Home – Home – Jornals – Thermophysics and Aeromechanics 2007 number 3

Seismic strain estimated from about 900 earthquake mechanisms in the Altai-Sayan area indicates that the area evolves mainly under N-S compression caused by the India-Eurasia collision. Plastic flow in the mountains of the western and central Altai-Sayan area is controlled by convergence of aseismic rigid blocks, including the Dzungarian microplate, the Minusa basin, the Tuva basin, Uvs Nuur and other basins in the region of Great Lakes in Mongolia. Earthquake rupture follows the existing fault pattern. The pattern of rigid blocks and mountain ranges correlates well with upper mantle thermal heterogeneity as imaged by seismic tomography.
Earthquake mechanisms in the presence of plate convergence depend on different factors. Slip geometry depends on focal depth at a given geodynamic regime, and the latter, in terms of the seismic process, is controlled by lateral (W-E) constraint. Reverse-slip earthquakes most often originate at shallow depths in regions of constrained compression, such as the Tien Shan, and strike slip is the dominant mechanism under non-constrained and moderately constrained compression. The direction of slip is governed by the parallel component of convergence and by the fault pattern. In regions of strain shadow, slip occurs mostly on normal planes, and shallow earthquakes have strike-slip mechanisms. The crust in the collisional region is divided into systems of rigid and plastic blocks (rheological structure) and of fault blocks (fault-block structure). The two types of systems coexist and determine the generally similar but specifically different features of local mass transfer.

Destruction of geomaterials and geomedia material, as well as general brittle and ductile materials, have been treated theoretically and experimentally using the general approach of nonlinear dynamic systems. The process of destruction in loaded solids (inelastic deformation, damage accumulation, fracture) is presented as a space-time evolution of a nonlinear dynamic system, which allows interpreting all deformation and fracture within the limits of a single theory. The space-time hierarchies of nonlinear systems were found out to undergo collective effects and self-organization. The experimental and theoretical studies of the evolution of loaded solids revealed their universal fractality and showed brittle fracture and plastic deformation to be self-similar processes at different scales, for which scaling parameters have been estimated. The evolution of inelastic strain and destruction of solids is modeled numerically in terms of hierarchic systems.

An inverse solution to the 1D wave equation is obtained using the spectral Laguerre transform to find the distribution of wave velocities at some point of the medium. The problem is solved as optimization in which the function of Laguerre harmonics is minimized by the conjugate gradient or Newton's algorithms.
Reported are velocities of a wave defined by a stepwise constant function. The accuracy of the inverse solution for the Laguerre harmonics is investigated against the approximation accuracy in the boundary problem. The accuracy and efficiency of the Laguerre method are compared to those in the Fourier method.

We studied fault scarps produced by prehistoric earthquakes in the Barguzin fault zone and estimated the ages and the magnitudes of the scarp-forming events in each scarp segment from their structure, morphology, and scarp parameters. Morphological and structural data reveal two to four surface-rupturing events with displacement up to 5-9.5 m, and two events showed ¹⁴C ages of 4.5 and 9 kyr. The area of the Barguzin Fault may have experienced six 7.5 ≥ M < 8.0 earthquakes and two M ≥ 8.0 (8.0-8.2) events for the past 10-12 kyr.

Using GIS technologies, we carried out a complex spatial analysis of the seismic activity and fractal dimensionality of fault fields in the Tuvinian and adjacent Mongolian areas. Results obtained showed that seismic activity is intrinsic to zones with the low fractal dimensionalities (1.2-1.4) of fault systems.

New structural and tectonophysical data, combined with the published geophysical and seismological evidence, were used to map the Late Cenozoic fault pattern and crustal stress in the Barguzin rift. Faults striking in the NE direction are the most abundant elements of the rift structure. A special part in the Late Cenozoic patterns of faults and stresses belongs to an over 400 km long N-S lineament which shows up as a system of separate fault segments between 110

A rockfall was discovered on the left bank of the Verkhnyaya Angara River, 25 km away from the northwestern doorway of the North Muya tunnel of the Baikal-Amur Railway. We investigate the tectonic position of the rockfall and its linkage to a moderate earthquake using structural data and show that earthquakes of this intensity can produce notable ground failure if the local fault pattern is favorable for passage of seismic waves.

Research has shown that the creation of the Bratsk water reservoir considerably changed the seismic conditions in this area of the Siberian Platform. Seismic records revealed a significant increase in the energy classes of earthquakes with epicenters in the north of the reservoir, in trap intrusion zone. The change in engineering-geologic conditions and frequent seismic events affected the rate of development of gravitational deformations on the shore slopes.

We processed synchronous observatory MVS data at periods from 1.2 to 6 days to estimate lateral conductivity variations in the upper mantle. The inverse problem for depth-dependent conductivity distribution was solved using correlation of the measured surface components of the geomagnetic field. We applied spherical harmonic expansion of the complex amplitudes of time harmonics and multiple averaging of the amplitudes obtained for different SH sets. The chosen approximation approach was tested by comparing the EM field simulated for a smoothly inhomogeneous Earth with the exact forward solution. The SHA-analyzed observatory data for fifteen magnetic storms were used to map global apparent conductivity variations.

We processed data from geophysical survey archives of the 1950s acquired in intermontane basins in the Baikal rift, including a large collection of vertical electric soundings (VES) from the Barguzin basin, which remained only partly interpreted. The processing and reinterpretation became possible with the advanced computing facilities and software for forward modeling and inversion, and GIS tools. We estimated the electrical parameters and modeled the complex block structure of the uppermost basement and sediments beneath the Barguzin basin.

The structure and petrologic composition of new gold-ore provinces in southeastern East Sayan (Tissa-Sarkhoi cluster) are considered. Several morphogenetic types of gold mineralization have been established: quartz veins with beresitization zones, veinlet-disseminated ores in granitoids, and listwaenitization and sulfidation zones in effusions of the Sarkhoi Group and intrusive rocks of the Late Riphean Khorin-Gol complex. According to geochronological dates and some mineralogical and geochemical features, the gold mineralization is close in age to these Precambrian island-arc complexes. Parageneses of two stages of ore formation have been recognized: early high-temperature (250-460

Contents of Pt and Pd were determined in weakly mineralized rocks, ores, and flotation concentrates of the Aksug porphyry Cu-Mo deposit, northeastern Tuva. In all studied samples they are above the detection limits: Pt = 17-96 ppb and Pd = 9-924 ppb. These elements are unevenly distributed throughout the rocks and ores, with Pd/Pt varying from 0.5 to 37. Study of Pd-rich ores (up to 924 ppb, Pd/Pt = 37) on a JEOL JSM 5600 scanning electron microscope revealed finest (2-5 μm) merenskyite inclusions (25.20% Pd, 1.21% Pt, 72.31% Te) in chalcopyrite. The calculated crystallochemical formula of merenskyite from ores of the Aksug deposit is (Pd_0.862 Pt_0.023 Cu_0.026 Fe_0.025)Te_2.064. The merenskyite is associated with electrum (79.92% Au, 18.96% Ag), monazite, cobaltite, tennantite, and Sr-containing barite (4.6-18.0% Sr). Palladium mineralization occurs in massive chalcopyrite veinlets in zones of intensely propylitized rocks. The Devonian Aksug ore-bearing porphyry complex developed in the field of Early-Middle Cambrian intrusions of gabbro-diorite-plagiogranites associated with basalt-andesite effusions of island-arc complex. This might have led to high PGE contents in the Aksug rocks. The deposit formation proceeded with the participation of ore-bearing Cl-enriched fluids favoring the concentration and transport of PGE in porphyry copper systems.

The subject of study was the chemical composition of common fresh-water springs precipitating travertines in tectonically passive regions of the Kolyvan'-Tomsk folded area and northwestern Salair. Attention was paid to the specific character of manifestation, mineralogy, and petrography of the produced travertines. Results of the study of isotopic composition of carbon in hydrocarbonate ion of waters and carbonate travertines are reported. It is shown that the genetic type of CO₂ accompanying the formation of travertines is biogenic. Study of the equilibrium of the underground waters with aluminosilicate and carbonate minerals has shown that the travertines are the product of evolution of an equilibrium-nonequilibrium water-rock system. New mechanisms of travertine formation from cool fresh waters are proposed.

In dividing supracrustal strata, formation and horizon have been and are basic stratigraphic units. Stratigraphic boundaries of a formation, a natural geologic body, are drawn mostly on the basis of its composition. Paleontological remains constrain the formation in time and spatially locate it in the Earth's crust. Boundaries between formations can be of three types: strictly stratigraphic, parastratigraphic, and allostratographic. The stratigraphic interval can range from a fraction of a horizon or chronozone to several stages. At the boundary between two systems the adjacent parts of the formation can relate to both systems. The main stratigraphic characteristics for recognizing horizons are paleontologic (biostratigraphic) features, revealed by zonal, paleoecosystemic (ecostratigraphic), bioeventual, and other methods to make a basis for their immanent signature. Horizon can be characterized by boundaries of only two types: strictly stratigraphic and allostratigraphic. The stratigraphic interval of a horizon can vary from a single chronozone to a stage. Boundaries of neighboring horizons at the contact between two stages or systems should coincide with the latter. The stratigraphic units of the International Stratigraphic Chart, in contrary to formation and horizon, are characterized by borders of only one type - strictly stratigraphic.

Fossil seed assemblages of Paleogene and Neogene strata in northeastern Asia are reviewed based on data of Novosibirsk paleocarpologists and literature data. The composition and age of flora are refined, and recommendations on improving stratigraphic charts of deposits in northeastern Russia are given.

We obtained a macroseismic equation with a convergent solution at a hypocentral distance D ~ 0 (independent of magnitude) for relative shaking intensity. The logarithmic distance dependence of intensity turned out to be piecewise linear no matter whether it is expressed in relative units of intensity degree or in logarithmic ground motion velocity. The macroseismic intensity shows high correlation with motion velocity. Another result is the magnitude dependence of dominant periods of ground motion velocity for large earthquakes.

An analytical solution of Maxwell's equations for layered anisotropic media is presented in a form which allows estimating the sought parameters by layer stripping without round-off accumulation. The solution in each layer is reduced to the standard procedures of solving a fourth-order algebraic equation, multiplication, addition, and inversion of second-order non-singular matrices. The algorithm has no limitations on layer thickness and is applicable to both very thick and very thin layers. The new numerical code is straightforward and can be easily parallelized.

The Olkhon area in the western Baikal region belongs to the Baikal rift system. The terrain bears strong imprint of the Early Paleozoic structural framework produced by a multistage collision. The today's elevation pattern records the main features of inhomogeneous basement lithology. The topography of the area is generally governed by the tectonic style, and tectonic landforms remain weakly denuded and almost uneroded. Thus the Cenozoic geomorphic framework can be correlated to the Early Paleozoic basement structure.

With U-Pb zircon dating, we determined the age of rhyodacites composing sedimentary covers among coarse-terrigenous rocks of the lowermost Chaya Formation of the Akitkan Group (North Baikal volcanoplutonic belt). These rocks are considered to have formed during the sedimentation. The dates (1863 ± 9 Ma) permitted estimation of the age of basal beds of the Chaya Formation and substantiate the age boundary between the Khibelen and Chaya Formations of the Akitkan Group. The determined age and earlier dates of igneous rocks intruding the Chaya Formation deposits suggest that the latter accumulated for ~10 Myr.

The Yenisei Range and the adjacent territories in the east are subdivided into (1) the Mid-Angara intracratonic depression; (2) the Yenisei pericratonic trough; and 3) a marginal oceanic block, the Isakovka-Predivinsk area. The lower part of the Riphean succession is subdivided into two principally different sedimentary complexes - the Lower Sukhoi Pit Subgroup and the Upper Sukhoi Pit Subgroup (the Pogoryui-Alad'in interval of the succession). The fundamental nature of the events that separate these two complexes and the characteristic, rhythmically bedded structure of the Upper Sukhoi Pit Subgroup allow the latter to be ranked a separate straton, the Bol'shoi Pit Group. Its lower boundary is associated with the Grenvillian events commencing with the emplacement of the Teya granite-gneiss domes and other intrusive complexes dated at 1100-1000 Ma. In the sedimentation record these events are manifested as a sudden change from the slate complex, for which we keep the name Sukhoi Pit Group, to the rhythmically bedded succession of the Bol'shoi Pit Group. The latter is interpreted as a product of uproofing of an elevated hinterland to the west. Insofar as the amplitude of this elevated area decreases progressively toward the Mid-Angara trough, the Bol'shoi Pit erosional unconformity and the associated interval of nondeposition are absent from the area. In the west of the Yenisei Range, in contrast, there is a major stratigraphic gap in the sequence, which is associated with the aforementioned events. The hypothesis on intensive events separating the deposition of the Bol'shoi Pit Group of the Kerpylian Horizon and the Tungusik Group of the Lakhandinian Horizon is not supported by the new data. The change from carbonate facies into siliciclastics in the west was misinterpreted as an erosional unconformity, with basal deposits corresponding to the lower boundary of the Tungusik Group. The occurrence of the Upper Tungusik deposits overlying much older rocks is a result of the pre-Bol'shoi Pit erosion and the gradual expansion of the Tungusik transgression. Thus, there are no grounds to argue for significant pre-Lakhandinian events in the region. Hence, the Kerpylian and Lakhandinian in the Yenisei Range, as well as in other parts of the Siberian Craton, constitute two parts of a larger supraregional straton, which corresponds to the lower half of the Upper Riphean and is designated here the Mayanian. The fundamentally different nature of the events associated with the next, Baikalian stage of the development allows its tripartite subdivision in the region. Deposition of the Lower Baikalian (the Oslyanka Group) was preceded by the crustal extension at the junction between the continental and oceanic blocks and, possibly, the formation of one of the Yenisei Range ophiolite complexes, followed by the emplacement of the Tatarka-Ayakhta batholiths at around 850 Ma. Fragments of both complexes are found as clasts in the basal conglomerates of the Middle Baikalian Chingasan Horizon. The specific character of the pre-Baikalian events determines their apparently poor expression in the sedimentation (weaker metamorphism of the Oslyanka deposits compared with the Tungusik Group). Even the activity leading to the formation of the Tatarka-Ayakhta granites cannot be regarded as a full-scale orogenic process. Collisional events separating the Lower and Middle Baikalian are manifested as the erosional unconformity at the base of the Chingasan Group and the emplacement of the Glushikha granites (760-730 Ma). The Middle Baikalian age of the Chingasan deposits is constrained by the data from paleontology, historical geology, and geochronology. Furthermore, the presence of glacial deposits renders this straton as a global stratigraphic marker. Further expansion of transgression in the Upper Baikalian is linked to another important event, but additional paleontological and geochronological information is needed to date the Upper Baikalian (Chapa Group) more accurately. The Baikalian events synchronously manifested themselves in all structural-facies zones of the Yenisei Range and are coeval to structural complexes from adjacent areas of the Siberian Craton. The tripartite Baikalian, therefore, has a potential for being included into the General Scale of the upper Upper Riphean.

Triassic sections of the Lena lower reaches (northern Yakutia) were studied. Stratigraphy and paleontology of the Triassic deposits were refined and described in detail, and their age was constrained by different fauna groups. The first detailed local Triassic biostratigraphic scheme is reported, which includes ammonoid, nautiloid, and bivalve zones and subzones and foraminifer beds. The scheme is compared with the Canadian Triassic Zonal and Standard (International) Scales.

We studied the chemical composition of rock-forming minerals in gabbroids from the Chirii outcrop and the evolutionary features of parental basic melt during the crystallization of these rocks. Results were compared with data for basanites from pipes of the North Minusa depression. The mineralogical composition and thermobarogeochemical data of the gabbroids were examined in detail, and chemical analyses of rock-forming minerals (clinopyroxene, plagioclase, amphibole, biotite, titanomagnetite, and apatite) were carried out. Based on the homogenization temperatures of primary melt inclusions, we established the minimum temperatures and sequence of mineral crystallization in the gabbroids: clinopyroxene (>1160

A unique xenolith of eclogite, 23 × 17 × 11 cm in size and 8 kg in weight, was found in the Udachnaya kimberlite pipe. One hundred twenty-four diamond crystals recovered from it were analyzed by a number of methods. The diamonds differ in morphology, internal structure, color, size, and composition of defects and impurities. The xenolith contains diamonds of octahedral and cubooctahedral habits. In cathodoluminescence, the octahedral crystals have a brightly glowing core with octahedral zones of growth and a weakly glowing rim. In the cores of these crystals the N impurity is mostly present in the B1 form (30 to 60%). At the same time, N in the rim is chiefly in the A form. The cubooctahedral crystals show a weak luminescence. The content of nitrogen and degree of its aggregation are close to those in the rim of octahedral crystals. The diversity of morphology and impurity composition of diamonds from the xenolith can be explained by their formation in two stages. At the first stage, the diamonds formed which became the cores of octahedra. After a long-time interruption, at the second stage of diamond formation crystals of cubooctahedral habit appeared and the octahedral crystals were overgrown. Wide variations in nitrogen contents in the xenolith crystals allowed their use to estimate the kinetics of aggregated nitrogen. The data obtained show that the aggregation of A centers into B1 centers in the diamonds is described by a kinetic reaction of an order of 1.5.

TEM responses in an inhomogeneous medium are modeled in 3D using the vector finite element method for induction logging in petroleum wells. The algorithm is applied to HFIL diagrams obtained in wells that tap thinly laminated formations with regard to the true position of logging tools.

Sunshading is a powerful tool for the enhancement of edges in images. Given the azimuth and elevation of a source illumination, it calculates the reflectance from a surface which is composed of the data to be interpreted. It is a standard tool used in the interpretation of geophysical potential field data. In the great Oulad Abdoun phosphate basin, inclusions of sterile hardpan - so-called

The paper described the creative path of K.E. Tsiolkovsky, the founder of theoretical cosmonautics, who devoted his life to solving various problems in the field of aerodynamics and rocket engineering, creating dirigibles with a metallic shell, jet planes, and air-cushioned trains, and studying the origin of planets, the Sun, and the Universe. The main engineering proposals of a scientist of great originality, which found applications in modern rocket and space engineering, are briefly analysed. The versatility of his interests is demonstrated; his research is shown to deal with many fields of science and technology, including the kinetic theory of gases, geology, cosmology, biology, philosophy, sociology, theology, and language science.

The results of experimental study of a nonlinear varicose instability of the streaky structure generated by roughness element in unswept-wing boundary layer are presented. Features of the varicose breakdown of longitudinal steady streaky structure such as modulation of structure in transverse and streamwise directions by secondary disturbance, occurrence of the new streaky structures and L -structures downstream are shown. Spatio-temporal pictures of the hot-wire visualization of flow during spatial evolution of the streaky structures under influence of secondary high-frequency disturbance are discussed. Features of the adverse pressure gradient influence upon processes of the nonlinear varicose instability evolution and flow structure are revealed. Essential influence of the adverse pressure gradient on evolution of disturbances is shown. Comparison of varicose instability of the streaky structures generated in two different ways (the roughness element as in the given work, and continuous air blowing as in the earlier published work) is the carried out.

The main characteristics of an acoustic resonance developing in a channel flow past flat bluff bodies with different trailing-edge shapes have been experimentally examined. It is shown that the range of flow velocities at which the resonance is observed is wider for a model with sharp trailing edge compared to a plate with blunt trailing edge.

The behavior of the velocity vorticity vector on a discontinuity surface arising in the supersonic non-uniform flow of combustible gas around a body with the formation of a shock or detonation wave is studied. The free stream is generally vortical and has a given distribution of parameters. The formulas are obtained for the vorticity vector components in a special coordinate system related to the wave. It is shown that in this case the vorticity vector normal to the wave remains continuous across the discontinuity surface, and in the case of axisymmetric flows, also the quantity remains continuous, which is equal to the ratio of the tangent vorticity component to density, although the quantities themselves taken separately undergo a discontinuity.

A self-similar solution is obtained for a one-dimensional problem of diffusion mixing of vapor and gas, which is followed by condensation process. Two limiting cases of mixing are considered: in the first one, the vapor and gas occupy in their initial states the volumes of semi-infinite extension, in the second case, the vapor has a semi-infinite extension, and constant values of temperature and gas concentration are maintained at its boundary. The peculiarities of the temperature and concentration fields are analysed versus the vapor and gas temperatures, and the temperature values are found, at which the mixing occurs with the condensate formation.

The paper presents the developed physical and mathematical models, calculation procedure based on finite-element method, and also the software for the numerical studying the processes of the non-stationary conjugate heat exchange and phase transition during the surface processing with high-concentrated energy fluxes with stationary, pulse, and movable heat sources (fusing of coatings, surface layer quenching, surface cleaning, etc.). The proposed and realized method permits to study the processes within a wide range of the power density of external heat fluxes qÎ [ 10⁷; 10^14] W/m² with significantly different spatial and temporal scales. The results presented are of interest for understanding and simulation of the processes occurring at the surface processing of the coatings and materials with high-concentrated energy fluxes.

Results of experimental studies on the local characteristics of heat transfer from a lead heat carrier to the surface of a cooled tube in an annular gap are shown at control and alteration of oxygen admixture content under the conditions of power circuits with heavy liquid-metal heat-transfer agent. This work is aimed at obtaining the grounded formulas for engineering calculations of heat transfer surfaces. Investigations were carried out at the lead temperature of 400- 500

Chemical transformations at incomplete methane oxidation in the air medium were studied experimentally at reaction activation on the wall of an annular microchannel. Methane was oxidized incompletely on a rhodium catalyst deposited on an inner wall of the channel. Concentrations of the products of chemical transformations were measured in the outlet gas mixture for different reactor temperatures and stay times. We have determined the range of channel wall temperatures and stay times of the mixture corresponding to an increase in the portion of hydrogen and carbon dioxide indicating transition from predominant methane combustion to cascade chemical reactions with activation of steam and carbon dioxide methane conversions. It is shown that the kinetic model of chemical transformations of methane in the air medium depends significantly on the temperature of channel walls and stay time of the mixture. The effect of outer diffusion deceleration on the rate of chemical transformations at incomplete methane oxidation under the strained conditions is determined.

Results of experimental studies of low-frequency acoustics of gas-liquid bubble media aimed at the check-up of the theory of resonance dispersion of sound of a new type are presented. According to the theory, together with well-known high-frequency dispersion of sound in the gas-liquid media, connected with resonance of volumetric bubble oscillations and, respectively, with resonance compressibility, there should be low-frequency resonance dispersion of sound caused by resonance of related spheroidal-progressive bubble oscillations and, correspondingly, by resonance of the efficient dynamic density of a medium. It is shown that experimental data on the velocity and attenuation coefficient of sound in the bubble media prove the existence of resonance dispersion caused by related progressive-deformation oscillations of bubbles.

The stationary modes of the end-face tube electrodes operation are under consideration. The formation of cathode and anode jets which cause dramatic increase in the electrode erosion at the arc current growth has been explained. We have considered the ways to increase the life-time of the continuous operation of tube electrodes. The analysis of the thermophysical interaction of the arc spot and electrode surface has enabled us to choose the optimum metal for the electrode.

The AC plasma electric furnace with graphite electrodes was tested using methane as the modelling gas. Its advantage for production of hydrogen and fine soot was demonstrated. It was found that 1150- 1200

Conversion of coals with various degrees of metamorphism in supercritical water (SCW) was studied under the isochoric conditions at the temperatures of 380- 800