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Volume 521, Nº 1 (2025)
- Ano: 2025
- ##issue.datePublished##: 15.12.2025
- Artigos: 20
- URL: https://bakhtiniada.ru/2686-7397/issue/view/20227
GEOLOGY
Late Ediacaran glacial deposits of the Baykonur Formation, Middle Tianshan of eastern Kyrgyzstan: Age substantiation based on detrital zircon U–Th–Pb (LA-ICP-MS) geochronological study
Resumo
The results of U-Th-Pb (LA-ICP-MS) dating of detrital zircons reveal late Ediacaran ca 556–540 Ma age of the Baykonur Formation and eponymous glaciation in the Middle Tianshan (MTS) of eastern Kyrgyzstan. The widespread occurrence of the Baykonur diamictites in Kazakhstan and the Tianshan over a distance of more than 1600 km points to a significant extent of glaciation. The association of glacial deposits with shallow-marine fine-grained siliciclastic and carbonate facies indicates lack of connection with mountain glaciers. In the Tarim Craton, which in the Precambrian represented a single continent with the MTS, the stratigraphic correlative of the Baykonur Formation is the Hankalchough diamictite which has a similar age according to chemostratigraphic data. Paleomagnetic data indicating that in the Ediacaran the Tarim and MTS located at low latitudes <30° suggest that the Baykonur glaciation covered most of the Earth's surface and represented one of the largest glacial events in the Neoproterozoic.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):5-13
5-13
Time of single-act metamorphism of sedimentary rocks of the Yenisei complex (Angara-Kan block) based on U–Pb dating of monazite
Resumo
The rocks of the Yenisey complex form an extensive metamorphic belt along the western margin of the Angara-Kan block (south-western Siberian craton), forming a series of tectonic blocks in the Yenisey fault zone. This complex is represented by metasedimentary and metavolcanic rocks and differs from the granulites of the Kan complex by a lower degree of metamorphism. The timing of the formation of the Yenisey metamorphic complex is key to understanding the Proterozoic geodynamic events on the southwestern margin of the Siberian craton. This paper presents the first results of LA-ICP-MS dating of monazite from metasedimentary rocks of the Yenisey Complex. These rocks were found to have undergone single-act metamorphism in the range of 716–750 Ma. The PT-parameters of the metamorphism of the garnet-biotite schists are estimated to be about P = 7.2–8.2 kbar and T = 700–730°C and are in good agreement with those previously obtained for metavolcanic rocks of the Yenisey Complex.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):14-24
14-24
Phenomenon of reverse zoning in picrite gabbro-dolerites of the Talnakh intrusion
Resumo
The original data illustrating the phenomenon of reverse zoning in picritic gabbro-dolerites of the Talnakh intrusion are presented. Based on the distribution of petrogenic and rare earth elements, a sharp geochemical boundary and differently directed trends in the evolution of the magmatic system for picritic gabbro-dolerites and overlying rocks of the main layered series are shown. For the first time, a new subtype of interrupted reverse zoning is revealed for layered intrusions, with the most primitive composition in the upper part of the picritic gabbro-dolerites and a more fractionated composition in the lower part of the main layered series. It is shown that picritic gabbro-dolerites cannot be the lower part of the main layered series during fractionation «in situ» and be formed within the framework of a single mechanism.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):25-32
25-32
U‒PB AGE OF DETRITAL ZIRCON GRAINS FROM MIDDLE JURASSIC SANDSTONES OF THE NORTHEASTERN FLANK OF THE NAGONDZHA TERRANE (ULAKHAN-SIS RIDGE, SAKHA REPUBLIC)
Resumo
U‒Pb (LA-ICP-MS) dating of detrital zircon grains from the Middle Jurassic deposits of the northeastern flank of the Nagondzha Terrane was carried out. The sandstones contain zircon grains from Archean to Middle Jurassic. The weighted weighted average age of the youngest zircon population is 167.6±1.2 million years (Bajocian-Bathonian). The intensity of the 168 Ma peaks and the presence of synchronous pyroclastic material in the deposits suggest the proximity of active volcanic centers to the sedimentation area in the Bajocian-Bathonian. This confirms the existence of island volcanic arc on the Omulevka microcontinent in the Middle Jurassic. Volcanic arc supplied clastogenic material to the eastern part of the Oymyakon paleobasin. Other sources of detrital material included Paleozoic volcanic-sedimentary rocks of the basement of this arc, as well as Precambrian and Paleozoic metamorphic, igneous and sedimentary rocks developed within the Prikolyma and Omolon Terranes. The main difference between the studied sandstones and the Middle Jurassic terrigenous rocks of the Polousnyi Terrane is the presence of a significant number of zircon grains with Meso-Neoproterozoic ages, probably redeposited from the Paleozoic terrigenous strata of the Omulevka and Prikolyma Terranes.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):33-39
33-39
Middle to late Ordovician age of granitoids hosting the Shatyrkol-type quartz-vein copper deposits (Kendyktas Ridge, Southern Kazakhstan)
Resumo
Middle to Late Ordovician age of formation has been obtained for the granitoids of the Kurday-Shatyrkol complex in Southern Kazakhstan (the Kendyktas Ridge) hosting the Shatyrkol and Zhaisan quartz-vein-type copper deposits. U-Pb (SIMS) geochronological studies of the rocks from different phases of the Kurday-Shatyrkol complex yielded the age estimates of 464–457 Ma for quartz diorite and monzonite of the first phase. and the age range of 454 to 450 Ma for granodiorite and alkaline granite of the second and third phases. Proceeding from the new data the Kurday-Shatyrkol complex is comparable to the ore-bearing Middle to Late Ordovician granitoids of the Northern Kazakhstan and Northern Tien Shan. which allows referring them to a single large copper-gold-type metallogenic province.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):40-51
40-51
COMPARISON OF GEOCHEMICAL CHARACTERISTICS OF CHERTS AND LIMESTONES OF CAPE UERING OF WRANGEL ISLAND (LOWER CARBONIFEROUS COMPLEX, NORTHEAST RUSSIA)
Resumo
The article presents the results of geochemical analysis of samples of stones and limestones from a fragment of the Lower carboniferous section of Cape Waring on Wrangel Island. It is shown that not all the ratios used in the analysis of the conditions of formation of silicon and carbonate rocks can be used in interpretation. The identification of the influence of hydrothermal action on the formation of rocks is determined unambiguously by geochemical data. The biogenic/abiogenic origin of flints and the presence of terrigenous impurities in limestones are also unambiguously established. However, the genesis of carbonate and flint rocks in terms of lithological and stratigraphic characteristics does not coincide with what is established by geochemical parameters. This is primarily due to the presence of a terrigenous impurity in limestones, which changes the characteristics of carbonate rocks.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):52-61
52-61
GEOLOGY OF ORE DEPOSITS
The first SM–ND and U–Pb (ID-TIMS) data about the age of formation and metamorphism from Northern Kamennik PT–PD deposit (Fedorovo-Pansky layered complex, Kola peninsula)
Resumo
For the first time, complex Sm–Nd and U–Pb isotope-geochronological analyses of gabbronorites associated with Pt-metal mineralization at the Pt–Pd deposit of Nothern Kamennik (Fedorovo-Pansky layered complex, Kola Peninsula) were carried out. For barren gabbronorites underlying the main ore body and Lower layered horizon (LLH), an Sm–Nd age of 2498±46 Ma with εNd(T) = –1.4 was obtained, while the age of ore-bearing gabbronorites with elevated PGE and Au content was 2484±26 Ma with εNd(T) = –1.0. The yielded ages are similar and coincide with those of zircons from gabbronorites, for which U–Pb ages of 2497±4 Ma were determined. Isotopic Sm–Nd data on metamorphic minerals (apatite, zoisite) yielded the age of metamorphism of rocks in the complex at 1.96–1.5 Ga, which corresponds to Svekofennian metamorphic events widely represented on the Fennoscandian Shield and industrial PGE-Cu-Ni complexes.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):62-69
62-69
GEOCHEMISTRY
Influence of Ca,Mg-carbonate melts compositions on the solubility of sulfur under PТ-parameters of the lithospheric mantle
Resumo
Experimental studies aimed at the estimation of the solubility of sulfur in Mg,Ca-carbonate melts under lithospheric mantle conditions (MgCO3–S, CaMg(CO3)2–S, CaCO3–S and (Mg,Ca)CO3–S systems, Ca# (CaO/(CaO+MgO) (molar)) = 0, 0.2, 0.5, 0.8 and 1.0; pressure 6.3 GPa, 1450–1550°C, 20 hours). It was experimentally demonstrated that melts of alkaline earth carbonates are capable of dissolving from 1.9 to 6.5 wt.% S, while for the first time it was established that the solubility of sulfur directly depends on both temperature and the CaO/MgO ratio in the melt. In particular, it has been demonstrated that the solubility of sulfur in a melt of Ca-carbonate is 6–7 times higher than in a melt of Mg-carbonate. The obtained results indicate that sulfur-enriched melts of alkaline earth carbonates can be considered as potential metasomatic agents, not only capable of transporting sulfur and carbon, but also being potential media for graphite crystallization and diamond growth.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):70-77
70-77
Anomalous concentrations of molybdenum in modern sediments of the background lake in the Arctic (Murmansk region)
Resumo
The analysis of the geochemical characteristics of the sediments of Lake Portlubol, located in the northern part of the Murmansk region, revealed elevated concentrations of Mo, U, Th, REEs, and other elements compared to the upper crust. For Mo, the highest concentration coefficient was established at 92.5. Additionally, the studied sediments showed 39–86 times exceeding concentrations of Mo compared to the background levels of the element in the sediments of the lakes of Karelia. Age assessment of the sediment core from Lake Portlubol indicated that the upper 9 cm of sediments formed over 165 years, with sedimentation rates varying from 0.6: mm/year. Considering that the highest concentrations of Mo (up to 137.1 mg/kg) in the sediment core from Lake Portlubol were found in deeper layers, the anthropogenic influence of the last three centuries could not have affected its elevated level. It is suggested that the main source of Mo in the sediments of the studied water body is the rocks of the Litsevsky ore district, where, in addition to the primary uranium mineralization, elevated concentrations of Mo (up to 600 mg/kg) have been established.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):78-86
78-86
Fluoride fluids: solubility of NaF cr in water at temperatures of 5‒443°C and thermodynamic properties of F – and NaF aq
Resumo
The solubility of NaFcr (villiaumite) in water was experimentally determined for the first time in a wide range of temperatures T = 5‒443°C and pressures P = 1‒1000 bar. At high TP-parameters, the solubility was 1.5‒4 times lower than the values predicted by the SUPCRT97 thermodynamic database. Within the HKF model, the thermodynamic properties of NaFaq were estimated and the HKF parameters of the basic ion F–, necessary for describing its properties in the region of elevated (>100°C) temperatures, were significantly refined. The obtained experimental data allow to estimate the maximum possible level of fluorine concentration in hydrothermal alkaline fluids, which is determined by the solubility of NaFcr.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):87-92
87-92
PALEONTOLOGY
First multituberculate mammal from the upper Cretaceous Nemegt formation at Gurilin Tsav locality in Mongolia
Resumo
The multituberculates were dominant mammals in the Campanian ecosystems of Djadokhta and Barungoyot formations of Mongolia, where they were represented by an endemic Asiatic clade Djadochtatherioidea. In contrast, only one multituberculate species, Buginbaatar transaltaiensis Kielan-Jaworowska et Sochava, 1969, is present in the Maastrichtian Nemegt Formation of Mongolia, provisionally attributed to the North American clade Cimolomyidae. It is known by cranial remains from the Khaychin Ula locality. Here we report on a multituberculate distal humerus fragment from the Gurilin Tsav locality, the second occurrence of multituberculates from the Nemegt Formation. This humerus is most similar with the humerus from the Maastrichtian Hell Creek Formation of Montana, USA, tentatively attributed to a cimolomyid Meniscoessus robustus (Marsh, 1889). If the Gurilin Tsav humerus belongs to Buginbaatar, this may support attribution of this taxon to Cimolomyidae.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):93-97
93-97
SEISMOLOGY
Two types of seismic activity prior the 2006 eruption of Alaska's Augustine volcano
Resumo
The changes in volcanic seismicity regimes on example of the 2006 eruption of the Augustine volcano in Alaska are analyzed in the paper. During the long-term volcanic swarm preceding the eruption, two processes with different seismicity regimes were identified. The first can be associated with general radial deformations caused by an increase in pressure in the underground magma pit; such a regime has a high value of the slope of the magnitude-frequency distribution and a low degree of clustering. The second process, presumably, can be associated with a dike intrusion and local destruction of rock under the pressure of the dike. This process has a slope parameter of the magnitude-frequency distribution close to 1 and shows a high level of clustering before the most significant events, which are followed by lulls.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):98-106
98-106
OCEANOLOGY
Features of the transformation of hydroacoustic waves into seismoacoustic waves in the conditions of the deep sea and the sea of intermediate depth
Resumo
During the processing of experimental data from a coastal laser strainmeter obtained at the time of generation of hydroacoustic waves at a frequency of 22 Hz at various depths of the sea, it was found that the propagation of hydroacoustic waves from the place of their generation to the place of registration of transformed seismoacoustic waves occurs according to a law close to spherical.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):107-109
107-109
On an impact of horizontal inhomogeneity of sea surface temperature in the upwelling vicinity on the tangential wind stress
Resumo
The influence of the horizontally – inhomogeneous ocean surface temperature (SST) field in the vicinity of a coastal upwelling (belonging to the Eastern boundary upwelling systems) on the regional characteristics of the wind stress field is analyzed. It is shown that the change in the turbulent regime of the near-surface boundary layer of the atmosphere during the transition from the upwelling region with a relatively low SST to a warmer offshore zone is the main mechanism determining the influence of spatial inhomogeneity of SST in the vicinity of upwelling on the tangential wind stress and its vorticity. It is concluded that modern satellite data and atmospheric re-analyses highly likely underestimate the magnitude of the vorticity of the tangential wind stress and its contribution to the total upward moving rates of the subsurface layers in the vicinity of upwellings of the type under consideration.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):110-115
110-115
ATMOSPHERIC AND HYDROSPHERIC PHYSICS
Selective absorption in the visible spectrum of dust haze over Middle East in spring 2022
Resumo
Based on monitoring data from AERONET stations in spring 2022, variations in the optical and microphysical characteristics of dust aerosol during a large-scale dust haze in the Middle East were analyzed. It was shown that the coarse fraction of dust aerosol dominates the particle size distribution, with a modal radius ranging from 1.70 to 2.95 µm. The imaginary part of the refractive index of dust aerosol particles reaches 0.042, and the single scattering albedo varies from 0.70 to 0.99. Selective absorption of dust aerosol at a wavelength of 675 nm was found to be associated with the presence of the mineral goethite in the dust aerosol particles. The selective absorption at a wavelength of 440 nm, attributed to hematite, is relatively small in the examined dust haze: the imaginary part of the refractive index reaches approximately 0.005, and the single scattering albedo varies from 0.90 to 0.99. Regional emission sources of dust aerosol were identified.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):116-122
116-122
EXTREME MAGNETIC STORM OF MAY 10–19, 2024: COUPLING BETWEEN NEUTRAL AND CHARGED COMPONENTS OF THE UPPER ATMOSPHERE AND THE EFFECT ON RADIO SYSTEMS
Resumo
Active exploration of space for communication, navigation, and Earth remote sensing in recent decades has drawn increased attention to the study of the Sun’s impact on the Earth and requires creating effective models for space weather forecast. Magnetic storms that produce disturbances in the ionosphere and atmosphere are the strongest manifestation of space weather. Among such events is the magnetic storm that started on May 10, 2024, during which the auroral oval reached 19° N. Over the past 20 years since the last magnetic storm of similar intensity was observed, new scientific facilities have been put into operation as part of the National Heliogeophysical Complex of the Russian Academy of Sciences. A huge decrease in the electron density (by a factor of five relative to the background level) and record-breaking airglow of the upper atmosphere (the atomic oxygen red line airglow exceeded 25 kR) compared to the strongest storms in solar cycle 23 were recorded. The combined optical and radio-physical measurements in Eastern Siberia, supported by data from global networks, demonstrated the correlation between the temperature increase in the upper atmosphere and a strong decrease in the ionospheric electron density at mid-latitudes due to increased recombination during the storm. Combined measurements from ionosonde and high-frequency radar networks have shown a significant deterioration in the conditions of radio wave propagation. The complementarity of the currently deployed scientific instruments opens up new opportunities for monitoring the state of the near-Earth space, as well as for studying and modeling dynamic processes during such extreme phenomena with unprecedented detail.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):123-135
123-135
CLIMATIC PROCESSES
Summer atmospheric blockings in the Northern Hemisphere: changes in recent decades (1993–2023)
Resumo
The analysis of summer atmospheric blockings in the Northern Hemisphere (NH) under climate changes in 1993–2023 was carried out. The results of the analysis indicate a significant increase in blocking activity in the summer seasons in the NH atmosphere in recent decades. The noted trend is manifested against the background of a general increase in the NH surface air temperature in summer seasons. The sensitivity parameters to changes in the NH surface air temperature in summer seasons of the total duration of summer atmospheric blockings, their number, average duration, size and intensity are estimated. In particular, a statistically significant estimate of an increase in the total duration of summer atmospheric blockings by three quarters under the increase in the average summer surface air temperature of the NH by 1K is obtained.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):136-141
136-141
SOIL SCIENCE
The effect of soil gels on the stability of soil
Resumo
The process of wind and water erosion of soils is often considered as three successive stages: separation, transport and deposition of particles. This approach does not take into account the effect on erosion of organomineral soil gels, which cover and bind soil particles together. The aim of the work was to check the relationship between soil gels and stability of soils. The aim of the work was to verify the assumption about the effect of soil gels on the water stability and mechanical strength of soils. The method of determining the water stability of soils, scanning electron microscopy and determination of the strength of soil aggregates using vibrational sieving were used in the work. During the research, it was found that drying soils of natural humidity of various types in the air stream with a velocity of 2 m/s reduced their water stability by about 1.5 times compared with drying in standing air. To study air samples that affected the soil, it was bubbled through water. Examination of these samples using a scanning electron microscope showed that they contain fragments of soil gels and organic supramolecular formations (SMF). It was also found that SMF were blown not only from moist, but also air-dry soils. It is shown that the introduction of polyvinyl alcohol into soils strengthens gels and increases the mechanical strength of soil aggregates. Moreover, the effectiveness of the polymer on moist soils is higher than on air-dry soils.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):142-147
142-147
GEOECOLOGY
Phthalates in the snow cover of the Selenga River basin: content, sources and spatial distribution
Resumo
The content and spatial distribution of six priority phthalates in the snow cover of the city of UlanUde were studied for the first time. Ulan-Ude is located in the basin of the Selenga River, the main tributary of Lake Baikal. Snow samples were collected before the spring melting at 17 points located in the floodplains of the Selenga and Uda rivers and in the zones affected by various pollution sources. The snow water was analyzed by the gas chromatography-mass spectrometry (GC-MS) method. The analysis showed that the total content of phthalates varied from 0.76 to 9.09 μg/L. Dibutyl phthalate, di-(2-ethylhexyl) phthalate, and diethyl phthalate are dominant compounds. The obtained results on the distribution of phthalates in the snow cover within the urban agglomeration showed a slightly different dynamic of the accumulation from the previously studied pollutants. The highest contents were revealed in places with a high transport load in the zones of solid waste landfills characterized by natural depressions in the relief. Although the level of air pollution in Ulan-Ude is assessed as very high, the content of phthalates in the snow cover is significantly lower than that noted in other cities. Analysis of the phthalate content in the snow cover in Ulan-Ude is important for assessing the contribution of atmospheric sources to water pollution.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):148-154
148-154
Migration of radionuclides from horizontal boreholes loaded with vitrified high-level radioactive waste
Resumo
For the disposal of high-level waste mined and borehole types deep repositories are proposed. The migration of actinides (241Am, 244Cm) and fission isotopes (137Cs, 90Sr) from repository with several horizontal boreholes was predicted by mathematical modeling. The concentrations of radionuclides in near-surface waters were calculated as function of number, depth and spacing between the boreholes, permeability of the surrounding rocks, and time of waste storage prior to disposal. The advantage of horizontal boreholes over vertical ones is the weak convection of waters caused by heat generation by the waste. With the same thickness of the rocks separating the waste from the surface, the temperature in the near field of a horizontal borehole is lower than in the case of a vertical borehole, so the intensity of leaching of radionuclides from the glass matrix by water will be also lower.
Doklady Rossijskoj akademii nauk. Nauki o Zemle. 2025;521(1):155-162
155-162