卷 525, 编号 2 (2025)

For the first time the data on Quaternary geology of land and sea were correlated on the example of the Solovetsky Archipelago and the adjacent shelf. Geomorphological analysis and the use of structural methods for studying moraines allowed to reconstruct the paths of glacier movement and reveal the role of the Bolshoi Solovetsky and Anzer Islands as ice lobe dividing zones formed on protrusions of the pre-Quaternary basement. It is shown that deglaciation in the area of the Solovetsky Archipelago was rapid, and as a result of Late Glacial transgression a proglacial basin was formed here, which rapidly turned into a glacio-marine basin, and already in the Early Holocene became purely marine. Earlier assumptions that in the Solovetsky inter-island in the Boreal and Atlantic periods of the Holocene there were unique hydrological conditions with water temperature, increased in comparison with the modern one by 1-2°, which in turn led to the blooming of malacofauna, are confirmed and substantiated.

New data on the composition of Upper Jurassic sandstones forming the base of the Kameshkov depression on the southwestern edge of the Chukchi terrane are presented. The rock-forming components include fragments of cleaved terrigenous rocks and volcanic material such as altered pyroclastic ash and glass components, angular quartz crystalloclasts, and unrounded felsite fragments. The U-Pb isotopic detrital zircon dating revealed the presence of a young population with a unimodal distribution and a peak of 145,6 Ма, which corresponds to the age of the deposits determined by the findings of Buchia piochii (Gabb). Other age populations are typical for the Triassic rocks of the Chukchi Terrane. The studied sediments accumulated on the southwestern margin of the Chukchi microcontinent in shallow marine conditions due to erosion of underlying deformed Triassic strata of the, in the immediate vicinity of a volcanic activity. The similarity of the Tithonian-Berriasian deposits composition in most Upper Jurassic-Lower Cretaceous depressions of the Chukotka terrane and the sharp change of provenances at the Kimmeridgian-Tithonian boundary are traced. We interpreted the strike-slip setting of basins formation on the Chukotka margin in the Late Tithonian, associated with the accretion of the Kulpolney island arc.

We propose a new outlook on the problem of the anomalous configuration of the Devonian geomagnetic field. The scattered distribution of paleomagnetic vectors identified in basic magmatic formations of the Minusa Depression resulted from the input of non-dipole sources of the main geomagnetic field when its strength was at a minimum. Fast alternations of ultra-brief episodes of decreasing paleointensity in the usually dominant geocentric axial dipole caused by extra-frequent reversals led to an increasing role in the shape of the geomagnetic field being played by the equatorial dipole and/or higher-order zonal harmonics, as well as global magnetic anomalies. Using statistical analysis in the observed pseudo-chaotic distribution of paleomagnetic vectors, we demonstrate clusters that could reflect the input of such sources. The calculated paleopoles coincide with the position of global magnetic and gravitational anomalies, showing their present-day position. The best fit is achieved by placing the Siberian paleocontinent near the northwestern African coast, above the hotspots, whose activity in the Devonian period could theoretically have caused the formation of known mantle plume provinces, including the Minusa Depression.

Two dyke complexes, pre-ore and post-ore, were identified for the large Vorontsovka gold deposit of finely interspersed gold (Carlin type), and age estimates for the latter were obtained. The gold deposit is located in the eastern part of the Tagil zone of the Urals and is localized in the southwestern exocontact part of the Auerbach gabbro-diorite-granodiorite intrusive. The ore field contains close-arranged bundles of Devonian pre-ore and Carboniferous post-ore mafic dykes, ranging from picrobasalts and gabbro to quartz diorites and monzonites. The enrichment of high–ion lithophilic elements (Cs, Rb, Ba, Pb, Sr) with relatively high-charge and rare-earth elements, Ta-Nb-minimum and Pb-maximum indicate the formation of dykes of the Vorontsovka deposit in a suprasubduction environment in a sufficiently thick continental crust. The late dyke group mainly includes high-potassium mafic rocks somewhat enriched in phosphorus (K₂O > 2 wt.%, P₂O₅ up to ~1 wt. %); they correspond to the magmatites of the shoshonite series and correspond to a large extent to the riftogenic and intraplate regimes. The isotopic composition of lead in dyke rocks is characterized by a linear trend and indicates mixed mantle-crustal sources of the initial substance. Lamprophyres have the least radiogenic lead, and the most radiogenic lead is characteristic of the granodiorite apophyses of the Auerbach intrusion. Lead isotopic compositions of igneous rocks and ores form a single trend on Pb-Pb diagrams, which reflects the genetic relationship of mineralization with deep magmas. The “mantle” lead in the dykes probably reflects the nature of their parent magmas, while the “crustal” lead is considered as the result of assimilation of the frame substance when the melts reach the level of the upper crust. As a result of isotopic studies of K-Ar and Sm-Nd isotopic systems, data on the Carboniferous age of post-ore basite dykes were obtained for the first time – 346 ± 4 Ma (⁴⁰Ar/³⁹Ar method) and coincidental estimate, within error, of 340 ± 35 Ma (Sm-Nd method). Rather high positive εNd values (from 4.4 to 5.3) indicate the mantle source of their magmatic melts. The petrogeochemical features of the rocks of the late dyke series, as well as their Early Carboniferous age (346–340 Ma), suggest a post-collisional mode of their introduction.

The Cenozoic volcanism of the Baikal Rift, associated with the Indo-Asian collision, exhibits geochemical signatures of melting from an olivine-free mafic source, excluding a significant contribution from peridotitic mantle. Analysis of volcanic rock compositions (primarily basalts and trachybasalts) indicates that the magmas were generated by the melting of garnet-pyroxene lithologies, formed through the sinking of thickened lower crust into the lithospheric mantle. Geophysical data confirm anomalous crustal thickening (up to 55 km) in the southwestern part of the rift, where the most extensive volcanic fields are observed. The proposed model explains the volcanism as a result of gravitational instability and lithospheric delamination triggered by collisional deformation. The passive nature of the magmatism suggests its connection to tectonic processes rather than active upwelling of deep mantle material. This study presents the model for the formation of late Cenozoic basaltic melts in the Baikal Rift, attributing their origin to the remelting of lower crustal material within the lithospheric mantle.

Bimodal rock complexes from basalt to trachyte and rhyolite were studied in the Late Cenozoic intraplate province of Central and East Asia. Three magma evolution paths were revealed: tholeiitic (Wangtian’e volcano), alkaline (Changbaishan volcano), and highly alkaline (Udokan lava plateau). The analysis of chemical and isotopic (Sr, Nd and Pb) characteristics suggests that the tholeiitic melt was formed by melting of suprasubduction-altered lithospheric mantle consisting of peridotite with high proportion of eclogite. The alkaline melts were produced by interaction of tholeiitic melt with fertilized mantle peridotite with the formation of pyroxenite and subsequent melting of the pyroxenite-peridotite source in the asthenospheric mantle. The highly alkaline silica-deficient melts were formed by melting of the metasomatized lithospheric mantle consisting of peridotite and garnet pyroxenite. The latter was produced by metasomatic reaction between a small amount of eclogite melt with peridotite. The evolution of the resulting melts followed three independent scenarios. The tholeiitic magmas of Wangtian’e volcano evolved initially following the Fenner trend of crystallization differentiation, which was subsequently changed to the Bowen type of differentiation, leading to the formation of trachyte magmas. The second scenario corresponding the pure Bowen trend of fractional crystallization was characteristic of the alkaline magmas of the Changbaishan volcano. Their deep differentiation in the system of shallow magmatic chambers led to the appearance of the trachyte-comendite-pantellerite association. The third scenario occurred during the formation of the Udokan alkaline trachytes and included a combination of Bowen-type crystallization differentiation and contamination of trachyte melts by Archean-Proterozoic basement rocks in the system of peripheral magmatic centers.

Based on an extensive dataset (44 mineral pairs), we provide the temperature estimates for the crystallization of magmatic olivine (Mg# 88–89) and associated early mineral phases (spinel-group minerals, ilmenite, rutile, and phlogopite) from volcaniclastic kimberlites of the Udachnaya-East pipe. Using several geothermometers (olivine–chromite, olivine–ilmenite, and ilmenite–titanomagnetite), we apply strict compositional constraints corresponding to the calibration ranges of each thermometer to ensure maximum accuracy. In these study additionally presents 96 new chemical analyses of crystalline inclusions within magmatic olivine

: The first results of a detailed paleocryolithological study (Permogorie section case study) in the upper reaches of the Severnaya Dvina show that conditions existed for the development of frost cracking in Northeastern Europe at the end of the Bølling-Allerød interstadial (ca. 13.3-12.7 cal. kyr BP). Freezing occurred in two stages – syncryogenic with the formation of ice-wedges and epicryogenic with the formation of composite ice-wedges. The relic layer of seasonal thawing could reach a thickness of 1.0–1.5 meters. The data obtained confirm the formation of permafrost rocks in the Late Glacial period, but do not yet allow us to judge the continuous or discontinuous of permafrost in the northeast of the East European Plain at the Pleistocene-Holocene boundary.

The results of numerical modeling of tsunami waves on July 29, 2025, which occurred after a powerful earthquake with a magnitude of 8.8 near the southeastern coast of Kamchatka (Russia), are presented. These results are compared with instrumental data from nearby DART buoys, measured wave heights on the islands of Paramushir and Shumshu, as well as mariograms in Kurilsk (Iturup) and Hanasaki (Hokkaido). The comparison of calculated and instrumental data is very good.

The article describes deformation anomalies recorded by remote laser strainmeters and provides estimates of seafloor displacement in the focus of the tsunamigenic earthquake that led to the tsunami.

New paleoceanological data for the northern Norwegian Sea were obtained for the marine oxygen isotope stages (MIS) 8–6. Dinocyst analysis performed on the sediment core AMK-5536 showed local environments were formed in harsh conditions with probable presence of sea ice during cold MIS 8 and 6. In the warm MIS 7, a sharp increase in dinocyst concentrations, high species diversity, and the appearance of warm-water species with the presence of the typical species Spiniferites septentrionalis were noted. The optimum of MIS 7 corresponds to the time of 241–234 ka. The warming was short-lived and pronounced, with a greater influence of warm and saline surface North Atlantic waters than at present and a northward shift of the Arctic Front. The reconstructed surface water temperature was approximately 2.9–3.6°C higher than the modern one.