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Volume 524, Nº 1 (2025)
- Ano: 2025
- ##issue.datePublished##: 15.09.2025
- Artigos: 20
- URL: https://journals.rcsi.science/2686-7397/issue/view/24222
GEOLOGY
FIRST GEOCHRONOLOGICAL EVIDENCE OF EARLY PALEOGENE TECTONOTHERMAL EVENTS IN THE ARGA-TASS THRUST ZONE (NORTHEAST YAKUTIA): RESULTS OF (U,Th)—He DATING OF PYRITE
Resumo
During the geological survey conducted between 2017 and 2021 in the western part of the Kolyma-Omolon microcontinent, a zone of structural transformations was identified within the southeastern margin of the Middle Jurassic Rassokhinsky (Rassoshinsky) granitoid massif. Quartz veins and veinlets containing native gold are associated with this zone. Research revealed that the sulfur isotope composition in sulfides from this zone (δ34S ~ −15 ‰) is significantly lighter compared to that in molybdenite from the central part of the granitoid massif (δ34S ~5 ‰). Additionally, (U,Th)—He dating of idiomorphic pyrite crystals extracted from hydrothermally altered trachytes near a large quartz vein yielded an age of 65±2 million years (n = 4). These findings, combined with geological observations, suggest early Paleogene tectonic-thermal activity in the region, which facilitated the redistribution of ore components.
Doklady Earth Sciences. 2025;524(1):5-13
5-13
LITHOLOGY
PRE-VENDIAN DISCONFORMITY AND SEDIMENTATION IN THE LATE CRYOGENIAN GLACIATION: STRUCTURAL RELATIONSHIP OF SEDIMENTARY EVENTS IN THE SOUTHWEST OF THE SIBERIAN PLATFORM
Resumo
The article considers the relationship of deposits and their associations in the lower part of the Early Vendian (Late Cryogenian) Marninskaya Formation of the Oselok Group of the alongside Sayan Ridge sedimentary basin of the Siberian Platform. The main method for comparing genetically diverse deposits is lithofacies analysis and correlation of successive sections linking deposits into systems. In the Late Cryogenian (Early Vendian) glaciation, four stages of sedimentation were stabilised: (1) permafrost and thermokarst, (2) glaciation, (3) initial thawing of the glacier and formation of upper glacier stagnant lakes with aleuro-argillaceous sediments and package of cap dolomites, (4) complete regional thawing of the glacier and formation of glaciofluvial fans. The key elements of correlation were kurum breccias that formed at the first stage as a result of the rise of the paleocontinent and its "dry" freezing, and tillites during its glaciation in the wet stage. Pre-Vendian disconformity has been formed at some studies: a denudation of craton in result of general its denudation, a curum sliping down, termokarst dilution of the Riphean carbonate rocks, exaration by glacier and erosium by glaciofluvial rivers. Deposits of the carbonate platform, which overlap the glaciofluvial fans, are attributed to the eustatic type of the time of the onset of the Ediacaran global deglaciation.
Doklady Earth Sciences. 2025;524(1):14-20
14-20
STRATIGRAPHY
SEQUENCE STRATIGRAPHY OF QUATERNARY DEPOSITS OF THE CONTINENTAL MARGIN OF CRIMEA
Resumo
The article presents the results of seismoacoustic studies of the Crimean shelf, carried out in 2018–2024 by the staff of the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, using seismoacoustic and acoustic profilers. The studies made it possible to detail the position of the shelf and slope morphoelements, clarify the seismostratigraphic reference of reflecting horizons, and perform a sequence stratigraphic analysis of the Pleistocene-Holoocene part of the section of the continental margin of Crimea. As a result of the seismostratigraphic and sequence stratigraphic interpretation of seismoacoustic profiles carried out in 2018–2024 on the continental margin of Crimea in the interval corresponding to the Quaternary period, transgressive-regressive cycles and associated tracts of high and low sea level stands were identified. It was noted that regressive-transgressive processes significantly influenced the conditions of sedimentation.
Doklady Earth Sciences. 2025;524(1):21-31
21-31
GEOLOGY OF ORE DEPOSITS
LATE SILURIAN AGE OF INTRUSIVE ROCKS OF THE BESTOBE GOLD DEPOSIT (NORTHERN KAZAKHSTAN)
Resumo
The Late Silurian age of their crystallization has been substantiated for granitoids of the Stepnyak complex, which are associated with the quartz-vein gold deposit Bestobe (Northern Kazakhstan). U–Pb (SIMS) geochronological study of the rocks of the Zapadnaya and Centralnaya intrusions, as well as small bodies in the Dalnaia zone area, was carried out. Estimates of the age of 425–420 Ma have been obtained for quartz diorites, quartz gabbro, granite porphyry and porphyry diorites. These dates are significantly younger than the known Middle-Late Ordovician age of crystallization of the Stepnyak complex in the Aksu, Stepnyak and Zholymbet deposits. Therefore, the heterochromous formation of the Stepnyak complex and the pulsation characteristic of intrusive arrays introduced over about 20 Ma have been assumed.
Doklady Earth Sciences. 2025;524(1):32-41
32-41
GEOCHEMISTRY
SATURATION DEGREE OF THE ARAL SEA WATERS BY CaF2 IN THE MODERN PERIOD
Resumo
Fluorine concentrations in waters from the residual basins of the modern Aral Sea (the Small Aral Sea, Lake Tshchebas, western basin of the Large Aral Sea, and Chernyshev Bay) in a natural state and in equilibrium with CaF2 (the mineral fluorite) were determined. For the first time, the state of saturation by CaF2 of Aral waters with a mineralization of 86–153 g/L was established, which allows the possibility of fluorite chemogenic precipitation from them. With a further increase in mineralization to 306 g/L, the course of this process becomes impossible due to the increasing excess of the equilibrium with CaF2 concentration of fluorine over its natural content.
Doklady Earth Sciences. 2025;524(1):42-47
42-47
GALLIUM IN CORUNDUM FROM DEPOSITS OF VARIOUS GENETIC TYPES
Resumo
Corundum α-Al2O3 is a rare component of some metamorphic and igneous rocks. Corundum contains trace elements Cr, Ti, Fe, V, Ga, Si, Mg, Be, etc. replacing Al in the octahedral position. Corundum forms isostructural series with some oxides of these elements due to the proximity of ionic radii. In addition, the radius of the trivalent aluminum ion is very close to the ionic radius of trivalent gallium, which results in isomorphic substitution of aluminum by gallium. Gallium is a dispersed rare metal that is widely used in radio electronics and the semiconductor industry. Five modifications of Ga2O3 have been established, where one of them α-Ga2O3 is isostructural to corundum. The authors studied the main trace elements (Be, Mg, Ti, V, Cr, Fe and Ga) in corundum from various deposits worldwide using in situ laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS). The maximal amounts of this element are found in corundum of magmatic genesis, while the highest Ga values were recorded by the authors in corundum of the Ilmenogorsk complex with amounts to 370 μg/g. The detected gallium contents in corundum from this object are almost 25 times higher than the Clarke number. In addition, the analysis of literary data showed that the Ilmenogorsk corundum contains the largest amount of gallium among primary deposits of blue corundum in the world. According to our data, the concentration of gallium in nepheline of underlying urities of apatite-nepheline rocks within the Khibiny deposit is 50 μg/g. In Russia, more than 70% of Ga production occurs precisely due to apatite-nepheline ores with an average element content of about 24 μg/g.
Doklady Earth Sciences. 2025;524(1):48-55
48-55
THE ROLE OF FLUORINE IN HYDROTHERMAL TRANSPORT OF TIN Sn(IV) FROM EXPERIMENTAL DATA
Resumo
The solubility of SnO2(cr) (cassiterite) in H2O-HF±NaF solutions was determined at 25 (1 bar) –250°C (P
sat). Several experiments were carried out in HClO4 and NaOH solutions at 250°C. In HF-bearing solutions, the main Sn(IV) species are the hydroxofluoride complexes HSnO2F(aq) (Sn(OH)3F(aq)) and SnOF2(aq) (Sn(OH)2F2(aq)), the latter predominating at 200°C at high HF concentrations up to 1m [mol (kg H2O)−1] and being the main hydroxofluoride complex of Sn(IV) at >300°C. In alkaline fluoride solutions, the main complex is SnO2F− (Sn(OH)4F−). New experimental data were regressed together with literature data with calculation of the standard thermodynamic properties and parameters of the HKF (Helgeson-Kirkham-Flowers) model equation of state for Sn(IV) hydroxofluoride complexes and SnO2(aq) (Sn(OH)4(aq)) complex. These parameters are suitable for modeling tin transport up to 500°C, 5000 bar with the possibility of extrapolation to higher PT parameters. The solubility of cassiterite in acidic fluoride fluids increases sharply with increasing temperature: an increase in temperature from 100 to 400°C leads to a more than tenfold increase in solubility, which at 400°C, 500 bar reaches 20 ppm at a total fluorine concentration of 1 wt. %. Under reducing conditions, the dependence of solubility on temperature will be more pronounced due to the formation of Sn(II) complexes at supercritical temperatures.
Doklady Earth Sciences. 2025;524(1):56-63
56-63
MINERALOGY
GOLD-TELLURIDE MINERALIZATION OF THE BILLYAKH ZONE OF THE TECTONIC MELANGE OF THE ANABAR SHIELD
Resumo
For the first time, the mineralogical features of ore gold extracted from crushed quartz metasomatites of the Billyakh zone of the tectonic melange of the Anabar Shield have been studied in detail. Ore mineralization is represented by chalcocite, bornite, chalcopyrite, tellurides of Au, Ag, Cu, Pb and Bi. Native gold is characterized by a wide variation in fineness (from 550 to 926‰) and an admixture of Cu (up to 7.87%). Most often, it forms symplectic intergrowths with Au tellurides – calaverite and kremerite. Inclusions of chalcocite, bornite, altaite, tellurobismuthite, rickardite, petzite and clausthalite have been identified in native gold and Au tellurides. Discovery of low-temperature gold-telluride association in mineral parageneses of ore-bearing rocks and as inclusions in native gold allows us to distinguish the epithermal gold-telluride mineral type of mineralization.
Doklady Earth Sciences. 2025;524(1):64-73
64-73
TYPOMORPHIS, COMPOSITION AND PROBABLE SOURCES OF ALLUVIAL GOLD IN THE SOUTHERN PART OF THE OCCH-PARMA UPLAND (SOUTHERN TIMAN)
Resumo
For the first time, a comprehensive study of the morphological features and chemical composition of alluvial gold discovered in the Ochparma Upland (Southern Timan, Vol River) has been conducted. It has been established that gold grains are predominantly plate-like, scaly and flat-cake-shaped with a shagreen and tuberculate surface; their size varies within 0.1–0.25 mm. The internal structure of the particles is heterogeneous. The main impurity in gold is silver (Ag 0.1–31.39 wt. %), and individual grains contain copper (Cu 0.78–1.25 wt. %). Riphean schists of the Pokyuk suite, characterized by sulphide mineralization, are considered as a probable primary source of gold in the Southern Timan. Authigenic gold associated with pyrite has been discovered in these rocks for the first time. Pyrite contains inclusions of galena, cubanite, scotchite and lanarkite, indicating hydrothermal-metamorphic transformations of the rock. The fineness of alluvial gold (650–850‰) and the presence of Co (up to 5.85 wt. %) and As (up to 4.08 wt. %) impurities in pyrite suggest its connection with the gold-quartz type of the primary source. The similarity of typomorphic features of alluvial gold in the Southern and Middle Timan indicate the possible existence of a single gold ore zone within the Timan Ridge.
Doklady Earth Sciences. 2025;524(1):74-86
74-86
PALEONTOLOGY
EARLY CAMBRIAN MICROFOSSILS AND TRACE FOSSILS FROM SOUTHWESTERN BELARUS (KOBRIN-1k BOREHOLE)
Resumo
Herein we analyze a stratigraphic distribution of organic-walled microfossils and trace fossils in the Kobrin-1k borehole at the eastern Podlassko-Brest Depression in Belarus. The Ryta and Stradech formations host two fossil assemblages (I – with Teophipolia lacerata – Ceratophyton sp., and II – with Retiranus cf. balticus – Sokoloviina costata – Ceratophyton sp.) corresponding to Rovno–Lontova regional stages of the Lower Cambrian. The data considerably expand the paleontological characteristic of the section and provide new basis for biostratigraphic subdivision and age-estimation of the Vendian–Cambrian transitional interval of the East European Platform.
Doklady Earth Sciences. 2025;524(1):87-94
87-94
GEOPHYSICS
A REGIONAL UPPER CRETACEOUS MAGNETOSTRATIGRAPHIC SECTION OF WEST SIBERIA
Resumo
The results of magnetostratigraphic studies of the Upper Cretaceous of West Siberia are presented. A regional Upper Cretaceous magnetostratigraphic section of this territory was developed by comparing and linking Upper Cretaceous the reference sections of the south of Western Siberia, its center and north. The reliability of paleomagnetic data was determined by the possibility of identifying the primary component of natural remanent magnetization and the structural similarity of the developed scale with the world magnetic polarity scale. Upper Cretaceous of the geomagnetic field in the period from the Upper Albian to the Lower Paleocene, lasting approximately 38 million years, reconstructed from the vectors of natural remanent magnetization, experienced 5 reversals (at the level of magnetozone boundaries) and recorded 3 normal and 2 reverse polarity regime. A regional Upper Cretaceous magnetostratigraphic section of West Siberia includes five magnetozones – three of normal N1K1–2(al2–st), N2K2km2
, N3K2mt2
and two of reverse (R1K2km1
and R2K2mt1
) polarity, compared with the world magnetic polarity scale. The scientific significance of the work is the first developed Upper Cretaceous regional magnetostratigraphic section of West Siberia. In applied terms, this section will allow for local, regional, interregional and global correlation of sections and geological events, as well as their dating.
Doklady Earth Sciences. 2025;524(1):95-101
95-101
SEISMICITY RESPONSE OF NORTHERN CALIFORNIA GEOTHERMAL ZONES TO SHARP VARIATIONS OF GEOMAGNETIC FIELD
Resumo
In order to clarify the role of fluids in the process of electromagnetic triggering of earthquakes, by analogy with the dynamic triggering effect on the earthquake preparation zone, a statistical analysis of seismicity of three geothermal fields of Northern California (Long Valley, Coso, and Geysers) was carried out during 24 sharp variations in the X-component of the geomagnetic field Bx (|dBx/dt| > 50 nT/min) recorded at the Fresno observatory in the period 1991–2024. A statistically significant increase in seismicity of geothermal fields with a delay of 2–10 days after the geomagnetic variation is shown, when the daily number of earthquakes exceeds their average number determined for the previous 15 days, plus triple the value of the standard deviation σ. At the same time, a weaker increase in seismic activity after sharp variations in the geomagnetic field is observed for the entire territory of Northern California. This effect indicates not only the presence of a triggering potential for steep-edge geomagnetic field variations in certain sensitive zones, but also the possible role of fluids in the electromagnetic triggering of earthquakes.
Doklady Earth Sciences. 2025;524(1):102-107
102-107
SEISMOLOGY
RECURRENCE OF STRONG EARTHQUAKES IN THE SOURCE ZONE OF THE TSETSERLEG EARTHQUAKE OF JULY 9, 1905, NORTHERN MONGOLIA
Resumo
Paleoseismological studies in the source zone of the Tsetserleg earthquake of July 9, 1905 with M=7.6–7.7 were carried out. Ruptures of 3 strong earthquakes were recorded in the studied sections. According to the results of the study of seismic ruptures in the trenches, in addition to the earthquake of 1905, 2 strong rupture forming earthquakes have occurred here over the past 3336–3454 years. The penultimate event was dated in the section of deformed floodplain deposits – 1309–1455 years ago. According to the data obtained, the average recurrence period of strong earthquakes along the Tsetserleg fault is 1100–1300 years.
Doklady Earth Sciences. 2025;524(1):108-113
108-113
OCEANOLOGY
INVASIVE DIATOMS IN SINKING MATERIAL OF THE LOFOTEN BASIN (NORWEGIAN SEA)
Resumo
This paper presents the first detailed study of invasive diatom species in sinking material from a sediment trap deployed in the Lofoten Basin of the Norwegian Sea for a year (2017–2018). 11 invasive diatom species were identified; the most prevalent were Fragilariopsis oceanica, Podosira glacialis, Thalassiosira antarctica, Neodenticula seminae, Shionodiscus oestrupii, etc. Multivariate analysis has shown a reliable relationship between the invasive diatom fluxes variability and the contents of N, P, TOC and the Si/Al ratio. The appearance of N. seminae in the Lofoten Basin sinking material is related to the global transport of warm North Atlantic water masses from the Labrador Sea. Sea-ice-associated diatoms are increased slightly from October to December and more significant from March to April with the course of seasonal variability of the sea ice cover in the Arctic Ocean and the removal of sea ice through the Fram Strait into the North Atlantic.
Doklady Earth Sciences. 2025;524(1):114-123
114-123
LINEAR MAGNETIC ANOMALIES ON THE ASEISMIC NINETYEAST RIDGE
Resumo
For the first time the detailed map of the magnetic anomalies (ΔTa) for the equatorial section of the Ninetyeast Ridge were constructed as a result of generalization of magnetic data from five expeditions at the polygon near the Site 216 DSDP. On the basis of its analysis and interpretation, new conclusions about the tectonic structure and evolution of some objects within the studied polygon were made and the boundaries of linear magnetic anomalies were established. For the first time, it was found that the spreading linear magnetic anomalies C31r and C32n.1n do not terminating at the base of the Ninetyeast Ridge but continue from adjacent basins into it limits. The spreading rate calculated from these anomalies for the axial part of the ridge is estimated at 45 mm/year. In the Warton Basin, the position of the 90° E submeridional fracture zone, along which the rupture and displacement of the axes of linear magnetic anomalies occur, was clarified.
Doklady Earth Sciences. 2025;524(1):124-132
124-132
FAR FIELDS OF WAVE DISTURBANCES FROM A SOURCE FLASHED UNDER THE ICE COVER
Resumo
The problem of far wave fields on the boundary of ice cover and homogeneous liquid of finite depth generated by a pulsed source of disturbances that flared up under the ice is solved. In the linear approximation, an integral representation of the solution is obtained and, using the stationary phase method, an asymptotic representation of the solution for various modes of wave generation is constructed. The spatial and temporal evolution of wave packets of ice cover disturbances propagating from the flared source of disturbances is investigated.
Doklady Earth Sciences. 2025;524(1):133-138
133-138
CLIMATIC PROCESSES
CHANGES IN METEOROLOGICAL RISK FACTORS FOR HIGHWAYS IN THE EUROPEAN PART OF RUSSIA IN THE RECENT DECADES
Resumo
An analysis of changes in meteorological risk factors on highways during the cold season over the past four decades has been conducted. Based on high-resolution ERAS-Land reanalysis data, assessments of the recurrence of heavy snowfalls, air temperature transitions through zero degrees, and meteorological conditions characteristic of ice glaze phenomena were performed for highways M-1, M-4, M-11, M-12, and R-21 in the European part of Russia along their entire lengths. These assessments were carried out for the periods 1980–1999 and 2004–2023, as well as for the differences between them. Sections of highways with increased exposure to meteorological factors were identified. The most significant reduction in the number of days with heavy snowfalls was observed on M-4 (by 12.4%), M-12 (6.3%), and M-11 (5%). For some sections of the analyzed highways, 10–16% increase in the number of days with temperature transitions through 0°C was found. The recurrence of days with meteorological conditions characteristic of ice glaze phenomena decreased on M-4 but increased on the other highways, with the most significant growth on M-12 and R-21. The most noticeable reduction in the recurrence and intensity of the analyzed meteorological risk factors was observed on M-4 sections in the North Caucasus. The results can be used to develop measures for reducing transportation risks associated with adverse weather events and changes in their intensity and frequency in a warming climate.
Doklady Earth Sciences. 2025;524(1):139-147
139-147
GEOECOLOGY
MONITORING OF ORGANIC CARBON CONTENT IN SOILS OF AGRO-ECOSYSTEMS OF THE CENTRAL CHERNOZEM REGION
Resumo
The research was conducted in 2010-2022 in the Belgorod region, which is part of the Central Chernozem Economic Region and located on the southwestern and southern slopes of the Central Russian Upland. The purpose of the research was to analyze the results of monitoring the organic carbon content in the soils of agroecosystems in conditions of large-scale biologization of agriculture. The study found that typical and leached chernozems lost 40.0–42.0% of organic carbon during long-term use in agriculture compared to their counterparts in natural ecosystems. On average, for the studied subtypes of slightly washed chernozems, the decrease in the content of this parameter, compared with non-washed arable soils, is 14.5–16.4%. In the genetic horizon B and the upper layer of horizon C, the content of organic carbon was lower than in the arable by 1.87–2.22 and 5.30–6.98 times, respectively. As a result of the implementation of comprehensive measures aimed at increasing the supply of organic matter to the soil and reducing its losses, the weighted average organic carbon content in the arable soils of the region increased by 0.174%, which corresponds to the accumulation of 19.1 carbon units/ha. A direct linear relationship has been established between the levels of organic carbon and easily hydrolyzable nitrogen in soils.
Doklady Earth Sciences. 2025;524(1):148-155
148-155
ASSESSING THE CONTRIBUTION OF ARTIFICIAL RADIONUCLIDES IN THE FORM OF MICROPARTICLES TO THE TOTAL RADIOACTIVITY OF BOTTOM SEDIMENT SAMPLES FROM THE YENISEI RIVER
Resumo
The study reveals the presence of microparticles with increased activity concentrations of artificial radionuclides (60Co, 137Cs, 154Eu, and 241Am) in bottom sediments (BS) of the Yenisei River in the area affected by the operation of the Mining-and-Chemical Combine of Rosatom. In the present work, for the first time, radioactive microparticles were detected in the BS collected from three sections of the River while about 25 years ago, microparticles were only found in one section of the River. According to their radionuclide composition, the microparticles are divided into two groups: mononucleic and polynucleic microparticles. The contribution of radionuclides 137Cs, 154Eu, and 60Co contained in the microparticles to the total BS activity varies from 81 to 95%, exceeding the values previously reported for microparticles in floodplain soil and BS. 241Am is included in both groups of microparticles, exhibiting the highest contribution of activity in the form of Am-microparticles to the total activity in BS from all study areas – up to 99.6%. The presence of microparticles in the Yenisei River floodplain increases the non-uniformity of radionuclide distribution over the area, which makes it difficult to assess the total radionuclide contamination level in the River floodplain and the mobility of radionuclides in the ecosystem.
Doklady Earth Sciences. 2025;524(1):156-165
156-165
CHEMICAL PRECIPITATION CHARACTERISTICS OF URANIUM ON CALCIUM PHOSPHATES
Resumo
Groundwater purification from uranium compounds near sludge storages of nuclear fuel cycle (NFC) facilities by precipitation of apatite group minerals and/or directly uranium (IV, VI) phosphates is a sound method. In laboratory experiments, we demonstrated the efficiency of uranium immobilization in the solid phase of Ca-phosphates during neutralization of natural and technogenic wastewater from two nuclear plants with Na2HPO4 solutions with the removal of more than 98% of uranium. Analysis of the sediment by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM-EDS) confirms the formation of hydroxyapatite and the brushite mineral CaH(PO4)(H2O)2. When identifying the oxidation state of uranium by XPS, the presence of uranium in the oxidation state of U4+, U5+, and U6+ was observed, with U5+ for up to 30–35 at. %. Our study is the first to demonstrate the possibility of immobilization of uranium in three oxidation states from neutral technogenic and model solutions, which was represented at normal temperature, without oxidation-reduction manipulations and biota presence. Similar results were previously obtained during the oxidation of UO2 to UO2+x only. At the same time, a series of thermodynamic calculations showed that precipitation of U(VI) under atmospheric conditions (open system) can lead to the formation of surface minerals with distinct hyperstoichiometry, including U4O9 and U3O8.
Doklady Earth Sciences. 2025;524(1):166-174
166-174