In this study we focus on the investigation of the absolute intensity records of two volcanic subsequences, aiming to enrich the global paleointensity database for the last 5 Ma, which currently shows important dispersion. We present new absolute paleointensities obtained from the Plio‐Pleistocene volcanic sequence of Korkhi (Djavakheti Highland, Georgia) (41°27′31″N, 43°27′55″E). Korkhi is divided into two lava flow subsequences dated at 3.11 ± 0.20 Ma and 1.85 ± 0.08 Ma. Paleomagnetic directions previously published (Sánchez‐Moreno et al., 2018, https://doi.org/10.1029/2017GC007358 ) show a normal polarity in the lower Korkhi subsequence and a reverse‐to‐intermediate polarity in the upper Korkhi subsequence. The new paleointensity determinations are obtained through two different Thellier‐type protocols (Thellier‐Thellier and IZZI) and the corrected multispecimen method. We utilize different selection criteria and interpretation approaches (TTB, CCRIT, BiCEP and multimethod), and we make a critical evaluation on their application on complex magnetic behaviors, such as often found in volcanic rocks. Finally, we obtained a paleointensity of 70 μT in upper Korkhi and 14 paleointensities in lower Korkhi that vary between 5.2 and 37.2 μT. These results agree with a recently proposed non‐Geocentric Axial Dipole (GAD) hypothesis for the last ∼1.5 Ma (Cych et al., 2023, https://doi.org/10.1029/2023JB026492 ), and with low field strength for the 3–4 Ma.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23050239

We present here the first regional set of Sr-Nd-Pb isotopic compositions, major and trace element compositions and KAr ages for a representative suite of back-arc samples of the Sredinny Range (SR) of Kamchatka. Together with previously published analyses, this unique dataset allowed us to trace the source heterogeneity and invoke new mechanisms to explain the variably enriched geochemical signatures. Our results indicate that the Sr isotopic ratios and the LILE content of the studied rocks were mainly influenced by the subduction fluid. Neodymium isotopes, as well as the HFSE and REE distributions in the rocks, require a more complex explanation, depending on the geographical location of the studied samples and the age of their eruption. Melts representing Miocene rocks of the northern part of the SR and most of the rocks from the eastern and central flanks of the SR (from Miocene until present) were produced from a depleted MORB-like metasomatized mantle, and were then exposed to varying degrees of crustal assimilation and fractional crystallization. Higher HFSE contents and lower 143Nd/144Nd ratios in the western flank lavas, as well as high HFSE contents in the Quaternary lavas of the northern part of the SR and some of the lavas from the eastern flank of the southern part of the SR, require an alternative source for their enrichment. Delamination of the lithosphere explains the unusual, enriched signature of these rocks, whereas their variably enriched neodymium isotope ratios identify the various ages of the separation of the lithosphere from the mantle. The Nd isotopic composition of the rocks together with their HFSE content, therefore, serves as an unusual tracer for the enriched mantle domain, showing the presence of the older lithospheric blocks and indicating the timeframes for this source involvement in magma generation.

This article presents and discusses the results obtained by X-ray fluorescence and KAr methods regarding pumice pieces found at two archaeological sites: Ust'-Karenga XVI (9000-8000 cal BP) and Kovrizhka III (similar to 13,000 cal BP) (Vitim River, Transbaikalia, Russia). KAr dating and geochemical characteristics of pumice from the Kovrizhka and Ust'-Karenga sites indicate that they are a product of the eruptions of the Udokan volcanic field, and not the Vitim volcanic field, which are two volcanic regions of Transbaikalia. Ancient people residing at both sites were aware of the same resources within the territories, despite the fact that they lived at different times; this is evidenced by the fact that the archaeological material found in the ritual pit of Ust'-Karenga XVI is similar in terms of cultural remains to the archaeological finds of the Kovrizhka group of sites of the age range from similar to 6700 to 13,000 cal BP. In this work, we assume that ancient people used not only stone resources but also thermal springs of the territory of the Udokan volcanic field. Based on the paleogeographical data of the region, we reconstruct the possible routes used by ancient humans to deliver and/or exchange raw materials necessary for economic purposes. Our new data in combination with previously published data for Transbaikalia and other regions of Siberia suggest that the connection between the ancient populations living in these areas often persisted at distances >1000 km.

The paper presents the results of comprehensive studies of the phenomenon of slow relaxation of the speed of sound in structurally inhomogeneous materials after vibration exposure to a finite amplitude of deformations. The results were obtained on the experimental setup created for these studies, which ensured high accuracy in measuring the linear and nonlinear acoustic characteristics of various materials. The results of an experimental study of relaxation in a carbonate rock, which is a structurally heterogeneous material with a complex system of internal bonds, are presented. The measurements made it possible to determine the dependences of the relaxation parameters on the amplitude and excitation time, as well as the effects due to the finite amplitude of the probing wave. An interpretation of the obtained results is given and the effects that have not received an exhaustive explanation are noted.

A geochronological and isotope-geochemical study of alkaline basalts from three areas of young magmatism within the northeastern part of the Arabian Plate (Southeastern Turkey), Batman, Kurtalan and Alemdağ, was carried out. The obtained isotope data have indicated that the volcanism in the studied region developed over 5 mln years from the end of Miocene to the mid of Pleistocene during four pulses separated by breaks in magmatic activity: 6.1-4.9 Ma (Batman area, hawaiites), ~3.0 Ma (Alemdağ plateau, phase I, basalts), 2.0-1.9 Ma (Alemdağ plateau, phase II, tephrites), and 1.5-1.3 Ma (Alemdağ plateau, phase III, basalts; Kurtalan area, basalts). A comparison of spatial-temporal regularities of magmatic activity evolution in the studied part of the Arabian Plate and within the largest basalt plateau of Arabian foreland, Karacadağ plateau, located to the west, was carried out. The results of Sr-Nd-Pb isotope-geochemical studies show that the development of young basalt volcanism within the northern part of the Arabian Plate was characterized at different time by participation of various mantle sources in magma generation under this region. Initial pulses of magmatic activity are associated with melting of Arabian subcontinental lithospheric mantle (SCLM). The processes of fractional crystallization combined with crustal assimilation (AFC) have played an important role in the petrogenesis of lavas as well. In the subsequent time, a deep mantle source (PREMA) with a depleted isotopic composition of Sr and Pb played a leading role in the formation of basaltic magmas of increased alkalinity. The melts generated by this source were mixed with the SCLM material in various proportions at different stages of magmatism with a limited participation of AFC processes in the petrogenesis of the rocks. It was concluded that young basalt volcanism of elevated alkalinity in the northeast of the Arabian Plate is not related to the collision of the Eurasian and Arabian plates genetically, but presumably manifested here as a result of the migration of the initial rift geodynamic set from the Red Sea basin to the north along Levantine and East Anatolian transform faults with associated convective wave flows in the lower part of mantle under this part of the Earth.

A method for the preparation of a hybrid material by modifying the surface of carbon fiber with barium hexaferrite particles using ultrasonic treatment was proposed. Scanning electron microscopy, Raman spectroscopy, and X-ray diffraction were used to identify the barium hexaferrite and to reveal the structural specific features, degree of ordering and homogeneity of the carbon fibers modified with barium hexaferrite. A vibrating magnetometer was used to determine the specific magnetic moment of the obtained hybrid, which was found to be equal to ∼2.03 A m2 kg−1.

Three samples of aqueous magnetic fluids based on magnetite particles stabilized with double layers of surfactants have been synthesized. The samples have been stabilized with lauric and oleic acids, as well as their salts, taken in three different combinations. The viscosity of the synthesized samples has been measured as depending on the concentration, temperature, and shear rate. With increasing temperature, the viscosity of a sample of the fluid stabilized with a double layer of lauric acid does not decrease relative to the viscosity of water, as has been previously observed for classical magnetic fluids, but rather increases. For a sample stabilized with two layers of lauric and oleic acids, the temperature dependence of the relative viscosity is nonmonotonic. The relative viscosity of a sample stabilized with a double layer of oleic acid is actually independent of temperature. To determine the concentrations of the samples, measurements of magnetization curves were carried out followed by their granulometric analysis. It has been found that the dispersity of the samples remains unchanged upon dilution. The initial magnetic susceptibility of the fluid samples has been shown to increase with concentration more slowly than it has been predicted by the modified effective field model. In contrast to the effective field model (and other ones), the coefficient at the quadratic term in the expansion of the initial susceptibility in terms of the Langevin susceptibility has turned out to be significantly lower than 1/3. Thus, new theories of dipole–dipole interparticle interaction must be developed to describe the properties of magnetic fluids stabilized with double layers of surfactants.

We consider the problem of Rayleigh wave scattering by an inclusion of small wave sizes in the form of an oblate ellipsoid located under the free surface of an elastic isotropic half-space. The material parameters of the filling of the inclusion can have an arbitrary contrast with respect to the material parameters of the elastic medium containing the inhomogeneity. The solution of the problem is based on the formalism of the Green’s functions of a force source in a half-space and the reciprocity theorem for an elastic medium. The examples demonstrate the possibility of diagnosing the presence of a cavity, as well as estimating its sizes and orientation by analyzing the features of the distribution of the displacement vector projection amplitudes in the scattered field.

A simple and affordable in situ synthesis of a carbon fiber@magnetite hybrid for use as a filler in shielding polymer materials is proposed. The presence of magnetic particles on the carbon fiber was confirmed by X-ray diffraction, and the effect of modification on the structural properties of the components and the magnetic properties of the system was analyzed. The analysis of the structural characteristics and the magnetic properties of the components obtained during the synthesis process was carried out. The modification of the surface of the carbon fiber with magnetite made it possible to obtain for the resulting hybrid a magnetic moment value that is three times higher than that of a mechanical mixture of carbon fiber and magnetite with the same composition.

The results of integrated studies of the slow relaxation of the sound speed in structurally inhomogeneous materials after vibratory action with a finite strain amplitude are presented. The results were obtained using an experimental setup created for these studies, which ensured highly accurate measurements of the linear and nonlinear acoustic characteristics of various materials. The results of an experimental study of relaxation in carbonate rock, which is a structurally inhomogeneous material with a complex system of internal relationships, are presented. The measurements made it possible to determine the dependence of the relaxation parameters on the amplitude and time of excitation, as well as the effects caused by the finite amplitude of the probing wave. The results are interpreted, and effects that have not received an exhaustive explanation are noted.

A unique feature of the Kamchatka Peninsula is an extensional structure running for more than 400 km along the peninsula—the Central Kamchatka Depression (CKD). Some geodynamic models associate the formation of the CKD with the movements of East Kamchatka toward the Pacific Ocean due to retreat of the northern edge of the subduction zone. However, isotope–geochronological data on the time of the CKD formation have been lacking up to the present time. Therefore, we could not directly associate the CKD emergence with the stages of the Kamchatka tectonic evolution and the intensity of its recent deformations. This work presents the chemical compositions and K–Ar ages of effusive rocks from the KL-1 borehole drilled in the northern part of the CKD. Samples from the depth interval of 50–475 m, represented by medium-K basalts and high-K basaltic trachyandesites date back to 0.7 to 1.5 Ma. By their composition, these rocks are close to effusive rocks forming the base of the Klyuchevskaya group of volcanoes. Before this study, the age of the effusives had been estimated as much younger, up to 0.3 Ma. Below, in the interval of 475–505 m, a pack of sands and boulder conglomerates was described. They unconformably overlap the aphyric and olivine–pyroxene porphyritic andesibasalts with interlayers of volcanic ash and volcanic sands of the same composition. At the depth of 905–1513 m, the borehole recovers highly altered tuffs, mafic and intermediate in composition, interbedded with andesites and andesibasalts. The K–Ar estimation of 3.5 ± 0.4 Ma was obtained for the least altered sample of medium-K andesibasalt from the depth of 1255 m. We suggest that the altered effusives at 905 m and below are associated with the completion of accretion of the Kronotskii Island Arc and with the formation of the modern structure of the Kamchatka Peninsula. The CKD setting occurred after this event in the interval of 1.5–3.5 Ma.

We report, here, the composition and K-Ar ages of a representative collection of volcanic rocks that erupted within three monogenetic volcanic fields in the active fault zone of the Sredinny Range of Kamchatka: Tigilsky Dol, Mount Oxi massif and Anaunsky Dol. The studied rocks display a wide range of compositions (medium-K, moderate-Mg, high-K, high-Ti and high-Mg basalts, and high-LREE picrobasalts); the high-Mg varieties are confined to faults. Five main periods of volcanic activity were investigated, 4.3-3, 2, 1.5, 1 Ma and from 0.3 to <0.05 Ma. Primitive lavas first emerged on the surface at 3.5 Ma. There was a massive outpouring of high-Mg lavas at 1.5-1 and 0.3 Ma, which could have been related to the formation of the fault zone. This is the first report of rocks in Kamchatka with a high-LREE picrobasaltic composition (1.5 Ma). The Fo content of the olivine phenocrysts reaches 93.2 mol%, which is the highest value known for Quaternary Kamchatka basalts. A very heterogeneous source, even for individual eruptions is indicated by the minor element contents in the olivine (Ni, Mn and Ca); Cr-spinel - olivine paragenesis show that all the rocks studied crystallized in the same temperature range (1111-1292 C), whereas the oxygen fugacity for the different samples varied from & UDelta;QFM +0.7 to +2.0 log. units. A melt inclusion study showed that the Mg basalts of the Mt. Oxi massif and the high-LREE picrobasalts of Tigilsky Dol had different fluid sources that were enriched and depleted in water and Cl, respectively. We argue that the fluid source for the Mt. Oxi massif was likely the remains of the Pacific slab under the Sredinny Range, whereas, for the high-LREE picrobasalts of Tigilsky Dol, it was the lithospheric lithologies. The low content of S and high content of Cu in the oxidized high-LREE basalts provide additional evidence that they originated from the re-melting of sulfur-poor lithospheric lithologies. Both the fault zone and the lithosphere reactivation in the region are likely linked to the regional stress field.

On 29 September 1957, the so-called Kyshtym accident occurred at the USSR’s first nuclear weapons plutonium production facility. The East Ural State Reserve (EUSR) was established in the most contaminated part of the radioactive trace, where a substantial part of the forests died in the first years after the accident. The purpose of our study was to evaluate the natural restoration of forests and to verify and update the taxonomic parameters that characterize the current state of forest stands in the EUSR. Data on the forest inventory of 2003 and results of our research of 2020 performed by the same methods on 84 randomly selected sites served as the basis for this work. We developed models to approximate growth dynamics and then updated the 2003 taxation-related forest data for the entire EUSR. According to these models and ArcGIS construction of new data, forest-covered lands make up 55.8

The present paper reports a study of rocks in Mts. Baidara and Semkorok, which are situated in the northwestern flank of the Kumroch Range. The rocks are Amf-Px basaltic andesites and andesites, and are characterized by an arc type of trace element distribution. Some mineralogical and geochemical features in the composition of lavas sampled at Mt. Baidara (low concentrations of K2O, as well as of the entire range of REEs, of large-ion elements, thorium, and uranium) and at Mt. Semkorok (low concentrations of light REEs) are substantially different from the rocks of the adjacent Shiveluch Late Pleistocene–Holocene volcanic massif. The K-Ar isotopic lava ages are ~0.7 Ma (Baidara) and ~1.3 Ma (Semkorok), suggesting the inference that the eruptions might be related to the initial phase in the formation of the northern subduction segment in the Pacific plate.

In toxic substance detection devices based on ion mobility spectrometry with atmospheric pressure chemical ionization, hydrated ammonium NH_4^ + (H 2 O) n is increasingly used as a reagent ion instead of the commonly used hydrated hydroxonium H 3 O + (H 2 O) n ion and ions preceding and accompanying its formation. The use of hydrated ammonium makes it possible to increase the specificity of devices in the presence of such problematic interferences as exhaust gases of internal combustion engines and motor fuel vapors. In this paper, the mechanism of increasing specificity in the presence of alkanes, significantly predominant in these interferences, is justified. In the absence of ammonia, which is used to produce hydrated ammonium, the chemical ionization of alkanes occurs as a result of fast exergonic reactions with ions preceding ( O_2^ + ∙ , N_2^ + ∙ , N_4^ + ∙ , H 2 O + ^∙ , and H 3 O + ) and accompanying (NO + and NO + (H 2 O)) the formation of hydrated hydroxonium. When ammonia is added, these ions react with it and are almost completely consumed in fast exergonic reactions. Thereby ammonia suppresses the chemical ionization of alkanes by precursor and accompanying ions. The direct chemical ionization of alkanes with the help of hydrated ammonium does not occur due to the endergonicity of the reactions and the almost complete shift of their equilibrium towards the formation of the initial reagents. As a result, the devices do not give false-positive signals when exposed to alkanes. In addition, the devices do not produce false-negative signals when analytes are detected in a mixture with alkanes, since hydrated ammonium is practically not consumed in reactions with alkanes.

Slow time relaxation of elastic moduli with typically logarithmic time dependence is observed in many media interesting for materials science. This phenomenon is related to internal structure and is, hence, important for the development of present-day materials. Here, we provide a general explanation showing a close link between slow time phenomena and fluctuations on the microscopic and mesoscopic scales. We look for the origin of slow time phenomena in random walk or diffusion processes on microscopic scales. Some bonds occurring in the metastable state make a transition through the energy barriers due to small fluctuations slightly perturbing the statistical equilibrium. If the number of the excited bonds is small compared to the total number of bonds in a heterogeneous material, the process of the transition as a whole can be considered as mesoscopic fluctuations. Averaging over all transient bonds or states is revealed in the observed macroscopic relaxation of elastic moduli, velocities, and others. The functional dependence on time in the relaxation process has been shown to be controlled by the profile of energy barriers. The results obtained point to their possible applications in materials science.

This paper presents new results from geological-stratigraphic and isotope geochronological studies of young lavas in the northeast part of the Javakheti Highland, Lesser Caucasus, Georgia. We provide a first description of the Algeti complex-structured valley lava flow about 55 km in total length; no information on this feature is available in the geological literature. We show that young magmatism in the northeast part of the Javakheti region has been evolving in the time interval of 3.2–1.5 Ma B.P. Its earlier phases have produced the longest (up to 100 km) valley basaltic lava river of those known in the Lesser Caucasus (the Khrami flow) (3.19 ± 0.10 Ma B.P.). Subsequently (2.7–2.5 Ma B.P.), the eruptions continued to form extensive lava plateaus there (Tsalka, Gomareti, and other plateaus). In the Late Piacentian–Early Gelasian (2.7–2.0 Ma B.P.) the active vents in the northern Javakheti Range started to form the Algeti basaltoid valley flow, with this process lasting for 1 Ma. The terminal phase of its formation (1.9–1.5 Ma B.P.) was probably related to eruptions of the volcanic cones in the area of Lake Tabatskuri. These data, along with the reconstruction of the history of young magmatism, enabled us to trace the main patterns in the generation of the present-day relief and the network of river valleys in the area of study in the Lesser Caucasus.

The Precambrian paleosols are good proxies for deciphering paleoredox conditions. They are also good indicators of thermal events that affect the metamorphic terrane. The Rb-Sr isochron ages of the Precambrian paleosols are good indicators of the timing of alkali metasomatism. This work presents zircon U-Pb, whole-rock Rb-Sr isochron, and K-Ar ages of a metamorphosed and metasomatized paleosol occurring at the base of the Paleo-proterozoic Aravalli Supergroup, Northwestern India, to constrain the time of major thermal events. The Aravalli paleosols (sericite schists) have witnessed a complex history of metamorphism and metasomatism. The LA-ICP-MS U-Pb ages of zircons from the two paleosol samples are 2586 +/- 45 Ma and 2793 +/- 21 Ma, similar to the zircon ages for the parent Ahar River Granite. Five paleosol samples define an Rb-Sr isochron age of 1394 +/- 22 Ma with (87Sr/86Sr)i of 0.7493 +/- 0.0034 (2 sigma) and an MSWD of 3.9, pointing to the timing of the latest alkali metasomatism affecting the paleosols. The whole-rock K-Ar ages of sericite-rich paleosol samples range from 940 +/- 30 to 873 +/- 25 Ma, corresponding with the emplacement of Erinpura Granite. Thus, the Aravalli paleosol recorded more than two billion years of thermal events in its multi-geochronometers. The correlation between Rb-Sr isotope compositions and REE contents in paleosol samples suggests the REE mobility during K-metasomatism.

Considerable interest in the study of the NH_4^ + (H 2 O) n reagent ion is due to its successful application in ion mobility spectrometry and chemical ionization mass spectrometry. In this work, we obtained calculated data on the structure and properties of NH_4^ + (H 2 O) n ions ( n = 0–4), which are necessary for studying the chemical ionization regularities, predicting and interpreting ion mobility spectra and mass spectra. We computed the structure and refined the isomeric composition of NH_4^ + (H 2 O) n ions using quantum chemical methods. The most complete set of isomers for n = 3 and 4 (7 and 23 isomers, respectively) was revealed. It was found that the most stable NH_4^ + (H 2 O) n isomers are characterized by a branched non-cyclic structure with an NH_4^ + core and the maximal number of NH…O ionic hydrogen bonds. The thermodynamic parameters of hydration reactions for the most stable NH_4^ + (H 2 O) n ( n = 0–3) isomers were computed. The calculation accuracy achieved is comparable to the error of the experimental determination of the thermodynamic parameters. We computed the composition of the reagent ion for typical experimental conditions.The calculations showed that the reagent ion is represented by NH_4^ + (H 2 O) n ( n = 0–2) ions. Using the structural data found and data on the composition of the reagent ion, we calculated its reduced mobility by the trajectory method with two different algorithms. The calculated reduced mobilities agree with the experimental values.