bluuebunny/crossref_metadata_2025 huggingface dataset:
Biogeochemical Assessment of Toxicity and Radioecological Danger of the Transboundary Kara-Balta River
Authors: Djenbaev B. M. , Solodukhin V. P. , Kaldybaev B. K. , Zholboldiev B. T. , Lennik S. G. , Severinenko M. A. , Karmysheva W. J.
Published: April 2024

The paper presents the results of researches of the concentration of chemical elements and natural radionuclide in the environmental objects of the Kara-Balta transboundary river basin (adjacent territories of Kyrgyzstan and Kazakhstan). The level of contamination of floodplain soils and bottom sediments of the Kara-Balta River with such chemical elements as U, Sb, As, Th, Pb, Sc, Co, Cu, Mo, Zn, V, Sr, Ba, Cs was established. Based on the calculated indicators of the contamination factor (CF), enrichment factor (EF), and index of geoaccumulation (Igeo), it was found that Sb, As and Br make the largest contribution to soil and bottom sediment pollution in the Kara-Balta water basin. At three checkpoints, an increased concentrations of U, B, Li, Sr, Mo were found in the water samples of the region’s reservoirs, which is related to the influence of the tailings of the Kara-Balta mining plant. The elevated concentrations of As, B, Ba, Co, Mn, Sb, V, and Zn were also established around the mouth of the Kara-Balta River, which flows into the Tasotkel reservoir (Kazakhstan). The results of the research can be explained by the fact that a significant part of the Kara-Balta transboundary river basin is located in the zone of a uranium natural–technogenic province.
Current development of V.I. Vernadsky's biogeochemical ideas
Authors: Ermakov V. V.
Published: April 2024

The essence and development of a new scientific direction in geochemistry and biology – biogeochemistry, created by V.I. Vernadsky, are considered. The special attention is focused on the concepts - living matter, biogenic migration of chemical elements, chemical elemental composition of organisms and its ecological significance. The analysis of the development of the functions of the biosphere (ecological, concentration, information) is given. The differentiation of the chemical elemental composition of organisms in the conditions of man-made of the biosphere is shown. The role of biogeochemistry in the development of biotechnology and the formation of biogeochemical indication of the ecological state of biosphere taxon is presented. The analysis of the achievements of biogeochemistry and existing problems is given.
Theoretical and Methodological Approaches to the Analysis of Peculiarities of Spatial Distribution of Endemic Diseases of a Geochemical Nature
Authors: Korobova E. M. , Baranchukov V. S. , Kolmykova L. I.
Published: April 2024

Over millions of years of geological history (Phanerozoic), the co-evolution of all living organisms took place in condtions of fierce competition for resources and opportunities for maximum reproduction, which, given the geochemical heterogeneity of the primary (pre-Quaternary) biosphere, resulted in a self-regulating ecological niche system, within which all local biocenoses and their animal and plant species were adapted to the parameters of the habitat to the maximum extent. However, with the development of the brain and the emergence of reason, the situation changed radically. Humans became the dominant species and began to develop new territories, including geochemically unfavourable ones, which caused the formation of zones of persistent endemic diseases. Based on this premise, for all existing species, there must be territories with physiologically optimal habitat conditions, i.e. those in which the species was formed in its present form. This implies that by being able to determine the geochemical parameters of the undisturbed biosphere, it is possible to obtain characteristics corresponding to the ecologically ideal ones for local animal and plant species. In theoretical terms it has allowed to put forward the hypothesis that by fixing the difference between the observed and ideal geochemical conditions it is possible to build maps of risk of diseases of geochemical nature, including those caused by technogenic pollution. The article presents a methodology and examples of such mapping. The results obtained may have an important practical value in improving the system of sanitary and epidemiological services, in solving problems of carrying out preventive measures to minimize endemic morbidity eliminating endemic diseases.
Role of Biogeochemical Processes during Groundwater Deferrization
Authors: Litvinenko Z. N. , Kondratyeva L. M.
Published: April 2024

The paper is devoted to the biogeochemical aspects of the treatment of iron-bearing groundwater, which are associated with the formation of biofouling in the pore space around wells after aeration of the aquifer and on technological equipment. Structure and activity characteristics of microbial complexes as a result of pumping groundwater from production and observation wells under changing redox conditions are presented. Scanning electron microscopy was used to study the microstructure and elemental composition of biofilm growths. It has been established that the accumulation of iron and manganese by microbial biomass occurs due to the encrustation of the surface of bacterial cells immersed in a polymer matrix represented by a constant base of three elements: Al, Si, and Ca. The survival of microbial complexes in biofouling is due to the high natural potential and ability to carry out biogeochemical processes in a wide range of oxygen concentrations (aerobic and anaerobic conditions).
Participation of small mammals in the biogenic transit of trace elements under chemical pollution of the environment
Authors: Mukhacheva S. V. , Bezel V. S.
Published: April 2024

The participation of small mammals (SM) in the migration of essential (Cu, Zn) and toxic (Cd, Pb) trace elements (TEs) in forest ecosystems under conditions of severe industrial pollution of the environment (1990–2000) by a large copper smelter (Middle Urals, Russia) and after a significant reduction in its emissions (2010–2019) was considered. The peculiarity of transit food flows (TFF) in the pollution gradient was determined by the composition and abundance of animals of different trophic groups (phytophages, mixophages, zoophages), as well as the specifics of their diet. The reduction in emissions was accompanied by positive changes in the SM communities, expressed in an increase in the number and structural rearrangements of trophic groups (TG), which led to partial changes in the composition and amount of food consumed, as well as the content of TEs in them. By the end of the observation period in the background zone, the animal-controlled TFF remained stable for most TEs (Cu, Zn, Cd), for Pb it decreased by a factor of 2, but not as a result of reduced emissions. In contaminated areas, the value of TFF Zn has not changed, Cd has increased, Cu and Pb - decreased. It was concluded that in the taiga zone the main contribution to the dynamics of biogenic TEs flows over time and space was made by a group of mixophages that dominated the pollution gradient.
Local biogeochemical cycles of trace elements in agroecosystems of Western Siberia
Authors: Sindireva A. V.
Published: April 2024

The article presents the results of long-term field experiments (2005-2022) to study the distribution and migration of trace elements in the soil-plant-animal system on the example of agrocenoses of the southern forest-steppe of Western Siberia. A biogeochemical assessment of the content of trace elements (Pb, Cu, Zn, Ni, Cd, Cr, Se) in trophic chains under certain agroecological conditions is given. The analysis of geochemical factors affecting the accumulation of trace elements in various types of soils and plants growing on them has been carried out. Normative quantitative characteristics of the action of trace elements on the chemical composition of the soil, productivity and quality of plants of grain, fodder and vegetable crops have been established. The relationship of macro- and microelements when they enter plants is shown, depending on the level and ratio of chemical elements in the soil, the physiological needs of the plant organism at different stages of ontogenesis.The parameters of the intake of trace elements into the body of animals with plant food under the conditions of model experiments have been established. Structural and functional changes in animal organs during feeding with crop products grown with different content of trace elements are analyzed.
Ecological and Geochemical Assessment of Snow Cover in the Area Affected by the Apatite–Nepheline Production of the Kola Peninsula
Authors: Dauvalter V. A. , Sandimirov S. S. , Denisov D. B. , Dauvalter M. V. , Slukovskii Z. I.
Published: April 2024

The chemical composition of the snow cover in the area of industrial development of the apatite–nepheline deposit is analyzed to estimate the ecological and geochemical environmental impact of the mining enterprise. It has been established that the snow of the studied area of the Khibiny is enriched in Cl– and Na+ ions (on average 38 and 41 µeq/L), and relations between basic ions (Cl– and Na+ Ca2+ K+ = Mg2+) and mineralization value (from 1.7 to 6.4 mg/L) are typical for precipitates in the coastal regions of the northern European Russia. The average content of total nitrogen and phosphorus in the snow of the impact zone is 495 and 26 μg/L, respectively, which is 3 and 5 times higher than in the background zone. This is explained by their influx into the atmosphere with dust emissions from the mining enterprise. The content of organic matter (CODMn and TOC 5.5 and 5.8 mg/L) in the snow of the impact zone is about two times higher than in the snow of the background zone and in the water of the Khibiny water bodies. Probably, the elevated content of organic matter in the snow is associated with the supply of organic substances-reagents from the tailing dump, which are used to obtain apatite concentrate, as well as the intensive growth of unicellular green algae Chlamydomonas nivalis (Bauer) Wille under conditions of an increased content of nutrients and long daylight hours. The concentrations of a number of heavy metals (Zn, Mn, Cu, Cr, Pb, Cd) in the snow of the impact zone exceed their contents in the water of water body of the impact zone (13.4, 5.4, 3.8, 0.8, 0.65, 0.035 μg/L, respectively). These metals enter the snow as a part of dust emissions from the mine, and as polluted air masses from the industrial regions of Eurasia.
The Birkachan Epithermal Au–Ag Deposit in the Kedonsky Middle Paleozoic Volcanic Belt (Russian Northeast)
Authors: Volkov A. V. , Savva N. E. , Prokofiev V. Yu. , Ishkov B. I. , Murashov K. Yu. , Dolomanova-Topol A. A. , Sidorova N. V.
Published: April 2024

The Birkachan deposit in the Middle Paleozoic Kedonsky Volcanic Belt (KVB) is unique in Northeast Russia for its stockwork epithermal Au–Ag ores. The deposit is located in the northeastern part of the Gurnik volcanotectonic depression, in the Kedonsky segment of the KVB. The deposit is localized in the lying side of a large sublatitudinal thrust fault, due to which it was overlain in the Jurassic–Early Cretaceous by allochthon rocks and, therefore, was slightly eroded, as evidenced by the preserved fragments of the argillisite cap. The ore-bearing Gurnik sequence is composed of felsic tuffs and lavas with intercalations of ignimbrites. The main ore-bearing zone of the Birkachan deposit is 4.5 km long and 200–300 m wide consists of several echelon-like vein zones of northeast strike, falling to the southeast at angles of 55°–70°. Most of the ore bodies are linear stockworks. Single, lenticular rich ore bodies represented by mineralized breccias have been found at deep horizons. In the section, the system of ore bodies of the Birkachan deposit forms a fan-shaped structure. The main textures of ores are vein-disseminated, breccia, and rhythmically banded. The ores are enriched in comparison with the upper continental crust in a rather narrow range of elements (Au, Ag, Sb, As, Mo, W, and Li) and are poor in rare-earth elements, among which light lanthanides predominate. The sulfide grade of ores is 0.1–0.5%. The vein minerals in ores are dominated by quartz, sericite, and siderite. Among the ore minerals, pyrite dominates, with fahlore, native gold and chalcopyrite, and minerals of the series acanthite → Se–acantite → naumannite, pearceite, and Se–pearceite being less common. The average fineness value of native gold is 643‰. The parameters of mineral-forming solutions correspond to typical medium-temperature fluids of epithermal low-sulfidized deposits: homogenization temperature of 93–291°С, salt concentration of 0.2–7.0 wt % eq. NaCl, and fluid density of 0.71–0.99 g/cm3. The main indicators of fluid composition are CO2/CH4 = 15.8–23.6, Na/K = 2.3–4.3, and K/Rb = 2007. The prospects for increasing the reserves of Au and Ag are associated with further study and exploration of the flanks and deep horizons of the deposit.
Copper in Hydrothermal Systems: a Thermodynamic Description of Hydroxocomplexes
Authors: Akinfiev N. N. , Zotov A. V.
Published: April 2024

The experimental data available in the literature on the solubility of Cu(met.) and Cu2O (cuprite) in water under hydrothermal conditions have been processed. Key experiments were carried out on the solubility of cuprite at 300 C, saturated vapor pressure of H2O, vs. pH of the solution. As a result, a set of values of thermodynamic properties for 25°C, 1 bar and parameters of the HKF (Helgeson-Kirkham-Flowers) and AD (Akinfiev-Diamond) equation of states for Cu(I) hydroxocomplexes was obtained, which make it possible to describe their behavior in a wide range of temperatures (0 – 600 C), pressures (1 – 3000 bar) and densities of aqueous fluid (0.01 – 1 gcm–3). As it has been shown by thermodynamic modeling the Cu+ ion is prevalent in the acidic and weakly alkaline regions of the aqueous solvent over the entire temperature and pressure range studied. The effect of the neutral CuOH hydroxocomplex begins to show up in the alkaline region at T 300 C and grows with increasing temperature. The second copper hydroxocomplex Cu(OH)2– shows up only in the strongly alkaline region, and the temperature has almost no effect on its behavior
Cadmium behavior in sulfur-bearing aqueous environments: insight from CdS solubility measurements at 25-80°C
Authors: Bazarkina E. F. , Zotov A. V. , Chareev D. A. , Truche L. , Tarnopolskaya M. E.
Published: April 2024

The present experimental study explores the effects of temperature and sulfur in Cd aqueous geochemistry under reduced conditions. Greenockite CdS solubility is measured in H2O-H2S-HClO4-NaHS solutions at 25-80°C as a function of pH and sulfur concentration. Based on solubility product measurements in highly acid solutions, the standard thermodynamic properties of greenockite (CdS) are revised, and the recommended value of ∆fG0298.15 for greenockite CdS(s) is -151.5±0.3 kJ mol-1. The stability of greenockite (CdS) is higher than predicted by calculations using previous literature data. At 80°C, the stability constants for Cd-HS complexes are measured for the first time, the values are 10–5.65±1.00 for CdS(s) + H+ = CdHS+, 10–6.00±0.40 for CdS(s) + H2S0(aq) = Cd(HS)20(aq), 10–3.87±0.10 for CdS(s) + H2S0(aq) + HS- = Cd(HS)3-, and 10–3.53±0.20 for CdS(s) + H2S0(aq) + 2HS- = Cd(HS)42-. Modeling of Cd behavior at 3-200°C shows that Cd-HS species are more important than previously believed. The fraction of Cd(HS)n2-n (n = 1-4) complexes increases with mH2S and decreases with T. Thus, in euxinic marine environments with mH2S ≥ 10-5, Cd speciation changes from Cd-Cl to Cd-HS. This speciation change is expected to affect Cd isotope fractionation and should be accounted for when applying Cd isotopic signature as a paleo tracer in marine sediments. The new thermodynamic data are indispensable for modeling Cd behavior in response to pH, T, and mH2S. As a function of these parameters, sulfur has the main control on Cd geochemistry being the main factor of Cd precipitation at low mH2S and favoring Cd mobilization at high mH2S.
FEATURES OF THE INTERACTION OF SHEELITE WITH HCl SOLUTIONS AT 400 AND 500 ° C, 100 MPa AND VARIOUS f(O2) (ACCORDING TO EXPERIMENTAL AND CALCULATED DATA)
Authors: Redkin A. F. , Kotova N. P.
Published: April 2024

Experimental studies were carried out on the solubility of scheelite in HCl solutions in the concentration range from 0.01 to 0.316 mol•kg-1 H2O at 400 and 500°C, a pressure of 100 MPa and the fugacity of oxygen (hydrogen) specified by the buffers Cu2O-CuO, Fe3O4-Fe2O3, Ni-NiO and Co-CoO. It was found that scheelite in HCl solutions at the specified parameters dissolves incongruently. In solutions containing from 0.01 to 0.0316 m HCl, minor amounts of tungsten oxides WO3 and (or) WO3-x are found in the run products, along with scheelite. In solutions containing from 0.1 to 0.316 m HCl, the formation of calcium tungsten bronzes (CTB) CaxWO3 is observed, the average composition of which corresponds to the formula Ca0.07WO3. Based on the analysis of the experimental data obtained, the free energies of the formation of tungsten oxides WO3, WO2.9, scheelite and calcium of tungsten bronze were calculated. Using mutually agreed thermodynamic data, the solubility of Sch in solutions of HCl, (Na,K)Cl with the participation of alumino-silicates is calculated. It is shown that the scheelite has a wide area of congruent solubility in saline systems.
Redox conditions of formation of the Priiskovy massif rock and their metallogenic consequences (South Sikhote-Alin, Primorye)
Authors: Konovalova E. A. , Taltykin Yu. V, , Yurchenko Yu. Yu. , Mishin L. F.
Published: April 2024

The same Cenomanian (96.91 ± 0.88 and 96.5 ± 1.2 Ma) age of amphibole granodiorites of the magnetite and ilmenite series in the southern part of the Priiskovy massif has been established. Among the relatively homogeneous central ilmenite zone of the Sikhote-Alin orogenic belt, the local occurrence of magnetite rocks of the Priiskovy massif explains the distribution of deposits and ore occurrences of the studied site. All deposits and ore occurrences of tin within the boundaries of the Priiskovy massif are located in the zone of distribution of rocks of the ilmenite series (reducing conditions), and deposits and placers of gold and manifestations of polymetallic mineralization are located in the zone of rocks of the magnetite series (oxidizing conditions)
THE WORLD’S LARGEST FOUTA DJALLON–MANDINGO BAUXITE PROVINCE (WEST AFRICA): PART 4. THE MECHANISM OF ZONING FORMATION IN LATERITE BOXITE-BEARING WEATHERING CRUSTS
Authors: Makarova M. A. , Mamedov V. I. , Boeva N. M. , Shipilova E. S. , Vnuchkov, D. A. , Bortnikov N. S.
Published: April 2024

Obtained as a result of detailed exploration and year-round observations of the hydrogeological regime at large deposits, as well as special hydrochemical studies of various types of water and changes in the gas composition of the underground atmosphere in the lateritic weathering crust of the largest bauxite-bearing province FDM, thanks to a reliable factual base, allowed us to draw a number of important conclusions on the conditions and features of the formation of zoning in the lateritic weathering profile for the first time. The weathering profile consists of two metasomatic columns spatially combined in plan, but vertically separated: the upper, lateritic cover, composed mainly of the products of the final hydrolysis of lateritic weathering, that is, hydroxides and oxides of iron and aluminum; the lower one, composed of clayey eluvium, products of hydration and decomposition of aluminosilicates - polymineral clays and kaolinite. In both columns, the processes of changing begin with the same rainwater, but differ in hydrodynamic parameters in each of the columns. Changes in the weathering profile occur in accordance with the main patterns of low-temperature infiltration metasomatism. The modern hydrogeological and gas regime in the bauxite-bearing lateritic covers controls the mineralogical and geochemical zoning. Peculiarities of biological and soil processes, hydrodynamics and hydrochemistry in the weathering profile lead to the threshold nature of the change in physicochemical and biochemical conditions, providing the action of geochemical (oxidative, reducing, gley, adsorption) barriers - the main mechanism of zonal distribution of matter in lateritic crusts.
DIAMOND CRYSTALLIZATION AND PHASE COMPOSITION IN THE FeNi – GRAPHITE – CaCO3 SYSTEM AT 5.5 Gpa
Authors: Sonin V. M. , Tomilenko A. A. , Zhimulev E. I. , Bul’bak T. A. , Chepurov A. A. , Timina T. Yu. , Chepurov A. I. , Pokhilenko N. P.
Published: April 2024

An experimental simulation of diamond crystallization in the system FeNi - graphite - calcium carbonate at a pressure of 5.5 GPa and a temperature of 1400℃ was carried out. Two sample assembly configurations were used. In the first one – the starting materials were put layer by layer, and in the second one - the components were mixed. It has been established that calcium carbonate, when interacting with the FeNi-melt, decomposes with the formation of Ca,Fe oxides and the release of CO2. Magnetite may be present as an accessory phase. Due to the formation of solid reaction products (Ca,Fe oxides) during layer-by-layer filling of the growth volume, the presence of calcium carbonate between graphite and FeNi-melt prevents diamond crystallization in the graphite layer and carbon transport to diamond seed crystals. When the components are mixed in the growth volume, diamond synthesis and growth onto seed crystals occur. The phenomenon of segregation of diamond crystals together with calcium carbonate and oxide phases, the products of the reaction in the bulk of the metal, has been discovered. Aliphatic, cyclic, and oxygenated hydrocarbons, including heavy compounds (C13-C17), CO2, H2O, nitrogen- and sulfonated compounds, were identified in the fluid phase captured by diamonds in the form of inclusions during growth. The composition of the fluid phase in the studied diamonds is more oxidized compared to the composition of fluid inclusions in diamonds grown in the FeNi – graphite system without carbonate. The results obtained correlate with the data on natural diamonds, among which there are crystals with “essentially carbon dioxide” compositions of fluid inclusions, which indicates the possible participation of crustal carbonate matter in the processes of diamond formation during subduction into the deep mantle.
MINERAL RESOURCES OF THE NUCLEAR INDUSTRY OF RUSSIA AND ISOLATION OF RADIOACTIVE WASTE
Authors: Petrov V. A. , Yudintsev S. V.
Published: April 2024

The tasks of ensuring the sustainable development of the nuclear energy industry in Russia are considered, which are aimed at solving the problems of the initial and final stages of the nuclear fuel cycle from the reproduction of the mineral resource base of uranium to the management of high-level liquid waste from the reprocessing of spent nuclear fuel. An analysis was made of the trends in the development of the mineral resource base of uranium in connection with the predicted growth in electricity generation at nuclear power plants. Based on the example of the territory of southeastern Transbaikalia, within the framework of topical mineralogical studies, new approaches to the allocation and justification of prospecting areas are proposed based on models of mineral-forming systems of uranium deposits using Earth remote sensing data, GIS modeling and neural network technologies. A detailed analysis of trends in solving the problems of the final stages of the nuclear fuel cycle has been carried out. For isolation and subsequent disposal of the REE-actinide fraction of high-level waste, it is proposed to use phosphate glass ceramics with monazite
THE LITHIUM BOOM: LITHIUM SOURCES AND PROSPECTS FOR THE RUSSIAN LITHIUM INDUSTRY
Authors: Tsivadze A. Yu. , Bezdomnikov A. A. , Kostikova G. V.
Published: April 2024

The explosive development of renewable energy in recent years is reshaping the geopolitical picture of the world. Solar panels and wind turbines have become the symbol of the new energy transition, while lithium-ion batteries have become its basis and the driver of development. It was lithium-ion batteries that made it possible to overcome the main problem of renewable energy - inconstancy and uncontrollability. The article highlights the lithium problem, the reasons for the volatility of lithium prices, the main sources of lithium and the difficulties of its production. In addition, the prospects of development of lithium industry in Russia and current domestic developments in lithium mining technology are considered
Critical and Strategic Minerals in the Russian Federation
Authors: Vikentiev I. V.
Published: April 2024

Global development and scientific and technological progress are intensifying the use of mineralraw materials (MRMs)—the necessary basis for the production of high-tech products. The advanced producing countries of these products are in dire need of various raw materials, which are critical and, as a rule, are supplied from third countries. Strategic is a mineral raw material, which is of particular importance for ensuring the economic development of the country, its defense and security. Due to the complex structure of extraction, processing and consumption of raw materials, many of its types are in short supply. In the world literature, the concept of “deficient MRMs” in its content most closely corresponds to “critical MRMs,” that is, raw materials that are critically needed for industry and are characterized by a significant risk of their supplies. Most critical raw materials are needed for production promising high-tech industrial products and new materials and, in particular, for “green technologies” in connection with the course of decarbonization of the economy actively pursued by world powers. In the production of such products, the consumption of MRMs is growing rapidly, especially rare-earth elements (REEs), V, Li and platinum-group elements (PGEs). From the list of 61 kinds of MRMs that are strategic for Russia, the extraction of oil, gas, Cu, Au, PGEs, Ni, apatite ores, K salts, and diamonds (as well as nonlisted coals, Fe ores, Na salts, V, B ores, magnesite, and chrysotile asbestos) fully covers their current domestic consumption in the Russian Federation and the achieved level of export. U, Mn, and Cr ores; Zr; high-purity quartz raw materials (SiO2); bauxite (Al); graphite; fluorite and nonstrategic barite; kaolin; and bentonite are deficient; their exploitation only partially provides domestic consumption, which is largely dependent on imports; it is carried out in insufficient volumes in the presence of significant reserves of relatively low quality. The most deficient in this list are Ti, Li, Ta, Nb, and REEs (usually, there are groups of heavy and light rare earths (HREEs and LREEs, respectively)): their domestic consumption is provided mainly by imports with very limited production (despite large reserves, including low quality ores). Re, Be, Nb, Ta, HREEs, Y, Sc, LREEs, Ge, Ga, Li, Hf, and Co, and, of nonstrategic MRMs, Bi and Sr, should be considered critical MRMs in the Russian Federation. The most important source of dispersed/ associated elements is represented by raw materials of mining enterprises of nonferrous metallurgy: Cu and Zn subsectors, In, Ge, Ga, Cd, Tl, Se, Te, Sb, Bi, etc.; Al subsectors, Ga; for Au and Au–Ag deposits, Sb, As, Te, Se, Bi, Tl. An associated source of lithium is represented by brines of gas-condensate fields. The issues of assessing complex raw materials for high-tech industry are considered using the example of pyrite, porphyry, and gold-ore deposits of the Ural folded region, which play an important role in its overall metallogenic potential.
Epithermal Deposits of Kamchatka, Russia
Authors: Bortnikov N. S. , Tolstykh N. D.
Published: April 2024

The results of studying the epithermal deposits of Kamchatka, one of the most promising gold-mining provinces of the Russian Federation, are generalized. The deposits are divided into acid–sulfate (Ac-Sul) and adularia–sericite (Ad-Ser) types (Heald et al., 1987). The disadvantages of the scheme, which is the most popular in the English-language literature and is based on the sulfidation state of mineral parageneses in ores (LS, IS, and HS types), are shown. The classification that we proposed includes differences in mineral associations in circum–ore metasomatites, which are determined by the acidity–alkalinity and an oxidation state of mineral-forming fluids, and are clearly diagnosed at the first stages of studying the deposits. Kamchatka epithermal deposits of the Ad-Ser-type are associated with andesite volcanism of the volcanic belts. Gold ore associations are concentrated in quartz, carbonate–quartz, and adularia–quartz veins, as well as in sericitized metasomatites, which are replaced by argillizites and propylites towards the periphery. The Ad-Ser-type is characterized by combination with polysulfide (Pb, Zn) (Amethyst, Kumroch, Vilyuchinskoe deposits), sulfosalt (Ag, Sb, As, Bi, Sn) (Ozernovskoe, Baranyevskoe), and selenide (Ag, Se) (Amethyst, Asachinskoe, Rodnikovoe) assemblages. Low-fineness native gold (220–310‰) is typical of the early polysulfide assemblage. With an increase in the fugacity of Te and Se, the gold fineness increases to 510–740‰, and with the progressive activity of Sb, As and Bi and the formation of sulfosalt associations, it reaches 998‰. The homogenization temperatures of primary fluid inclusions in quartz from gold-bearing associations of the Ad-Ser-type are 260–250°C; the minerals crystallize from solutions containing no more than 3 wt % NaCl eq. Maletoyvayam, the only Ac-Sul-type deposit in Kamchatka, is localized in quartz, secondary quartzites, and alunite–sericite–kaolinite–quartz metasomatites. Gold-bearing parageneses indicate the leading role of selenium in mineral formation, contain high-fineness native gold, sulfoselenotellurides, tellurides, and selenides of Au, which crystallize from acidic fluids with salinity of 1–5 wt % NaCl eq. at temperatures of 290–175°C.
The Ak-Sug Porphyry Copper–Gold–Molybdenum Deposit, East Sayan: Noble Metal Mineralization, PT-Parameters, and Composition of Ore-Bearing Fluid
Authors: Kuzhuget R. V. , Ankusheva N. N. , Khertek A. K. , Mongush A. O. , Butanaeva Yu. V.
Published: April 2024

Ore mineralization of the Ak-Sug Porphyry Copper–Gold–Molybdenum deposit formed during three stages: 1) porphyry-copper mineralization with simple sulfides in quartz–sericite and quartz–sericite–chlorite metasomatites, 2) subepithermal Au–Bi–Te–Pd-quartz mineralization in quartz–sericite metasomatites, and 3) intermediate-sulfidation Au–Ag mineral assemblages with selenides, tellurides, and Sb and As sulfosalts in argillisites. Fluid inclusion studies (microthermometry, Raman spectroscopy) of quartz and mineral thermometry (an assemblage of Au and Ag tellurides) showed that porphyry copper and subepithermal mineralization precipitated from hydrocarbon–aqueous–chloride (Na–K ± Fe) fluid with salinity of 20.1–32.8 wt % NaCl eq. at 435–375°C and hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 7.5–15.0 wt % NaCl eq. at 415–325°C, respectively. The epithermal mineral assemblages precipitated at ∼0.55 kbar from hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 1.4–12.6 wt % NaCl eq. at 370–200°C. The latest low-temperature (240–190°С) and diluted (3.5–4.9 wt %) fluids are characterized by variations in Na and K chlorides; Fe2+, Fe3+, Ca, and Mg carbonates; and Na, K, and Mg sulfates. The S isotopic composition of the fluid of different mineral assemblages varies from –2.7 to +0.3‰ and suggest that they are derivatives of a single porphyry system. The δ18О values of the fluid of porphyry copper (7.4‰) and subepithermal (7.0‰) stages indicate its magmatic genesis, whereas those of the epithermal stage (from +1.2 to +7.2‰) are evident of mixing of magmatic fluid and meteoric waters (from +0.4 to +5.7‰). Our isotopic data, combined with mineralogical–geochemical peculiarities and formation conditions of ores, provide tracing the principles of the evolution of mineral assemblages, temperatures, composition, and fluid salinity at the Ak-Sug deposit upon the transition from porphyry copper to epithermal stage.
Porphyry and Related Deposits of Northern Eurasia
Authors: Vikentyev I. V. , Bortnikov N. S.
Published: April 2024

It is hard to overestimate the economic importance of the ore deposits of the “porphyry family” and related ones, in particular, epithermal, in the modern world. These deposits are represented by industrial concentrations of a wide range of metals, mainly copper, gold, molybdenum, tin, etc. In Northern Eurasia, they are localized in terranes of different ages—from the Early-Middle and Late Paleozoic (for example, in the Urals and other segments of the Central Asian orogenic belt) to the Mesozoic (Transbaikalia), Mesozoic-Cenozoic (Pacific Ore Belt) and Cenozoic (Kamchatka). The tectonic nature of the corresponding terranes varies from island-arc and marginal-continental in connection with subduction zones along ancient convergent continental margins to post-collision segments and zones of intraplate development (tectonic-magmatic activation) of consolidated continental structures. The history of the study of porphyry copper and related deposits in Northern Eurasia covers the period from 1901 (Turya district of the Northern Urals and Kedabek deposit in Transcaucasia) to the present. In Soviet period, the largest gold-molybdenum-copper-porphyry deposits of Kounrad (Kazakhstan), Almalyk (Uzbekistan) and Kajaran (Armenia) were discovered and studied, as well as in Russia—Peschanka (Chukotka), and in the post-Soviet years—Malmyzh (Khabarovsk Krai). In the overall balance of copper reserves in Russia, porphyry copper deposits take the leading positions, second only to the reserves of sulfide copper-nickel deposits. Porphyry copper deposits play a much more significant role in the structure of the mineral resource base of copper in Kazakhstan, and the predominant one— in Uzbekistan. The main focus of this thematic issue is on gold-copper-porphyry and related deposits. In recent years, new perspectives have been opening up for studying natural associations of different types of porphyry mineralization.
Reconstruction of Lateral Rows of the Late Cambrian and Early Ordovician Active Continental Margin Structures in the Paleozoids of Northern Kazakhstan
Authors: Degtyarev K. E. , Tretyakov A. A. , Salnikova E. B. , Kotov A. B. , Kovach V. P. , Plotkina Yu. V.
Published: April 2024

A comprehensive study of the Upper Cambrian and Lower Ordovician complexes of Northern Kazakhstan was carried out, their ages were substantiated, the structures and compositions of the rocks were investigated. It has been ascertained that the Upper Cambrian formations comprise coarse clastic strata, mafic alkaline effusive rocks and gabbro, while felsic volcanic rocks and granites are represented only by boulders in conglomerates. The Lower Ordovician rocks contain basalt-rhyolite series, felsic alkaline volcanic rocks, and granitoids. The lateral rows of structures of the active continental margin have been reconstructed for the Late Cambrian and Early Ordovician. In the Late Cambrian, the lateral series includes only the structures of the rear extension region, where complexes with the within-plate geochemical characteristics were formed. In the lateral series of the Early Ordovician structures, the frontal volcanic area with the island-arc volcanic rocks and the rear extension area with the intraplate felsic volcanic rocks and granites, were revealed. It is assumed that the differences in the lateral rows of structures may be associated with a change in the tectonic mode of the active continental margin at the Cambrian–Ordovician boundary, when the transform mode with no evidence of suprasubduction magmatism was replaced by convergent magmatism accompanied by the wide distribution of island-arc volcanic rocks.
Southeastern Flank of Knipovich Ridge (Northern Atlantic): Basement Structure and Neotectonics from Geophysical Data and Experimental Modeling
Authors: Sokolov S. Yu. , Agranov G. D. , Shkarubo S. I. , Grokholsky A. L.
Published: April 2024

Acoustic basement of the Knipovich Ridge southeastern flank was interpreted on the time-domain CDP seismic sections and calibration of Bouguer gravity anomalies to depth was done with construction of basement structural map for the area with an oceanic crust type. On this map, to the east from Knipovich Ridge, there is the longitudinal uplift, which is the northern continuation of the Senja fracture zone and interpreted as a transverse ridge on the transform fault board. This uplift is framed by linear clusters of the off-axis seismicity epicenters, indicating the activation of this area structures. The CDP seismic data above the identified uplift show deformations of the Pliocene‒Quaternary sedimentary cover with reverse fault and shear kinematics. Physical modeling of structure formation in the area of the Knipovich Ridge clearly demonstrated the fe-atures of the main tectonic elements during oblique spreading. The result, especially close to reality, was obtained by conducting combined experiments with bending the weakened zone to large angles between the direction of stretching and perpendicular to the axis of the weakened zone. At the same time, the a-ppearance of typical accretion swells and nontransform axis displacements simulating the structures of the southeastern flank of the Knipovich Ridge is close to reality. The series of experiments conducted to study the possible formation of the spreading axis jump in an easterly direction to the continuation of the Senja fracture zone showed the fundamental possibility of this structure activation, which we consider as one of the reasons for the formation of features observed in geophysical data. The current position of the active zones of the region, seismicity, the structure of the basement and the structure of the sedimentary cover indicate a shift in the activity of the main tectonic elements in the east direction relative to the current position of the extension axis. The likely scenario for further development of the region will be the transformation of the Knipovich Ridge into one or the series of transform faults parallel to the western edge of the Barents Sea shelf and the series of short spreading segments between them.
Orenburg Radial-Concentric Structure at Great Depth: Experimental Modeling under Fluid Dynamic Loads and Comparative Analysis of Sandstone Samples from Oil Fields in Western Siberia
Authors: Danilova E. A.
Published: April 2024

The study of the deep structure of the Orenburg radial-concentric structure in the basement of the Russian Platform based on seismotectonic and geomorphological data has been carried out. Interpretation of temporal regional seismic profiles crossing the structure was performed, identifying the main deep faults and measuring their dip angles. It was revealed that the radial-concentric structure is a large flower structure. Its structure involves the main multidirectional deep faults dipping at angles of \(\perp \)60°–85° and limiting horst or reverse fault zones in the basement. The hierarchy of faults structure has been established. Oil and gas fields are confined to the main deep dislocations of the Orenburg structure and represent flower structures of minor sizes. An experimental modeling of the formation of “flower” structures was performed based on the analysis of the results of studies using data from the acoustic emission activity of rocks and under the action of fluid dynamic loads performed at the “UIK-AE” unit (Institute of Geophysics, Ural Branch of RAS, Russia) on sandstone core samples from reservoir rocks of oil fields in Western Siberia. The developed model showed that the formation of flower structures can occur without horizontal shear due to lateral compression and deep pressure. With the help of the seismo-acoustic emission method, characteristic noise was recorded during the formation of cracks in core samples, sound attenuation before splitting, and then its sharp explosive increase from a break in the continuity of the rock. Analysis of the core of wells drilled within the Orenburg radial-concentric structure revealed signs of hydrothermal fluid discharge in the sedimentary cover rocks, such as wavy (or flat) layering, bizarre textures and intervals of breccias, shell-shaped inclusions, stillotite seams, fluid textures. It is concluded that the genesis of the Orenburg radial-concentric structure is associated with the impact of deep heat flows, fluids, high pressure and has a commonality with the explosive ring structures of shields and platforms.
Localization of the Source of a Strong Historical Earthquake in Central Tuva Using Folklore-Historical and Paleoseismological Data
Authors: Ovsyuchenko A. N. , Butanayev Y. V. , Koshevoy N. G.
Published: April 2024

The article presents the results of studies of the source of a strong earthquake in Central Tuva. The studies were carried out using both the widespread geological and geomorphological approach of paleo-seismological orientation, and the methods of historical seismology. Primary information about the source and its location was found in folklore sources with a toponymic reference, using which traces of the earthquake were found and mapped on the field. Traces of earthquakes are confirmed by seismic ruptures in the zone of the Ulugkhem active fault and secondary evidences. Preliminary dating of the event is 1715‒1758, magnitude Mw = 6.5‒7.0. The intensity of the earthquake at the epicenter reached VIII–IX (ESI-2007 scale). In the zone of the Ulugkhem active fault, the consequences of the catastrophic explosion of 1950, which led to human casualties and destruction, were mapped. The results of the research make it possible to clearly define the northern boundary of the Kyzyl intermountain basin as a fault with reverse-sinistral kinematics of displacements in the Holocene, and identification of the epicentral zone of a historical earthquake is necessary to assess the seismic hazard of the most densely populated region of Tyva Republic.
Structure Formation of the Southeast Indian Ridge at the Early Stages of Development: Physical Modeling
Authors: Agranov G. D. , Dubinin E. P. , Grokholsky A. L. , Leichenkov G. L.
Published: April 2024

The authors of the article studied the features of the structure formation of the earth’s crust in the early period of the formation of the Southeast Indian Ridge, associated with the separation of Australia from Antarctica and the advancement of the rift zone to the west within the ancient oceanic lithosphere towards the large magmatic province of Kerguelen, formed by the activity of the plume of the same name. The separation of Australia and Antarctica covered a long period of continental rifting (~160‒80 Ma), which then turned into ultra-slow spreading (~80‒45 Ma), then into slow spreading (~45‒40 Ma) and then into stationary spreading at average rates (after 40 Ma). The advance of the rift zone towards the ancient oceanic lithosphere gave way to the accretion of young oceanic crust on the emerging Southeast Indian spreading ridge. The early stages of development of the young spreading ridge are captured in the modern structural plan of the study region. The advance of the rift zone from the continent into the boundaries of the ancient oceanic lithosphere led to the formation of the Naturalist Plateau and the Bruce Bank near the Antarctic margin. The split of the ancient oceanic lithosphere and the formation of a young crust on the Southeast Indian Ridge led to the formation of conjugated Diamantina and Labuan suture zones, fixing the position of the initial rift split. The transition from ultraslow spreading at the initial stage of oceanic crust formation to stationary spreading with medium velocities is clearly recorded in the change in the irregularity of the accretionary relief. The Southeast Indian Spreading Range westward collided with a large igneous province during the formation of the Kerguelen Plateau and separated the Broken Range from the plateau. The authors carried out physical modeling of the conditions for the occurrence of rifting and spreading processes, as well as structure formation in the region of the Southeast Indian Ridge.
Geodynamic Evolution of Intra-Oceanic Island‒Arc Systems: Expansive (Izu-Bonin‒Marian), Accretionary (Nemuro‒Olutorsky) and Stationary (Aleutian) Types
Authors: Chekhovich V. D. , Sukhov A. N.
Published: April 2024

The authors propose a typification of intra-oceanic island‒arc systems according to the geodynamics of their development in the oceanic space. The currently existing and reconstructed (represented by terranes on the margins of the continents) intraoceanic island-arc systems of the late Mesozoic-Cenozoic are subdivided into expansive, accretionary, and stationary types. Systems of the expansive type (Izu-Bonin–Marian and Lesser Antilles) grow both towards the subducting oceanic plate and towards the free oceanic space – their geodynamics is determined by processes in the oceanic plates. The mantle currents under the overhanging lithospheric plate are directed towards the subducting plate. Accretionary systems such as the Olyutor–East Kamchatka, Nemuro–Lesser Kuril, and Talkitna systems have completed their development as part of active continental margins. The paleotectonic reconstruction of such systems shows that these systems in the course of their development were reduced to relict terranes, tectonically aligned with continental margins. The geodynamics of intra-ocean systems of the accretion type also depends on processes in oceanic plates, but leads to the opposite result compared to expansive systems. This is due to the direction of mantle flows under the overhanging plate, which is opposite to the expansion type, i.e. coinciding in direction with the mantle flow under the absorbed plate. The stationary Aleutian island-arc system is intercontinental and its development in space, as well as the formation of internal structures (the Paleogene island arc of the Bowers Ridge), depended on the difference in the relative movement of the Eurasian and North American lithospheric plates. The most specific feature of this system is the absence of signs of back-arc basin opening, which invariably characterizes expansive and accretionary island-arc systems. It is assumed that this specific feature of the system may be related to the mantle flow under the overhanging slab, which has a transverse direction with respect to the direction of the subducting slab. The Aleutian system, from the moment of its formation, was and remained autochthonous in relation to the North American and Eurasian continents.