Search

New data on the concentration and spatial distribution of the benz(a)pyrene and polycyclic aromatic hydrocarbons in bottom sediments in the testing area of the Baikal Pulp and Paper Plant (BPPP) waste water discharge in 1981–1988 and 2010 are presented in this paper. The bottom sediments in this section of the lake are strongly polluted with polycyclic aromatic hydrocarbons.

The role of the short-lived 134Cs radionuclide in the formation of the radioecological background in the marine environment of the Arctic is studied. This paper analyzes the data collected during long-term observations of the Murmansk Marine Biological Institute, Russian Academy of Sciences, on the levels of the 134Cs radioisotope in the marine and coastal environments of the Barents and Kara seas, including the high-latitude archipelagos: soils, lichens, algae, fish, seawater, and bottom sediments. The geography of the 134Cs distribution in marine and coastal environments is also examined, and the acting and potential sources of transport of this radioisotope into marine ecosystems of arctic seas are identified. 134Cs is rarely included among radioactive contaminants nowadays, and its specific radioactivity is insignificant. Its short half-life makes it a marker of the contamination that happened recently, such as the emissions from the Fukushima-1 nuclear power plant and local sources in the region studied. The possile local sources in the Barents and Kara seas are nuclear-powered fleet facilities and glaciers of high-latitude archipelagos. Findings of 134Cs in some samples of modern bottom sediments for fjords of the Svalbard Archipelago and its outer continental shelf suggest 134Cs transport with meltwater from the Svalbard glaciers. This paper provides data on the modern background of the 134Cs specific radioactivity in the Barents and Kara seas. In the case when an increase in these background levels is detected, an immediate search for the sources of 134Cs entry into the environment must be undertaken.

This paper is devoted to the problem of studying the rheological properties of seafloor sediments during the sampling process with the use of a gravity corer. The problem of gravity corer penetration through the soil with a complicated visco-elasto-plastic rheology is considered. Estimation of the mechanical properties of bottom sediments is among the most important problems emerging during the exploration of the hydrocarbon fields located on the Arctic shelf. Proper evaluation of the reaction of infrastructure objects to external effects (earthquakes, large waves) is needed to reduce the risks of serious accidents on the shelf. This paper presents a new approach to determining the parameters governing the stability of the infrastructure: static elastic moduli of seafloor sediments and their plastic and viscous properties. The dynamics of gravity corer penetration, with a measurable dependency of its acceleration, acts as a source of information regarding these parameters. The inverse problem of reconstructing the mechanical properties of seafloor sediments from the characteristics of this dependency has to be solved. This paper presents the results of solving the corresponding direct problem with the use of the finite element method. The possibility to estimate the mechanical properties of seafloor sediments from data on parameters such as time passed until the complete cessation of the tube sampler and the depth of its penetration is demonstrated.

This paper reports on the physical-chemical parameters and vertical distribution of different types of fluid inclusions in quartz from the Au-bearing interval of the Kola Superdeep Borehole. We assume that gold ore mineralization was formed when a deep flux of CO2 interacted with brines at depths of 10 205-9269 m due to tectonic factors. In this paper, we discussed the role of these processes in the formation of the orogenic gold deposits including the gold mineralization of the Southern Pechenga structural zone.

This paper addresses seismic imaging of fault zones and analysis of the seismic data with the use of the fault facies model developed at Uni Research CIPR. Simulated and ideal seismic images were produced to generate a statistical ensemble of realizations of this model. The comparative analysis presented in this paper is focused on the statistical characteristics of the initial geological model and its seismic images. This paper analyzes cross-correlations between seismic images and ideal seismic images. The method proposed makes it possible to establish an exact correspondence between the initial fault facies models and the seismic images of these models.

In our previous publications [1–3], we have madean attempt to estimate the relationship between theconditions of fluorite and monazite formation and thelikely composition of their rareearth component. Inthis paper we are trying to apply this approach to amore complex and less studied mineral, namely apatite. Because of the wide abundance of apatite andmonazite as accessory minerals, the geochemicalpeculiarities of their composition are often discussedin publications. The close association of apatite andmonazite is registered; either inclusions of monaziteare observed in fluorapatite or fluorapatite coronas,sometimes with xenotime and allanite, are the result ofmonazite replacement [4–7]. It was demonstrated in[4] that under the influence of metamorphosing solutions primarily REErich light fluorapatite was transformed into REEpoor dark fluorapatite with monazite inclusions (Fig. 1a). Figure 1b from [5] demonstrates monazite replacement by fluorapatite andallanite. These studies are remarkable, because theycontain the compositions of REE components of syngenetic monazite and fluorapatite.In this paper we report the results of thermodynamicmodeling of REE partitioning between monazite, fluorite, and fluorapatite in the temperature range of 500–100°C depending on the initial concentration of HFobtained using the HCh software [8, 9]. The calculations were performed at

Platinumbearing dunite–clinopyroxenite–gabbro complexes of the Urals have attracted the attentionof researchers for a long time and are currently beingstudied in detail. In addition, despite the increasingvolume of information, the conditions of petrogenesisof these associations are still debatable. Of specialimportance are the problems of the formation of dunitecontrolling chromite–platinum mineralization [1–4].The problems of genesis of these ultrabasic rocks wereconsidered in numerous papers; most of them containdata on the significant role of magmatic processes incrystallization of dunite [3, 5–8]. At the same time,most published papers providing evidence for themagmatic nature of dunites from zoned platinumbearing complexes of the Urals practically do not contain direct proofs of the participation of hightemperature silicate melts.Investigations of basic–ultrabasic complexes ofSiberia, the Urals, the Far East, and the Central Atlantic demonstrate that analysis of chrome spinellids andmelt inclusions in them is the most promising way toobtain direct information on the genesis of ultrabasicrocks [9–13]. This approach was applied for study ofthe condition of crystallization of dunite from theNizhnii Tagil ultrabasic massif (Platinumbearing Beltof the Urals).Information on the geological structure of theNizhnii Tagil massif, petrography, mineralogy, and orepotential has been discussed in many publications [1–4, 6, 7, 14]. It forms an ellipselike body in plan with thecentral part composed of a large dunite core surrounded by a clinopyroxenite rim of complex morphology. Petrostructural investigations allowed theauthors of [7] to distinguish protogranular, porphyroclastic, and mosaic–granoblastic types of microtextures. The first type is considered as primary corresponding to the class of protomagmatic adcumulatetextures. The two other types are formed later in theprocess of hightemperature plastic deformation andsyntectonic recrystallization.Investigation of dunite samples from the NizhniiTagil massif mainly corresponding to the protogranular (primary) type allowed us to discover and studymelt inclusions in accessory chrome spinellids. Theconsidered chromites are almost intransparent and donot provide direct observations during heating;because of this feature, a special methodology [10, 12]was applied. Chrome spinellid grains were heated upto 1320–1330°C in graphite microcontainers of a special microthermocamera in the course of hightemperature experiments. After being kept for 10 min,they were quenched in water in order to obtain glass ininclusions. Glasses of quenched inclusions andchrome spinellids were studied on a CamebaxMicroXray microanalyzer and on a LEO 1430 VP scanningelectron microscope at the Institute of Geology andMineralogy, Siberian Branch, Russian Academy ofSciences (Novosibirsk).According to the values of the chromium and magnesium mole fractions, chrome spinellids (with meltinclusions) from dunite of the Nizhnii Tagil massif arepractically consistent with chromites from dunite ofthe platinumbearing Konder and Inagli massifs(Siberian Platform). The studied chrome spinellidsdiffer from minerals of ultrabasic rocks from modernand ancient (ophiolites) oceanic structures. As awhole, chrome spinellids from platinumbearing massifs are characterized by a high chromium mole fraction (Cr# = 78–89%). Chromites from oceanic complexes provide a single trend of Cr# decrease (from65 to 45%) at a significant decrease in Mg# (from 78to 28%).The studied primary melt inclusions (10–40 µm)are regularly located in grains of accessory chromite.Inclusions have round morphology, being in equilibrium with host chromite, and are often slightly faceted. Before experiments they contained a set of vari

412 Ultrahighpressure metamorphism is considered as an indicator of the modern style of plate tectonics, generally, and of subduction, in particular (1). Accord� ing to some data, the formation of this style started on the Earth in the Neoproterozoic (1); according to other data, it began 2 b. y. before, at the Meso- Neoarchean boundary (2). The absence of ultrahigh� pressure complexes with an older age than the Neoproterozoic is an important argument in favor of the first hypothesis. In this paper we describe the results of petrological investigation of a metagabbro dyke in the Gridino eclogite complex (Karelia) dem� onstrating that ultrahighpressure events were realized in the subducting lithospheric slab already in the Pale� oproterozoic. The Gridino complex is part of the Belomorian mobile belt of Karelia (3-5). It represents a tectonic plate of northwestern strike occurring in the coastal area and on the islands of the White Sea up to 60 km from Sukhaya Bay in the northwest to the Suprotivnye Islands in the southeast at a width of 6-7 km. The main volume of the complex is represented by migma� tized gneiss containing rock boudines of various sizes and compositions (3, 4). Rocks of the basic composi� tion (metabasites), namely eclogite and amphibolites, strongly prevail among boudines in gneiss; amphiboli� tized metaultramafites, marbles, zoisite, and scapolite rocks are rarely observed. The complex is cut by dykes and small massifs of metagabbronorites metamor� phosed under the conditions of the eclogite and upper amphibolite facies, as well as intrusions and veins of plagiogranites (3). Dating of eclogites from this com� plex demonstrates a wide range of ages from the Neoarchean (2.74 Ga) to the Paleoproterozoic (1.9 Ga) (3-5). This paper contains the results of study of metagab� bro dyke cutting migmatized amphibole-biotite gneiss on Bezymyannyi Island. Metagabbro has massive structure, with fineto mediumgrained, heterogranoblastic texture. The main rockforming minerals are garnet, clinopyrox� ene, plagioclase, orthopyroxene, biotite, amphibole, and quartz, which are related to different stages of metamorphic evolution of the rock, according to the

In suture zones of the Urals, geological and physical-chemical conditions for formation of large ore and nonmetalliferous deposits existed during each geodynamical environment of development of the Urals. The development was predetermined by the duration and discontinuous-continuous existence of these structures, and the latter promoted the development of polygenetic and polychronic pegmatites of various types (by depth and productivity) and other postmagmatites. It has been shown in the example of the Ufalei metamorphic block that pegmatites of different ages (from R2 to P) are often spatially combined. In this paper, two age diagrams are presented: the first one is for geological events that took place in the Ufalei metamorphic block; the second one is for Vendian pegmatites in it. The value of this paper is determined by the fact that the data obtained in Ufalei block could be used for study of postmagmatites within its analogs, which are gneissic-amphibolitic complexes of the Northern Urals, and especially by the fact that the project “Polar Urals, Industrial Urals” is implemented there.

773 Discovery of hydrothermal activity in the ridge zones of the World Ocean in the late 1970s allowed us to understand the importance of endogenic material during the formation of hydrothermal ores and to determine the mechanisms of abiogenic hydrothermal methane generation. The formation of organic com pounds in the zones of hydrothermal activity proceeds under the influence of a number of physicochemical and biogeochemical (extremophile consortiums of bacteria and archaea) factors [1–3]. This paper reports on study of the concentration and molecular composition of alkanic and isoprenoid hydrocarbons (HC) in hydrothermal rift zones of the Mid Atlantic ridge and reveals features of the distribu tion, genesis, and transformation of organic matter (OM). Samples of different morphologies and mineral compositions were collected using the deep manned submersible Mir 1 and Mir 2 on the 47th, 49th, and 50th voyages of the R/V Academician Mstislav Keldysh in 2002–2005. The main ore minerals of the deposits were represented by chalcopyrite, sphalerite, marca site, and pyrite. Relationships between these minerals in different hydrothermal constructions and in their individual elements are not constant and vary signifi cantly [4]. Study of the composition and HC distribution allows us to reveal the main sources of HCs and the peculiarities of the geological and geochemical trans formations under the conditions of the formation of a deep circulating system. This paper describes the results of study of HCs from hydrothermal sulfide ores of the fields Broken Spur, Snake Pit, and TAG (table). The hydrothermal field Broken Spur is located within the axial trough along the top of a low (200– 300 m) neovolcanic arch. Its activity started

The observed heat flux from the Earth is created mainly by the heat released due to radioactive decay, secular cooling of the Earth, and solidification of the growing inner core. The structure of convective flows and, accordingly, the geodynamic manifestations of convection depend on the proportion in which the mantle is heated from below by the flux from the core and from the inside by internal heat sources. For a long time, the heat flux from the core was estimated under the assumption that almost all of it is carried to the surface by plumes in hot spots. However, this leads to an imbalance and a deficit in the total heat of the Earth. In this paper, the sources of the Earth’s heat are analyzed and a heat balance consistent with the available set of observational data is presented. The distribution of the heat flux density at the boundary with the core and on the surface is calculated, and it is shown that plumes carry to the surface only a part of the heat coming from the core even in the simplest convection model with constant viscosity.

The paper presents the results of modeling the stress–strain state of the epicentral zone of the strong crustal Hanshin–Awaji earthquake, which occurred in the area of Kobe (Japan) on January 17, 1995, with a magnitude M of 6.9. In this work the author’s method for modelling and analyzing the stress–strain state of the epicentral zones of crustal earthquakes was used. The geological, tectonic, and seismological data for the earthquake region are used as input data and boundary conditions for modeling. In this work it is shown that the main rupture arising at the origin of the earthquake is generated in a zone of high stress intensity at a certain ratio of the main tectonic stresses and propagates through areas of anomalously high stress concentration, causing maximum displacements in these zones. The results provide new insights into the focal mechanism of an earthquake, aimed at predicting the location and magnitude of strong crustal earthquakes in earthquake-prone areas.

This paper reports the results of satellite image and seismological data analysis obtained when considering the causes of a landslide on the Yelbashinskii dump at the Kolyvan anthracite deposit. The potential for determining the natural vibrations of large objects from low-frequency seismological records and monitoring thereof has been demonstrated.

This paper presents the results of observations and processing of experimental data on long-term (2012–2018) continuous electric field measurements and compares them with the meteorological parameters. Based on the field observations analyzed, the daily average electric field correlates with the daily average total cloud cover regardless of the season with a correlation coefficient of –0.48, while the correlation coefficients between the average electric field and temperature vary from –0.39 in winter to 0.41 in summer. Theoretical estimates of the stratus cloudiness effect on the electric field in the surface layer confirm a decrease in the daily average electric field strength to 70% in fair weather field.

This paper presents the reconstruction results of catastrophic avalanche characteristics. The avalanche occurred on the slope of the Gora Otdelnaya ski resort on January 9, 2021 (Norilsk). It had a peak pressure of 0.266 MPa and led to the destruction of a suburban settlement, covering an area of about 0.9 ha. Six people got caught in the avalanch, of whom three were killed. The virtual and calculated boundaries of the maximum avalanche run-out distance are given. The causes of the catastrophe are also under investigation. An avalanche hazard assessment methodology for the Russian Arctic region and other poorly studied areas with no long-term avalanche observations is suggested.

The upper part of the subsurface component of the Earth’s cryosphere—polygonal peatlands—are considered in this paper. The polygonal peatlands are widespread in the cryolithozone in northwestern Siberia. When the upper permafrost layer thaws under the influence of climatic fluctuations, the ice-bearing transition and intermediate layers in the polygonal peatlands serve as a buffer zone. Therefore, the identification of these layers is a crucial task. The specific features of the layers, their relationship with ice of various origins, and the properties of peat have been determined. The differences in the structure of the intermediate layer, associated with polygonal microrelief of the surface, have been revealed. Thawing of the transitional layer against the background of modern warming has been recorded on the basis of monitoring of a seasonally thawed layer. To identify the transitional and intermediate layers, the indicators—the cryogenic structure, degree of preservation, color, water content, and density of peat—have been determined.

Granitoids of the Uda complex are distributed within the southeastern marginal part of the Siberian craton and its folded framing. Geochemical, isotope (Nd, Sr), and geochronological (U–Pb ID TIMS) studies of two massifs (Chalbuk-Yakon and Uyan-Tavitchak) of this complex of the Dzhugdzhur Block of the Stanovoy suture were carried out; the results are presented in this paper. It is found that formation of these massifs took place in the Early Cretaceous (116 ± 1 Ma) in the geodynamic setting of lithospheric extension. The initial magma for these granitoids was formed from a mixed source: Early Precambrian lower crust and mantle, with a clear predominance of the crustal component. The granitoids of the Uda complex of the Dzhugdzhur block most likely represent the eastern end of the Udsko-Zeya (Stanovoy) post-collision magmatic belt, stretching for more than 1000 km along the southern framing of the Siberian craton parallel to the Mongol–Okhotsk suture zone and stitching various tectonic blocks of the northeastern part of the Central Asian fold belt. There is every reason to believe that, further to the west, the Udsko-Zeya (Stanovoy) belt passes into the West Transbaikal rift system, the formation of which took place in the interval of 170–110 Ma. In other words, it can be assumed that in the Mesozoic, in the southern framing of the Siberian craton, there was a giant unified rift system stretching for more than 2000 km.

This paper analyzes measurement data on the ionic composition of the upper atmosphere at altitudes of 810–830 km in the period from 2009 to 2018; the measurements were made with RIMS mass spectrometers onboard the space vehicles Meteor-M no. 1 and Meteor-M no. 2. The spatial–temporal variability of the O+ concentration is analyzed in view of the solar activity (Wolf numbers) during a reversal of the solar magnetic field. It is found that the Sun’s magnetic field reversal occurred during the solar maximum of the 24th solar cycle and was accompanied with a significant increase in the concentration of O+.

An increase in the flux of energetic particles under thunderstorm clouds is a result of the multiplication and acceleration of particles of secondary cosmic rays in the electric field of the cloud. Study of the particle multiplication mechanisms requires an assessment of the electrical properties of clouds. In this paper, we propose a method for evaluating the electrical structure of a cloud that creates a flux of energetic particles. The developed technique for estimating the distribution of a charge in the cloud is based on the ground-based measurements of the electric field and energetic particle flux. The technique was used to study the clouds that create the descending fluxes of energetic particles observed at the Aragats Research Station. The characteristic charge distribution involves a two-layer structure with a charge density of 0.5–5 nC/m3 in the lower layer and –0.2…–3 nC/m3 in the upper layer. The total charges of the two charge regions are in the range of 1– 20 and –1…–30 C, respectively.

The Uyandina–Yasachnaya volcanoplutonic belt (UYVB) is located in Northeast Asia. As one of the largest volcanic belts in the region, it extends for 900 km from the headwaters of the Kolyma River in the northwesterly direction. The Late Jurassic UYVB overlaps the folds of the Cherskii collision belt. The UYVB rocks are characterized by highly variable facies indicating the heterogeneous nature of the belt. The UYVB has been studied at the cross section of the Indigirka River. This paper reports the first data on U–Pb dating of zircons and the geochemical features of rocks. The concordant U–Pb age of volcanic rocks is 150 ± 2–152 ± 2 Ma (Kimmeridgian–Volgian of the Late Jurassic). It is concluded that the formation conditions of the volcanic rocks change upward through the section, from those typical of mature island arcs to those more typical of active continental margins.

Measured gravity anomaly values serve as initial data for density models reconstructing the Earth’s crust and upper mantle. As a preliminary step, the data is corrected for the effects of topography. In this step the field of the plane-parallel layer is considered. In the case of a highly disturbed topography such an approach may introduce a significant error into the results of the interpretation. In this paper, we show that the inaccurate approximation of the topography and neglect of the planet sphericity introduce an error into the calculated field that is two orders of magnitude higher than the sensitivity of modern gravimeters. Here we propose a versatile method for the interpretation of gravity data that does not require prior corrections for topography. This method is based on an algorithm that was developed previously by the authors for fast computation of the gravity field for density models of an arbitrary geometrical shape. The algorithm allows the values of gravity anomalies to be calculated for real topography without additional computational costs (use of irregular grids of the density model and field is possible). Consequently, the interpretation of the observed gravity data can be carried out using the field values measured on the relief with account for the Earth’s sphericity. This way the density model limited from above by the surface of the topography is considered. This approach will significantly improve the accuracy of determining the parameters of the model.

This paper addresses changes of Antarctic Bottom Water (AABW) transport through the Vema Fracture Zone based on direct measurements and Glorys12v1 reanalysis. Instrumental measurements of currents and other principal hydrological characteristics were carried out during the 45th cruise of the R/V Akademik Nikolaj Strakhov in November 2019. According to the current velocity measurements in 2019, the transport in the Vema Fracture Zone is 0.9 Sv. Moreover, based on the distribution of dissolved oxygen concentration, it is more correct to consider the isotherm 1.7°С rather than 2°С as the upper boundary of the AABW. The reanalysis showed very good agreement with direct measurements. The average transport of bottom water during the reanalysis period is 0.66 Sv. In general, there is a tendency towards an increase in both transport and temperature over the 25-year period covered by reanalysis. The measurements of the bottom water temperature during twenty successive samplings showed changes from 1.36 to 1.41°С within a day. This interval almost completely covers the entire range of values observed in previous years.

This paper analyzes data on the concentration and dynamics of 137Cs and 90Sr in marine organisms on the Arctic shelf under modern conditions (2013–2018). It is shown that the radiation pollution of the Arctic sea biota is low and poses no danger to humans. The dynamics of radionuclide pollution of macrophyte and fish suggests that self-purification of the biotic component of the ecosystem occurred in several stages determined by a change in the generations in the hydrobiont populations. Fish are most sensitive to radiation pollution and the most studied component of marine biota. In the study of modern radioactive contamination of the Arctic seas, attention should be focused on local waters, where an increase in isotope concentrations could be possible owing to the episodic leakage of radioactive materials.

The paper presents new 40Ar/39Ar age determination of basalts from the Franz Josef Land archipelago. The obtained set of dates confirms the predominance of products only of Early Cretaceous age, which is also confirmed by results of paleomagnetic studies. Analysis of the entire set of geochronological data, taking into account information on their magnetic polarity, indicates that the interval of active magmatism occurred at the latest Barremian–Aptian and corresponds to the beginning of the Cretaceous Normal Superchron (C34n) at about 125 Ma. Significantly older age estimates are not related to the time of formation of the FJL basalts as a part of the High Arctic Large Igneous Province.

The paper presents the results of GNSS observations, provided by the authors in 2010-2019 years, in the zone of contact of tectonic structures of the Siberian platform, West-Siberian plate and West-Sayan orogenic area. We presented the first time assessment of the velocities of modern horizontal movements and the structural-kinematic model of block movements in a southern sector of the Yenisei Ridge. This model enables to assess the geodynamic safety of disposal of high-level radioactive waste in granite gneisses rocks of the Nizhne-Kansk massif.

This paper presents the results of a study on peat deposits and radiocarbon dating of basal peat horizons in 43 peatlands located on three key sites within Meshchera Lowlands and Moksha Polesie. Peatlands formed by upland paludification processes and located on watersheds and terraces rising above floodplains were selected for the analysis. The obtained data indicate that the peatland formation process has been ongoing in these regions throughout the entire Holocene epoch and that this process has been affected by the fire regime in the area. In periods with higher wildfire frequencies (8800–5800 and 4200–3200 calendar years BP), changes in the water balance on flat and poorly drained plains occurring after the destruction of forest stands intensified the waterlogging processes.

The present paper presents new U–Pb and Sm–Nd age data obtained for granulites of the Cheremshanskaya Unit enclosing metamorphosed volcano-sedimentary sulfide ores, in which sulfur isotope mass-independent fractionation (MIF–S) was established. Zircons from orthotectites that cut hosted paragranulites yielded aconcordant U–Pb age of 1866.8 ± 7.6 Ma, reflecting the final stage of granulite metamorphism. The model age (ТND (DM)) of ~3.0 Ga obtained for graphite–sulfide–cordierite (±Bt) and garnet–biotite–orthopyroxene paragneisses indicates that the protolith of sedimentary rocks was formed in the Mesoarchaean. As evidenced from various sources, the Sm–Nd isotopic characteristics of orthotectites differ from those of paragneisses.

The new results of experimental study of the Na2MgSiO4–Mg2SiO4 section of the SiO2–MgO–Na2O model system at 22–24 GPa and 1600–1900°C are discussed in this paper. An association of Na-bearing ringwoodite (up to 0.42 wt % Na2O) and the phase with the composition Na2MgSiO4 with a cristobalite-type structure was obtained at 22 GPa. Incorporation of Na in ringwoodite occurs through the mechanism Mg2+ → 2/3Na+ + 1/3Si4+ and results in an increase in the cell parameter in relation to that of pure Mg2SiO4 ringwoodite. A paragenesis of Na-bearing bridgmanite (up to 0.67 wt % Na2O), periclase, and anhydrous sodium phase X (Na2Mg2Si2O7) is formed at 23–24 GPa. Based on the data obtained, high-pressure Na–Mg silicates, Na2MgSiO4 and Na2Mg2Si2O7, may be considered as mineralogically probable mantle phases within the locally metasomatized mantle regions, although their finds as inclusions in diamond crystals are unlikely.

This paper analyzes the possibility to reduce the carbon footprint of exported products by implementing forest climate offset projects amid the introduction of the carbon tax on imports of high-carbon products, including those exported from Russia, by the European Union. The role of forests as absorbers of greenhouse gas (GHG) emissions differs significantly in Russia and in the EU. It is suggested that the EU’s climate neutrality policy aimed primarily at the reduction of direct CO2 emissions by sectors such as power, industry, and agriculture is a consequence of the insignificant role of European forests in greenhouse gas absorption. By contrast, Russia can achieve climate neutrality not only by reducing greenhouse gas emissions, but also by increasing their absorption by forests and implementing forest climate projects (FCPs). Taking into consideration the UNFCCC baseline and additionality requirements, three FCP types can be proposed for implementation in the Russian Federation. The possibility to monetize the carbon sequestration function of Russian forests in the framework of carbon offset projects is assessed.

This paper addresses the results of instrumental observation of acoustic oscillations in the atmosphere above the city of Moscow during the COVID-19 quarantine period. Instrumental observations made by the Geophysical Monitoring Center (GMC) at the Institute of Geosphere Dynamics (IGD), Russian Academy of Sciences, show that the quarantine-related decrease in production activity caused significant changes in the amplitude and spectral characteristics of acoustic noise above the city, as compared to the long-term averages. During the quarantine period, the amplitude of the main spectral components and the average amplitude of acoustic noise decreased by more than two times. The diurnal variation of the amplitude of noise caused by production activities in the daytime was much less evident. Our findings can be useful in determining the characteristics of technogenic noise sources and assessing its contribution to the total acoustic noise level of the city.

This paper proposes a new method for determining the seismic parameters of the subsurface below a seismic station using the waveforms of converted waves. The subsurface below the seismic station is represented by a plane-layered model. In contrast to other methods, the new approach does not involve determining all the elastic parameters of each of the layers. Instead, it is proposed to use a combination of parameters related directly to the object under study. In our case, we estimate the depth dependencies of the seismic velocity and density. The quality of solutions is assessed based on the rms distance between the observed waveforms and the seismograms derived from the averaged depth dependences of the seismic parameters. The approach proposed is applicable to a wide range of inverse problems in geophysics.

This paper describes a new approach to calculating the vertical turbulent diffusion coefficient and its variability, based on the use of modern asymptotic analysis in the singularly perturbed reaction–diffusion problems in combination with information obtained at one of the atmospheric monitoring stations. The capabilities of this method are demonstrated by using the diffusion model that describes changes in the vertical distribution of concentrations of anthropogenic impurities due to turbulent diffusion. Field measurements of the carbon monoxide concentration at various altitudes above Moscow are used in order to control the adequacy of the mathematical model and the efficiency of the calculation algorithm. Based on the analytical calculations, taking into account the initial and boundary conditions, which are consistent with the field observations, the vertical profiles of the turbulent diffusion coefficients and their seasonal changes are determined. The estimated reliability of the values recovered confirms the high efficiency of the proposed method and its high potential in the assessment of emissions and in the numerical atmosphere models.

This paper reports on a study of the phytoplankton calcium carbonate pump in the Norwegian and Barents seas in July–August 2017. Coccolithophores, a unique marine phytoplankton group, are an important supplier of calcite to bottom sediments. In the seas under study, coccolithophores were represented by the two species Emiliania huxleyi and Coccolithus pelagicus. Intensive C. pelagicus growth has been detected in the Barents Sea for the first time. The contribution of these species to calcite production has been assessed, and the main environmental factors that promote their bloom have been identified. The data obtained provide bases for prediction of the distribution of these species and, as a consequence, for identification of the specificities of the functioning of a calcium carbonate pump.

This paper reports on the nature and history of the mineral-rich frost heave mounds—lithalsas—developed on the first terrace of the Sentsa River in Okinsky District of Buryatia. An ice core of the lithalsa was exposed by drilling of a 20-m borehole. The most typical feature of the isotopic diagrams, which we obtained for the ice core, is their cyclical pattern illustrating isotope minima at depths of about 3–5 m, 9–12 m, and 18–21 m, separated by two distinct isotope maxima. Most likely, this demonstrates the cyclicity of the triple flooding of the growing frost heave mound and the subsequent active evaporation of lake-march waters, which are the main source of moisture for the lithalsa ice core. Based on the detailed radiocarbon dating of organic material from the upper horizons of the highest and surrounding lithalsas, we determined the time of their formation. Organic material in drained frost-susceptible soils was intensely accumulated during the period from 0.5 to 0.2 ka BP. This is the time of the beginning of the formation of permafrost, active ice-formation, and the associated frost heave and lithalsa growth. The age of at least three of four mounds studied is not older than 200 years, it coincides with the cooling at the beginning of the 19th century.

On December 18, 2018, at 23:48 UTC a meteoroid exploded in the Earth’s atmosphere, at a height of 25.6 km over the Bering Sea, causing a shockwave. The mass of the Bering Sea meteoroid was estimated at 1600 tons, and its diameter, at 9–14 meters. If these assessments are correct, it was the second largest explosion of a space body in the Earth’s atmosphere for the past 30 years. Station IS44 of the international system of infrasonic monitoring, nearest to the epicenter of meteoroid explosion, is located on the peninsula of Kamchatka at a distance of 1024 km. At the IS44 station, an infrasonic signal from the meteoroid explosion was recorded. This paper presents the analysis of this infrasonic signal and an assessment of the energy of this event.

It is generally accepted that PKP‑waves precursors, which are observed on a real data ahead of PKP‑waves, are explained by scattering on small-scale inhomogeneities in the lower mantle. In this paper, a stable analytical solution (without interference) was obtained for the wave field of longitudinal waves in a layered (discrete) ball of planetary size. The calculations of the total wave field, rays and travel-time curves of longitudinal waves for the spherical model of the Earth AK135 with a carrier frequency of 1 hertz are presented. The analytical solution showed that at angles smaller than 145 degrees ahead of the PKP‑waves, low-amplitude waves appear, with a higher frequency of about 1,3 hertz. Indeed, these high-frequency oscillations have the form characteristic for waves scattered at a certain object. The ray pattern and the travel-time graph show that these high-frequency oscillations are due to exclusively to the spherical geometry of the Earth. This could be explained by the interference of refracted and reflected longitudinal waves in the bottom of a discrete outer core. This field propagates even further towards smaller angles due to the interference of diffraction waves.

The generalized equations of solution motion are given both in porous media and in cavities taking into account the osmotic effect. In certain cases, commonly small relevant corrections play a key role since they are mainly causing the solution motion. Based on the generalized equations, a number of problems have been solved that are of practical value. Owing to the limited volume of this paper, only a simplified example is given.

This paper describes the technology for recording surface wave signals and sea level fluctuations in the coastal areas of the World Ocean based on real-time analysis of the surveillance camera “live video” presented on the Internet. A wave signal obtained by the method described in Crotone Port (Italy) is compared with the data from a nearby station of the Global Sea Level Observing System (GLOSS). This example demonstrates the high recording quality of the seiche oscillation system in the port with periods from 40 to 2 min, which is comparable to GLOSS. In addition, in contrast to the GLOSS stations, signals obtained through video contain responses of even shorter period (up to tens of seconds) seiches, swell waves, wind, and ship waves.