Rock Content Research Articles

Методика прогнозирования зон скопления сероводорода в сильвинитовых пластах калийных рудников и экспресс-определения газоносности пород по сероводороду

Intensification of potash salt mining, widespread use of high-performance continuous miners, involvement of gasbearing formations in mining are accompanied by release of natural poisonous gases into the atmosphere of mine workings, which explains the need to ensure safe working conditions for the miners. The article presents the researche results that helped to develop a methodology for predicting accumulation zones of one of the most hazardous poisonous gases, i.e. hydrogen sulfide. A correlation was established between the hydrogen sulfide concentration, presence of organic substances and the content of magnesium chloride in the rocks. The article describes methods to determine the accumulation areas of hazardous sulfurcontaining gases based on the trench sampling and laboratory test data, which makes it possible to take timely protective measures to ensure safety of the miners. The developed method is based on creation of the correlation fields for various geochemical attributes such as the NaCl, KCl, MgCl2 content and others. A close correlation between the content of organic carbon in the rocks and magnesium chloride indicates the degree of salt recrystallization, as evidenced by an increase in the hydrogen sulfide content. In addition, the article describes an express method to determine the gas content in rocks, which enables a quick and accurate assessment of hydrogen sulfide concentration directly in the mine workings, thus providing the possibility of prompt response to the hazards. Thus, the methodology proposed by the authors serves not only to identify the potentially hazardous areas, but also to prevent dangerous situations associated with the release of poisonous gases in potash mines. The research and practical approaches described in the article as well as the developed recommendations contribute to enhancing the efficiency of mine ventilation, which in turn leads to minimization of the risks to health and life of the miners.

Необходимость и область применения нержавеющих анкеров

Corrosion wear of the rock bolt elements with loss of their bearing capacity is sometimes observed in operation of the rock bolt support. Studies carried out in the mine workings secured with resin grouted rebar bolts allowed us to determine the patterns of corrosion wear of the rock bolt elements and measures to prevent it. Development of the rock bolt element corrosion is observed when they are moistened. The probability of free water content in the roof rocks increases with the growth of rock fracturing. The rate of the corrosion process increases with a decrease in the hydrogen index of water. Analysis of possible ways to prevent rock bolt support failures caused by the corrosion wear revealed that the most economical of them is the application of anti-corrosion coatings on the rock bolt support elements. Technical requirements were developed for the means of anti-corrosion protection of the metal rock bolt supports, they were selected among the anti-corrosion means available in the market of the Russian Federation, and their mine tests were carried out as the anti-corrosion coatings of the rock bolts in the most aggressive mine environment. According to the results of the mine tests, one anti-corrosion medium was identified that successfully passed the tests. The anti-corrosion coating created with this medium did not fail, corrosion failure of the rock bolt support elements was not observed. According to the test results, it was concluded that the anti-corrosion coating can prevent the failure of the rock bolt support operation. The field of application for stainless rock bolts is mine workings with long service life of the rock bolt support when the roof rocks are saturated water which pH < 7. The economic effect of using the rock bolts with anti-corrosion coating would amount to 6.6 million rubles/km. On average, only 4.2% of the rock bolts supplied to mines should have an anti-corrosion coating. It is possible to predict the need for the use of stainless rock bolts before driving the mine working, which will allow determining the necessary volume of their purchase in advance.

Failure analysis of soil-rock mixture slopes using coupled MPM-DEM method

A 3-D concurrent MPM-DEM (material point method - discrete element method) scheme is proposed and developed in this paper to simulate soil-rock mixture slopes. The MPM and DEM are treated as two individual parts linked by the coupled contact force. Compared with MPM, the proposed MPM-DEM scheme provides a more realistic contact detection. Compared with DEM, the scheme can model such cases more efficiently and conveniently. Based on the characteristics of the soil-rock mixture, a CPU-GPU concurrent solving scheme is introduced, which can improve the efficiency and make full use of the computational resources of both GPU and CPU. The accuracy of the MPM-DEM scheme is validated by three benchmark examples, i.e., a block sliding on an inclined plane, granular flow impacting blocks, and collapse of hybrid granular columns. The failure mode and sliding distance of soil-rock mixture slopes are analyzed using the proposed MPM-DEM scheme and compared to a pure MPM. Influencing factors such as soil-rock friction and cohesion, rock content, and rock size are studied. The results indicate that this scheme can well capture the soil-rock interface and deal with complex interactions between soil and rock.

Triassic Thermal Pulse of TARIM Mantle Plume: Evidence from Geochronology, Geochemistry, and Nd Isotopes of the Mafic Dikes from the Halaqi Area, Xinjiang, China

Owing to the paucity of research on synchronous mafic rocks in the Tarim Basin, the late Paleozoic–early Mesozoic tectonic development of this region is not well defined. The Halaqi region is situated on Tarim’s northwest edge, and numerous mafic dikes can be found cross-cutting the Permian strata. The whole-rock geochemistry, zircon U–Pb age, and Sr–Nd isotopic signature of these mafic rocks have never been reported before, and this contribution can offer geochronological and petrogenetic investigations that provide fresh insight into the geodynamic development of the area. Major oxide contents in the Halaqi mafic rocks vary, including SiO2 (45.74–50.31 wt.%), Al2O3 (13.28–14.8 wt.%), FeOT (16.48–19.19 wt.%), MgO (7.58–10.32 wt.%), CaO (7.19–12.39 wt.%), Na2O (2.97–4.50 wt.%), K2O (0.24–0.63 wt.%), TiO2 (1.11–1.29 wt.%), MnO (0.14–0.16 wt.%), and P2O5 (0.13–0.17 wt.%). The mafic rocks are enriched in high-field-strength elements (e.g., Zr and Hf) and large-ion lithophile elements (e.g., Sr, Th, and U) but depleted in Nb, Ta, and P. The total REEs in the rocks are lower (ΣREE = 72.80–86.85 ppm), and HREEs are somewhat depleted in comparison to LREEs, with positive Eu anomalies (Eu/Eu* = 1.05–1.17) but weak negative Ce anomalies (Ce/Ce* = 0.91–0.93). Zircon U–Pb ages of 201–247 Ma were obtained from a total of 18 magmatic zircon grains found in the mafic rocks that were studied. These results point to a middle-to-late Triassic emplacement. The mafic dikes exhibit somewhat enriched Nd isotopic compositions (εNd(t) = –1.6~–0.2) and an older Nd model age (TDM = 1.24–1.37 Ga). The Halaqi middle–late Triassic mafic dikes are thought to have originated from the same tectonic background as the Permian Tarim Large Igneous Province, along with similar geochemical and isotopic compositions. This suggests that they are all products of the interaction between asthenospheric and lithospheric mantles in an intraplate extensional environment. Research indicates that the Triassic mafic magmatism in northwest Tarim could be the product of the continuous thermal pulse of the Tarim mantle plume and be a part of the Tarim LIP.

Experimental simulation of thermal evolution of nitrogen content and isotopes in source rocks: Implications for nitrogen cycling characterization and oil-source correlation

Sedimentary nitrogen isotopes have been widely used to reconstruct the nitrogen cycling and redox characteristics of ancient oceans, but they also have important value in the study of oil genesis, such as oil classification. However, the thermal evolution of nitrogen isotopes in the source rock and associated oil is currently unclear. In this study, the thermal evolution (from the oil generation to the dry gas stage) of three types of low-maturity source rock was simulated. And the content and isotope composition of total organic carbon (TOC) and total nitrogen (TN) of the pyrolyzed source rock, expelled oil and retained oil were measured. In combination with weight-quantitative analyses, the following conclusions can be drawn: (1) During the main oil and gas generation stage, the pyrolyzed source rocks lost 15.1–28.3% of TN, which is much lower than the loss of TOC (26.2–46.1%). This difference may be related to the fact that the TOC content of the generated oil and gas is two orders of magnitude higher than the TN. In addition, TOC loss occurred mainly within the oil generation-expulsion stage, whereas TN loss occurred mainly in the dry gas stage and higher maturity stage. (2) The nitrogen isotope compositions of three types of source rocks and associated kerogens became heavier by 0.5–1.5‰ as thermal maturity increased, which is similar to the change of organic carbon isotope compositions. The δ15N values of pyrolyzed source rocks generally have poor relationships with either the amount of expelled oil and gas or the TN loss, which is different from the δ13Corg values. The δ15N fluctuations may be attributed to three processes: oil generation-expulsion, N2 gas generation-expulsion, and inorganic N (like NH4+) expulsion. The bulk nitrogen isotope composition of source rocks is only slightly affected by thermal maturity and can be used to indicate the nitrogen biogeochemical cycle and water redox conditions during the deposition. (3) Similar to δ13Corg values, δ15N values of both expelled oil and retained oil increased gradually with enhanced thermal maturity, implying a control of kinetic isotope effect. Among the three types of source rock, two of them having relatively light nitrogen isotope compositions (δ15N value of ∼2.5‰) generated and expelled oils with similar nitrogen isotope compositions, while the third type, which has heavy nitrogen isotope composition (δ15N value of ∼13.0‰), generated and expelled oils with much lighter nitrogen isotope compositions (by 3–6‰). This finding shows that there may be significant nitrogen isotope fractionation during the generation and primary migration of oil from source rocks. The nitrogen isotopes should be used in oil-source correlation with caution, even though related mechanisms need to be further studied. Nevertheless, using a combination of organic carbon and nitrogen isotopes, the oil generated and expelled by the three types of source rocks could be distinguished. Therefore, the use of nitrogen isotopes for oil-source correlation under geological conditions should be combined with other isotope and molecular indicators.

Study on meso‑mechanical properties and failure mechanism of soil-rock mixture based on SPH model

This study adopts the Smoothed Particle Hydrodynamics (SPH) technique to accurately and efficiently replicate and forecast the mesoscopic behavior of soil-rock mixtures (SRM). It introduces a novel approach for generating rock blocks within the SRM, utilizing a method that randomly selects angles and lengths. In addition, this research proposes a method for discretizing any shaped region into free particles with specific material attributes, named the regional medium particle discretization method. It incorporates the Drucker-Prager constitutive model to develop the SPH numerical model for SRM. Furthermore, it examines the effects of different rock sizes and rock contents on the SRM's failure characteristics and mechanical properties. The findings revealed that, for identical rock contents, smaller rock samples exhibit a more dispersed failure surface with numerous secondary shear bands, whereas larger rock samples display a smoother and more concentrated failure surface. As the rock content decreases, shear bands typically form in the sample's center and are relatively straight. However, as the rock content increases, the shear bands' configuration becomes more intricate, often featuring multiple shear bands. This method offers a fresh perspective for exploring the mechanical properties of heterogeneous materials.

Genesis and metallogenic potential of the ca.90 Ma Jiangcisha magmatic rocks in the western Shiquanhe suture zone, Xizang, China

Numerous mineral deposits related to the ca.90 Ma magmatic activity were found in the northern and central Lhasa terrane. Recently, many Late Cretaceous intermediate and felsic magmatic rocks were discovered in the Jiangcisha area in the western Shiquanhe-Nam Tso Mélange Zone, separating the Lhasa terrane into northern and central subterranes. In this study, zircon UPb dating, whole-rock major and trace element geochemistry, zircon Hf isotopes and trace element compositions are used to determine the petrogenesis and mineralization potential of the Jiangcisha intermediate and felsic magmatic rocks. The zircon UPb ages of the diorite porphyry, dacite porphyry, and diorite sample are 92.2 ± 1.6 Ma, 90.0 ± 1.3 Ma, and 85.8 ± 1.7 Ma, respectively. The diorite porphyry and diorite samples have A/CNK values ranging from 0.65 to 0.91 and show elevated Mg# (44.78–53.11), Cr (108–338 ppm) and Ni (53.2–119 ppm) concentrations. These rocks also have high Sr/Y values (30.37–58.03) and low Rb/Sr ratios (0.04–0.33), with weak negative Eu anomalies (δEu = 0.75–0.95). Based on these values, these samples are high-Mg# calc-alkaline and metaluminous adakitic rocks. The dacite porphyry has a high SiO2 content (73.54–74.07 wt%) and significant negative Eu (δEu = 0.69–0.73) and Sr anomalies. Their Sr contents are 10 times lower than those of the diorite porphyry and diorite samples. The zircon εHf(t) values of these three magmatic rocks are high (7.61–12.69), and the Hf isotope two-stage model ages are young (0.41–0.78 Ga). The geochemical characteristics mentioned above indicate that the diorite porphyry and diorite were derived from the partial melting of the delaminated juvenile lower crust. However, the dacite porphyry is the product of plagioclase and K-feldspar fractional crystallization from the diorite porphyry. The zircons in the diorite porphyry and diorite samples have low Ce/Nd (3.66–29.04), logfO2 (−16.022-–12.976), and ΔFMQ (0.08–1.99) values and moderate Dy/Yb (0.22–0.37), 10,000 × δEu/Y (1.48–9.66), and (Ce/Nd)/Y (0.0025–0.0224) ratios. Compared to typical large porphyry-skarn CuAu deposits with dioritic rocks developed in the Tibetan Plateau, the relatively low oxygen fugacity and magma water content of the Jiangcisha dioritic rocks indicate their limited potential to form large porphyry and skarn CuAu deposits.

An appraisal of the observed crystallinities of volcanic materials

There is a broad consensus that magma eruptibility—the ability of magma stored in the subsurface to erupt onto Earth's surface—is strongly controlled by viscosity. Related to this, a critical parameter that controls viscosity is crystallinity. However, there is uncertainty in the crystallinities that distinguish eruptible from non-eruptible magmas, and whether highly crystalline magmas (>60 vol.%) could be erupted in some conditions. An underutilized but important source of information for understanding this relationship is the observed crystallinities in erupted volcanic materials, which by definition represent a set of eruptible magmas. Here we present a compilation of reported crystallinities for nearly 1000 volcanic samples of differing composition, tectonic setting, and eruption style, which provides valuable insight into the fundamental mechanisms which drive eruptions. Overall, the 95th percentile crystallinity value of our full dataset is 57 vol.%, and \>99 % of all non-dome samples have crystallinity ≤53 vol.%. This suggests that 50–60 vol.% crystallinity represents a fundamental limit for eruptibility for most volcanic rocks. Some dome samples are clear exceptions to this and are erupted with considerably higher crystallinities. There is also a significant correlation between crystallinity and whole rock SiO2 content as observed previously, but a shallow slope suggests whole rock and melt silica content have less impact on critical crystallinity for erupted magma than previously thought. Melt viscosity (as a function of SiO2, temperature, and H2O content) and crystallinity both play important roles on increasing effective viscosity, where melt viscosity plays a more important role at low crystal fractions, and crystallinity plays a more important role at crystallinities greater than ~40 vol.%.

Stability Analysis of Soil and Rock Mixed Slope Based on Random Heterogeneous Structure

Due to the complexity in the heterogeneous internal structure and interactions between rocks and soil, the slide of soil–rock mixed slope is usually more complex than that of a homogeneous soil slope. This paper investigated the stability of soil–rock mixed slopes with finite element method (FEM) based on random heterogeneous structure. An image-aided approach was used to generate the 2-D and 3-D digital rocks to ensure the morphology of digital rocks was similar with the real rocks. The 2-D and 3-D soil–rock mixed slopes were then generated by placing the digital rocks into the soil matrix. The generated heterogeneous structures of soil–rock mixed slope were imported into ABAQUS for numerical analysis. The effect of rock content, spatial distributions, material properties, and rock–soil interface on the stability of soil–rock mixed slopes were analyzed. Results show that the stability factor of the soil–rock mixed slope increases with the increase of rock content. The rocks can play a certain degree of antislide effect in the slope. The uneven spatial distribution of rocks has effect on the overall stability of soil–rock mixed slope. This effect is more significant when the rock content is moderate. Rocks distributed in the middle layer of the slope may improve the overall antisliding performance of the slope. The stability factor decreases with the increase of rock density. While the effect of rock elastic modulus on stability of soil–rock mixed slope is relatively limited. The contact condition at the soil–rock interface has effect on the overall stability of soil–rock mixed slope. It is recommended to properly determine the interface properties for stability analysis of soil–rock mixed slope.

Study on the impact of physical characteristics of soil-rock composite medium on its relative permittivity based on laboratory experiments

The permittivity of soil-rock composite media is crucial for interpreting data originating from geophysical surveys such as ground-penetrating radar (GPR) imaging. At present, relevant theoretical research on the correlation analysis between the electrical and physical parameters of soil-rock composite media has not yet resulted in a complete reference system. This makes it difficult to characterize soil-rock composite media using the electromagnetic characteristic parameters of rock and soil media. In this study, the indoor electromagnetic testing method was used to extract electrical parameters such as the relative permittivity of soil-rock composite, and the influence of water content, density, soil-rock ratio, and other factors on the electrical parameters of soil-rock composite medium was analyzed. Furthermore, an artificial neural network prediction model was established, and the accuracy of the model was evaluated. The results showed that the relative permittivity tends to decrease with an increase in saturation when the moisture content of the mixture is high. The rock has a lower permittivity value than the surrounding soil particles. When the rock content increases, the average permittivity and conductive permittivity of the composite medium decreases. The main factors affecting the electrical properties of soil-rock composite media (in order of their influence, from most to least) are water content, compaction degree, and soil-rock ratio. These results provide a reliable reference for field geophysical exploration.

Research on the Road Performance of Carbonaceous Mudstone Soil-Rock Mixtures under Multifactor Influence

To investigate the effects of compaction (K), rock content (RC), and wet-dry cycle (WD) on the road performance of carbonaceous mudstone soil-rock mixtures (CMSRM), orthogonal tests were designed to measure the unconfined compressive strength (UCS) and California bearing ratio (CBR). The correlation degree of K, RC, and WD with the UCS and CBR of CMSRM was investigated using orthogonal theory and grey correlation theory. Based on multivariate nonlinear regression analysis, mathematical models of the road performance of CMSRM were built. The results show that the UCS and CBR of CMSRM were positively correlated with K and negatively correlated with the WD. With increasing RC, UCS increased at first and then decreased, while CBR increased continuously. The failure modes of CMSRM change from tensile failure to shear failure as the K increases under uniaxial compression. The RC and WD affect the structural integrity of the failed samples. Combining the results of range analysis, variance analysis, and grey relational analysis, the most significant influence on the UCS is K, and the most significant influence on the CBR is RC. It is recommended to select 94%–96% for K and 40%–60% for RC in engineering.

Re-using excavated rock from underground tunneling activities to develop eco-friendly ultrahigh performance concrete

Excavated rock from underground tunneling activities constitutes a significant portion of the overall construction and demolition (C&D) waste, yet its efficient reuse is challenging. Here we propose an integrated approach combining the utilization of the excavated rock and the production of an eco-friendly ultra-high performance concrete (UHPC). As the first steps to assess the feasibility of the approach, the workability, mechanical properties, fracture toughness test, phase stability and shrinkage of the UHPC were comprehensively studied. The results show that increasing excavated rock content in UHPC leads to a reduction in flowability but improves flexural performance with the enhancement of phase stability. However, this enhancement effect diminishes with larger excavated rock sizes. The compressive strength of the mixture with 400 kg/m³ dosage and 5–10 mm size range achieve 104.1 MPa, which is better than the reference UHPC. Meanwhile, elevated excavated rock content obviously reduces UHPC shrinkage, notably within size 5–10 mm. In addition, an overall assessment was performed to evaluate the UHPC from both environmental and economic perspectives. The results indicate that incorporating excavated rock as aggregates into UHPC can result in cost savings of up to 9.5%, an 11% reduction in embodied energy, and a 15.5% decrease in embodied carbon. Additionally, this integration can yield superior properties compared to reference UHPC. This approach also reduces dependence on natural aggregates, promoting sustainability.

New data-driven estimation of metal element in rocks using a hyperspectral data and geochemical data

The inversion of Cu contents in rocks based on hyperspectral remote sensing is indicative of geochemical exploration as well as mineral resource exploration. Due to the strong redundancy of band information in hyperspectral data, characteristic band selection is the key to improving the accuracy of metal element inversion models in hyperspectral data. In this study, we proposed a framework that innovatively focuses on secondary screening method (SSM) as the core, allowing users to add different data preprocessing methods and machine learning algorithms to the framework based on expert experience, to obtain high-precision metal element inversion models suitable for sampling data. we first preprocessed the measured spectral curves using the first order derivative, second order derivative, continuum removal, multiple scattering correction and variance analysis to highlight band absorption characteristics. In addition, we performed SSM to obtain Cu-related characteristic bands, which were further used as input data to train and compare the performance of Partial Least Square Regression (PLSR), Support Vector Regression (SVR), Multi-Layer Perceptron (MLP), Random Forest (RF) and Gradient Boosting Regression Tree (GBRT). The results show that both the spectral pretreatment and modeling method could potentially impact the inversion accuracy. The accuracy of the ensemble method applied in fresh faces data (i.e., a CR-SSM-RF with R2 values of 0.77 and CR-SSM-GBRT with R2 values of 0.81) performed better than other models with an accuracy improvement of up to 80%. Compared to the full band model, the accuracy of characteristic bands selection model increased 50%. This also illustrates that the CR-SSM-RF or CR-SSM-GBRT model significantly improves the accuracy of the inversion of Cu contents in rocks compared to the original spectral reflectance. Our study provides a new idea for selecting different spectral preprocessing methods as the input values for the future model and will also offer an executable framework for the inversion of Cu contents in rocks of different lithology on a large scale in the future.

Selective extraction of silver(I) and photometric determination di-(2-naphthyl)-thiocarbazone (dinaftizone) in the organic phase

A method for the selective, simple and accelerated extraction-photometric determination of silver has been developed, based on the selective extraction of silver(I) from a strongly acidic medium in the presence of iodide ions and dimethylformamide and its complexation with dinaphthizone directly in the organic phase.The apparent molar extinction coefficient of the dinaphthizone complex of silver (I) at a maximum light absorption of 505 nm is 4.75·104. The calibration graph is linear in the range of 0.5-50 μg of silver (I) in 10 ml of extract. The determination of silver is not interfered with by large amounts of foreign ions in quantities up to 100,000 times within 2-5%. The extraction-photometric method developed for the determination of silver is recommended for analyzing silver content in diverse materials, including ores, rocks, industrial wastes, and other substances characterized by complex chemical compositions. Notably, this method is particularly advantageous as it eliminates the need for separating accompanying elements, streamlining the analytical process. By employing this extraction-photometric technique, analysts can achieve accurate and reliable results in the determination of silver content even in samples with intricate chemical matrices. This method enhances efficiency and expedites the analysis of materials that may contain a variety of elements besides silver.

Convolutional neural network for predicting the TOC content of source rocks in the Shahejie Formation, Liaohe Western Depression

The total organic carbon (TOC) content is an important index to evaluate the quality of hydrocarbon source rocks. It is proposed that accurate and effective prediction methods of TOC content are beneficial to the progress of conventional and unconventional oil and gas exploration research. The Liaohe western depression is rich in oil and gas resources. Among them, the Shahejie Formation Section 4 is the main oil-generating layer, and a comprehensive and accurate evaluation of its organic matter content can provide ideas for shale oil exploration in this area. Based on this, this article proposes three methods for quantitative prediction of TOC content in the Shahejie Formation Section 4 in the Liaohe western depression: simple linear regression, ΔLogR, and convolutional neural network (CNN) simulation, which has different correlation coefficients of 0.3, 0.55, and 0.88. Compared with the laboratory sample analysis and testing results, the prediction results of the three methods show that the CNN simulation method is more reliable and accurate for predicting TOC content. Therefore, this method is more suitable for evaluating hydrocarbon source rocks in the Liaohe western depression and has great potential for application in the evaluation of hydrocarbon resources in the future.

Assessment of factors determining the rate and direction of plant communities development on coal mining spoils (the case study of the Gorlovskoye anthracite deposit)

The aim of the study. Identification and assessment of specific succession processes on self-revegetating coal mining spoils of the Gorlovskoye anthracite deposit, as related to the abiotic factors. Location and time of the study. The coal mining spoils of the Gorlovskoye anthracite deposit (54.568880 NL, 83.588956 EL), Novosibirsk region, Iskitimsky district, June 2023. Methods. The properties of soil substrates in technogenic landscapes were determined by officially attested and widely used methods of soil analyses. In field conditions, soil hardness was measured with a penetrometer, then soil density was calculated from its values using the dependence function. Total carbon and nitrogen contents were determined using a Perkin Elmer 2400 Series II CHNS/O analyzer. Statistical processing of the data was carried out using cluster, principal components and Spearman's correlation analyses. Results. In the anthracite coal mining spoils in the forest-steppe conditions of West Siberia, the high content of physical clay and clay-producing rocks in the developing soils promotes predominantly herbaceous plant groups, whereas slope areas with a high content of stones benefits the growth of woody vegetation.

Application of geophysical techniques based on multi-attribute inversion in predicting high-quality source rocks

Total organic carbon (TOC) content is an important indicator for evaluating the quality of source rocks. Conventional laboratory analysis and testing, single well interpretation, and other methods are limited by sample data or the number of well locations, and cannot comprehensively and accurately predict the planar distribution of TOC content in source rocks. Based on this, a method for predicting TOC content using seismic inversion with multiple attributes is proposed. The basis for applying seismic attributes to study TOC of source rocks is the inherent relationship between seismic and logging data. By using logging data to calculate TOC, the correlation between seismic attributes of well side seismic traces and logging is established, and seismic attributes are converted into TOC of source rocks. The results show that the TOC content in the third section of the Shahejie Formation of the Liaohe Depression is relatively high, distributed in the range of 1% to 5%. The trend of planar variation is manifested as a gradual decrease from the centre of the depression to both sides, and the centre is concentrated in the Panshan and Qingshui area. The overall prediction effect is good, proving the strong feasibility of this method.

Use of solid mining waste to improve water retention capacity of loamy soils

Purpose. The research explores the possibility of increasing the fertile properties of agricultural soils of loamy type by adding burnt-out dump mass from coal enterprises. Methods. Laboratory research on parameters of penetration and retention capacity of sorbed and meniscal water for diffe-rent burnt-out rock fractions. The burnt-out rock was sampled from the mine No. 5/6 waste rock dump in the city of Myrnohrad, Donetsk Oblast, and divided into four fractions from 0.63 to 10 mm. The water penetration coefficient of the soil with the added dump mass is measured by the velocity of water seepage into the test samples. The ability of rock additives to retain film-sorbed and capillary water is assessed by comparing the weight of dry and moistened samples of crushed dump mass. Findings. The velocity parameters of water penetration into samples of loamy mixtures with burnt-out dump mass with fractions ranging from 10 to 0.63 mm in size have been determined. It has been found that an increase in the percentage of burnt-out rock in the mixture leads to an increase in the water penetration velocity from 1.2 ml/cm2·min with a rock content of 30% to 30.66 ml/cm2·min with a rock content of 70%. The highest penetration coefficients are achieved when adding rock with a small fractional composition of 0.63-3 mm, since an increase in grain size leads to a reduction in the coefficient by se-veral times. It has been determined that with an increase in the size of the rock fractions in a loamy mixture, the retention capacity of sorbed and pore water suitable for plant nutrition decreases by approximately 40%. Originality. For the first time, the parameters of penetration coefficients, as well as the accumulation of sorbed and meniscal water for mine waste in the Selidovo-Pokrovskyi district of Donbas, have been determined. Practical implications. The results obtained can be used to improve the physical properties of agricultural soils of loamy type by increasing their water retention capacity.

Evaluating the efficiency of metallized siderite concentrate electric melting

The Bakal siderites belong to poor, hard-to-enrich carbonate iron ores. The low content of phosphorus and non-ferrous metals makes siderites a valuable raw material for obtaining highly metallized concentrate suitable for use in steelmaking processes. Reduction of siderites in a rotating furnace at 1300 – 1350 °C followed by magnetic separation of waste rock allows to obtain a concentrate with metallization degree over 90 % and a content of waste rock of about 5 % suitable for steelmaking as raw materials. The purpose of this work is to evaluate the efficiency of the process aimed at obtaining metal from siderite ore including obtaining of highly metallized siderite concentrate in a recovery furnace, as well as its hot loading into ore-thermal furnace and melting process itself. To do this, the electric melting was calculated in the electric ore melting furnace providing for determination of a large number of parameters including the electricity consumption required for melting. As raw materials we used a highly metallized siderite concentrate (φmet = 92.3 %) containing 35 % of waste rock and, for comparison, a briquetted metallized siderite concentrate obtained from a lump concentrate in which a significant amount of waste rock was removed by wet magnetic separation. The results analysis shows that increase in concentrate temperatures from 25 to 1000 °C decreases specific energy consumption and at the same time increases the furnace productivity to values comparable to the parameters of melting briquetted concentrate. This confirms the efficiency of the developed process. To reduce the melting point of high-magnesium slag, it is proposed to use colemanite as flux.

Late Devonian gabbro-dolerite-monzonite-granodiorite complex in the basin of the Severnaya Sosva River (Northern Urals): New data on composition, age, and geochemistry

Subject research. Hypabyssal intrusive gabbro-dolerite-monzonite-granodiorite complex from the northern part of the Tagil megazone. Material and methods. Intrusive rocks situated among the Devonian strata of the East Tagil structural-formation zone at the North Urals were studied. Petrographic studies, silicate (XRF) analyses and determination of rare elements by ICP-MS method, study of U-Pb isotopic systematics in zircons from monzonites and quartz diorites, processing and interpretation of the data obtained using discrimination and spider diagrams, as well as indicator geochemical parameters were carried out. Results. It was found that the age and structural position of the studied rocks can correlate with the well-known Late Devonian Ivdel complex, differing from the typical composition of the latter by a significant content of rocks of medium and moderately acidic composition. The geochemical parameters demonstrate values characteristic of both suprasubduction (island-arc) and oceanic volcanites, which may indicate the formation of rocks of the studied complex in an environment of termination of the subduction process and separation of the subducted slab. The presence of significant volumes of diorites and monsodiorites is probably stimulated by contamination of crustal matter by the mantle melts. Conclusions. The obtained geological, petrographic, isotope-geochronological, and geochemical data do not contradict the model of separation of the subducted slab and the arrival of mantle highly depleted matter (close to oceanic basalts N-MORB) after the termination of the subduction process.