We report a single-crystal x-ray diffraction study of the martensitic 'alpha-quartz' to 'post-quartz' (P21/c) transition in Si-doped GeO2 (Ge0.96Si0 & sdot;04O2). In situ high-pressure measurements showed that the diffraction signal from the parent alpha phase persisted below 6.6 GPa, while signatures of the new phase appeared already between 2.7 and 4.2 GPa and became dominant at higher pressure. After decompression, the recovered sample contained threefold twin of monoclinic 'post-quartz' domains and minor amount of residual alpha phase, which enabled the explicit determination of their orientational relationships and solution of P21/c structure of the 'post-quartz' phase. Structural analysis indicates that the transformation is driven by small collective atomic shifts within the oxygen framework: triplets of corner-sharing tetrahedra in the (120) planes of the alpha phase act as precursors to triplets of octahedrally coordinated cations in the 'post-quartz' phase.

We present the results of synchronous observations of microbaric oscillations and variations of electric and magnetic fields during large fires of man-made origin in Moscow. The main instrumental observations were carried out at the Center for Geophysical Monitoring in Moscow at the Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (CGM IDG RAS). Using an analysis of the data, we show that large fires in a megalopolis are manifested in microbaric variations and variations of the electric and geomagnetic fields in the surface atmosphere. Under certain conditions (the absence of intense natural movements of air masses and sufficiently strong heating of the atmosphere in the combustion source), fires can lead to an increase in wind speed and direction in an area up to 25 km. The emergence of a dynamic region with altered thermodynamic characteristics above the fire zone causes the formation of infrasonic waves during the period of the most intense combustion. Strong fires lead to an increase in the concentration of fine particles in the surface atmosphere.

In order to determine how large urban agglomerations affect the biosphere, the Moscow Geophysical Monitoring Center (part of the Institute of Geosphere Dynamics, Russian Academy of Sciences) has been operating since 2014. The center organizes the continuous instrumental observations of geophysical fields and meteorological parameters in the near-surface atmosphere. The data obtained in the denter allow the specialists to assess the negative effects of the Moscow megalopolis on the environment, in particular, to reveal the sources of artificial disturbances in the geophysical fields. Taking into account that the new problems have emerged and that there is the necessity to expand the technical capabilities of the center, an upgrade was done in 2021–2022: the list of recording instruments was expanded and the observation methods and data analysis were updated.

During the cruise 70 of the R/V Akademik Oparin, geophysical, hydrological, and atmospheric studies within the shelf of the Chukchi Sea were conducted. New data were obtained on the structure of the sea bottom, sedimentary cover, features of the magnetic field, and the spatial distribution of greenhouse gases at the water–atmosphere boundary.

The structures of two K-richterite crystals with the crystal chemical formulas (K0.44Na0.32 □ 0.24)Σ=1(Ca1.18Na0.82)Σ=2Mg5Si8O22OH2 and (K0.83Na0.02 □ 0.15)Σ=1(Ca1.11Na0.89)Σ=2Mg5Si8O22OH2 synthesized at a pressure of 3 GPa and a temperature of 1000°С in the MgSiO3 + CaMgSi2O6 + K2CO3 + Na2CO3 + CO2 + H2O system were studied by single-crystal X-ray analysis and Raman spectroscopy. The monoclinic cell parameters were obtained: a = 10.0256(5) and 9.9748(11) Å, b = 17.9874(7) and 17.9879(16) Å, c = 5.2687(3) and 5.2746(6) Å, Ve.c. = 916.17(18) and 918.52(8) Å3, β = 104.520(12)° and 104.821(5)°, sp. gr. С2/m (12), and Z = 2. The sites M(1), M(2), and M(3) are inhabited by Mg2+, while site M(4) is occupied simultaneously by Ca2+ and Na+. The Na+ cations not included in M(4) are located in position A, which also accommodates K+ cations. Raman spectroscopy made it possible to reveal vacancies in position A in both samples. The structure corresponds to the “ideal” structure of richterite group minerals. The unit cell volume of the measured crystals is directly proportional to the K content in position A. Based on the generalization of new and published data, an equation of the dependence of Vu.c. for amphiboles of the richterite Na(NaCa)Mg5Si8O22(OH)2–K-richterite K(NaCa)Mg5Si8O22(OH)2 series with a low tremolite component on the K content in position A is proposed.

A model of the genesis of stishovite and other SiO2 phases in terrestrial matter is developed; it combines the physicochemical and geodynamic conditions of their formation. Based on the experimental data, a P–T diagram of SiO2 polymorphs in combination with the boundaries of geospheres and geotherm was plotted. Stishovite and other SiO2 phases of cosmic-impact synthesis were buried in the early Earth during the period of meteorite accretion (50 Ma). These SiO2 phases are completely assimilated by melts of the pyrolite global magma ocean that existed for 500 Ma. By 2.0 Ga, the magma ocean crystallized, and the Earth’s crust, upper mantle, transition zone, and lower mantle with layer D” (with seismic boundaries between them) were formed. During this period, the main mass of the Earth’s core was separated, which completed by 2.7 Ga. As a result, the gravitational field intensified, which contributed to the fractional ultramafic–mafic evolution of mantle magmas with peritectic reactions of ringwoodite–akimotoite in the transition zone and bridgmanite in the lower mantle with melts and the formation of stishovite (shown experimentally at 20 and 26 GPa). These reactions in diamond-forming carbonate–silicate–carbon melts provided the formation of stishovite, which was captured as a paragenetic inclusion by diamonds and transported to the Earth’s surface by magmas. The genesis of stishovite under the terrestrial conditions is controlled by global mantle convection as well. The subduction of lithospheric plates to layer D” near the liquid core was accompanied by the formation of stishovite, and then its transformation into poststishovite phases. When superplumes rise from layer D” to the Earth’s crust, the peritectic reactions of postperovskite and bridgmanite, and then ringwoodite–akimotoite, with melts are likely to form stishovite and cause its subsequent transformation into low-pressure SiO2 phases. With the emergence of the Earth’s crust, the impact-meteorite genesis of stishovite resumes. Stishovite that formed under the terrestrial conditions appears as an inclusion in ultradeep diamonds on the Earth’s surface. Stishovite of cosmic-impact synthesis is preserved in meteorite craters. In both cases, stishovite is a metastable phase.

Анализируется частота фундаментальной моды F собственных колебаний Земли 0S2, выделенная в спектрах геомагнитных вариаций в Геофизической обсерватории (ГФО) «Михнево» ИДГ РАН, в период сильных землетрясений. Показано, что величина F принимает разные значения в зависимости от даты события, причем значения F выше в периоды, характеризующиеся уменьшением скорости вращения Земли, и ниже - в периоды ее увеличения. По результатам сопоставительного анализа результатов магнитных измерений и данных каталога открытого доступа IERS получена эмпирическая зависимость между вариациями F и скоростью вращения Земли. The frequency of the fundamental mode F of the Earth’s natural oscillations 0S2, identified in the spectra of geomagnetic variations at the Mikhnevo observatory of the IDG RAS, during strong earthquakes is analyzed. It is shown that the value of F takes different values depending on the date of the event, and the values of F are higher during periods characterized by a decrease in the Earth’s rotation rate, and lower during periods of its increase. Based on the results of a comparative analysis of the results of magnetic measurements and the data of the IERS open access catalog, an empirical relationship was obtained between the variations in F and the Earth’s rotation rate.

High-pressure high-temperature (HPHT) crystalline monosulfide solid solution (Mss) phases (FexNi1−xS, x = 0.90, 0.75, 0.50, 0.25), troilite (FeS I), and α-NiS of the Fe-Ni-S system were synthesized at 7 GPa and 900–1550 °C. The structural parameters of the obtained phases were refined by XRD using the Rietveld method. Factor group analysis revealed the number of active Raman modes for FeS I and α-NiS. Raman spectra of troilite, α-NiS, and Mss phases were obtained. It was shown that the Raman spectra of Mss phases and α-NiS have a similar topology. The Raman spectra of the experimental phases in the Fe-Ni-S system were analyzed with non-negative matrix factorization, which provided a meaningful concentration dependence of the spectral patterns. The spectral components were assigned to the FeS I and α-NiS structures. The structural and spectroscopic studies show linear dependencies of unit cell parameters and spectral components on composition and confirm the existence of a series of monosulfide solid solution FexNi1−xS.

Abstract—The disturbances of the geomagnetic field in the surface atmosphere were considered during a series of strong earthquakes that occurred on April 2–3, 2024, in the vicinity of the island of Taiwan. The data from the Mikhnevo Geophysical Observatory of the Sadovskii Institute of Geosphere Dynamics, Russian Academy of Sciences, and the observatories of the international INTERMAGNET network were analyzed. It was shown that in the absence of sole-related global disturbances of the Earth’s magnetic field, earthquakes were accompanied by geomagnetic variations with a maximum amplitude of 10 nT and a total duration of about four hours. The delay time of the magnetic effect relative to the main shock of the first earthquake was 60 min. The ionospheric effect of the event considered was established in the form of variations in the critical frequency of the F2 layer of the ionosphere on the basis the ionograms of height–frequency sounding obtained at the Okinawa ionospheric monitoring station and freely available on the website of the Japanese National Institute of Information and Communication Technologies.

— The geophysical effects of a strong seismic event as two earthquakes with magnitudes of 6.8 and 4.9 occurred on September 8, 2023, in Morocco at close times 22:11 and 22:30 UTC with an epicentral distance between the foci of ~4 km were considered. The data of a number of INTERMAGNET observatories and the magnetic recording results obtained at the Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences, were used. In the absence of considerable global disturbances of the Earth’s magnetic field, earthquakes were accompanied by a series of three positive bay-shaped geomagnetic variations with a maximum amplitude from ~1 to ~10 nT, following each other after ~60 min. The maxima of the induced magnetic field variations were observed almost synchronously at a distance from ~800 to ~10000 km. The magnetic effect delay time relative to the main shock of the first earthquake was ~70 min. Taking into account the almost planetary nature and high synchronicity of the magnetic field disturbances caused over a significant range of distances, as well as the time delays corresponding in order of magnitude to the travel time of the seismic signal of a distance multiple of the Earth’s dimension, it is suggested that the magnetic effect of the seismic event in question was caused by a global source such as an excited geodynamo. The ionospheric effect of the seismic event under consideration is reported as variations in the critical frequency f 0 F 2 calculated from the data obtained by the ground-based sounding station of the del Ebre Observatory.

The variations of the Earth’s magnetic field in the period 2013−2023 are considered on the basis of data from the INTERMAGNET network observatories located in the South Pacific Ocean. It was shown that El Niño in 2015 was accompanied by anomalous geomagnetic variations with an amplitude of up to 120 nT with a well-manifested increase in their mean-square deviation by 1.5 times relative to the average values of 2013. For the period from the end of 2022 to the beginning of 2023, a dramatical increase in the variations of the geomagnetic field and an increase in their mean-square deviation by 2.5 times relative to 2021 was recorded. This fact may indicate the beginning of the activation of a strong El Niño, the maximum intensity of which should be expected in 2024.

Relevance. Gas flares or seeps consisting of bubbles continuously rising from the seabed have been recorded throughout the World Ocean at depths ranging from several meters to three kilometers or more. Measurements of the gas composition of the rising bubbles shown that they are dominated by methane (CH4). The East Siberian Arctic Shelf contains more than 30% of the world CH4 and carbon dioxide reserves, preserved in bottom sediments by underwater permafrost. In the shallow seas of the East Siberian Arctic Shelf, the main mechanism for transporting CH4 from bottom sediments into water is bubble transport. Therefore, it is extremely important to estimate the amount of CH4 transported by rising bubbles from bottom sediments into the water column and the atmosphere. Aim. Estimation of CH4 quantity transported by chains of rising bubbles from the seabed to the atmospheric surface layers. Methods. The manuscript presents a study of the mechanism of gas exchange between rising bubbles and a liquid column, carried out using a specially designed stand that allows simulating local upwelling. Results and conclusions. The paper shows that chains of bubbles coming from the seabed with intensities of ~40 ml∙min–1 and ~110 ml∙min–1, taking into account the hydrostatic pressure, deliver 206 mg∙min–1 and 616 mg∙min–1 of CH4 to the bottom layer of the water column, respectively. The results obtained during laboratory studies allowed us to specify the flux of CH4 from bottom sediments to the atmospheric surface layers. Taking into account the quantity of gas exchange and local upwelling, the amount of methane delivered to the atmospheric surface layers was 69 mg∙min–1 and 286 mg∙min–1. The paper presents an acoustic estimate of the amount of CH4 transported by the seep, which includes the considered chains of rising bubbles. According to calculations, the flux of CH4 into water from this area in 2012 was ~40 g∙min–1. At the same time, the amount of CH4 transported by this seep into the atmospheric surface layers, taking into account local upwelling and gas exchange occurring between the rising bubbles and the liquid column, is ~24.5 kg per day or ~9 tons per year.

The typomorphic features and ages of monazites from two zones of ore-bearing pegmatites of the Burpala massif (Western and Britolite) were studied. This made it possible to clarify the stages of formation of the vein phase of the intrusive rocks. Information on the relationship of monazites with rock-forming and ore minerals was also obtained. Using the CHIME method, the isochronous Th-U-Pb age of monazites from rare-metal pegmatites was calculated: 287 ± 54 Ma (Western zone) and 273 ± 69 Ma (Britholite zone). The obtained age values for the rare-metal pegmatites of the Burpala massif are in good agreement with the available geological and geochronological information and indicate the existence of several stages of their formation, which allows us to supplement the magmatism scheme of the vein complex (mariupolites → foyaites → rare-metal pegmatites of the Western zone → rare-metal pegmatites of the Britholite zone → apatite-fluorite rocks → carbonatites→ alaskites and alkaline granites). The obtained age for monazites from two zones of pegmatites is close by time of formation to the pulaskites of the main phase and rare-metal pegmatites of the North-Western zone of the Burpala massif and belongs to the general Late Paleozoic stage of intraplate magmatism in the northern framing of the Angara-Vitim batholith.

We present the results of instrumental observations of acoustic oscillations, geomagnetic variations and variations of the atmospheric electric field during the fall and explosive destruction of the bolide in the southeast of Turkey on September 02, 2023. It is shown that the destruction of the bolide under the action of aerodynamic forces, which occurred in three stages, was accompanied by an acoustic signal of a characteristic shape and manifested in variations of the magnetic and electric fields in the near-surface layer atmosphere. The total energy of the event, estimated by the acoustic effect, was ~ 9×1012 J, which corresponds to about 2.15 kt in TNT equivalent. The maximum amplitude of geomagnetic variations caused by the explosion of the bolide ranged from 0.2 to 2.1 nT depending on the distance. At the same time, the amplitude of variations of the vertical component of the atmospheric electric field at the Mikhnevo observatory (distance ~1900 km) was ~70 V/m. The ionospheric effect of the event under consideration is demonstrated in the form of variations of the critical frequency f0F2 obtained as a result of processing ionograms of height-frequency sounding of the ionosphere at the Rome station.

The results of instrumental observations of acoustic oscillations, geomagnetic variations, and variations in the atmospheric electric field are presented for the period of fall and explosive decomposition of a bolide in southeastern Turkey on September 2, 2023. It is shown that its decomposition under the influence of aerodynamic forces, occurred in three stages, was accompanied by an acoustic signal of specific morphology, and resulted in variations of the magnetic and electric fields in the subsurface atmospheric layer. The total energy of the event estimated from the acoustic effect was ~9 × 10 12 J, which approximately corresponds to 2.15 kt of TNT. The maximum amplitude of geomagnetic variations induced by the bolide explosion varied from 0.2 to 2.1 nT depending on the distance. The amplitude of variations of the vertical component of the atmospheric electric field in the Mikhnevo Geophysical Observatory (at a distance of ~1900 km) was ~40 V/m. This event showed an ionospheric effect in the form of variations in the critical frequency f 0 F2, which was a result of processing the ionograms of height-frequency sounding of the ionosphere at the Rome station.

Influence of the supercritical C-O-H-fluid (7.5 wt.%) onto melting phase relations of the multicomponent multiphase diamond-forming system olivine-jadeite-diopside-(Mg-Fe-Ca-Na-carbonates)-(C-O-H) in experiments at 6 GPa and 700–1200 °C (the upper mantle conditions) has been studied. The peritectic reaction of olivine and jadeite-bearing melt with garnet formation has been retained as a key mechanism of the ultrabasic-basic evolution of diamond-forming melts. The CO2-fluid and silicate components react forming carbonate phases. The H2O-fluid together with carbonates has essentially lowered temperatures of the liquidus and solidus boundaries. The phase of supercritical water fluid and water-bearing carbonate nesquehonite (Nes) MgCO3·3H2O were identified with the Raman-spectroscopy method after crystallization of the completely mixed silicate-carbonate-(C-O-H-fluid) melt.

Spontaneous alpha-Si1-xGexO2 single crystals were synthesized using the set of crystal growth techniques: hydrothermal (X-Ge = 0.09, 0.20), flux (X-Ge = 0.45, 0.70) and recycling (X-Ge = 0.96). The XRD and spectroscopic studies with non-negative matrix factorization show linear dependences of structural parameters and Raman shift on germanium content and confirmed the existence of a complete series of alpha-Si1-xGexO2 solid solution. The synthesized samples of the solid solution were studied by Raman spectroscopy at the ambient conditions and for the first time at high pressures up to similar to 30 GPa. The obtained results suggest a phase transition "alpha-quartz -> post-quartz" for Si1-xGexO2 in the examined pressure range. The formation of the possible intermediate phase (quartz-II) was detected for Si1-xGexO2 with X-Ge = 0.09, 0.20 and 0.45 at 11, 10 and 7.5 GPa, respectively. The linear dependences of the pressure value of phase transitions on germanium content were observed. At decompression, the post-quartz phase remained stable that was determined by Raman spectra for all compositions of solid solution. Obtained experimental results revealed the correlation of the chemical composition, spectroscopic characteristics, and structural deformations at ambient conditions and at high pressures.

An analysis of variations in the microbaric background and the terrestrial magnetic and electric fields in the surface layer of the atmosphere accompanying strong earthquakes that occurred on February 6, 2023, in Turkey, is presented. The analysis involved the results of instrumental observations performed at the Moscow Center for Geophysical Monitoring and the Mikhnevo Observatory (Institute of Geospheric Dynamics, Russian Academy of Sciences), as well as the data obtained by a number of magnetic observatories of the INTERMAGNET network. It is shown that, in addition to the seismic effect, these earthquakes were accompanied by variations in the magnetic and electric fields, as well as by the generation of infrasonic waves recorded at a considerable distance from the sources.

(Mg,Fe)CO3 solid solutions not only play a crucial role in carbon storage and transport within the deep mantle, but also serve as a great case for studying the spin transition behavior of Fe2+ in the fairly isometric sixfold coordinated octahedral sites. However, simultaneously high temperature and pressure measurements on the spin crossover of (Mg,Fe)CO3 remain scarce, which greatly limits our knowledge about the pressure-induced spin transition of (Mg,Fe)CO3 under extreme conditions. In this study, we investigated three representative synthesized (Mg,Fe)CO3 samples at high temperatures and pressures up to 65 GPa and 900 K using Raman spectroscopy coupled with diamond-anvil cells using neon (Ne) as a pressure-transmitting medium. Interestingly, (Mg,Fe)CO3 exhibits abnormal vibrational properties and spin phase diagrams at high temperatures and pressures. The onset of spin crossover for the three (Mg,Fe)CO3 samples decreases with increasing temperatures from 300 to 500 K, followed by an inverse increase at higher temperatures. Moreover, the width of spin crossover is similar to 7-9 GPa at 800 K, compared to 3-4 GPa at 300 K. Notably, iron-rich (Mg,Fe)CO3 displays a narrower width of spin crossover than its iron-poor counterpart. These findings provide insights into the effects of temperature and iron concentration on the pressure-induced spin transition of (Mg,Fe)CO3.

The response of the microbaric background and variations in the Earth’s magnetic and electric fields to the paroxysmal activity of the Stromboli Volcano (October 9, 2022, Italy) was analyzed using the results of instrumental observations carried out in the surface atmosphere. The stage of active volcanic eruption was accompanied by the generation of an acoustic signal and pronounced variations in the geomagnetic and atmospheric electric fields at considerable distances both during the period of volcano activity and with the arrival of the infrasonic wave at the observation point. The volcanic eruption was noted to cause a response as critical frequency variations of the F 2 layer in the ionosphere.