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Quantum-chemical calculations show a tendency of SiO₂ molecule to transform from linear to isomeric cyclic (bent) form and back. In the latter case, the energy released during the transition isomeric SiO₂ ® linear SiO₂ is about 240 kJ/mole. This hypothetic structural transition of submolecular SiO₂ fragments in mantle minerals is supposed to initiate deep-focus high-energy earthquakes at the upper-lower mantle boundary. It is at this depth (600-670 km) that the subducting oceanic slab is delaminated: Its upper part moves «horizontally» along the upper-lower mantle boundary, while its lower part separated into blocks subsides into the lower mantle and reaches the D″ layer to accumulate there.

The Transbaikalian region comprises several known geologic structures: the Mesozoic Mongolia-Okhotsk orogen, the Cenozoic Baikal rift system, and the world largest Angara-Vitim granitic batholith. They all formed upon heterogeneous Neoproterozoic-Early Paleozoic continental-margin complexes of the Siberian craton. The region is subject to the influence of mantle plumes, which induced Meso-Cenozoic volcanism and controlled structural and lithological changes in the crust in the early history. Transbaikalia, which has been a scene of multiple tectonic events, is a model area for geophysical (in particular, gravity) surveys for various geological and geodynamic applications. As a novel approach, we interpret geological and geodynamic data from the region with reference to the pattern of free-air and Bouguer gravity anomalies revealed by satellite altimetry. Bouguer anomalies highlight large structures in the lithospheric mantle which were produced in the Cenozoic mainly by the activity of mantle plumes. Basaltic lava fields were confirmed to be almost coeval with mantle anomalies and to record the presence of the plume head at the crustal base. However, the origin of the Late Paleozoic Angara-Vitim granitic batholith was only tentatively attributed to the plume activity, based on gravity data. Mesozoic metamorphic core complexes (MCC) and basins that formed during the evolution of the Mongolia-Okhotsk orogen show up clearly on the map of free-air anomalies. Most of the MCC revealed in Transbaikalia coincide with oval gravity highs and border negative elongate features corresponding to Mesozoic basins. The zone of Cenozoic tectonism stands out in the pattern of free-air anomalies as maximum gravity contrasts, with the values changing from -110 to -120 mGal in basins to +90 or +100 mGal in ranges. This zone encompasses rift basins filled with Cenozoic or, locally, Mesozoic sediments, which jointly form a domino-like system of rhomb-shaped structures typical of the Baikal rift system and, in general, of Cenozoic Central Asia resulted from the far-field effect of the India-Eurasia collision.

A new concept of the geologic structure and geodynamic evolution of the Mongol-Okhotsk Orogenic Belt is proposed. The problems of recognition of the Amur composite microcontinent (Amuria superterrane) and substantiation of its existence are considered. We present recent data on the geologic structure, composition, age, and paleomagnetism of the Neoproterozoic-Paleozoic complexes, one of the main elements of Amuria: Argun terrane and adjacent Transbaikalian and Mongolian structures. In particular, we refine the age of Precambrian and Paleozoic stratified and igneous units. The absence of an Archean-Paleoproterozoic crystalline basement is shown. Using our paleomagnetic and paleontological data, we substantiate the equatorial position of the Argun terrane in the immediate vicinity of Siberia in the period 560-525 Ma. The results of the research and analysis of available geological data on the Argun terrane and adjacent Transbaikalian and Southeast Asian structures clearly show the fallacy of the concept of the Amur composite microcontinent as a single tectonic element whose collision resulted in the folded structures of the Mongol-Okhotsk belt. This conclusion is of crucial importance for the reconstruction of the Neoproterozoic, Paleozoic, and Mesozoic geodynamic evolution of the eastern part of the Central Asian Orogenic Belt.

Possible manifestations of the Hall effect in the Earth’s magnetic field during magnetotelluric sounding are considered. Numerical calculations are made for the magnitude of the effect for a three-dimensional heterogeneous earth, using modifications of the Trefftz method suitable for accounting for anisotropy. Versions of the measurement that allow easy detection of manifestations of the Hall effect are analyzed.

A metallogenic belt zoning is observed in folded areas of all metallogenic epochs from Precambrian to Cenozoic. The changes observed across the strike of folded areas on geological mapping are usually treated as geodynamic, petrologic/metallogenic, or temporal specialization of corresponding belts (terranes) and zones. However, there are serious petrological reasons to expect a significant downward change in the basicity of igneous rocks and the composition of related mineralization in folded areas. The change may be caused both by the relationship between the densities of magmas and country rocks and by the relationship between the solidus temperatures of different magmas and the thermal gradient pattern on the path of magma ascent. More basic igneous rocks and related mineralization should be detained at deeper levels of the lithosphere because of the higher density and higher solidus temperature of magmas. During the orogeny, the vertical differential movements of several adjacent terranes located between deep-seated faults can create some keyboard-like structures composed of parallel belts variously uplifted and subsided, similarly to white and black keys of a piano. In more uplifted and then more denuded belts and blocks of such structures, the ore-magmatic complexes earlier located at deeper levels can be exposed at the surface. As a result, a metallogenic belt zoning can be generated, which can be absolutely of no (or only partial) relation to any prefolding primary sedimentary or other material or temporal specific features of terranes. The possibility of such nature of metallogenic belt zoning is shown here with the use of geophysical data for two important ore-producing regions of Russia: eastern Transbaikalia and southern Primorye. The model is proposed as one of the possible ways of formation of metallogenic belt zoning in some other folded areas. This research work will probably favor a more profound analysis of the nature of metallogenic belt zoning in the considered and other regions of the world with the application of modern geophysical methods. The use of the described regularities of the stage arrangement of igneous rocks of different basicity and oxidation state and genetically related hydrothermal ores can facilitate prospecting for ores of different metals and their 3D forecasting in keyboard-like structures of Phanerozoic orogens and ancient platforms.

The paper studies low-temperature (77 K) radiolysis of various modifications of silica, such as macroporous glass (MPG) with a pore diameter of 2000 and 1500 Å, regular sodium glass, and fused quartz by the electron paramagnetic resonance (EPR) method. Paramagnetic centres in various modifications of SiO₂ may vary significantly, depending on origin, the presence of impurities, treatment conditions, and radiation activation of samples, as demonstrated. Hole centres in oxygen and silicon atoms and electron centres in silicon atoms and alkaline metal ions are the main paramagnetic centres in γ-irradiated SiO₂; their contribution in glasses and quartz is 90–95 and ~70 %, respectively. The number of radical centres in all silicas (H^•, Si^•, >Si^•–H) does not exceed 3–4 %. The radiation yield of atomic hydrogen G_H = 0.02–0.4 per 100 eV. Spectra of НО₂^• radicals and SiO₂^• macroradicals are recorded during heating of irradiated samples in the oxygen atmosphere. According to the data of quantum chemical calculations, the doublet with the splitting α^H = 12.5 mT registered during heating of irradiated MPG and quartz belongs to formyl radicals that are formed from the self-hydrogenation reaction of natural impurities of CO in silicas. The doublet with α^H ≈ 1.0 mT, g = 2.002 is referred to hole centres –Si⁺(OH)H in the surface silicon atoms containing hydroxyl groups and the H atom.

A method for the selective removal of indium from solutions (sol.) of acid leaching of Waelz zinc oxide (0.02–0.1 g/dm³ In) was proposed. It is an alternative technique for extraction. Adsorption over modified montmorillonite that is the Меtоsol reagent (reag.) in dynamic mode allows maximally implementing the reagent exchange capacity with the optimum cycle of sorption/desorption operations. Adsorption of iron (II) and zinc ions in static mode was detected. It is driven by the formation of intermolecular bonds with the developed surface of modified aluminosilicate. The formation of a stationary front of indium ion sorption from a polycomponent solution over the Меtоsol mineral sorbent due to predominant adsorption of In³⁺ compared to Fe²⁺ and Zn²⁺ was found in dynamic mode. The latter cations are replaced by In³⁺ ions that form chelates with ionogenic groups of di(2-ethylhexyl)phosphoric acid. Output curves of sorption of In ions at unit load V_sol/V_reag = 1–2.7 h^–1 and temperatures of 298–328 K are mainly S-shaped. The inflection point is shifted to the low-value range of the specific volume of the past solution (V_sol/V_reag), which indicates slowing down the ion diffusion rate in sorbent. Indium ions passing into the filtrate comes much earlier (V_sol(1)/V_sol = 3.33–0.66), the width of the chromatographic front (ΔV_sol /V_reag = 12.1–12.35) increases, the full dynamic exchange capacity (FDEC = 0.572–0.237 µmol-eq/g) and the utilization rate of the resin bed are decreased with increasing the linear rate (ω_0.5) of the transmission of the eluent through a column in the range 4.78 to 12.74 cm/h. The width of the chromatographic front (ΔV_sol /V_reag = 12.1–10.24) decreases; the full dynamic exchange capacity (FDEC = 0.572–1.293 mol-eq/g) and the utilization rate of the resin bed (η = 0.226–0.256) are increased, which testifies monitoring the process of sorption of indium by mixed diffusion. The Меtоsol reagent allows selectively extracting indium from production solutions in dynamic mode.

Mechanochemical synthesis of sodium thiosulphate pentahydrate (Na₂S₂O₃•5H₂O) was carried out for the first time in a planetary ball mill by mechanical activation of a suspension of sodium sulphate (Na₂SO₃) and sulphur (S). The degree of Na₂SO₃ + S = Na₂S₂O₃ reaction in suspension solution at soft and short mechanical activation conditions is almost 95 %, as established by methods of iodometric titration, X-ray phase and thermal analysis.

An increase in the octane number of straight-run fractions of normal hydrocarbons С₅–С₆ up to 92 points by research octane number (RON) through their catalytic isomerisation appears to be an effective solution of the critical applied task of changing the structure of the domestic gasoline pool. Isomerisates have a high octane number and do not contain hazardous sulphur compounds, aromatic hydrocarbons and particularly, benzene. Herewith, selection of the optimum technology for isomerisation of light gasoline fractions considering a peculiarity of a specific refinery is an important scientific and technical issue. Additionally, a number of complex multiple-factor tasks, such as ensuring of a specified quality and quantity of raw materials, maintaining the optimum activity of the used catalysts, and also providing the optimum operation modes for each complex block considering energy and resource efficiency in manufacturing might arise. To describe nonstationary catalytic processes of catalytic processing of light alkanes the mathematical modelling method is used. This paper assesses the operating efficiency of catalysts for isomerisation of light gasoline fractions based on Pt/SO₄^2–/ZrO₂ and Pt/Cl^–/Al₂O₃ using the mathematical modelling method for nonstationary catalytic processing of hydrocarbon raw materials. Catalysts based on sulphated zirconium oxide retain high activities and stabilities during the entire operating cycle, while catalytic systems based on chlorinated alumina are deactivated faster. Isomerisation process scheme with the recycle of unreacted C₅ and C₆ hydrocarbons involves significant capital and operating costs, however, its use will allow increasing the RON of isomerisates in 10–12 points.

The paper justifies factors and causes of hard washability of finely disseminated copper-nickel ore, the main of which are incomplete and insufficiently selective expansion of sulphide and rock-forming mineral aggregates due to low mechanical interactions in ball mills, with the result that a large number of non-ferrous and precious metals pass to concentration production wastes adding to technogenic accumulations. Technological possibilities of high-energy and high-velocity impact grinding in a disintegrator, wherein increased destructive effects lead to an increase in expansion of aggregates, were explored. The opportunity to control energy and free kick speed allows carrying out the destruction mainly along the boundaries of mineral intergrowths and reducing the amount of the fine fraction slurry in grinding products. However, an increase in the disintegration rate to 7200 rpm did not result in obtaining flotation size products –0.071+0.02 mm, and a substantial part of ore remains in the larger, difficult-to-float condition. With a view to optimising opening of mineral associations by granulometric composition, the principle of stage grinding that allows consistently in the regimes of increasing energy effects regrinding larger ore fractions and liberating minerals from genetic associations with increased strength was proposed. This methodological approach allowed in the optimum rate mode destructing sulphide minerals and obtaining during flotation separation concentrates with increased content of non-ferrous metals, which offers opportunities for improvement of metallurgical methods for processing concentrates. More high-energy destruction allows liberating residual amounts of sulphides in rock associations and transferring into reject materials to 50 % of ore rocks. It is noteworthy that herewith, a large number of nickel compounds found in aggregates with rock formations are released, which is of great importance for increasing nickel extraction into concentrates. The carried-out research demonstrates that high-energy grinding is an advanced method for selective destruction of aggregates and mineral liberation in finely impregnated ores prior to concentration processes.