The Precambrian Chernaya Rechka Formation (Igarka Uplift) hosts a high-amplitude positive carbonate carbon and dispersed organic matter δ13С isotope anomaly (up to +12.4‰) spanning over 500 m of the section. Variations of δ13Сcarb and δ13Сorg are synchronous and do not depend on local sedimentary environments, since the studied anomaly-bearing carbonates were accumulated in different zones of the carbonate ramp. The oxygen isotope composition of these carbonates and other geochemical criteria indicate an insignificant impact of postsedimentary processes on the preservation of isotope systems. Variations of trace elements in the carbonate fraction from the stratotype section of the Chernaya Rechka Formation indicate its accumulation in alternating anoxic and oxic environments that did not affect the carbon isotope composition. It is shown that the limestones, which outcrop on Plakhinskii Island and contain widespread molar-tooth structures, also belong to the Chernaya Rechka Formation in terms of the chemical and isotope composition. The profound positive δ13С anomaly was putatively caused by a global deficiency of 12С in the paleo-ocean related to the accumulation of methane hydrates and the burial of nonoxidized organic matter. Together with the geochronological and stratigraphic data, minimum 87Sr/86Sr values (0.7074) in the Chernaya Rechka Formation reveal the lower Ediacaran (lower Vendian) age of the unit (635–580 Ma). Among the closest stratigraphic analogues of the Chernaya Rechka Formation are the Dal’nyaya Taiga Group (Patom Basin) and coeval stratigraphic sequences in the southern Siberian Platform. The global nature of the positive δ13С anomaly provides its correlation with other coeval C-isotope events worldwide.

The paper discusses the applicability of the horizontal-to-vertical spectral ratio for ground motion (H/V method) to estimate the seismic intensity increment and trace the bedrock surface covered by soil layers. The first issue is the classic seismic microzoning problem; the second is related to structural mapping of the upper part of the geological profile. The authors assess the possibility of using a single station to estimate the intensity increment without synchronization of data at a given point at a site with records based on reference rocks. It is shown that such an approach is invalid, because the maximum variations in the H/V ratio during a day may reach 2.7 times; a degree of intensity of 0.8 will correspond to such variation. At the same time, it is shown that the resonance frequencies of soil layers are stable. If the mean velocities of seismic waves are known at some points of profile surface, the position of the underlying bedrock top can be traced with confidence.

As a result of a review of methods for the identification of group events, it is argued that to date there is no universal algorithm for detecting formations of a physical nature in the structure of seismicity. Therefore, the method of catalog declustering should be selected both for the existing structure of the source data and for a specific task. It is proposed to use the declustering of earthquake catalogs with great caution, since such a procedure can significantly distort the seismic hazard assessment. Information on earthquakes in the Yano-Indigirskaya lowland in northern Yakutia, was collected which seismicity is relatively poorly studied. An analysis of the data of 43 seismological agencies resulted in a catalog of 3161 earthquakes from 1920 to 2020 that has been compiled with a representative magnitude of M-W = 3.3 to distinguish the grouped events. The catalog was declustered using different methods, and the seismicity has also been divided into concentrated (group) and scattered (background) components. It is shown that these components differ significantly in recurrence plots and M-max estimates, which significantly affects the seismic hazard assessment.

There are several ways of setting seismic impact on bedrock for calculating the impact on the free field. In the paper, two ways of setting the initial seismic impact on bedrock are analyzed: artificial and synthetic accelerograms. For assessing the effect of the soil profile in transferring seismic signals from bedrock to the free field, four seismogeological models were used. Linear and nonlinear (equivalent-linear approximation) behavior of soil profiles were studied. Summing all results of calculations, we conclude that there are no significant differences in expected seismic impact on the free-surface depending on how the input is set at bedrock. Systematically larger values when synthetic method is used is not more than 10%, which is not evaluated as being significant.

A method is proposed for calculating seismic hazard curves in a free-field. The applicability of the method is illustrated by a hypothetical situation characteristic to seismotectonic and ground conditions in platform areas: low local activity, proximity to a deep focal area, and a shallowly basement overlain by a consolidated soil profile. Presentation of the ground conditions by single parameter Vs30 (average velocity of transverse waves in upper 30 m of the soil profile) is not sufficient. Although such a description gives generally higher spectral amplitudes, it does not take into account amplification due to possible resonance phenomena; meanwhile, energy absorption in the soil profile due to inelastic behavior is ignored.

El Ediacárico terminal inlcuye una serie de cambios drásticos en los ciclos biogeoquímicos, muchos de los cuales se asocian con modificaciones evolutivas en los registros fósiles correspondientes. Entre ellos destacan las condiciones redox, las cuales pueden haber causado un impacto profundo en la evolución animal temprana. Este trabajo destaca el significado de la lito-, bio- y quimioestratigrafía en la investigación geobiológica del tiempo profundo.

The paper investigates the effect of different methods for preprocessing earthquake catalogs (declustering, i.e., removal of dependent events from them, and selection of the magnitude of completeness) on seismic hazard assessment. Seismic catalogs of the Kamchatka and Caucasus regions have been used for the analysis, because synthetic catalogs do not always reflect the real features of regional seismicity. Test sites were selected for these regions. Three declustering methods are considered that leave different numbers of events in the catalogs. The plotted seismic hazard curves indicate a complex interaction of catalog declustering and selection of the magnitude of completeness. Since both methods affect the b -value, it cannot be predicted in advance, which will lead to an increase or decrease in the estimate for b . After it is applied, the declustering method leaves the largest number of events in the catalog, but does not always give the highest seismic hazard rating. Therefore, it is necessary to be extremely careful and attentive when declustering a catalog. At the very least, it should be borne in mind that the end result may be unpredictable.

The effect of the upper part of a layered profile on calculated seismic hazard parameters is analyzed. The behavior of the soil profile is studied as part of equivalent linear modeling with the example of six seismogeological models. Peak ground acceleration of the input signal varies from 0.1 to 0.6 g. It is shown that the character of the dependence of physicomechanical properties in the layer on the strain value leads to variations in the amplitudes of the response spectrum on the free surface and displacement of the maximum of the frequency spectrum. An increase in the thickness of the upper layer significantly influences the shape of the response spectra. Variations in the PGA values, damping coefficients, strain values with depth are calculated, as well as the velocity profiles for different soil layers with respect to the degradation curves. It is demonstrated that restricting the upper limit of the damping coefficient to 15% does not lead to noticeable changes in the shape of the response spectra on the free surface. The soil column begins to decrease the peak value of the input signal when its level exceeds 0.3 g.

The ground layer response to seismic loading is analyzed in the paper. Two approaches to the site profile behavior are considered: elastic (linear) and viscoelastic (equivalent linear modeling). Four typical soil profiles are taken into account; input peak values are within the range from 0.1 to 0.6g. In all profiles, when ignoring the nonlinear behavior, the calculated impacts are still within the standard response spectrum. When the nonlinearity is taken into account, the pattern is completely different. The standard spectrum is abundantly conservative for high frequencies; meanwhile, it substantially underestimates the level of hazard at low frequencies. Therefore, the shape of standard spectra as a whole does not adequately describe a seismic hazard, especially when the input signal is higher than 0.2g.

The Southern Iran territory, including the Zagros region and the margins of the Arabian and Eurasian plates, is a seismically active area with large industrial facilities of Iran. In this respect, studying modern geodynamics of this area is a top research task. This article presents a part of the studies conducted by the IPE RAS Seismological Expedition led by the Doctor of Physics and Mathematics S.S. Arefiev in 1999–2001. The research team studied the seismic setting on the construction site of the Bushehr Nuclear Power Plant. The main results discussed in the present article are the focal mechanism solutions based on the data of the IPE RAS seismic network. The network was deployed in the junction area of the Fars and Dezful tectonic provinces (north of the Bushehr NPP) and covered an area of 100´100 km. A specific feature of the seismic network was that it comprised local networks, and each local station was focused, first of all, on determining the precise locations of earthquake epicenters in a particular section of the crust. However, the scarcity of stations in such local networks and the technologies available at that time did not allow us to determine the mechanisms of earthquake foci. This problem was solved by integrating the seismological and tectonophysical methods. In the analysis, we used the tectonophysical approach that is usually applied to reconstruct stresses from the data on slickensides. This approach is based on a specific algorithm of the kinematic method developed by O.I. Gushchenko, which is used in the absence of sliding direction signs. It became possible, in addition to a few signs from the first P-wave arrivals (1–2 confident signs), to use the data on the S-wave polarization direction. By applying the Gushchenko algorithm to such data, the areas of P and T axes were quite reliably localized on a single hemisphere for determining the focal mechanisms. The focal mechanisms computed for 72 earthquakes correspond to the Kazerooni-Borazdzhan shearing zone and, at the same time, are indicative of the presence of crust incision me­chanisms in the Bushehr Peninsula. The focal mechanisms computed in our study, as well as the mechanisms reported in the Global CMT Project Catalogue, show that the Bushehr Peninsula is located near the western boundary of the zone of strike-slip faults, which extends from the north (Zagros) to the south (the Persian Gulf) and widens as a horsetail-shape structure. In the crust of the Persian Gulf coast, the intensity of the strike-slip component in the earthquake focal mechanism is minimal. The earthquake mechanisms in this region are mainly related to thrusting, reverse faulting and even the crust incision.

Catalytic hydrotreatment is a promising technology to convert pyrolysis liquids into intermediates with improved properties. Here, we report a catalyst screening study on the catalytic hydrotreatment of pyrolysis liquids using bi- and tri-metallic nickel-based catalysts in a batch autoclave (initial hydrogen pressure of 140 bar, 350 °C, 4 h). The catalysts are characterized by a high nickel metal loading (41 to 57 wt%), promoted by Cu, Pd, Mo, and/or combination thereof, in a SiO 2 , SiO 2 -ZrO 2 , or SiO 2 -Al 2 O 3 matrix. The hydrotreatment results were compared with a benchmark Ru/C catalyst. The results revealed that the monometallic Ni catalyst is the least active and that particularly the use of Mo as the promoter is favored when considering activity and product properties. For Mo promotion, a product oil with improved properties viz. the highest H/C molar ratio and the lowest coking tendency was obtained. A drawback when using Mo as the promoter is the relatively high methane yield, which is close to that for Ru/C. 1 H, 13 C-NMR, heteronuclear single quantum coherence (HSQC), and two-dimensional gas chromatography (GC × GC) of the product oils reveal that representative component classes of the sugar fraction of pyrolysis liquids like carbonyl compounds (aldehydes and ketones and carbohydrates) are converted to a large extent. The pyrolytic lignin fraction is less reactive, though some degree of hydrocracking is observed.

Fluids play a very important role in processes of the chemical and physical evolution of crustal and mantle rocks. The influence of certain rocks on chemical reactions between fluid components is studied. Experimental results of the catalytic activity of serpentinite, ophitic gabbro, and lizardite–antigorite asbestos relative to vapor conversion of methane (CH4) have been obtained with the formation of syngas at atmospheric pressure and temperatures up to 850°C. Such transformations are assumed to be able to take place under natural conditions in fluid systems that accompany massifs of seabed ultrabasic rocks, as well as kimberlite pipes. Proceeding from the studies performed, options of the practical use of various crustal rocks as catalysts of fluid transformations have been proposed. The experimental results confirm the initial theses of the authors’ concept with respect to the role of heterogeneous–catalytic mechanisms of transformations of fluids in the Earth’s crust.

High metal loading NiCu-based catalyst of Picula™ series produced by sol–gel technique was applied to furfural hydrogenation in the presence of hydrogen. This reaction represents the stabilization of pyrolysis oil that involves the selective reduction of aldehydes and ketones to alcohols and unsaturated C–C double bonds of pyrolysis oils components. The catalysts were pre-reduced at 250 and 300 °C. According to XRD analysis results, copper is mainly in the metallic state, and Ni is mostly in the form of oxide and silicate. XPS measurements reveal that hydrogen treatment at 250 °C leads to the partial reduction of Ni to the metallic state (6 %) while further reduction at 300 °C leads to an increase in this proportion up to 39 %. A 100 % selectivity towards furfuryl alcohol was achieved at 130 °C and 5 MPa of hydrogen in a batch reactor using decyl alcohol as a solvent. In the experiments with i-propanol as a solvent at 110–170 °C the main product was furfuryl alcohol, but minor components traced back were tetrahydrofurfuryl alcohol, 2-methylfuran and isopropyl furfuryl ether. The lower catalyst reduction temperature promotes the formation of isopropyl ester, while a higher reduction temperature favors further furfuryl alcohol hydrogenation.

In the last decade, the number of ground motion prediction equations (GMPEs) significantly increased due to the higher quality and expansion of networks recording strong ground motions throughout the world. Therefore, the key point in seismic hazard assessment is the selection of a suitable ground motion prediction equation. This work presents the review of the modern state of the problem, the discussion of the criteria for selecting the models to include in the logic tree. The models chosen as part of the big international projects for stable continental regions are described in more detail. Several models have been proposed for use in the stable regions of the central part of the Russian Federation and have been compared. Despite numerous attempts to develop the formal criteria for the selection of a certain model, the construction of the logic tree for each particular problem is based on the expert opinions.

In this paper, the effects of process conditions on catalyst performance and product properties are reported in both batch and continuous set-ups.

Experimental results on the influence exerted by pyridine additives on the selectivity of the process in which the styrene fraction is purified to remove the microscopic admixture of phenylacetylene at low (up to 30°C) temperatures by selective hydrogenation with catalysts on an aluminoborosilicate or silica matrix with filler-metals in the form of platinum or palladium are presented. It was shown that pyridine-modified catalysts in these systems are effective in the selective hydrogenation of phenylacetylene for purification of raw styrene. The modification of a platinum catalyst on the aluminoborosilicate support results in that a deep degree of purification (>95%) is achieved even at low (up to 50°C) temperatures. Use of catalysts composed of 0.160 wt % Pt and silica woven-glass fabric, modified with pyridine additives, leads to a substantially lower loss of styrene (from 0.48 to 0.31% in some cases) in the temperature range of 30–50°C. It was demonstrated that addition of substances containing a unshared electron pair can noticeably affect the selectivity of the process in which the styrene fraction is purified from its impurity content even in the order of 0.01%. Depending from the substrate composition and active filler-metal, the temperature, together with changing the support properties, exerts varied influence on modified metallic catalysts, which is manifested in change in the activation energy and, as a consequence, in that of the hydrogenation mechanism.

Catalytic hydrotreatment is an attractive technology to convert fast pyrolysis oil to stabilized oil products for co processing in conventional crude oil refinery units. We report here the use of novel bimetallic NiCu- and NiPd-based (Picula) catalysts characterized by a high Ni content (29-58 wt %) and prepared using a sol gel method with SiO2, La2O3, kaolin, ZrO2, and combinations thereof as the support, for the catalytic hydrotreatment of fast pyrolysis oil. The experiments were performed in a batch autoclave (1 h at 150 degrees C, 3 h at 350 degrees C, and 200 bar initial pressure at 350 degrees C). The catalyst with the highest nickel loading (58 wt % Ni) promoted with Pd (0.7 wt %) was the most active, yielding oil products with improved properties compared to the crude pyrolysis oil (lower oxygen content, higher solubility in hydrocarbons, and less tendency for coke formation). For all Picula catalysts, except the ZrO2-based catalysts, methane formation was considerably lower than for Ru/C, the benchmark catalyst in catalytic hydrotreatment of fast pyrolysis oil. To anticipate possible catalyst deactivation at very long times on stream, catalyst regeneration studies were performed using thermogravimetric analysis. Analyses of the regenerated catalysts (X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer Emmett Teller surface area) showed the occurrence of active metal agglomeration.