Doklady Rossijskoj akademii nauk. Nauki o Zemle

U–Th–Pb (LA-ICP-MS) geochronological studies of detrital zircon from the Quaternary deposits of the western part of the Ufaley block in the Middle Urals, in a tectonic fragment composed of amphibolite-gneiss complex and associated bodies of Precambrian clinopyroxenites, were performed. The main statistical age maximum corresponds to the range of 2100–2000 Ma. Several small peaks correspond to the range of 3200–2500 Ma. So there is the real reason to believe that rocks of the Early Precambrian age are present within the Ufaley block. They were not previously identified here.

In the extreme south of the Urals, zircons from eclogites and amphibolite were dated in metamorphites of the East Mugodzhar zone. Of the 4 eclogite samples, close (and the most “ancient” – 520±4 million years) concordant age values were obtained in 3 samples, which probably corresponds to the age of the protolith. Concordant dates of 472±3 million years and 379±3 million years reflect the time of the main stages of metamorphism of the East Mugodzhar, the more ancient – high-pressure, and the second – amphibolite facies metamorphism. The presence of ancient and at the same time different-aged zircons, probably with traces of rounding, indicates the primary sedimentary nature of the studied amphibolites. The youngest zircons from the Mugodzhar eclogites have an age of 282±2 million years, corresponding to the collision stage. The obtained data show that the Mugodzhar metamorphic complexes are not Early Proterozoic or Riphean formations (as was previously believed), but represent Lower-Middle Paleozoic complexes of the middle part of the earth's crust. That is, these metamorphites by their nature are fragments of the deep part of the island-arc system of the eastern sector of the Urals, which were later brought to a near-surface level during the rise and erosion of individual regions of the Urals.

The first U–Th–Pb zircon data for Pyrkataginsky massif granitoids, located in the central part of Kuul Rise of Anyui-Chukotka fold system on the coast of East Siberian Sea are provided. They indicate the intrusion of granitoids in Albian time (106–104 Ma), which corresponds to Albian granitoid magmatism of Chauna province of Chukotka (110–100 Ma [1]) and coincides with Aptian-Albian postcollisional extension after termination of collision between Chukotka-Arctic Alaska microcontinent and Siberian continent with earlier accreted Kolyma-Omolon microcontinent. Increased alkalinity and geochemical features of Pyrkatagin massif granitoids, as enrichment of LIL and LREE, depletion in Ta, Nb, Ba, Sr make them similar to other postcollisional granitoids of Chauna province. The comparison of granitoids of the massif and granitoids with different types of mineralization is carried out.

By the time the decision was made (Rosstandart Order 07.07.2023 № 490-st) on the inclusion of hydrogen in the all-Russian classifier of minerals in Russia, research on the geological and economic analysis of the possibilities of industrial development of hydrogen resources had not been conducted. Moreover, fossil hydrogen has been studied extremely poorly. The current situation requires the accelerated development of a hydrogen search concept based on the scientific justification of the most promising regional areas of work. In the article, the authors present their vision of this problem and propose possible solutions. In particular, the necessity of organizing scientific and technological hydrogen polygons is argued, the tasks of which will include: (i) the development of theoretical ideas about the role of hydrogen in the evolution of the Earth; (ii) detailing the mechanisms of hydrogen localization in the geological environment; (iii) the development of criteria and methods for geological and economic assessment of hydrogen prospecting, exploration and production; (iv) conducting geological and commercial research at the most promising sites for the development and testing of methods for searching for deposits of hydrogen and related minerals.

The U-Pb dating of zircons from igneous rocks of the Central Chukotka area (left bank of the Amguema River) indicated that two granitic batholiths (Telekai and Chanuan massives) and the series of smaller plutons have been formed during 143–127 Ma time span. This age is substantially older than that determined for the greater part of the North Chukotka's granites (109–100 Ma). Both new and published isotopic age data infer that there was a large subduction related magmatic belt at the margin of the Chukotka continental block – at least, during the Late Jurassic and Neocomian time. Then, the newly discovered Early Jurassic U-Pb ages of Chukotka's igneous complexes (ca. 196 Ma) imply much longer duration of magmatic activity at the margin of the Chukotka microcontinent. The Albian granitic plutons of the observed area (106–100 Ma) were controlled by a different fault system, and they are probably related to a separate magmatic event.

Using the Dolivo-Dobrovol’sky index and information-based parameters on the basis of new experimental data, the problem of symmetry and structural complexity of the mineral matter of the deep geospheres is considered in the framework of the pyrolite model of the Earth’s mantle. It is shown that, in contrast to the previously made conclusions about the increase of the symmetry of minerals with depth, the behavior of the quantitative parameters of symmetry and structural complexity is nonlinear. The symmetry increases (and the structural complexity decreases) to the boundary of the decomposition of ringwoodite into bridgmanite and magnesiowustite (660 km), after which there is a decrease of the Dolivo-Dobrovol’sky index to 18.40 and an increase of the atomic parameter of structural complexity to 2.786 bit/atom. This behavior is due to the uneven and opposite effect of temperature and pressure on the symmetry and complexity of the crystalline substance, which is caused by the nonlinear nature of the averaged geotherm of the Earth's crust and mantle. Information parameters of structural complexity are a more sensitive indicator of symmetry than the Dolivo-Dobrovol’sky index, which is due to the former taking into account the features of the crystal structure of specific minerals.

For the first time, a high-resolution record of natural events covering the Late Glacial and Early Holocene (14 150–9 730 cal BP) was obtained for the southern part of the Kama-Vychegda watershed based on drilling sediments in lake Novozhilovo (Kama-Keltma lowland, Upper Kama basin). The article presents the results of the study on the reconstruction of sedimentation conditions, based on paleobotanical, sedimentological and radiocarbon dating analyses. The beginning of the lake's formation was apparently preceded by a period of predominantly alluvial morpholithogenesis, which is thought to correspond to the LGM. There were four stages in the evolution of the lake basin, with the first three characterized by lacustrine-alluvial sedimentation that was predominantly mineralogenic in nature, and the fourth stage marked by typical lacustrine organic-rich sedimentation. The first stage covered the Bølling-Allerød interstadial period from 14 150 to 13 500 cal BP, and it was characterized by the accumulation of sand under conditions of high water flow. At the boundary between the Allerød and Younger Dryas periods, bioproductivity increased significantly. During the second stage, which lasted from 13 500 to 12 420 cal BP, water exchange slowed down and organic-mineral lake sediment formed. The third stage, known as the transitional sedimentation period, refers to the Younger Dryas and Early Holocene periods (12 420–10 700 cal BP). During this time, alluvial inputs predominated, with a decrease in organic matter content. Finally, the fourth stage, the eutrophic lake stage (10 700–9 730 cal BP), was characterized by a high organic matter content in sediment, and an increase in the size of silty particles.

Modern geophysical survey technologies are progressing fast. One notable milestone of this progress is substantial increase of georeferencing performance with benefits of advanced satellite radionavigation. This article delves into the advantages of employing multiple altitude (also referred to as multilevel) aeromagnetic measurements conducted using unmanned aerial vehicles for deriving vertical gradient. This approach contrasts with conventional methods that rely on the calculation of the corresponding transform of the anomalous magnetic field. A comparative analysis was conducted on two study areas, characterized by distinct magnetic anomalies. One region exhibited strong anthropogenic disturbances against a background of a relatively calm regional magnetic field, while the other demonstrated weaker anthropogenic anomalies. The comparison between the maps of the anomalous field gradient calculated directly and derived from multilevel survey in both regions underscores the potential benefits of straightforward gradient measurement methods.

The results of a study of the water mass structure in a poorly studied area of the eastern basin of the Tropical Atlantic (Kane Gap) according to data from the 63^rd cruise of P/V “Akademik Ioffe” in 2022 are presented in the paper. Variability of the average monthly characteristics of these waters using the GLORYS12v1 reanalysis for 1993–2022 is shown. Intermediate waters in the section are represented by a mixture of Antarctic intermediate water (AAIW) and Mediterranean water (the share of the latter reaches 34%). It has been established that the North Atlantic Deep Water (NADW) is represented by two layers: the Upper NADW with a maximum of salinity and the Middle NADW with a maximum of oxygen. The bottom water layer contains a mixture of Antarctic Bottom Water (AABW), the Lower and Middle components of the NADW. This mixture, coming primarily from the Vema Fracture zone region, is properly to call Northeast Atlantic Bottom Water (NEABW). Its upper limit corresponded to the isotherm of 1.95°С and the Si/P ratio equal to 33. In this work, using the conservative PO, the proportion of AABW in NEABW, which is about 20%, was calculated. According to the GLORYS12v1 on a seasonal scale in the bottom layer, a significant negative relationship was established between the variability of potential temperature and the meridional speed of currents. Significant trend for an increase in the average annual potential temperature (by 0.06 °C) and a decrease in salinity (by 0.005 psu) in general for the period 1993–2022 was revealed.

Ore crusts with a germanium content of up to 96 ppm were discovered in the Sea of Japan. This is tens of times higher than the clarke of the Earth’s crust. Germanium-rich crusts were dredged together with intermediate and felsic volcanic rocks. The crusts are composed predominantly of iron oxyhydroxides (goethite) and contain germanium in the dispersed state.

We present a purely thermal convection 2D model of the Earth’s liquid core, occurring on the background of the secular cooling of the planet. The model includes equations of thermal convection in the Boussinesq approximation and the Coriolis force. Metallic iron with 0.9 wt. % Н is chosen for the core composition. The results of modeling show that large vortexes, the 2-D analogues of Taylor columns, are formed in the liquid core prior to crystallization, which might be responsible for the early Earth magnetic field. The early stages of the solid core crystallization are characterized by a chaotic and shapeless growth. Continuing growth of the solid core results in rearrangement of the convection structure decreasing its average velocity but increasing heat flow at the core-mantle boundary due to increased amount of heat of crystallization. The solid core reaches its present size in 0.5 Gy. Averaged temperature profile of the modern liquid core differs significantly from the adiabatic.

The point of limited availability of water (PLAW) characterizes the lower boundary of the area of the most productive moisture for plants. The analysis of experimental methods for determining PLAW indicates their labor intensity and low productivity. The aim of the study was to develop a high-performance and accurate method for determining PLAW. 18 samples from various soils were used in the work. To determine the PLAW, a method was proposed in which soil samples were placed in a Schott funnel, moistened with excess water, and then the water was pumped out using a water jet pump. As the water was removed from the sample, the interval between drops falling from the funnel increased. A jump in the intervals between drops was considered an indicator of the end of the experiment. Experiments have shown that the soil moisture content obtained by vacuuming correlates with the values calculated for the lowest soil moisture capacity (according to Dolgov) by 87%. The values of the PLAW obtained by the secant method (according to Voronin) for some of the soil samples do not fall out of the obtained dependence. Using the method, it was shown that soil drying leads to a decrease in the value of the measured PLAW. An explanation of the results from the position of the presence of organomineral gels in soils is proposed.