Proceedings of Voronezh State University. Series: Geology
ISSN: 1609-0691 | Issues per year: 4 | Impact-factor RSCI 2021: 0,330 Scientific journal that publishes research papers in Russian on the results of original geological investigations as well as the analytic reviews on actual problems of Geology, unpublished before papers of the high education institutions scientists from VSU in main, RAS’s and other science centers of Russia’s regions. Indexed and abstract: International Reference Data Base GeoRef; Russian Science Citation Index (RSCI) on a platform Web of Science; Russian Science Citation Index (RSCI); List of Peer-reviewed Scientific Journals, entering to the international abstract databases and the systems of citing, recommended by the Higher Attestation Commission of the Russian Ministry of Education and Science for publication of principal scientific results of competitors for scientific degrees of science’s doctor and candidate. Editor-in-chief: Arkadiy D. Savko, PhD, Dr. habil. in Geology and Mineralogy, Professor, Head of the Department of historical geology and paleontology (Voronezh State University)
In memory of Irina Konstantinovna Koval
Copyright (c) 2025 Proceedings of Voronezh State University. Series: Geology
In Memory of the Tregub Tamary Fedorovna
Facies analysis of Aptian quartz sands using the example of the Stebaevskoye field (Lipetsk region)
Introduction: quartz and glass sands are a valuable resource widely used in industry. In the northeastern Voronezh anteclise, the potential for discovering large deposits of glass and construction sands is associated with deposits of the Volchinskaya and Devitskaya formations of the Aptian stage, Miocene (Putudanskaya series), and Upper Pliocene (Goryanskaya series). The Aptian formations are of greatest interest. Characteristics and geological structure of the study site: The Stebaevskoye construction sand deposit was selected as a model study site. The useful medium-grain sand sequence is confined to the lower sub-sequence of the Devitskaya Formation of the Lower Cretaceous, while the fine-grain sand corresponds to the upper part of the Volchinskaya Formation of the Lower Cretaceous. Three facies are distinguished at the deposit from bottom to top: 1 – coastal-marine facies of white, fine-grained sands of the Volchinskaya Formation, consistent in grain size distribution; 2 – deltaic facies of cross-bedded, inequigranular sands of the Devitskaya Formation, filling the bed of a buried paleo-river; 3 – proluvial-alluvial, bright orange, highly clayey, substandard sands and sandy loams. Facies analysis: to study the hydrodynamic activity of the sedimentation environment, the results obtained during drilling and laboratory work were applied to a map. The average fineness modulus of sand for each studied well was used as the main parameter for constructing the facies model. The Arcgis software package's 3D Analyst module was used to plot the color dependence, where the dynamics of fineness modulus change were determined in plan view. To study the pattern of fineness modulus change in the cross-section, a scatter plot of fineness modulus versus well core sampling depth was used. The study data indicate that coarse-medium-grained sands form in the channel facies, while fine-grained sands form in the coastal-marine facies. Conclusion: to predict the discovery of deposits for construction and glass raw materials, the facies distribution of Aptian sedimentary deposits should be considered. Analysis of available data allows us to predict the Kruto-Khutorskaya, Studeno-Khutorskaya, and other promising areas to the northwest for the discovery of construction and glass sand deposits, confined to the paleovalley of an ancient river and the shallow-marine facies of the Aptian period, located close to the regional capital, Lipetsk, which are of interest for industrial development.
Morphological redescription of miospore marker of Givetian deposits of the Central Devonian field
Introduction: when conducting comprehensive biostratigraphic studies of Devonian deposits on the territory of the Central Devonian field, the emphasis is on expanding and detailing core studies to determine the boundaries of stratigraphic units. Compliance with strict morphological rules when classifying taxa became the basis for re-describing and renaming some species of Paleozoic miospores, previously identified according to the classification of S. N. Naumova. Re-description of species allows updating the taxonomy of dispersed miospores and increases the validity of biostratigraphic conclusions. Methodology: core material from wells of the Central Devonian field was studied. The total number of samples studied − 69. Results and discussion: the results make it possible to clarify the taxonomy of dispersed miospores and increase the validity of palynostratigraphic studies. The data obtained can be used to create new generation maps, to correlate local stratigraphic schemes with regional schemes of Givetian deposits of the East European platform, as well as to detail and expand the palynological classification, which is important for reconstructing the geological history of the region. Conclusions: as a result of palynological studies, a new description of the miospore marker Rimosisporis ocularis was presented, taking into account its morphological characteristics according to the current nomenclature. In the middle part of the zone (EX) in the subzone (CV), this taxon appears and marks this stratigraphic interval.
Ecological and geophysical studies of buried erosional incisions in an industrial and urbanized area (using the example of the Milchanka River, Gomel, Belarus)
Introduction: the work is devoted to the study of erosional incisions of small rivers in urban areas buried by technogenic soils using a complex of geophysical methods. Methodology: a complex of geophysical methods was used, consisting of gravimetry and electrical exploration (vertical electrical sounding and electrical profiling using the resistance method, water and soil resistivity metering, surveying the gradient of the natural electric field potential). The equipment used: ERA-MAX electrical exploration complex, GNU-KV gravimeters. Results and discussion: the valley of the small Milchanka River buried during urban construction was studied. The erosional incision of the river is reflected in the form of a negative anomaly of the gravitational field with an amplitude of 0.5−1.16 mGal and a width of about 200 m. During the interpretation of the results of gravimetric studies, the parameters of the decompaction zone corresponding to the buried incision were determined. Electrical profiling showed that the loosening of the rock mass is due to the absence of a moraine in the uppermost part of the section (an increase in apparent resistivity at a spacing of AB=60 m) and a layer of Paleogene sandstones at a depth of more than 25 m (a decrease in apparent resistivity at a spacing of AB=200 m). According to the interpretation of electrical exploration data, the buried valley of a small river is a drain for sediments infiltrating from the built-up surface, in which there are no impermeable layers, which causes a high risk of groundwater pollution. Conclusion: the proposed complex of gravimetry and electrical exploration allows for prompt and sufficiently complete mapping of an erosional incision buried in an urban area and an assessment of environmental and geological risks.
New data of the Eopleistocene herpetofauna from the Morozovka-1 locality (Odessa region)
Introduction: the herpetofauna from the Eopleistocene locality Morozovka-1 has already been studied previously. Due to the poor preservation of the fossil remains and the lack of comparative material, only three of the eight snake vertebrae could be identified to species level. Recently, while sorting through the collections, two more snake vertebrae were discovered. Small numbers of studied materials on the Eopleistocene herpetofauna of Eastern Europe makes it necessary to clarify previous determinations and to further identify previously unstudied snake vertebrae from this location. Research methodology: for species identification, fossil vertebrae were compared with vertebrae of modern species. Systematic par: a description of new and redescription of previously described snake vertebrae is given. They are identified as: Coronella austriaca, Elaphe sauromates, Elaphe dione, Colubrinae indet., Colubridae indet., Vipera berus, Vipera ursinii s.l.. Discussion and conclusions: taking into account previously studied materials, the remains of amphibians and reptiles from the Morozovka-1 (Cherevichnoye-1) locality are represented by the following forms: layer 4: Pelobates fuscus aut vespertinus – 1, Pelobatidae indet. – 1, Anura indet. – 1; Testudines indet. – 1, Lacerta agilis L. – 1, Elaphe dione – 1, Colubrinae indet. – 1, Natrix natrix (L.) – 2, Natrix tessellata (Laur.) – 1, Colubridae indet. – 1, Vipera berus – 1, Vipera ursinii s.l. – 1; layer 5: Coronella austriaca – 1, Elaphe sauromates – 1. Based on the quantitative ratio of remains of species that prefer different biotopes, one can assume a forest-steppe environment with the participation of broadleaf and mixed forests alternating with open spaces and sparse forests. The climate was most likely close to the modern climate in the area of the locality.
The first discovery of Paleoproterozoic highly fractionated granites in the south of the Vorontsovka terrane of the Volga-Don Orogen
Introduction: granites make up a significant part of the continental crust and contain information about the geodynamic regimes of the upper part of the lithosphere. According to their characteristics, they are divided into unfractionated, which are usually considered in terms of alphabetical classification, and fractionated, which are formed from magmas that have undergone significant fractional crystallization processes. Such magmas are usually high-temperature and fluid-saturated, which is reflected in the absence of mafic minerals and the presence of minerals from rare earths. They are enriched in LILE, have low Nb/Ta and Zr/Hf ratios, negative Eu* anomalies, and a tetrad effect in the REE distribution. The article is devoted to mineralogy, geochemistry and petrogenesis of a new type of highly fractionated granites of the Vorontsovka terrane. Methodology: the chemical composition of the samples was determined using an S8 Tiger X-ray fluorescence spectrometer (Bruker AXS GmbH, Germany) at Voronezh State University. Small and rare elements were determined by the induction-coupled plasma method with mass spectrometric termination of analysis (ICP-MS) in the laboratory of Physical and Chemical Methods of Mineral Matter Research at the Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences. Local analyses of minerals were performed using a Jeol 6380LV scanning electron microscope with an INCA 250 quantitative energy dispersion analysis system at Voronezh State University and a Tescan Mira IV scanning electron microscope with an X-Max 80 energy dispersion (EDX) spectrometer at Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. Results and discussion: granitoids are massive medium-grained rocks with hypidiomorphic and poikillitic structures. They are composed of plagioclase (35−40 vol. %), microcline (up to 30 vol. %), quartz (20−25 vol. %), muscovy (up to 10 vol. %) and biotite (up to 10 vol. %). They are characterized by high SiO2 contents (71−75 wt. %) and alkalis (K2O+Na2O = 9−14.2 wt. %) with a predominance of potassium over sodium (K2O/Na2O = 1.1–5.6), low concentrations of Al2O3 (9.4−12.8 wt%). They are depleted of siderophilic, highly charged, and lithophilic elements, with the exception of Li (4−130 ppm) and Rb (120−140 ppm). They contain low concentrations of REE (∑REE = 11−36 ppm), with a moderate enrichment of LREE relative to HREE (La/YbN = 2.87–13.48) and a negative Eu anomaly (Eu/Eu* = 0.4–0.56). They are ferruginous, alkaline and metalominous rocks, which does not allow them to be attributed to any of the types of alphabetical classification, and suggests that they belong to a highly fractionated type. This is indicated by the presence of fluorite and xenotime, high concentrations of Li and Rb, and low ratios of Nb/Ta and Zr/Hf. The compositions of the studied granites and S-type granites of the Vorontsovka terrane form a single trend of fractional crystallization and suggest that Paleoproterozoic (2050–2070 Ma) S-type granites were fractionated. The temperature of biotite crystallization and saturation of the melt with zirconium indicates the formation of melts within the middle crust. The formation of S-type granites occurred as a result of melting of immature Vorontsovka series meta-sediments as a result of increased heat flow on the flank of the collisional orogen. Conclusions: in the southern part of the Voronotsovka terrane, alkaline and metalominous ferroan granitoids have been identified for the first time. The distribution of petrogenic and REE indicates that they belong to a highly fractionated type, while petrographic characteristics and features of geochemical affinity indicate that S-type melts were fractionated.
Spectral characteristics of microseismic emission of coal rock masses of Donbass
Introduction: the matter of characteristic spectra of the microseismic emission recorded in the result of monitoring studies in the settlement of Obiedinenny (city of Makeyevka, Donetsk People's Republic), which is located above the Kalinovskaya-Vostochnaya mine, is examined in this article. The results of the analysis of microseismic emission amplitude-frequency characteristics are considered and an assessment of their potential use for predicting the structure of the upper partition of geologic cross-section is made. The research methodology included: the analysis of microseismic emission amplitude-frequency characteristics. The assessment of rock density distribution by depth was made based on the assumption that the fundamental Rayleigh wave mode amplitude and frequency depend on the rock stratification depth and its density. Results and discussion: in the result of the research, it has been established that microseismic emission amplitude distribution by depth differs depending on the microseismic emission components used and on the time of day. It has been established that the spectral characteristics of microseismic emission near a large upthrust associated with significant rock-fracture zones differ markedly from those recorded at undisturbed areas. An assumption has been made that due to stress redistribution in the course of mining operations, an upthrust zone turns into an area of microseismic events reinvigoration related to cracks formation and propagation. Spectral ratios of averaged nighttime and daytime spectra over a long period of time have been obtained. A difference between the spectral ratio structure in the upthrust influence zone and the spectral ratio structures in tectonic no-disturbance zones has been established. Conclusion: therefore, the research results demonstrated that under the conditions of heavily industrialized built-up areas, the approach basing on the fundamental Rayleigh wave mode amplitude and frequency dependance on the rock stratification depth and density requires being subjected to methodological revision. Analysis of microseismic emission spectral characteristics can be used for detecting rock mass fracture areas associated with tectonic disturbance influence zones.
Paleogeographic conditions of accumulation of Callovian and Oxfordian deposits of the Boloshnevo section (Ryazan region)
Introduction: one of the easily accessible Callovian-Oxfordian sections of the Ryazan region, Boloshnevo, was studied by M. A. Rogov, who described the ammonite assemblage, identified substages, and proposed a zonal division. This outcrop was studied by I. N. Makarikhin from 2023 to 2025. Sedimentary rock and fossil samples were collected. The aim of this article was to interpret the paleogeographic history of the basin in this area, taking into account new data. Results and Discussion: 1) a collection of 170 invertebrate fauna specimens was analyzed; 2) the formation conditions of the studied deposits were reconstructed. Conclusions: 1. The paleontological characteristics of the section have been significantly expanded. In addition to the ammonites found by M.A. Rogov, other ammonites, belemnites, bivalves, gastropods were discovered. Sedimentation conditions at the end of the Callovian age changed from extremely shallow water (up to 10 m) with active hydrodynamics to deeper water (30–40 m) with calm hydrodynamics. During sediment accumulation, a current existed in the water column. Moreover, it passed through the immediate vicinity of the section under discussion during the accumulation of layers 2 and 4.
Evolution of the accumulation of titan-zircon placers of the Earth history
Introduction: a large number of publications are devoted to the study of titan-zircon placers. In these works, the geology, material composition, genesis of placers, as well as their role as a source of strategic types of mineral raw materials are examined in detail. At the same time, the evolution of the accumulation of titan-zircon placers, with rare exceptions, remained unexplored. Filling this gap is proposed in this article. Methodology: when writing the work, numerous literary and own sources were used, containing information on titan-zircon placers. The main methods of research were comparative lithological, stratigraphic, formation, facies, as well as factor analysis. Results and discussion: in the history of the Earth, the accumulation of placers occurred constantly. A study of the distribution of their reserves on a stratigraphic scale showed that from the late Archean to the present, the formation of the placers in question occurred constantly. But the vast majority of industrial placers have been known since the Middle Devonian. The following stages of concentration of titan-zircon minerals are distinguished: 1 − Pre-Middle Devonian, 2 − Middle Devonian-Early Carboniferous, 3 − Late Triassic-Middle Jurassic, 4 − Cretaceous, 5 − Cenozoic. The first stage includes the "history" of the formation of titan-zircon accumulations, when at different stratigraphic levels for a long time there was an accumulation of mainly non-industrial concentrations of the metals in question. A feature of the placers of the second stage is the noticeable influence of the endogenous factor on their formation. This is expressed in the appearance in the demolition sources of significant volumes of igneous rocks with accessions, the flow of explosive ore material into sedimentation basins. The imposition of metamorphism processes on placers, as it was on Timan, led to a change and redistribution of titan minerals. The third stage, unlike the previous one, is characterized by a close connection between placers and the large-scale Late Triassic-Early Jurassic era of powerful coring. This led to the appearance of the first eluvial deposits of the metals in question and placers of their near transport. But the main reserves of titan and zircon were still concentrated in long-range transport deposits. At the fourth stage, after the Cimmerian orogeny, CVs were formed in the Late Jurassic-Early Cretaceous and planation of territories, during the erosion of which in the Barremian-Aptian time, titan-zircon placers of near transport began to form in monomineral quartz sands. Extensive transgressions with deepening of marine basins in the Late Cretaceous determined the formation of placers of long-range transport in glauconite-quartz sands. The last stage is characterized by the largest formation of titan-zircon placers in the history of the Earth, especially Oligocene-Miocene and modern ones. This is caused by a number of favorable factors. Among them are the widespread development of CVs, especially in warm climate zones, a sharp increase in the length of coastlines, frequent changes in hydrodynamic regimes as a result of transgressions and regressions, relief contrast, which contributes to the removal of large volumes of terrigenous material with heavy minerals into sedimentation basins. Conclusions: in general, the evolution of placer formation is cyclically directed. The focus is expressed in an increase in the reserves of titan and zircon metals over time, especially in the Cenozoic, and cyclical – in the presence of stages of a combination of factors favorable for placer formation.
Epochs of formation of titanium-zirconium placers in the Phanerozoic of the Voronezh anteclise
Introduction: titanium-zirconium placers of different ages are known in the sedimentary cover of the Voronezh anteclise. They are considered in a number of publications. At the same time, over the past fifteen years, as a result of geological survey and thematic work carried out by employees of the Voronezh State University, new data on the distribution and composition of placers have been obtained, which formed the basis of this article. Methodology: field and laboratory studies of Mesozoic and Cenozoic sands were carried out to study titanium-zirconium placers. Sampling was carried out using the furrow method, thin interlayers were sampled pointwise. The main attention in the description and sampling was paid to the structural and textural features of the rocks. In the laboratory, the granulometric and mineral composition of sand deposits was determined. Samples were quartered, the clay fraction was washed out, and the silt-sand fraction was dispersed. A quantitative analysis of heavy and light fraction minerals was carried out. Based on the complex data, lithological-facies and mineragenic constructions were made. Results and discussion: six placer formation epochs were distinguished − Early Frasnian (Yastrebovskaya), Barremian-Aptian, Cenomanian, Early Santonian, Early Campanian and Oligocene-Miocene. In the Early Frasnian, volcanogenic-sedimentary placers were formed in the southeast of Voronezh anteclise, in which the main mineral is ilmenite. Cretaceous and Paleogene-Neogene placers are titanium-zirconium, usually occur on watersheds and have a small overburden thickness. Useful components are ilmenite, rutile, leucoxene, and zircon. In the Barremian-Aptian, long-distance placers were formed in quartz sands in the northern part of the Voronezh anteclise territory. In the Cenomanian epoch, a large placer deposit Central with a high content of heavy-fraction minerals was formed in glauconite-quartz sands on the northeastern slope of the Voronezh anteclise. Complex placers with heavy minerals and nodular phosphorites are typical there for the Santonian age. In the Campanian placers of the northwest of the Voronezh anteclise, heavy minerals, like quartz grains, can have a phosphate shell. Oligocene-Miocene placers are developed in the southwest of the Voronezh anteclise, are associated with quartz sands and are distinguished by an increased content of zircon and rutile. Conclusions: in the history of the Voronezh anteclise, conditions for the formation of titanium-zirconium placers repeatedly arose. The most important factors were tectonic and facies, secondary -− stratigraphic and paleogeographic. The evolution of placer formation over time is also traced, which is expressed in the migration of useful component accumulation areas across the Voronezh anteclise territory and among them in the increase in the share of the most stable heavy minerals as a result of recycling processes.
Biostratigraphic characteristics of the Chaplygin Formation Devonian of the Central and Southeastern parts of the Voronezh anteclise
Introduction: in the section of the sedimentary cover of the Voronezh Anteclise, the Givetian and Frasnian deposits take a great part. They are a difficult object to study from different coastal continental facies that are rarely and unevenly paleontologically characterized. Therefore, for biostratigraphic characteristics of these deposits, a variety of paleontological material (palynological, paleobotanical and paleoichthyo­logical), was involved. Materials and Methods: the objects of the study were core material from the boreholes Novokhoperskaya 8750/1 and Shchigry-19 (Osinovka), as well as by previously obtained palynological results from boreholes located in Voronezh, Lipetsk and Belgorod regions of the Voronezh Anticlise. Standard methods were used to obtain the palynological material. Results and interpretation of the results: the results of comprehensive studies of the Devonian Chaplygin Formation of the Central and Southeastern parts of the Voronezh Anteclise are presented. Three miospore assemblages (PK2-PK4) correlated with the miospore assemblages of the Lower Frasnian Zones of Belarus. Miospore assemblages PK2-PK3 contain species typical to the Raistrickia bucera Zone from the base of the lower Frasnian (Zhelon Horizon) of Belarus, for which two phases of development are proposed: the initial, incomplete composition of R. bucera-1 miospores and a fairly complete, abundant number of R. bucera-2 species. Miospore assemblage PK4 corresponds to the Sinuosisporis vermiculatus Zone from the upper parts of the Zhelon Horizon. In the R. bucera-1 Zone, the higher plant Svalbardia aff. avelinesiana and the antiarch Asterolepis radiata were established for the first time. The Chaplygin Formation is placed in the lower half of the Lower Timan Subhorizon. Conclusion: the complex paleobotanical and macrofaunistic studies have made it possible to supplement and clarify ideas about the age of the Chaplygin Formation. For the first time, using new core materials in single continuous sections of the Yastrebov and Chaplygin Formations, we have identified sequential miospore assemblages for the central and southeastern parts of the Voronezh Anteclise from the lower, middle and upper parts of the Chaplygin Formation. These miospore assemblages are correlated with assemblages of the Lower Timan palinozones Raistrickia bucera and Sinuosisporis vermiculatus, established for the first time in Belarus at the base of the Frasnian stage, which makes it possible to attribute the Chaplygin Formation to the lower half of the Lower Timan Subhorizon. As a result of our research, we have expanded the biostratigraphic characteristics of the studied formation due to new findings of macroflora and ichthyofauna. The antiarch Asterolepis radiata and the higher plant Svalbardia aff. avelinesiana (archaeopteridae, class Progymnospermopsida) were found in the sediments of the R. bucera Zone. It was discovered in the Frasnian Chaplygin Formation (R. bucera Zone) and is the first find in Russia.
Silver-bearing tetrahedrite-(Cd) from quartz veins of the Tochilnogorsk deposit – the first find in the Urals
Introduction: tetrahedrite-(Cd) has the formula Cu6(Cu4Cd2)Sb4S12S1 and is a rare mineral, usually forming precipitates of fractions of a mm. To date, the mineral is known in about seventeen deposits and ore occurrences in the world. In Russia, tetrahedrite-(Cd) is found in two places: in the Zmeinogorsk deposit in the Altai Krai and in the Krasnoye ore occurrence in the Bodaibo District of the Irkutsk Region. This paper describes the first find of silver-bearing tetrahedrite-(Cd) from the Tochilnogorsk deposit in the Urals. The Tochilnogorsk deposit of refractory stone is located in the Rezhevsky District of the Sverdlovsk Region, approximately 500 m from the village of Tochilny Klyuch. Methodology: the chemical composition of tetrahedrite-(Cd) was analyzed in polished washers using a TESCAN MIRA LMS (S6123) scanning electron microscope with an INCA Energy 450 X-Max 80 (Oxford Instruments) EDS attachment at the Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, analyst L. V. Leonova. Results: tetrahedrite-(Cd) was encountered as inclusions in rock crystal crystals in cavities of a quartz vein, where accumulations of anglesite, cerussite, and crocoite crystals are noted. Tetrahedrite-(Cd) forms isometric grains up to 8 μm in size intergrown with larger galena, no more than 60 μm in size. The chemical composition of the fahlore varies slightly within one grain. The mineral contains a large amount of silver from 7.02 to 8.36 wt.% and in one analysis an admixture of tellurium of 1.15 wt.%. Conclusion: for the first time in the Urals, in the ancient Tochilnogorskoye deposit located in the Rezhevsky district of the Sverdlovsk region, silver-bearing tetrahedrite-(Cd) was encountered. The mineral forms intergrowths with galena in rock crystal crystals in the cavities of quartz veins in association with crocoite, anglesite and cerussite. Due to the large amount of silver in the mineral, it belongs to the silver-bearing variety of tetrahedrite-(Cd). Fahlore from the Tochilnogorskoye deposit is close in composition to tetrahedrite-(Cd) from the Krasnoye gold occurrence in the Bodaibo district of the Irkutsk region in Russia and from the lead-zinc mineralization of the Tyndrum mine in Scotland. Formation of silver-bearing tetrahedrite-(Cd) occurred in low-temperature hydrothermal conditions.
Features of the borates in kimberlite rocks
Introduction: the conducted studies have shoun a wide variety of kimberlite diatremes on ancient platforms of the world in size, morphokogy and depln of the foci, the internal Structure, the features of the composition of billing rocks, the content and Composition of primary (deep) minerals, the composition of bulk of kimberlites the degaee and nature of the processing of the latter in postmagmatic and hypergepic conditions and features. Some of the listed features of kimberliteare due to the manitestation of endogenous factors and some are exogenous. Of particulat importance the presence around the kimberlite diatremes of the Siberian Platform (SP) of terrigenous-carbonate formations of the Silurian, Ordovician, Lower, Midale and Upper Cambrian, represented by limestones dolomites, mergelites and intermediate differenes of these rocks. In the central part the section of the host rocks. Especially high concentrations of the latter werw found in the Lower Cambrion Sediments of depths of 900-1200 m.Significant volumes, of highly minerakized waters (prines) were also buried in the Lower Cambrium sediments,which Significantly affected the material composition of kimberlites in diatremes discovered in this territory. The composition of the strata containing the diatremes, the geokogicak and structurak features, of their placement, the degrec of pneumalite-hydrothermal and hypergenie transformation leol to abunden secondary transformation of kimberlites, in many cases turhing them info apokimberlites. Оbjects, research methodology and discussion of the result: among secondary minerals of kimberlites of some Siberian platform (SP) diatremes borates have been identified, discovered in small saline veins and veinlets. Ekaterinite associates with colorless, orange-red and bluish halite, anhydrite, calcite and serpentine. Ekaterinite usually forms sinter inclusions in orange-red halite in bulges of small veins, and in veinlets it is observed in the form of aggregates, individuals in which are located along the long side in parallel to each other and perpendicularly to substrate. The color of ekaterinite changes from pink- to cherry-red, and orange-red segregations of the mineral dominate in monogene veinlets. Mixture of oxides and ferric hydroxides serves as the coloring matter. Some individuals of ferroszaibelyite have prolate shape. In some cases individuals resemble laths, in others – they are needle-shaped. Development of prolate segregations of ferroszaibelyite to some degree is conditioned by specificity of their growth and by structure of the mineral proper (chain structure of borates) as well. The mineral is usually of brown color. In kimberlite pipes boric minerals occur in small veins and veinlets of halite, crossing serpentinous kimberlite at individual depths. Since boric minerals are usually related with salts, there is a supposition that boron was brought into kimberlites together with soluble salts from hosting sedimentary saliferous deposits. In the course of serpentinization boron practically scatters and only at magnesia available, together with brucite, insignificant quantity of ascharite emerges. Direct dependence of boron content on composition of volatile phase is observed for kimberlites, under influence of which their metasomatic alteration is realized. Conclusion: that is why enrichment of underground brines by boron should be connected to a significant degree with abyssal sources of this element. Magnesium and iron (Fe), necessary for formation of ferroszaibelyite, were mobilized from pore solutions of hardening serpentine, which become nearly purely magnesia with lowering of temperature. Ekaterinite was formed in other than ferroszaibelyite conditions in oxide environment, about which inclusions in mineral of oxides and ferric hydroxides testify.
Geology, Prospecting and Exploration of Solid Minerals, Minerageny
The manifestation of subaqueous gas hydrate formations in the electromagnetic transient
Introduction: the detection of gas hydrate (GH) accumulations is an important task both as a useful mineral and as an unstable component of the technosphere. Gas reserves in the gas hydrate state are quite large and exceed its reserves in a free state, which, along with the estimated volumes of world reserves, makes gas hydrates one of the most promising types of energy resources. An obvious advantage of gas hydrate deposits is also their shallow occurrence depths (in comparison with traditional gas) and their widespread distribution in the near-surface layers of the lithosphere, including in water areas; Methodology: the study is based on a numerical experiment – a comparison of the results of solving the electromagnetic (EM) direct problem for a normal and anomalous one-dimensional conducting polarizing geoelectric model; Results and discussion: geoelectric models of subaquatic GH clusters for freshwater and marine conditions are proposed, calculations of the EM signal are made on electrical installations of different sizes. Based on the difference between the anomalous and normal signals and their discrepancy, conclusions are made about the manifestation of an anomalous object; Conclusion: the study of the anomalous effect of GH showed the possibility of their detection by electrical installations. In a freshwater reservoir, a polarization signal associated with a gas hydrate layer appears in the transient process. For marine conditions, the presence of GH is more contrasting when it reaches the seabed; when an overlying layer of permafrost appears, the anomalous effect decreases, especially strongly for installations with a short source length. Generally, the studied object is contrastingly manifested in measurements by electrical lines. A large share of the anomalous effect is associated with the contrast of the object in terms of resistivity and appears during the early stage of the transient (EST). The anomalous effect associated with polarization properties (at a late stage of formation) appears on smaller installations, but in terms of the amplitude of the discrepancy it is inferior to the anomalous effect during the EST.
Results of geological and geophysical studies of the Nerkayu complex in the Nether-Polar Urals
Introduction: among researchers, there are currently conflicting views on the origin of the Nerkay complex, the history of metamorphic and post-metamorphic transformations, their number, sequence, and time of manifestation. Given the inaccessibility and poor exposure of the Nerkayu complex, the combination of geophysical and petrophysical methods represents a valuable research tool for studying high-pressure metamorphic formations. Methodology: rock density was determined by hydrostatic weighing using Mettler Toledo laboratory balances on whole rock samples. The magnetic susceptibility of rocks in powder form was measured using a KAPPABRIGE KLY-2 device with a measurement accuracy of 0.2−1%. Petrographic description of the rocks was carried out in polarized sections using a Polam-215 polarizing microscope. Ore minerals were studied using a Tescan VEGA3 LMH scanning electron microscope. The chemical composition of the rocks was obtained by the method of wet chemistry and the complex method of wet chemistry and X-ray fluorescence analysis. The interpretation of geophysical material consisted of a comprehensive interpretation of gravitational and magnetic fields, as well as transformants, using the comparison method, i.e. using a map overlay using the results of petrophysical grouping of rocks. Results, discussion and conclusions: six subgroups of rocks with different densities and magnetic properties have been identified. The primary petrophysical groups, represented by metabasites and crystalline schists, were delineated based on density parameters, material composition, and textural and structural characteristics. The crystalline schists are further divided into two categories based on material composition and density. The first category, formed by sedimentary rocks (pararocks), and the second, formed by major igneous formations (orthorocks). Although the rocks are completely or partially recrystallized, studies of metabasites and schists have shown that their petrophysical properties are primarily determined by the density of the primary composition (protolith). Differences in the magnetic properties of metabasites have allowed the delineation of the area of distribution of metasomatic processes (diaphthoresis). The local nature of the distribution of magnetite in para- and orthorocks allowed to identify non-magnetic and magnetic varieties among them. The results of qualitative interpretation of geophysical data made it possible to divide the Nerkayu complex into two areas: northeast and southwest. In the northeastern part, which is most susceptible to post-metamorphic processes, the areas of unchanged or slightly altered metabasites in the east and ferromagnetic, difluorinated and metasomatically altered amphibolites in the west are mapped along the contours of local gravity and magnetic anomalies. In the southwestern part of the Nerkayu Complex, predominantly reduced gravity and magnetic values are observed over widely developed schists of sedimentary origin.The presented example of geological and geophysical research on the Nerkayu complex will assist specialists engaged in the reconstruction of the primary composition and geodynamic position of metamorphic complexes in the northern Urals region in their understanding of the relationship between the physical properties of rocks and geophysical fields and the deep structure of the Nerkayu complex.
Mineral and chemical composition of the ravine alluvium at the Kamyshin city area (Volgograd region)
Introduction: valleys under the erosive relief conditions makes transit and accumulation functions formed under the natural and technogenic factors. Researching the alluvial formation at the urbanized areas has practical discipline for analysing the flow of the substances. Purpose: researching the material composition of the ravine alluvium at the Kamyshin city area (Volgograd region). Methodology: in 2022 have been collected 22 samples of the alluvial formations, including 20 samples along the ravines and 2 samples at the mouths of the small rivers. The analysis of the mineral composition has been made on a x-ray difractometr D8 ENDEAVOR; the analysis of the chemical composition has been made on a X-ray equipment «Spectroscan MAKS-GVM», microscopic researching of samples has been made on a microscope MBS-10. Results and discussion: in the composition of the ravine alluvium the 3 main situations of the accumulation are reflected. Without deep erosion and soils accumulation in the thalweg which arrived from the lateral tributary valley and also with surface wash, the proportion of quartz decreases to 50–60 % (SiO2 40–60 %); the composition of the hydromica, the kaolinite and feldspar are increased. Increasing loss of ignition and Al2O3 in the petrochemical composition. When there are no deep crossing and accumulation soil from the lateral tributary valley and form the surface wash in the thalweg next process carry: increasing the composition of the hydro mica, the kaolinite and feldspar, increasing loss of the ignition and content of Al2O3 in the petrochemical composition. When there is no bogging up of the mouth ravine, the biogenic accumulation of the chemical elements plays the main role in the decreasing the proportion of quartz (>50 %) and SiO2 (<40 %), increasing of the cola-spar, chlorate and hydro mica; the loss of the ignition is at maximum value. Increased content of several micro elements is connected with technogenic addition and specificity of the sources of this addition. In the composition of the technogenic material contains particles of the slag, broken bricks, coal smut, ash, metallic microspherol, synthetic fiber, plastic, glass. Conclusion: The composition of the ravine alluvium in the cities is the result of the erosive and accumulative processes at the water collection area which reflect geological and geomorphological circumstances and technogenic flows of the substances of different sources. Analysis of the ravine alluvium has practical discipline for the geoecological zoning of the city area, the control of the contains of water that has been brought to the receiving basin and making the nature preserving decisions.
Forecast of changes in the hydrodynamic regime of the Metegero-Ichersky aquifer complex during the operation of the Internatsionalnaya pipe (Western Yakutia)
Introduction: during the operation of the Internatsionalnaya pipe, a significant increase in groundwater inflows to the mine field is predicted from the current 10-15 m3/hour to 1000 m3/hour in 2027, associated with the opening of the Icherskaya suite collectors. An increase in the inflow to the mine field of the deposit will require multiple intensification of the reinjection process, currently implemented in the collectors of the Metegero-Icherskaya aquifer complex within two areas located in the zone of dynamic influence of the regional Western fault. The adopted technical solutions will affect the hydrodynamic regime of the studied aquifer complex. Forecasting the hydrodynamic regime is an important component of ensuring the environmental safety of the reinjection process, in terms of determining the boundaries of the repression spreading dome, as well as timely response to the creation of an excess pressure front. Methodology: the main forecasting method was hydrogeological modeling. When constructing the hydrodynamic model, the hydrogeological characteristics of the Metegero-Ichersky aquifer complex were detailed. The initial parameters of the complex were adopted based on the materials of previously completed pilot and research work for the entire period of field development and were adjusted at the stage of model calibration. The forecast of changes in the hydrodynamic regime was carried out using the Feflow hydrogeological modeling program. Results and discussion: new information was obtained on local changes in the hydrodynamic regime of the Metegero-Ichersky aquifer complex. Maps and diagrams of piezometric surfaces are presented, the development of a depression funnel and an imposed repression spreading dome is traced. By 2029, the piezometric surface of the Metegero-Ichersky aquifer complex will acquire a dipole appearance, the depression funnel around the Internatsionalny mine will coincide with the repression spreading dome from the Western fault. In the future, the piezometric surface of the aquifer will not undergo significant changes. Conclusion: the implementation of hydrodynamic and hydrogeological calculations made it possible to estimate the predicted total productivity of injection sites taking into account the current state of injection wells, as well as to forecast the availability of the need for handling drainage waters of the Internatsionalny mine. The predicted piezometric surface marks obtained as a result of modeling make it possible to predict the possibility of further injection of drainage brines into the Metegero-Ichersky aquifer complex.
Neotectonic and relief features of the territory of the Central African Republic
Introduction. the scientific problem in studying the relief of the territory of the Central African Republic is to clarify its relationship with the tectonic structure. The purpose of the article is to highlight the main elements of the relief and evaluate their role in reflecting the structure of the foundation. Methodology. the object of study is located within the center of the African continent. The sequence of the study included the description of the main divisions of the relief of the territory, analysis of the geological structure in relation to the relief. Lineaments are identified based on visual decoding of space images. Possible association with the rupture failures for which their possible kinematics is determined. The deciphering feature used is a standard hydronetwork. The materials used in the work were, besides the results of deciphering space images, published materials on geology of the region. Results and discussion. the relief of the territory is characterized as a result of the studies. Based on the linear atomic analysis, a diagram of the breakable tectonics was drawn. It is compared with data from the geology of the region. Conclusion. the following conclusions can be drawn from the studies: The lineament fields, reflects ruptured foundation disturbances only fragmentarily and is apparently related to new tectonics ruptures. The main minerals of the region in area distribution depend largely on the nature of the new tectonics movements.
Lithology of bituminous sandstones of Ashalchinskoye deposit, South Tatar arch
Introduction: the development of bitumen deposits in sandy strata using the method of steam-assisted gravity drainage is accompanied by unpredictable circulation of high-temperature fluids due to the complex distribution of permeable and impermeable zones in rocks. The applied task is to determine the causes and features of internal heterogeneity in bitumen deposits based on the lithological and granulometric characteristics of productive strata. The object of the study is Ufimian (Lower Permian) sandstones of the Ashalchinskoye bitumen deposit in the Republic of Tatarstan. Methodology: granulometric analysis data on bituminous sandstones of the Ashalchinskoye deposit were processed using methods of basic and multivariate mathematical statistics in the STATISTICA 10 software. Optical and electron microscopy and X-ray computed microtomography were used to study the hollow-pore space. Results and discussion: the studied sandstones belong to the quartz graywacke group. In addition to quartz, they contain feldspars, micas, pyroxenes, amphiboles, as well as fragments of igneous rocks of the Ural Mountains, which are cemented by carbonate and bitumen matter. The predominant fraction of sandstones is fine-grained (0.25-0.1 mm), which is also the most bitumen-saturated. The results of cluster and factor analysis made it possible to identify “bituminous” and “lithological” groups of granulometric parameters. According to microtomography data, it was established that pores with a volume of less than 0.01 mm3 predominate in sandstones. Conclusion: the degree of bitumen saturation of the Sheshmian sandstones is associated with their granulometric composition. The content of bitumen substance over 10 % is specific for fine-grained varieties with a particle size of 0.25-0.1 mm. Low carbonate content of sandstones is one of the factors in the prospects for developing bitumen deposits using the steam-assisted gravity drainage method.
New data on the morphology of the Maastrichtian pycnodonts (Gryphaeidae, Bivalvia) of Eastern Mangyshlak (Western Kazakhstan)
Introduction: to this date, a lot of literature has been published on Late Cretaceous bivalves from the Caspian Sea and adjacent areas. However, the issue of the reliability of determining the taxonomic affiliation of the shells themselves remains stay relevant. Not only the preservation of the latter, but also the variability of their morphological features have repeatedly created significant difficulties for specialists who were compelled to introduce new taxa of a species and subspecies rank. Some difficulties also arise when researchers have to compare their shells with only a textual description, as is the case with the right flaps of some Late Cretaceous representatives of Pycnodonte. In this study, the author attempted to partially solve the above-described difficulties based on the material presented by two valves extracted from the Late Maastrichtian deposits in Western Kazakhstan by A.S. Alekseev. Results: the article presents the results of the present study of the morphology of shells of some ostreids from the terminal layers of the Maastrichtian stage of Aksai ravine (Ustyurt Plateau, Mangyshlak Peninsula). Based on the studied morphological features, it was determined that only one of them belong to the species Pycnodonte vesicularis Lamarck, 1806. The geometric parameters of the drilling trace on the surface of the left leaf are described, followed by its comparison with those ones from Western and Central Europe. Conclusion: in the course of the study, it was possible to reliably establish that only the right wing belongs to Pycnodonte vesicularis. As for the left one, according to a very satisfactory degree of preservation, the author confines himself to the definition Pycnodonte sp. Despite this, the hole on the surface of the last (left) flap allowed to restore to a certain extent the trophic relationship between the two classes of mollusks – bivalves and gastropods. It can be considered a reliable fact that within the Late Cretaceous waters of Mangyshlak, the role of predator was assigned to some small-sized representatives of gastropods. A similar phenomenon has already been noted by foreign authors on the Late Cretaceous fossil material of a number of countries in both the Northern and Southern hemispheres, which led some of them to create and improve their systems based on drilling traces in many ways similar to those from the Caspian region.
Mineralogical and Geochemical Features of «Hot Stones» Based on the Example of the Khlebopek Placer Deposit (Bodaybinsky District, Irkutsk Oblast, Russia)
Introduction: «Hot stones», frequently detected in the waste dumps of placer deposits after gold washing using metal detectors, are a nuisance for prospectors seeking nuggets, as they do not contain «visible» gold. However, their study is of significant scientific and practical interest, enhancing our understanding of gold geochemistry, its concentration processes in placers, and potential exploration criteria for both primary and placer gold deposits. Methodology: the mineralogical and geochemical features of «hot stones» from the Khlebopek placer deposit were studied using optical and electron microscopy, atomic emission spectroscopy (ICP-OES), and X-ray diffraction analysis. Results and Discussion: «Hot stones» are heterogeneous in specific gravity, elemental, and mineral composition, despite producing identical signals on gold-tuned detectors. The signal arises from the presence of both magnetic and conductive minerals within the stones, which interact with the electromagnetic field generated by the detector coil. Their combined action forms a complex structure of conductors, magnetic minerals, and piezoelectrics. «Hot stones» contain mineral forms of gold and silver, where noble elements exist not only in zero-valent states but also in oxidized forms, such as tellurides and stibnites. The association of «hot stones» with micro- and nanoforms of gold aligns with the electrical precipitation model. A unique feature of these stones is their exceptionally high content of nickel minerals. Conclusions: the notion that «hot stones» primarily consist of magnetic iron minerals is incorrect. Their mineral composition is far more diverse. «Hot stones», containing noble elements in oxidized forms with micro- and nanoparticles, serve as the source that begins to form zero-valent gold upon entering the hypergene zone. Gold-bearing pyrite-pyrrhotite ores and their associated magnetic anomalies, easily detectable by UAV-based magnetometric surveys, can serve as regional exploration criteria for both lode and placer gold.
Thorium and rare earth sulfates – new minerals of the Bykogorsk deposit (features of internal structure, chemical composition, genesis)
Introduction: the Bykogorskoye uranium deposit was mined using the underground (heap) leaching method. The technological features of mining and the long period of deposit development led to the formation of rich secondary sulfate mineralization in the mine's tunnel chambers. This article provides information on the unique uranium, thorium and rare earth fluorine-containing sulfates of the Bykogorskoye deposit. Methodology and factual material: during the field work, adit No. 10 (horizon 495 m) was studied. Flaky crystals of hademite exhibiting weak UV reflexes were found. During a detailed study of the discovered hademite crystals on an optical microscope, numerous small (1−30 μm) dark and brown precipitates of various morphologies were recorded in them, representing individual mineral phases. The selected crystals were studied in detail on a Jeol-6380 LV scanning electron microscope (laboratory of the Voronezh State University Central Collective Research Institute). The chemical compositions of the minerals were determined on an INCA-250 energy-dispersive microanalyzer. Gamma spectrograms of radiogenic minerals were obtained using a 4x4 cm NaJ (Tl) single crystal with a Burle 2060 photomultiplier. Results and discussion: the studied hademite crystals are not uniform in composition. Areas with a high average atomic number (Zcp) were found - hademite (HD2) with an increased (up to 7 wt.% UO3) concentration of uranium and areas with low Zcp values. (HD1) not containing uranyl ions. A detailed study of the hademite surface using a scanning electron microscope revealed mineral inclusions with high Zcp parameters. Local microprobe analysis established two original mineral phases - 1) fluoride aluminosulfates of rare earths (ST1) with an increased content of ThO2 (up to 6 wt.%); 2) fluoride aluminosulfates of thorium (ST2) with a very high content of ThO2 reaching 51 wt.%. The studied hademite is a young mineral in which radioactive decay products have not yet accumulated. The gamma spectrogram does not show any daughter products of Ra226 decay (Pb214 and Bi214). Conclusion: the formation of fluorine-containing aluminosulfates is associated with underground (heap) leaching processes widely used at the Bykogorskoye deposit. There are two main variants of aluminosulfate crystallization: 1) rapid evaporation of sulfuric acid solutions on the walls of the workings. 2) chemical precipitation associated with an increase in the pH of the environment.
Petrophysical and petrological characteristics of granitoids of the Pavlovsk complex (Voronezh crystalline massif)
Introduction: the study of the Pavlovsk migmatite-granite-granosienite complex is of key importance in the formation of the geodynamic model of the Losevo suture zone development. The presence of an overlapping sedimentary cover does not allow for a direct study of the morphology and thickness of the complex under consideration, which makes it necessary to use the results of modern geological and geophysical modeling. The purpose of this work is to create a reliable basis for interpreting the results of geological and geophysical modeling based on a set of interrelated data (petrographic description, petro- and geochemistry, physical properties). Methodology: analytical studies of the material composition included the manufacture and description of grinders (20 pieces) and X-ray fluorescence analysis (45 samples), which was performed on the S8 TIGER device at the VSU Center for the collective use of scientific equipment. The density of rocks was studied by hydrostatic weighing using scales "HIGHLAND" HCB-1502. The magnetic susceptibility was determined by a KM-7 kappameter. The velocity of the longitudinal waves was measured with an ultrasonic flaw detector UK 10PMS. Discussion of the results: granitoids of the Pavlovsk complex in the studied sample are represented by granosyenites, moderate-alkaline/alkaline granites, leucogranites and alkaline syenites. Granitoids of the first phase are represented by a long petrochemical series from calcareous to alkaline series, granitoids of the second generation phase are from calcareous to calcareous-alkaline. The density of granitoids varies from 2.61 to 2.70 g/cm3 with an average value of 2.65 g/cm3, and late-phase leucogranites with an average value of 2.63 g/cm3 are distinguished within the subgroup. The distribution of the magnetic susceptibility of granitoids of the early phase is bimodal in nature: an extremum with a positive asymmetry and an average value of 18×10-3 SI units includes amphibole-biotite granitoids and granosienites; the second maximum with an average value of 45×10-3 SI units refers to alkaline syenites. Leucogranites of the late generation phase are distinguished by a single peak with an average value of 12×10-3 SI units. In terms of the velocity of longitudinal waves, the studied sample of rocks has a similar range of parameter variability from 5500 to 6400 m/s. The density is correlated with iron, magnesium, and calcium oxides (R=0.8). The magnetic susceptibility of rocks is closely correlated with the content of high field strength elements (R=0.7). The data obtained is summarized in a table. Conclusion: the close correlations of the composition with petrophysical properties make it possible to accurately segregate the rocks of the complex and the framing according to the measured physical parameters, which makes it possible to reliably interpret the results of geological and geophysical modeling with subsequent integration of the latter into geodynamic models.
Ecological and geological conditions of the territory of the Urengoy oil and gas condensate field
Introduction: needs of ecology-geological conditions research defines by its key role in evolution of lithosphere environmental functions. Methodology: the characteristics of the ecological and geological conditions are given on the basis of the engineering surveys results during 2015-2021 at the development of Urengoi field facilities. The following ecology-geological conditions went into the questions: geological and geomorphological structure, geocryological conditions, hydrogeological structure. Assessment of the state of phytocenoses has been completed for environmental engineering survey units. Results and discussion: in geological terms, the most ancient deposits in the research area are opoka, opokamorphic clays and interbedded dense diatomaceous clays of the serovo series of the danian-lutetian stage of the paleocene epoch of the paleogene system with a up to 90 m of layer thickness. The holocene alluvial deposits of floodplain terraces in the form of sand, sandy loam, peat, patchy gravel, pebbles and boulders refer to the most recent formations. Various sites of the field are composed of marine and coastal-marine deposits, lacustrine-marsh, alluvial, lacustrine-alluvial and biogenic formations of recent age were found by the results of geological-engineering boring. As applied to lithology, these are peat, loam, sandy loam and sand. Research area is divided into three conventional zones of permafrost distribution: southern with island, central with intermittent and northern with continuous on the base of engineering and geological conditions. It has been found during summer survey the level of seasonal thawing out is in the depth range of 15−50 cm in the southern part of the field and is in the depth range of 10−57 cm north of the Evo-Yaha river. As applied to hydrogeology, the surveyed area belongs to the Ice (Arctic) macrozone of the first aquifer complex of the оligocene-quaternary deposits from the surface. This aquifer system consists of isolated, vertically oriented narrow troughs of underflow taliks of large rivers, bowl-shaped underflow taliks and rare interpermafrost taliks. The modern vegetation is represented by a combination of sparse forests, tundra and marsh communities, shrub-forb associations and cenoses of anthropogenically transformed habitats at the survey area. Сonclusion: the analysis revealed that the dominant geocryological conditions influence on the survey area ecosystems functioning. The presence of permafrost soils layer which causes geocryological processes that impede water exchange with underlying horizons, generally indicates the adverse of ecological and geological conditions through the spectacle of the ecological and resource potential of the area.
Pre-Paleozoic weathering crust on the southeastern coast of the Kanin Peninsula
Introduction: the Kanin Peninsula, which is a continuation of the Timan structures, has a similar geological structure and history of development. The weathering crusts, with which numerous deposits of ore and non-metallic minerals are associated in Timan, remain practically unexplored on the Kanin Peninsula. Geochemical study of weathering crusts – promising objects for searching for clay raw materials and placer deposits – is the basis for correlating paleontologically uncharacterized deposits, conducting paleogeographic and paleogeodynamic reconstructions, and clarifying the history of development and sedimentation patterns of a poorly studied region. Methodology: in order to establish the compositional features and genetic affiliation of the developed at the contact rocks of the Riphean basement and Paleozoic deposits, clay formations of the weathering crust, described and tested in the bedrock outcrop on the sea coast of the Kanin Peninsula, a study was conducted of the composition of petrogenic oxides, rare earth elements and clay minerals. Results and discussion: interpretation of the results of chemical analyses and the features of the distribution of REE and the phase composition of the clay fraction allowed us to conclude that the studied formations differ from the original rocks in the ratio of rock-forming elements, the content and composition of micaceous minerals and represent unmetamorphosed eluvium on the substrate of ancient highly hydrolyzed metaterrigenous rocks. Conclusion: the studied clay formations of the pre-Paleozoic weathering crust are diagnosed as rocks of the zone of lightening and mechanical disintegration, and the weathering crust belongs to the hydromica-kaolinite type of the siallitic stage.
Morphostructure of the southeastern part of the Kamchatka Peninsula
Introduction: the study area is located in the southern part of the Kamchatka Peninsula, southwest of Petropavlovsk-Kamchatsky. The purpose of the article is to study the morphostructural features of the territory and assess their relationship with the prospects for discovering thermal waters within the study area. The research methodology included: morphometric analysis of large-scale topographic maps, identification of linear elements of the morphostructure based on structural interpretation of space images, author's route observations with the study of the latest plicative elements and faults that can be reflected in the lineament field, establishing a connection between the interpretation results and geological survey data. Results and discussion: the following have been compiled: a morphoisohypse map with division of morphostructural and morphosculptural relief and a relief energy map reflecting the distribution of active modern vertical tectonic movements. Based on the interpretation of space images, lineaments have been identified, among which local and regional forms have been isolated. A model of their formation has been proposed. Possible connections between thermal waters and morphostructure have been outlined. Conclusion: from the position of morphostructural features of the territory, possible thermal water outlets can be associated with zones of increased rock permeability at the boundaries of positive and negative morphostructures, reflecting the relationship of neotectonic blocks. Regional lineaments of the disjunctive-plicative type with shear kinematics can be of particular importance. Within their limits, destructive fields with an increased degree of fracturing are of interest, in the contours of which concentration of fluid flows with elevated temperature can occur.
Vilyucha, Mutnovskaya and Zhirovaya rivers
Metallogeny of the Kibari orogenic belt of Burundi
Introduction: the analysis of the state of the mining industry in the Republic of Burundi is a topical issue for the industrial development of the country. The purpose of this study is to assess the geological, geochemical and geoecological situation of non-ferrous metal mining in the Republic of Burundi, assess reserves and the possibility of their use. Results and discussion: the data presented in the article are taken from the documentation of local and foreign companies, as well as government agencies involved in mining activities in the Republic of Burundi. The development of mining companies in Burundi based on exploitation allows to increase the stability of the system of analysis of collected samples, ore quality and the amount of exploited resources per year. Systematic analysis of samples in territories combined on the basis of data coming from different sources allows to significantly clarify information on reserves and evaluate the development technology and study the possibility of transferring mineral extraction to an industrial basis using modern methods and technology. Conclusion: It is recommended to solve all the above problems in the near future by adopting a new Mining Code of the Republic of Burundi, which will solve all the problems arising from artisanal mining, with the transition to industrial exploitation.
Modeling of a geoelectric section based on a set of feasible solutions of the inverse problem of vertical electrical sounding
Introduction: the article presents the theoretical foundations for constructing geoelectric models of subhorizontally layered media based on vertical electrical sounding (VES) data using serial solutions of the inverse problem. For this purpose, additive inversion technologies are used, based on the guaranteed approach of L. V. Kantorovich, which were previously proposed for solving inverse problems of gravity and magnetic exploration. Their distinctive feature is fundamentally new mathematical forms of presenting the results of quantitative interpretation in the form of a certain set of geologically meaningful invariants on a set of admissible solutions of the inverse problem. Methodology: for a set of solutions of the inverse problem with a power of at least 100, the discrete values ​​of a function dependent on spatial coordinates are calculated, characterizing the probability of belonging of individual fragments of the geological space to one of the studied geoelectric boundaries. An algorithm has been developed and implemented in the Python programming language, which sequentially performs the following operations: formation of a set of admissible solutions of the inverse VES problem using a genetic algorithm («DEAP» library); division of the geological space into a number of sub-regions consisting of elementary rectangular cells, with an assessment of the probability of intersection of each of them by the sought boundary of the layer with a given value of specific electrical resistance; construction of the most statistically reliable boundaries of the modeled geoelectric horizons; visualization of the obtained interpretation results (Matplotlib library). It has been established that smoothing of the assumed boundaries leads to improvement of interpretation constructions and can have a certain physical and geological justification. Results and discussion: the algorithm capabilities were assessed using a synthetic example and practical materials on the VES profile located near the village of Oktyabrsky in the Perm region, which includes 28 sounding points with a power line AB spacing of up to 320 m. In general, the geoelectric boundaries obtained using the developed algorithm are consistent with the specified model and the inversion results with the ZOND program. However, the probabilistic representation of the location of the geoelectric boundaries allows for a comparative assessment of the resolution of the VES method vertically and laterally. Conclusion: the presentation of the VES inversion results as a set of admissible solutions to the inverse problem and its spatial-statistical analysis and visualization of the results increases the reliability of the geological results of electrical exploration.
Petro-velocity crossection of the Donetsk coal basin
Introduction: recently, seismic exploration has gained increasing importance for the detection of hazardous methane accumulations in coal deposits. Reliable identification of such accumulations requires sufficiently accurate knowledge of the propagation velocity of elastic longitudinal waves in the rock (Vp) and its skeleton (Vp.sk), and elastic transverse waves (Vs). Despite extensive research conducted in previous decades, the parameters Vp.sk and Vs remain largely insufficiently studied. Therefore, to provide a petrophysical basis for seismic exploration, a comprehensive study of petrophysical velocity characteristics and their variation across the composite stratigraphic section of the basin has been carried out. Methodology: the composite velocity section was constructed by stacking partial sections according to the maximum pre-inversion burial depth of rocks (Hmax). The parameter Hmax was determined based on coal quality indices; Vp was obtained from acoustic logging; Vp.sk was calculated using the Wyllie equation; Vs was derived from correlation with Vp. To substantiate the observed regularities in the variation of petrophysical velocity parameters, data on the structural and mineralogical features of clastic and argillaceous rocks were employed. Results and discussion: a petro-velocity crossection of the coal basin was developed in the form of a family of curves describing the variation in total porosity, mineral density, secondary quartz content, fractured and cleaved grains, as well as Vp, Vp.sk, and Vs as functions of Hmax. The causes of velocity inversion in clastic rocks and the increase in velocity parameters in argillaceous rocks under constant porosity conditions were identified. Conclusion: a petro-velocity crosssection has been constructed for all granulometric varieties and post-diagenetic transformation stages of coal-bearing deposits in the Donbas region. The factors responsible for post-diagenetic increases in velocity parameters were clarified, namely porosity reduction and strengthening of the rock framework. It was established that velocity inversion at the boundary between stages 2G and 3G is caused by an increase in Vp.sk, resulting from the extension of clastic grain contacts below this boundary. It was also demonstrated that the post-diagenetic increase in Vp.sk of argillites at constant porosity is due to the strengthening of contacts and an increase in the mineral density of clay particles.