickel and platinum, have attracted the attention of researchers for several decades. Several hypotheses have been proposed to explain their formation. Two of them are the most widely accepted: the model of ore formation in an intermediate chamber from picritic melt enriched in sulphides and the formation of sulphides in situ through the assimilation of sulphate-bearing sediments by tholeiitic magma as it rises to the surface. The main questions regarding the genesis of these deposits are: the composition of the parental magmas that formed the ore-bearing massifs; the relationship between intrusions and effusive rocks; and the extent and role of assimilation of host rocks by magmas. These issues are discussed in the article using a large amount of analytical data obtained by the author during the study of the magmatic rocks and geological structures in the Norilsk area. Based on these data, it was concluded that none of the proposed models could fully explain all observed geological features of the deposits as well as the appearance of the unique sulphide ores. In order to solve the problem of the genesis of the Norilsk deposits, it is necessary to analyse the evolution of P3-T1 magmatism over time in the Siberian large igneous province, especially in its eastern part, and to determine its association with ore-forming processes; and its investigating it is a priority task for understanding sulphide ore formation. Solving this task should be based not only on geophysical data but also on studies of the geochemistry of igneous rocks within the province.
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Date submitted2024-04-16
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Date accepted2024-09-24
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Date published2024-11-12
Deep-buried Lower Paleozoic oil and gas systems in eastern Siberian Platform: geological and geophysical characteristics, estimation of hydrocarbon resources
The study of deep-buried oil and gas systems is a promising trend in the preparation of hydrocarbon resources. The study of the factors determining oil and gas potential is extremely important. The Lena-Vilyui sedimentary basin in the eastern Siberian Platform has a potential for the discovery of large oil and gas fields in deep-buried Cambrian deposits. The use of original methodological approaches to the analysis of black shale and overlying deposits, generalization of the results of lithological, biostratigraphic and geochemical studies of Cambrian deposits in territories adjoining the study area, modern interpretation of geophysical data showed that siliceous, carbonate, mixed rocks (kerogen-mixtite) of the Kuonamka complex and clastic clinoform-built Mayan deposits are most interesting in terms of oil and gas potential. Oil and gas producing rocks of the Lower and Middle Cambrian Kuonamka complex subsided to the depths of 14 km. The interpretation of modern seismic surveying data confirms the hypothesis of a limited occurrence of the Upper Devonian Vilyui rift system. Based on generalization of geological, geophysical and geochemical archival and new materials on the Lower Paleozoic deposits of the eastern Siberian Platform, a probabilistic estimation of geological hydrocarbon resources of the Cambrian and younger Paleozoic complexes in the Lena-Vilyui sedimentary basin was performed. Based on basin modelling results it was concluded that the resources were mainly represented by gas. It is presumed that oil resources can be discovered in traps of the barrier reef system as well as on the Anabar and Aldan slopes of the Vilyui Hemisyneclise. With a confidence probability of 0.9, it can be stated that total initial resources of oil and gas (within the boundaries of the Vilyui Hemisyneclise) exceed 5 billion t of conventional hydrocarbons. The recommended extremely cautious estimate of resources of the pre-Permian complexes is 2.2 billion t of conventional hydrocarbons. In the study area, it is necessary to implement a program of deep and super-deep parametric drilling without which it is impossible to determine the oil and gas potential of the Lower Paleozoic.
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Date submitted2024-04-22
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Date accepted2024-09-24
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Date published2024-11-12
On peculiarities of composition and properties of ancient hydrocarbon source rocks
Precambrian rocks are widespread within all continents of the Earth; that said, sedimentary associations of these deposits are of special interest in search for oil and gas fields. A wide range of paleontological, lithological and geochemical methods is utilized for conducting integrated geological-geochemical analysis and evaluating the initial hydrocarbon generating potential of organic matter of Precambrian source rocks. Investigated were peculiarities of depositional environments of the organic matter, specific features of its composition in sedimentary rocks and its generation characteristics. Own research efforts were performed in combination with generalization of other authors’ publications focused on Precambrian sequences enriched in organic matter – their occurrence, isotopic and biomarker characteristics and realization schemes of the hydrocarbon generation potential of Precambrian organic matter in the process of catagenesis. Geochemical peculiarities of initial organic matter are illustrated on various examples, type of the organic matter is determined together with the character of evolution of realization of its initial generation potential.
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Date submitted2021-12-20
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Date accepted2024-05-02
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Date published2024-08-26
A new formula for calculating the required thickness of the frozen wall based on the strength criterion
- Authors:
- Mikhail А. Semin
- Lev Yu. Levin
The study delves into the elastoplastic deformation of a frozen wall (FW) with an unrestricted advance height, initially articulated by S.S.Vyalov. It scrutinizes the stress and displacement fields within the FW induced by external loads across various boundary scenarios, notably focusing on the inception and propagation of a plastic deformation zone throughout the FW's thickness. This delineation of the plastic deformation zone aligns with the FW's state of equilibrium, for which S.S.Vyalov derived a formula for FW thickness based on the strength criterion. These findings serve as a pivotal launchpad for the shift from a one-dimensional (1D) to a two-dimensional (2D) exploration of FW system deformation with finite advance height. The numerical simulation of FW deformation employs FreeFEM++ software, adopting a 2D axisymmetric approach and exploring two design schemes with distinct boundary conditions at the FW cylinder's upper base. The initial scheme fixes both vertical and radial displacements at the upper base, while the latter applies a vertical load equivalent to the weight of overlying soil layers. Building upon the research outcomes, a refined version of S.S.Vyalov's formula emerges, integrating the Mohr – Coulomb strength criterion and introducing a novel parameter – the advance height. The study elucidates conditions across various soil layers wherein the ultimate advance height minimally impacts the calculated FW thickness. This enables the pragmatic utilization of S.S.Vyalov's classical formula for FW thickness computation, predicated on the strength criterion and assuming an unrestricted advance height.
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Date submitted2023-09-29
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Date accepted2023-10-25
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Date published2024-08-26
Laboratory studies of transformation of porosity and permeability and chemical composition of terrigenous reservoir rocks at exposure to hydrogen (using the example of the Bobrikovskii formations in the oil field in the northeast Volga-Ural oil and gas province)
The article describes the methodology for laboratory studies of reservoir rock exposure to hydrogen. The stages of sample research and the instruments used in the experiments are considered. A comparative analysis of the results of studies on porosity and permeability of core samples was performed. It was shown that after exposure to hydrogen, the porosity decreased by 4.6 %, and the permeability by 7.9 %. The analysis of correlation dependencies demonstrated a typical change in the relationship of these characteristics: after the samples exposure to hydrogen the scatter of the values increased and the correlation coefficient decreased, which indicates a change in the structure of the void space. Based on the research results, it was concluded that the decrease in porosity and permeability of the core samples occurred due to their minor compaction under the action of effective stresses. The chemical analysis of the rock showed no major difference in the composition of the basic oxides before and after exposure to hydrogen, which points to the chemical resistance of the studied formation to hydrogen. The experimental results showed that the horizon under consideration can be a storage of the hydrogen-methane mixture.
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Date submitted2022-11-21
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Date accepted2024-05-02
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Date published2024-08-26
M1 formation tectono-structural features and gas-oil potential within Archinskaya area Paleozoic basement (Western Siberia)
- Authors:
- Vladimir B. Belozerov
- Mikhail O. Korovin
Western Siberian Plate basement oil and gas potential evaluation largely depends on structural and stratigraphic complex architecture representation. New modern procedures for seismic data processing, detailed Paleozoic deposits stratigraphic studies and expanded geophysical well logging significantly change the representation of the basement rocks fold-block structure and previously developed hydrocarbon reservoirs models. Detailed studies conducted within the Archinskii uplift showed that Paleozoic sediments form a contrasting folded structure complicated by block tectonics. The significant block displacements amplitude determines the lithological and stratigraphic basement rocks erosional-tectonic surface, while the identified stratigraphic blocks control the oil productivity distribution within the Archinskaya area. The filtration-capacity heterogeneity folded structure of the Paleozoic sediments is reflected in the distribution of hydrocarbon saturation in the well section, forming independent gas, oil, and oil-water zones for the development process. The relationship between anticlinal structural forms of basement rocks to lowered, and synclinal to elevated blocks, determines the necessity to conduct exploration prospecting within younger stratigraphic blocks when assessing the deep Paleozoic oil and gas potential.
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Date submitted2023-11-10
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Date accepted2024-05-02
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Date published2024-08-26
Paleoproterozoic Saltakh Pluton, Anabar Shield: mineralogical composition, age and a geodynamic setting
- Authors:
- Nikolai I. Gusev
- Lyudmila Yu. Romanova
The Saltakh Massif is located in the northern Anabar Shield, in the Saltakh shear-zone. It consists of two-pyroxene schists and plagiogneisses metamorphosed under granulite-facies conditions. Their chemical composition is consistent with that of a differentiated series of rocks ranging from gabbro to tonalites with abundant alaskitic gneissose granite veins and bodies. The rocks are mainly high-potassium (K2O/Na2O > 0.50), high-magnesium (mg# 50-70), low-titanium (TiO2 0.35-1.31 wt.%) with low TiO2 concentration in clino- and orthopyroxene. Normative olivine makes up 6-9 % of metagabbroic rocks. The rocks display well-defined negative Ti, Nb, Ta, and P anomalies typical of subduction magmatism. The two-pyroxene gneisses show high Sr/Y ratios of 67.6-88 and (La/Yb)N of 24.8-25.6. Saltakh rocks are part of a shoshonite series, as indicated by Nb/La, La/Yb, Th/Nb and Ce/Yb ratios. All the rocks display positive εNd(T) values of 1.9-4.1 and εSr(T) of 0.77-17.8 indicative of a mantle source of magma and T(Nd)DM of 2,20-2,26 Ga. U-Pb zircon dating (SHRIMP II) has shown that the protoliths of Saltakh melanocratic rocks were dated at 2100-2086 Ma, and those of two-pyroxene plagiogneisses of tonalite composition were dated at 2025±7 Ma. Alaskitic gneissose granites were dated at 1969±7 Ma. The study of the trace element composition of zircon has revealed general enrichment in LREE. High LREE concentrations are due to secondary zircon alterations and the shoshonitic pattern of the melt, the high-temperature conditions of crystallization, and an anomalous fluid regime. The geodynamic setting in which the Saltakh Massif was formed was consistent with a pericontinental magmatic arc. The formation of alaskitic gneissose granites was due to anatexis provoked by later collision processes. Saltakh magmatic rocks were formed simultaneously with magmatic rocks from the Khapchan prospect which occur farther south, and were studied earlier (2095±10 Ma tholeiitic metadiorites and 2030±17 Ma calc-alkaline metatonalites). We interpret them as part of a metamorphosed juvenile Paleoproterozoic suprasubduction complex.
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Date submitted2023-07-27
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Date accepted2024-06-03
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Date published2024-12-25
Normalized impulse response testing in underground constructions monitoring
Impulse Response testing is a widespread geophysical technique of monolithic plate-like structures (foundation slabs, tunnel lining, and supports for vertical, inclined and horizontal mine shafts, retaining walls) contact state and grouting quality evaluation. Novel approach to data processing based on normalized response attributes analysis is presented. It is proposed to use the energy of the normalized signal calculated in the time domain and the normalized spectrum area and the average-weighted frequency calculated in the frequency domain as informative parameters of the signal. The proposed technique allows users a rapid and robust evaluation of underground structure’s grouting or contact state quality. The advantage of this approach is the possibility of using geophysical equipment designed for low strain impact testing of piles length and integrity to collect data. Experimental study has been carried out on the application of the technique in examining a tunnel lining physical model with a known position of the loose contact area. As examples of the application of the methodology, the results of the several monolitic structures of operating municipal and transport infrastructure underground structures survey are presented. The applicability of the technique for examining the grouting of the tunnel lining and the control of injection under the foundation slabs is confirmed. For data interpretation the modified three-sigma criteria and the joint analysis of the attribute’s behavior were successfully used. The features of the field work methodology, data collection and analysis are discussed in detail. Approaches to the techniques' development and its application in the framework of underground constructions monitoring are outlined. The issues arising during acoustic examination of reinforced concrete plate-like structures are outlined.
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Date submitted2023-05-19
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Date accepted2024-03-05
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Date published2024-08-26
Development and research of backfill compounds with improved elastic and strength properties for oil and gas well lining
This article describes operations from the well construction cycle where the cement rock behind the casing is subjected to dynamic action (impacts of the drill stem during drilling and normalization of the cement sleeve, secondary drilling operations, hydraulic fracturing, etc.). The developed cement mortar compositions were tested following API 10B-2, API 10B-6, API STD-65-2, and GOST 28985-91 standards. The composition of the cement system without the use of imported components (CM-5) was developed, which improved elastic and strength properties compared to existing industry solutions. An improvement in the elastic and strength features and technological properties of cement rock when using epoxy resins was identified, the optimal composition of the cement-and-epoxy grout was determined, and the internal structure of the formed backfill rock, its permeability, and porosity were studied.
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Date submitted2023-11-02
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Date accepted2024-03-05
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Date published2024-08-26
The polyphase Belokurikhinsky granite massif, Gorny Altai: isotope-geochemical study of zircon
Based on the isotopic-geochemical analyses of zircons from granites of the Belokurikhinsky massif in the Gorny Altai using the U-Pb method, the ages of three intrusion phases have been determined for the first time: the age of the first phase refers to the time interval of 255-250 Ma, the second and the third phases have similar ages of about 250 Ma. The formation time of the Belokurikhinsky massif is estimated as not exceeding 5-8 Ma. The δ18O values for zircons from granites of the second and the third intrusion phases average around 11.5-12.0 ‰, indicating a significant contribution of a crustal component in the formation of the parent melts for granites of these phases. The crystallization temperature values of the zircons by the Ti-in-zircon thermometer for three phases range from 820 to 800 °C. The P-T crystallization parameters of titanite from the first phase, determined using a titanite thermobarometer, average around 770 °C and 2.7 kbar. The zircons from the first phase mostly exhibits geochemical characteristics of typical magmatic zircons. The zircons from the second and the third intrusion phases either may be unaltered magmatic zircons or enriched in incompatible elements (LREE, Th, U, Ti, Ca, etc.) due to fluid influence, resembling hydrothermal-metasomatic type zircons in terms of their geochemical characteristics. A number of zircon grains from the second and the third phases of granites demonstrate anomalous geochemical characteristics – the REE distribution spectra atypical for zircons (including “bird's wing” type spectra with oppositely tilted of light and heavy REE distribution profiles), as well as significantly higher contents of certain trace elements compared to other varieties. Such an enriched zircon composition and wide variations in the incompatible element content are due to non-equilibrium conditions of zircon crystallization and evolution of the fluid-saturated melt composition during the final stages of the massif formation.
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Date submitted2023-08-02
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Date accepted2023-12-27
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Date published2024-04-25
Justification of the approaches to improve management strategy of the mining system based on the analysis of data on the mining of complex structural rock blocks
Long-term activity of mining enterprises causes the necessity to substantiate the strategies of management of the mining and technical system functioning in terms of improvement of ore quality control, which is determined by its change in the course of field development due to the priority development of the main reserves and, as a consequence, forced transition to the mining of complex structural rock blocks with a decrease in the recovery percentage, which is typical in case the ore component meets the requirements of the feasibility study in terms of grade at substandard capacity. In this case, it is possible to identify the recovery percentage and the potential for its increase by analyzing the long-term activity of the mining and industrial enterprise, namely, by analyzing the data of mining complex structural rock blocks with the subsequent establishment of the relationship between the primary data on mining and geological conditions and information on the quality of the mineral obtained from the technological equipment. Therefore, the purpose of the research was to substantiate the necessity of improving the management strategy of the mining-technical system functioning, which consists in the fact that on the basis of analyzing the mining data of complex structural rock blocks it is possible to determine the ore mass losses and their quantity and to lay the basis for the development of decisions on its extraction. For this purpose, the collected data on the mining of complex structural rock blocks, accounting the geological and industrial type of extracted ores, were considered in modeling the conditions and studying the parameters of technological processes, the implementation of which provides additional products. It was revealed that the ore mass from substandard thickness layers is delivered to the dumps, and ore mass losses have been estimated at 25-40 % per year. It is proved that determination of ore mass losses based on the analysis of data on mining of complex structural rock blocks, as well as timely solution of this issue can significantly increase the production efficiency of mining and technical system. Taking into account for the results obtained, the options for optimizing the production of the mining and engineering system were proposed.
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Date submitted2022-10-29
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Date accepted2023-10-25
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Date published2024-04-25
Assessment of rock massif sustainability in the area of the underground research laboratory (Nizhnekanskii Massif, Enisei site)
The study presents the results of the research on geodynamic and geological conditions of the Enisei site (Krasnoyarsk Krai), chosen for the construction of an underground research laboratory. The laboratory is being built at a depth of 500 m to assess the suitability of the rock mass for burying high-level radioactive waste. The rocks consist of weakly fractured gneisses, granites, and dikes of metadolerites. Field observations were conducted on bedrock outcrops. They included the determination of rock mass quality indicators, measurement of rock fracturing, and a rating classification of stability using N.Barton's method. GNSS observations were also made to monitor surface deformations. These data were used to develop a three-dimensional structural model, including lithology, fault disruptions, intrusive bodies, elastic-strength properties of rocks, and the sizes of zones influenced by faulting. It will serve as a basis for boundary conditions and the construction of three-dimensional variational models of stress-strain states, identifying zones of concentration of hazardous stresses, and planning in situ geomechanical experiments in underground mines of the laboratory. The obtained values of the modified QR index for the main types of rocks allowed their classification as stable and moderately stable, corresponding to strong and very strong rocks on Barton's scale and the massif rating according to geomechanical classification.
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Date submitted2023-03-14
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Date accepted2023-10-25
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Date published2024-04-25
Predictive assessment of ore dilution in mining thin steeply dipping deposits by a system of sublevel drifts
The purpose of research is the study of stress-strain state of marginal rock mass around the stope and predictive assessment of ore dilution with regard for changes in ore body thickness in mining thin ore deposits on the example of the Zholymbet mine. Study of the specific features of the stress-strain state development was accomplished applying the methodology based on numerical research methods taking into account the geological strength index (GSI) which allows considering the structural features of rocks, fracturing, lithology, water content and other strength indicators, due to which there is a correct transition from the rock sample strength to the rock mass strength. The results of numerical analysis of the stress-strain state of the marginal part of the rock mass using the finite element method after the Hoek – Brown strength criterion made it possible to assess the geomechanical state in the marginal mass provided there are changes in ore body thickness and to predict the volume of ore dilution. It was ascertained that when mining thin ore deposits, the predicted value of ore dilution is influenced by the ore body thickness and the GSI. The dependence of changes in ore dilution values on the GSI was recorded taking into account changes in ore body thickness from 1 to 3 m. Analysis of the research results showed that the predicted dimensions of rock failure zone around the stopes are quite large, due to which the indicators of the estimated ore dilution are not attained. There is a need to reduce the seismic impact of the blasting force on the marginal rock mass and update the blasting chart.
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Date submitted2022-05-20
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Date accepted2023-06-20
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Date published2024-02-29
Increasing the quality of zeolite-bearing rocks from Eastern Transbaikalia by applying directed energy
This paper presents the use of accelerated electrons to treat zeolite-bearing rocks from Eastern Transbaikalia to increase the efficiency of separating zeolites from rock-forming minerals via electromagnetic separation. The effectiveness of the liberation of zeolite minerals using accelerated electrons was analyzed. The results of dry electromagnetic separation of zeolite-bearing rocks are presented. The dependence of the extraction of iron-bearing minerals from zeolite-bearing rocks by electromagnetic separation on the magnetic field intensity for different particle sizes has been established. The main methods of zeolite-bearing rock enrichment and ore preparation were determined. A technological scheme for processing zeolite-bearing rocks, based on the use of accelerated electron treatment at the ore preparation stage, is presented, significantly improving the zeolite production quality.
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Date submitted2023-02-07
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Date accepted2023-06-20
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Date published2024-02-29
Origin of carbonate-silicate rocks of the Porya Guba (the Lapland-Kolvitsa Granulite Belt) revealed by stable isotope analysis (δ18O, δ13C)
- Authors:
- Dmitrii P. Krylov
- Ekaterina V. Klimova
Carbonate-silicate rocks of unclear origin have been observed in granulites of the Porya Guba of the Lapland-Kolvitsa Belt within the Fennoscandinavian Shield. The present work aims to reconstruct possible protoliths and conditions of metamorphic transformation of these rocks based on oxygen and carbon isotopic ratios combined with phase equilibria modeling. Isotope analysis and lithochemical reconstructions suggest that carbonate-silicate rocks of the Porya Guba represent metamorphosed sediments (possibly marls) with the isotopic composition corresponding to the Precambrian diagenetically transformed carbonates (δ18O ≈ 17.9 ‰, SMOW and δ13C ≈ –3.4 ‰, PDB). The chemical composition varies depending on the balance among the carbonate, clay, and clastic components. Significant changes of the isotopic composition during metamorphism are caused by decomposition reactions of primary carbonates (dolomite, siderite, and ankerite) producing CO2 followed by degassing. These reactions are accompanied by δ18O and δ13C decrease of calcite in isotopic equilibrium with CO2 down to 15 ‰ (SMOW) and –6 ‰ (PDB), respectively. The isotopic composition is buffered by local reactions within individual rock varieties, thus excluding any pronounced influence of magmatic and/or metasomatic processes.
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Date submitted2022-11-29
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Date accepted2023-03-02
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Date published2023-10-27
New data on the composition of growth medium of fibrous diamonds from the placers of the Western Urals
This article presents the results of studying microinclusions of fluids/melts in diamonds from the placers of the Krasnovishersky District (western slope of the Middle/Northern Urals), which make it possible to establish the evolution of diamond-forming media in the subcontinental lithospheric mantle of the eastern margin of the East European craton. Impurity composition of the studied crystals reveals three different types of diamonds, the formation of which was associated with separated metasomatic events. Microinclusions in B-type diamonds containing A and B nitrogen defects reflect an older metasomatic stage characterized by the leading role of silicic and low-Mg carbonatitic fluids/melts. The second stage is associated with the growth of A-type diamonds containing nitrogen exclusively in the form of A-centers. At this stage, the formation of diamonds was related with low-Mg carbonatitic media, more enriched in MgO, CaO, CO2, and Na2O compared to B-type diamonds. The third stage probably preceded the eruption of the transporting mantle melt and led to the formation of C-type diamond containing A and C nitrogen defect centers and microinclusions of silicic to low-Mg carbonatitic composition. The recorded trend in the evolution of diamond-forming fluids/melts is directed towards more carbonatitic compositions. Fluids/melts are probably sourced from eclogitic and pyroxenitic mantle substrates.
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Date submitted2022-08-24
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Date accepted2023-02-15
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Date published2023-08-28
Modelling of the stress-strain state of block rock mass of ore deposits during development by caving mining systems
The article is devoted to the analysis of approaches to modeling the stress-strain state of a block rock mass in the vicinity of a single mine workings and in the area of rock cantilever influence during the development of the Khibiny apatite-nepheline deposits. The analysis of the existing in international engineering practice ideas about tectonic disturbances as a geomechanical element and the experience of predicting the stress-strain state of a block rock mass was carried out. On the basis of the analysis, the formulation of the basic modeling tasks is carried out and its main results are presented. Methodological recommendations for solving similar problems were developed.
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Date submitted2022-12-01
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Date accepted2023-01-19
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Date published2023-12-25
Inclusions of diamond crystals in the tourmaline of the schorl-uvite series: problems of genesis
The mineralogical and geochemical features of diamond-bearing tourmaline crystals (schorl-uvite series) from garnet-clinopyroxene rocks of the Kumdy-Kol deposit (Northern Kazakhstan) have been studied in detail. The formation of the main rock-forming minerals (garnet + K-bearing clinopyroxene) occurred in the diamond stability field at 4-6 GPa and 950-1000 °C. Crystallization of K-bearing clinopyroxene at these parameters is possible in the presence of an ultra-potassic fluid or melt formed because of crustal material melting in subduction zones. Tourmaline crystals (up to 1 cm) containing diamond inclusions perform veins crosscutting high-pressure associations. The composition of individual zones varies from schorl to uvite within both a single grain and the sample as a whole. The potassium content in this tourmaline does not exceed 0.1 wt.% K2O, and the isotopic composition of boron δ11B varies from –10 to –15.5 ‰, which significantly differs from the previously established isotopic composition of boron in maruyamaite crystals (δ11B 7.7 ‰ in the core and –1.2 ‰ in the rim) of the same deposit. Analysis of the obtained data on δ11B in the tourmalines from the diamond-grade metamorphic rocks within the Kumdy-Kol deposit suggests the existence of two boron sources that resulted in crystallization of K-bearing tourmaline crystals (maruyamaite-dravite series) and potassium-free tourmalines of the schorl-uvite series.
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Date submitted2021-10-31
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Date accepted2023-03-02
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Date published2023-12-25
Improvement of technological schemes of mining of coal seams prone to spontaneous combustion and rock bumps
On the example of the Alardinskaya mine, the problem of underground mining of seams prone to spontaneous combustion and rock bumps in the conditions of the Kondomsky geological and economic region of the Kuznetsk coal basin is considered. The contradictions in the requirements of regulatory documents for the width of the inter-panel coal pillars in the mining of seams with longwalls in conditions of endogenous fire hazard and in the mining of seams that are dangerous due to geodynamical phenomena are discussed. These contradictions impede the safe mining of seams using traditionally used layouts with the danger of spontaneous combustion of coal and rock bumps. A mining-geomechanical model is presented, which is used for numerical three-dimensional simulation of the stress-strain state of a rock mass with various layouts for longwall panels using the finite element method. The results of the numerical analysis of the stress state of the rock mass immediately before the rock bump are presented, and the main factors that contributed to its occurrence during the mining of the seam are established. A dangerous degree of stress concentration in the coal seam near the leading diagonal entries is shown, especially in conditions of application of abutment pressure from the edge of panels’ gob. The analysis of the features of stress distribution in the inter-panel pillar at different widths is carried out. Recommendations for improving the layout for the development and mining of coal seams that are prone to spontaneous combustion and dangerous in terms of rock bumps in the conditions of Alardiskaya mine have been developed. The need for further studies of the influence of pillars for various purposes, formed during the mining of adjacent seams, on the stress-strain state of previously overmined and undermined seams is shown.