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Volume 523, Nº 1 (2025)
- Ano: 2025
- ##issue.datePublished##: 15.07.2025
- Artigos: 20
- URL: https://journal-vniispk.ru/2686-7397/issue/view/22193
GEOLOGY
First evidence of nanodiamond cluster formation in shungite in connection with seismogenic dynamic shear
Resumo
The first evidence for the natural transformation of initially amorphous carbon into graphite and diamond nanoclusters under the influence of high-speed dynamic shear and associated frictional heating of the carbonaceous substrate is presented on the example of Karelian shungites and seismogenic slickensides identified in them. Approximate estimates of the P-T parameters of these structural-material and phase transformations are given, and their position on the phase diagram of carbon is noted.
Doklady Earth Sciences. 2025;523(1):5-17
5-17
Direct signs of eruptive fluid-rupture breccias on the Ufa Plateau (East European Platform)
Resumo
New data on eruptive fluid-rupture breccias of the Ufa Plateau – geomorphological uplift on the eastern (cisural) periphery of the East European Platform (EEP), bordering the Cis-Ural foredeep, are presented. The plateau is represented by a 2.5–3 km thickness carbonate platform of D2-P1 age overlying a crystalline foundation of AR–PR age. In the apical part of the plateau and at its foot, there are strongly cavernous carbonate rocks, the so-called “foraminated breccia limestones” (FBL), which sometimes contain debris and pebbles from siliceous rocks as well as metamorphic and igneous minerals. There are indications of an association between xenogeneic material and eruptive fluid-rupture breccias, wherein the authors conducted special studies. FBL samples weighing 1–5 kg from various parts of the plateau were dissolved in a 10% HCl solution. In the insoluble constituent of several samples, microbreccias were found composed of debris (up to 1–2 mm) of amphiboles, pyroxenes, plagioclase, biotite, titanomagnetite, and serpentine, immersed in finely dispersed material with the same composition. Up to 50% of the matrix volume consists of magnetic and glass spheres and shapeless masses. The microbreccia matrix is very mild and easily breaks down when touched. Moissanite, native metal plates and their alloys (Ni, Fe–Ni, Fe–Cr–Ni, Fe) were noted in samples. The authors explain the presence of microbreccia fragments in the FBL by tectonomagmatic activation of the EEP margin during the Early Kungurian, crustal degassing, accompanied by the formation of eruptive fluid-rupture breccias, the removal of dispersed rock material of the crystalline basement, and the enrichment of weakly consolidated sedimentary rocks. As a result of thermal processes, magnetic and glass spheres were formed in the microbreccia.
Doklady Earth Sciences. 2025;523(1):18-27
18-27
STRATIGRAPHY
The oldest find of Inoceramus-like bivalves Aphanaia sp. in the Lower Sakmarian deposits of Northern Verkhoyanie, Northeast Asia
Resumo
The most ancient representatives of Permian Inoceramus-like bivalves, Aphanaia sp., dominants of later (Middle and Late Permian) benthic communities, have been discovered for the first time in the Lower Sakmarian deposits of Northern Verkhoyanie (Northeast Russia). The age of the find is confirmed by the presence of the zonal brachiopod species Jakutoproductus insignis Abramov et Grigorjeva. Previously, the oldest find of Inoceramus-like forms in the Northern Hemisphere was dated to the end of the Sakmarian. We associate such an early appearance of Inoceramus-like bivalves in the Permian sections of Northeast Asia with their invasion from the Gondwanan basins at the beginning of the major Echian transgression.
Doklady Earth Sciences. 2025;523(1):28-33
28-33
GEOLOGY OF ORE DEPOSITS
The nearly-coeval but metallogenically distinct tungsten-bearing intrusive complexes in the southern Tien Shan: first data on the isotope U–Pb dating (LA-ICP-MS method) of zircon from intrusive rocks of the Maikhura and Kabuty tungsten skarn deposits (Tajikistan)
Resumo
The paper presents first isotopic U–Pb data (LA-ICP-MS method) on zircon from the intrusive rocks of the Maikhura and Farkhob massifs, which the Maikhura tungsten-tin and Kabuty tungsten-polymetallic skarn deposits are associated with. These deposits, together with the other W and Au deposits, are part of the largest Au–W metallogenic belt of Tien Shan. The concordant isotopic U–Pb data for zircon “autocrysts” (302.5±2.3 Ma for granodiorite of the Maikhura massif, 305.1±2.3 Ma and 306.6±2.8 Ma for granodiorites of the Farkhob massif) indicate a nearly-coeval emplacement of these rocks in the Late Carboniferous. The younger (Early Permian) concordant isotopic U–Pb data for zircon “autocrysts” (292.2±2.3 Ma) have been obtained for biotite granites of the Maikhura massif. The metallogenic difference of these deposits highlights the difference of the respective intrusive complexes, whereas the coincidence of the age dates of the intrusive rocks can indicate a nearly-coeval timing of formation of magmatic chambers of different composition at various crustal and upper mantle levels and in a different protolith, which is characteristic of the post-collisional magmatism. Despite of the difference in the composition of the ore mineralization, its relationships to the nearly-coeval igneous complexes may indicate a certain genetic proximity of the tin-tungsten and tungsten-polymetallic-gold metallogenic types that is expressed in post-collisional metallogenic belts globally.
Doklady Earth Sciences. 2025;523(1):34-46
34-46
GEOCHEMISTRY
Effect of methane-hydrogen fluid on diamond crystallization in metal-carbon melt at p-t conditions of lithospheric mantle
Resumo
One of the unresolved questions of diamond genesis under reducing conditions in the Earth’s mantle is the role of the methane-hydrogen fluid. This paper presents the results of experimental studies on the influence of anthracene (C14H10) additives on the crystallization, properties and characteristics of diamond in metal-carbon melts under P-T parameters of the lithospheric mantle. It was found that an increase in anthracene content in the Ni7Fe3–C system from 0 to 2.69 wt. % at a pressure of 5.5 GPa and a temperature of 1400°C leads to a decrease in the degree of transformation of graphite into diamond from 100% to zero, which indicates the inhibitory role of the added impurity. Metal, graphite, methane and hydrogen were identified as the main phases of inclusions in the synthesized diamonds. It is substantiated that the fluid composition in the studied system is methane-hydrogen, and it is considered to be the main inhibiting impurity. It is established that with increasing anthracene content in the system, diamond growth on seeds is replaced by spontaneous crystallization, then metastable graphite and diamonds with anti-skeletal growth features are formed, and then only metastable graphite crystallizes.
Doklady Earth Sciences. 2025;523(1):47-53
47-53
PETROLOGY
Granodiorites in Tufaconglomerate Boulders of the Shurmak Formation of the Cambrian: Evidence of Continental Neoproterozoic Magmatism in the South of the Tuva Segment of the Central Asian Fold Belt
Resumo
A geochemical study and geochronological justification of the age of granitoids from the detrital part of tufa conglomerates of the Shurmak Formation in southern Tuva has been done. They have uniform composition and correspond to low-alkaline granodiorites, characterized by enrichment in light REE, Zr, Th, Hf and manifested minima in Eu, Nb, P, Ti. U–Pb dating with LA-ICP-MS method of detrital zircons from three granite boulders allowed us to determine their age: 784±2, 785±2, 773±2. All studied samples contain xenogenic zircons with ages of 1018, 1807, 1897, 1982, 1984, 2085 Ma, which is consistent with the Sm–Nd isotopic data for these rocks – T(DM2st) age 1.85 Ba, εNd(t) = –3.4. This suggests that they formed from a late Paleoproterozoic crustal source. At present, the existence of Neoproterozoic granitoids within the Tuva segment of the Central Asian folded complex has not been established.
Doklady Earth Sciences. 2025;523(1):54-62
54-62
Granodiorite-granite intrusions in central and southern Rudny Altai (Eastern Kazakhstan): age, compositions and geodynamic settings
Resumo
The granodiorite-granite intrusions included in Late Paleozoic Zmeinogorsk complex have been studied within central and southern part of Rudny Altai (territory of Eastern Kazakhstan). U-Pb dating (LA-ICP-MS) of zircons allowed to determine age of intrusions in 370–358 Ma interval that corresponds to Late Devonian (Famennian). This correlates with the age of the Zmeinogorsk complex granitoid intrusions in the northwestern (Russian) part of Rudny Altai. Granodiorites and plagiogranites predominate in the volume of intrusions, their geochemical features correspond to I-type granites. Granodioritic-plagiogranitic magmas may have formed as a result of partial melting of meta-basalts or meta-andesites under influence of mantle-derived magmas. Biotite leucocratic granites form the later intrusive phases; and they may have classified as fractionated I-type granites. They may have formed during fractionation in deep magma chambers with F-bearing fluid presence. Analysis of geological and geochemical data allows to conclude that the Famennian granodiorite-granite magmatism is most likely associated with subduction of the Ob-Zaisan Ocean lithosphere under the Altai active margin, which could have occurred obliquely (transform) to the continental margin.
Doklady Earth Sciences. 2025;523(1):63-71
63-71
Ulugtanzek rare-metal igneous complex and its occurrence in the structures of Sangilen (southwestern part of the Tuva-Mongolian superterrane)
Resumo
Geochronological studies of zircons from rare-metal granites of Verkhnekundus Nb–Ta and REE deposit located on the southwestern flank of Tuva-Mongolian massif were carried out. The age of 295±4 million years was obtained, that is in good agreement with the age of other alkaline rocks of this region – rare-metal granites of Ulug-Tanzek deposit. Opur isotopic studies show the similarity of the Nd isotope compositions of the rocks from Verkhnekundus and Ulug-Tanzek deposits. Considering the isotope characteristics of Sangilen block rocks, corresponding to the Mesoproterozoic crust, it was made the conclusion that rare-metal granites were formed with the participation of juvenile material.
Doklady Earth Sciences. 2025;523(1):72-83
72-83
MINERALOGY
Sulfur-Deficient Fahlore: Kenoargentotetrahedrite-(Zn) [Ag6]4+(Cu4Zn2)Sb4S12 and Kenoargentotetrahedrite-(Fe) [Ag6]4+(Cu4Fe2)Sb4S12 from the Epithermal Silver-Polymetallic Mangazeyskoye Deposit (Yakutia, Russia)
Resumo
For the first time in the ores of the epithermal silver-polymetallic Mangazeyskoye deposit (Yakutia, Russia), sulfur-deficient fahlore (kenoargentotetrahedrite-(Zn) and kenoargentotetrahedrite-(Fe)) was diagnosed and described using EPMA and single-crystal X-ray diffraction. Keno-fahlore was found as 5-7 mm crystals on a quartz druse. One crystal is a monomineral kenoargentotetrahedrite-(Zn), the other is a polymineral aggregate composed of early argentotetrahedrite-(Fe)-I and kenoargentotetrahedrite-argentotetrahedrite-(Zn) and late kenoargentotetrahedrite-(Fe)-II, pyrargyrite, and miargyrite. The average composition of the kenoargentotetrahedrite-(Zn) (wt, %): Ag 32.80, Cu 13.81, Zn 6.84, Fe 0.12, Sb 25.60, As 0.06, and S 20.39, calculated on the empirical formula (Ag5.79Cu0.21)Σ6(Cu3.93[Zn1.99Fe0.04]Σ2.03)Σ5.96(Sb4.01As0.02)Σ4.03S12S0.11. Composition of the kenoargentotetrahedrite-(Fe) (wt, %): Ag 25.39-27.90, Cu 17.55-19.76, Zn 0.80-2.67, Fe 3.70-5.60, Sb 26.04-26.65, As 0.07-0.17, and S 21.37-22.12, calculated on the empirical formula (Ag4.79–4.29Cu1.21–1.71)Σ6(Cu4.02–3.92[Fe1.82–1.23 Zn0.23–0.76]Σ1.97–2.05)Σ5.93–6.00(Sb4.04–3.97As0.02–0.04)Σ3.99–4.06S12S0.25–0.55. The refined unit cell parameters of the kenoargentotetrahedrite-(Zn) are cubic, space group а0 = 10.483…10.485 Å, V = 1152.17…1152.67 Å3, and Z = 2. The kenoargentotetrahedrite-(Zn) discovered at the Mangazeyskoye deposit is an extreme Ag-, Sb- and Zn-end-member of the freibergite series, which contains large Ag contents and almost absent of As and Fe contents, compared to the prototype of this mineral species from the Yindongpo deposit (Henan Province, China). The Mangazeyskoye deposit is the second location of kenoargentotetrahedrite-(Zn) in the world and has still been the only one where such an extreme, almost theoretical composition of this mineral is recorded.
Doklady Earth Sciences. 2025;523(1):84-101
84-101
Forms of Titanium Occurrence in Bauxite
Resumo
A comprehensive study of the distribution of titanium in lateritic-sedimentary bauxites from the Central deposit in Western Siberia, Sangaredi (West Africa), and in in situ bauxites from the Mainpat plateau deposits in India has been conducted. It has been found that titanium in bauxites presents as a relict (anatase, titanomagnetite) form and hypergenic (anatase, rutile) minerals, dispersed forms, as well as newly formed crystals (rutile), each of which exhibits specific morphological and geochemical characteristics. The distribution and forms of titanium occurrence in bauxites have a direct influence on the technological parameters of bauxite processing, which is crucial for optimizing the aluminum ore enrichment processes.
Doklady Earth Sciences. 2025;523(1):102-112
102-112
Apatite fission-track ages from the Archean Karelian Craton: First results
Resumo
The first apatite fission-track ages (AFTA) from surface samples of geological objects within the Archean Karelian craton – the Kivakka massif (AFTA 901±95 Ma (±2σ)), the Pirttiguba dyke (957±87 and 1024.3±90.9 Ma) and the Ropruchey sill (990±101 Ma) have been obtained. Obtained results indicate the absence of regional thermal events above 120°C within the Karelian craton over the past billion years. This suggestion is in agreement with low-temperature thermochronology data from conjugate sites in Finland. Time-temperature models of the studied magmatic bodies indicate a monotonic cooling of the rocks of the present-day surface of the Karelian craton throughout the Phanerozoic at a rate of 0.12–0.31°C/Myr. This corresponds to a denudation rate of 6–16 m/Myr (assuming a geothermal gradient value of 20°C/km).
Doklady Earth Sciences. 2025;523(1):113-120
113-120
Low-sulfide mineralization with high Pd–Pt–Rh tenor in anorthosites from the Yoko-Dovyren massif
Resumo
In the Yoko-Dovyren massif, during a geochemical study of taxitic PGE-bearing anorthosites of Reef I, a type of rock with a high ratio (tenor) of light platinum group elements (PGE) to sulfur was described for the first time. Such rocks contain a total of up to 10.5 ppm Pd–Pt–Rh and <0.06 wt. % S. They are combined in Reef I with already known anorthosites that have moderate PGE/S ratios and contain, according to our data, up to 6.5 ppm Pd–Pt–Rh in total and 0.3–1.5 wt. % S. High-tenor PGE anorthosite areas consist of plagioclase, may contain small amounts of olivine, and always contain orthopyroxene (several wt. %), presented by amoeboid poikilitic crystals up to 10 cm in size. They contain intergrowths of Fe-Ni-Cu sulfides and hydrous minerals, usually no larger than 100 μm in size and containing numerous submicron PGE grains. The extreme PGE/S ratio can be interpreted as the result of local accumulation of late fractions of a PGE-rich sulfide melt formed by crystallization of an immiscible sulfide liquid.
Doklady Earth Sciences. 2025;523(1):121-127
121-127
Brunovskyite, NaZrSi2O6(OH), a new mineral from the Khibiny massif
Resumo
Brunovskyite, NaZrSi2O6(OH), is a new mineral from the pegmatites of Mount Takhtarvumchorr, Khibiny Massif, Russia. The mineral forms white powdery masses or plate-like crystals bordering the grains of the original parakeldyshite, which it replaces. The mineral is triclinic, space group P-1. The unit-cell parameters refined from powder X-ray diffraction data are: a = 5.5472(4), b = 7.1960(6), c = 7.6177(5) Å, α = 64.880(6), β = 81.509(8), γ = 89.048(7)°, V = 271.94(3) Å3. The eight most intense powder X-ray diffraction lines are (I-d[Å]-hkl): 94‒6.50-010; 47‒6.22-011; 73‒3.94-1-1-1; 98‒3.41-002; 100‒3.03-121; 77‒2.976-1-2-1; 36‒2.744-200; 39‒1.7961-042. Brunovskyite belongs to the group of zirconosilicates and is dimorphic with keldyshite. The mineral is named in honour of Bruno Karlovich Brunovsky (1900–1938), a Soviet crystallographer who solved the first crystal structure in the Soviet Union.
Doklady Earth Sciences. 2025;523(1):128-135
128-135
GEODYNAMICS
The geodynamics before and after the February 6, 2023 Turkey duplet earthquake according to SAR interferometry data
Resumo
Using the Stacking-InSAR satellite radar interferometry method, time series of the velocity fields of vertical and horizontal geoblock displacements along the west-east direction were calculated in the period before and after the doublet earthquakes with magnitudes of 7.5 and 7.8 that occurred in Turkey on February 6, 2023. Segmentation into blocks with similar displacement velocities was performed using cluster analysis of displacement velocity fields. It has been found that the boundaries of blocks with different temporal geodynamics correspond to bends and transitions from one segment of the East Anatolian Fault (EAF) to another. In the area of the EAF bending in the south-east direction, an extensive small-block structure with different shift rates before the earthquakes was discovered, in the zone of which both epicenters of 7.8 and 7.5 earthquakes were located. Analysis of the temporal dynamics of displacement velocity fields in the period from 2016 to February 2023 confirmed that one of the significant early triggers of the doublet earthquake was an anomalous shift (about 20 cm) in the western direction of a small geoblock, which was associated with seismic activity on January 24, 2020. Data on the geodynamics of the region showed that significant shifts lasted first 8 months after the doublet earthquakes, after which the shift processes became stationary for this region.
Doklady Earth Sciences. 2025;523(1):136-145
136-145
TECTONICS
Landslide Processes in Central Laptev Sea Continental Slope and Their Relation with Tectonics
Resumo
Three horizons composed by mass transport deposits were distinguished on seismic cross-sections in the upper sedimentary section of Laptev Sea continental margin. Mass transport deposits originate in canyons and are transported into the Amundsen Basin on distance up to 350 km forming wide continental rise. Seismic activity and gas emission from sediments serve as triggers for canyons slope collapse with generation of slump flows. Canyons’ system origin on the slope eastward from Gakkel Ridge could be governed by extension of Eurasian Basin due to counter motion of the under-lithospheric current of upper-mantle convection sell under Arctic region.
Doklady Earth Sciences. 2025;523(1):146-152
146-152
Late Cenozoic Thrusts in the Foothills of the Southern Slope of the Khan Khuhei Range (Northwestern Mongolia)
Resumo
There are latest thrust structures in basement of the southern slope of Khan-Khuhei Range which have north-west and latitudinal dimension. The thrust plates are composed of rocks from the Upper Cambrian to Middle Pleistocene. The paper presents data on amplitudes and velocities of movements along the faults both in the Late Pleistocene and throughout the Late Cenozoic. It is shown that the velocities of tectonic movements significantly increase in the Quaternary and in particular in the Late Pleistocene. We can notice potential seismic hazard of the described thrust structures.
Doklady Earth Sciences. 2025;523(1):153-159
153-159
PALEONTOLOGY
Dsungaripterid pterosaur from the Lower Cretaceous of Transbaikalia, Russia
Resumo
A proximal fragment of tibiotarsus (fused tibia and fibula) from the Lower Cretaceous Murtoi Formation at the Mogoito locality in Buryatia, Russia, is attributed to a pterosaur Dsungaripteridae indet. on the base of a relatively large cnemial crest and considerable bone thickness of the tibia shaft. The pterosaurs from the Mogoito locality had previously been identified based on isolated teeth attributed to Ornithocheiridae. The described tibiotarsus represents the second record of Dsungaripteridae in Russia and the second pterosaur bone known from the Lower Cretaceous of Russia.
Doklady Earth Sciences. 2025;523(1):160-163
160-163
SEISMOLOGY
Further Development of the Matched Filter Method for Solving Seismological Problems
Resumo
The progress of seismology and geophysics as a whole depends on the detection thresholds and the accuracy of measuring physical signals. The repeatability of geophysical phenomena, such as earthquakes, allows for the efficient use of the matched filter (MF) as a detector of repeating signals. The MF detection threshold depends on the noise characteristics. For example, microseismic noise (MsN) is created by many physical sources and includes signals that may be partly coherent with the templates. Stochastic noise (StN), which is not present in a mathematically defined form in nature, is optimal for MF. In this paper, stochastization of MsN is achieved by adding StN generated by a random number generator to waveforms on seismic arrays (SA). The signal-to-noise ratio on SA increases by a factor of 5 in the presence of noise coherent to the signal in MsN. For MsN without dominant components, adding StN provides a gain of 2–3 times. A decrease in the rate of false alarms is observed, which also lowers the detection threshold.
Doklady Earth Sciences. 2025;523(1):164-168
164-168
OCEANOLOGY
Currents of the Azov Sea Based on Measurements and Spectral Analysis
Resumo
The work describes three states of water circulation in the Azov Sea based on previously conducted studies and unpublished previously results of studies in 2023–2024. Pronounced diurnal radiation tides are typical for warm, windless times of the year, when breeze winds develop. Seiche currents are often mixed with tidal currents, so it is difficult to observe the tidal structure in its pure form using current measurements. With fluctuations in wind parameters, the seiches of the Sea of Azov change rapidly both depending on the observation area and on the mode structure according to the cascade of scales. The strongest positive and negative water setups are inextricably linked with the single-node mode, the currents of which are able to change the shapes of coastal accumulative bodies, such as beaches and spits, in one cycle. The features of such a system of currents are still unclear. The third state is transitional, which is observed when the wind increases.
Doklady Earth Sciences. 2025;523(1):169-177
169-177
GEOGRAPHY
Carbon accumulation in peatlands of the Mordovian natural reserve during the Holocene
Resumo
The paper presents the results of the study of the Holocene carbon accumulation in four peatlands of different genesis and landscape position in the area of the P.G. Smidovich Mordovian State Nature Reserve, located on the southern border of the coniferous-broadleaved forests of the East European Plain. The analysis of the carbon content in the peat showed that in mineratrophic peat composed of vascular plant remains the organic carbon content is 46.9–60.9% (average 54.6%) and these values are generally higher than the carbon content in poor fen with woody-Eriophorum-Sphagnum and Eriophorum-Sphagnum peat, 43.6–50.1% (average 47.8%). Low carbon values (39.2%) were found for grass and woody-grass low decomposed peat in wet karst bog. The carbon accumulation rate in peatlands ranges from 5.2 to 84.9 g C/m2 per year, with an average value for the entire Holocene of 22.5 g C/m2 per year. Analysis of the distribution of carbon accumulation rate (CAR) in peat deposits by depth and age revealed similar patterns of carbon deposition in the four peatlands studied: an increase in CAR during the period 10500–7500 cal yr BP (calendar years before present) and a decrease in the intensity of carbon accumulation during the period 7500–3500 cal yr BP, which partly coincides with the Holocene Thermal Maximum, when the climate was warmer and drier than the modern one. The formation of the upper horizons of the peat deposits of the bogs and the carbon accumulation in the late Holocene showed individual specificity of different peatlands, with a general trend of CAR growth.
Doklady Earth Sciences. 2025;523(1):178-184
178-184