Home – Home – Jornals – Avtometriya 2010 number 5

The history of the Vendian-Early Paleozoic formation of protoliths of continental crust in the Gorny Altai segment of the Central Asian fold belt is considered, and their composition, isotopic characteristics, and formation mechanisms are estimated. We have established two stages of crust-forming processes in Gorny Altai: Early and Late Caledonian, with the different structures of formed geoblocks and nature and compositions of crustal protoliths.
At the Early Caledonian stage, fragments of oceanic lithosphere of basic composition (MORB, OIT, OIB) (T_Nd (DM - 2st) = 0.65-1.1 Ga) formed, as well as island arcs with andesite-basaltic and andesitic protoliths with low contents of incompatible elements (T_Nd (DM - 2st) = 0.7-0.9 Ga). At the Late Caledonian stage, the redistribution of the substance of these blocks and the external supply of material led to the formation of the heterogeneous crust of turbidite basins with an oceanic basement and andesite-dacitic upper-crustal protoliths (T_Nd (DM - 2st) varies from 0.8-0.9 Ga in the framing of the volcanic arc of Altaids to 1.4-1.6 Ga at the boundary of the Altai-Mongolian microcontinent).

We report data from the Khadarta, Khoboi, and Orso metamorphic complexes of the Olkhon terrane in the western Baikal region. High-grade rocks in the three complexes might have been derived from active continental margin rocks (island arc-backarc basin system). The backarc basin history possibly began at 840-800 Ma, according to SHRIMP-II U-Pb zircon ages of the Orso gneiss. Many tectonic units in the Olkhon terrane belonged to the active margin of the Barguzin microcontinent, which rifted off the Aldan province of the Siberian craton in the Early Neoproterozoic. The accretion of the microcontinent to the craton was accompanied by high-grade metamorphism recorded in the Khadarta and Khoboi granulites. The 507±8 Ma and 498±7 Ma SHRIMP-II U-Pb zircon ages of the latter complexes, respectively, may refer to the earliest evolution stage of the Olkhon metamorphic terrane. New data for the Olkhon terrane agree with the ages of other high-grade complexes along the southern Siberian craton (Slyudyanka, Kitoikin, Derba) and correspond to the initiation of the Central Asian orogen. With these data, the Olkhon metamorphic terrane has been interpreted as an Early Paleozoic collisional collage of fragments of the microcontinent's Neoproterozoic active margin.

New structural, petrological, chemical, isotope, and paleomagnetic data have provided clues to the Late Riphean-Paleozoic history of the Uda-Vitim island arc system (UVIAS) in the Transbaikalian sector of the Paleoasian ocean, as part of the Transbaikalian zone of Paleozoids. The island-arc system consists of three units corresponding to main evolution stages: Upper Riphean (Late Baikalian), Vendian-Lower Paleozoic (Caledonian), and Middle-Upper Paleozoic (Hercynian). The earliest stage produced the base of the system composed of Late Riphean ophiolite (971-892 Ma, U-Pb) and volcanic (837-789 Ma, U-Pb) and sedimentary rocks (hemipelagic siliceous sediments and dolerite sills), which represent the Barguzin-Vitim oceanic basin and the Kelyana island arc. The main event of the second stage was the formation of the large UVIAS structure (over 150,000 km²), which comprised the Transbaikalian ocean basin, the forearc and backarc basins, and the volcanic arc itself and consisted of many volcanotectonic units exceeding 100 km² in area (Eravnoe, Oldynda, Abaga, etc.). Lithology, stratigraphy, major-element compositions, and isotope ages of Vendian-Cambrian volcanic rocks and associated sediments indicate strong differentiation of calc-alkaline series and the origin of the island-arc system upon oceanic crust, in a setting similar to that of the today's Kuriles-Kamchatka island-arc system. The Middle-Upper Paleozoic stage completed the long UVIAS history and left its imprint in sedimentary and volcanic rocks in superposed trough basins. The rocks were studied in terms of their biostratigraphic and isotopic-age constraints, as well as major- and trace-element compositions, and were interpreted as products of weathering and tectonomagmatic rework of the UVIAS units. The synthesis of the data yielded a generalized geodynamic model of the UVIAS history.

New data testifying to Late Paleozoic tectonometamorphic processes at the West Transbaikalian segment of the Central Asian Fold Belt have been obtained. Zircon dating (SHRIMP-II) of highly metamorphosed rocks showed that the processes took place at 295.3±1.6 Ma. Based on these data, the Late Paleozoic ages of granitoids of the Angara-Vitim areal pluton (340-280 Ma) and some dike complexes in Transbaikalia (300-280 Ma), and the Late Paleozoic age of some carbonate-terrigenous strata dated earlier to the Early Paleozoic, we have substantiated the significant role of Hercynian tectogenesis in the consolidation of the regional continental crust. We have also shown that the Late Paleozoic endogenous events and accompanying sedimentation processes were related to the geodynamic conditions governed by the changing parameters of the subsidence of the Mongolo-Okhotsk oceanic subduction slab beneath the Siberian continent. Changes in the slope and rate of the slab subsidence resulted in A-subduction conditions in the distal part of the suprasubduction plate, which led to the formation of accretion-collisional orogen and the Angara-Vitim areal pluton.

The lithospheric structure of several marginal and interior units of the eastern Central Asian fold belt has been explored in 2D geophysical models. The obtained constraints on effective parameters (density, resistivity, temperature) of lithospheric blocks and their boundaries allowed correlation of geophysical structures to tectonic settings. The geological and geophysical (including paleomagnetic) data were used jointly to model the present structure of the lithosphere along 126°E between 56°N and 40°N and to construct a palinspastic model of the same area for the latest Early Jurassic (175 Ma).

The paper presents new data on physico-chemical parameters of the Neoproterozoic-Early Cambrian plume magmatism in the Paleo-Asian Ocean. The data on clinopyroxenes show the plume-related plateau basalt magmatic systems of the Katun' paleoseamounts, which interacted with mid-ocean ridge (MOR) magmas. The Kurai paleoseamount consists mainly of plateau basalt systems, and the Agardag ophiolites represent products of OIB-type "hot-spot" within-plate magmatism. Our study of inclusions showed that the melts of the Katun' and Kurai paleoseamounts crystallized at lower temperatures (1130-1190°C) compared to the Agardag ophiolites (1210-1255°C). The petrochemical analysis of the melt inclusions showed that the Katun' and Kurai magmatic systems are different from the Mg- and Ti-richer melts of the Agardag ophiolites: The former are similar to the magmas of the Nauru Basin and Ontong Java Plateau (western Pacific), whereas the latter possess geochemical affinities to OIB-type magmatism. The rare-element compositions of the melts of the Katun' and Kurai paleoseamounts correspond to those of the Ontong Java Plateau and Nauru Basin lavas. The numerically simulated parameters of the Katun' paleoseamount primary magmas agree with the data on the magmatic systems of the Siberian Platform and Ontong Java Plateau. For the Kurai paleoseamount, the simulated results suggest interaction of deep-seated OIB-type magmatic systems with MOR ones. The Agardag ophiolites were formed in relation to mantle plume activity at the initial stages of paleo-oceanic complexes formation.

The paper discusses geological, mineralogical, petrographic, and geochemical data on the Ureg Nuur volcanoplutonic association of high-Mg volcanic and subvolcanic rocks localized among Vendian-Cambrian accretionary structures in the Mongolian Altay. These rocks have a high potassium alkalinity (K₂O/Na₂O up to 1.2), are enriched in LILE and Sr, and have negative Zr-Hf and Nb anomalies in multielement spectra; this confirms the suprasubduction type of the source of melts. The geologic setting and established age (512.4±6.1 Ma, ³⁹Ar-⁴⁰Ar dating of biotite phenocrysts) evidence picritic magmatism at the accretionary stage of the development of the Altay fragment of the Paleoasian ocean. This indicates a large igneous province related to a mantle plume.

We discuss strike-slip tectonics as the key agent in the formation of the Early Paleozoic (Caledonian) collisional system of the western Baikal region. This tectonic setting implies existence of local syncompressional extension, with the ensuing conditions for mantle drainage and magmatism. Lower-middle crust collisional complexes exposed in the Olkhon area of the western Baikal region provide a record of synmetamorphic subalkaline-mafic magmatism associated with the early synorogenic collapse of the Olkhon collisional system, a part of the Central Asian collisional-accretionary belt.

In this paper we present complex geological, petrographic, and geochronological data of the study of intermediate-composition and acid intrusive and volcanogenic rocks from the Porozhnaya massif of the South Yenisei Ridge. For the first time in the Yenisei Ridge, Devonian and Triassic U-Pb age values (SHRIMP method) have been obtained for leucogranites - 387±5 Ma and alkaline trachytes - 240±3 Ma, which allows us to attribute them to two different complexes, despite the fact that these rocks were formed within the same Severnaya riftogenic structure. Geochronological Ar-Ar data (392-387 Ma) for micas from paragneisses and leucogranitic dikes of the Yenisei suture zone, on whose extension the Severnaya riftogenic structure is located, are also given in this study. These data on Devonian tectonic-magmatic events in the South Yenisei Ridge agree well with coeval events of continental rifting - the formation of intrusive and volcanogenic rocks of the Agul graben in the Prisayan region and the Minusa basin in the Altai-Sayan folded area. The formation of alkali trachytes and alkali syenites of the Severnaya riftogenic structure, for which an age of 240±3 Ma has been established, is related to the trap magmatism of the Siberian Platform.

According to U-Pb dating, the granitoids of the Tyrma-Bureya complex in the northern Bureya-Jiamusi superterrane of the Central Asian Fold Belt are not of Paleozoic, as previously thought, but of Mesozoic age (Nizhnyaya Stoiba massif, 218±2 Ma; Talakanka and Ust'-Dikan massifs, 185±1 Ma). They formed at the early stages of collision between the North Asian and Sino-Korean cratons and the intervening Amur superterrane.

The formation environments of stratiform ore deposits in the Neoproterozoic Baikal-Patom region (BPR) have been considered. A model for the formation of the Sukhoi Log gold ore deposit in the Bodaibo zone has been put forward. The first stage is gold concentration by a chemolithotrophic bacterial community. Independently established facts suggest that bacterial communities might also have contributed to initial metal accumulation in the sediments of the Kholodnaya Pb-Zn deposit. The ore beds occur in the high-carbon sediments of the side and trough of the back-arc basin. Sedimentation (Dal'nyaya Taiga and Zhuya regional horizons) took place during the "back-arc basin - foreland basin" transition. This transition is characterized by increased sediment bioproductivity, which is clearly evidenced from the increased biophile-element content and taxonomic diversity of organic remains. Hundreds of microfossil sites in the Neoproterozoic BPR host littoral benthos (cyanobacteria and brown algae) and plankton (green algae). Most microfossils in the outer shelf, on the basin side, and in its trough belong to chemolithotrophic bacteria. These bacteria are assumed to have accumulated metals in the vent field of the back-arc basin. Studies showed the ability of microorganisms (bacteria, algae, fungi, etc.) to accumulate Fe, Mn, Au, Pb, Zn, and other metals. Bacterial communities are particularly important for metal accumulation in the vent fields of rift zones and areas of arc volcanism. All these conditions were observed in the Neoproterozoic BPR.

The behavior of an inverted pendulum hinged on the wheel axis is studied. An algorithm is proposed for solving both the problem of pendulum stabilization in a given position relative to the vertical and the problem of controlling the velocity of the platform on which the pendulum is located under conditions of energy dissipation. Recommendations on choosing control system parameters are given, and the time of transitional processes is estimated.

We solve the problem of minimizing the ravine non-differentiable function defining the quality of the pole location in the synthesis of automatic control systems with reduced-order controllers. The relationship between the objective functions of the location of the polynomial roots and their derivatives is studied. The possibility of conversion from the non-differentiable characteristic of the location of the polynomial roots to a smooth characteristic of its derivative.

In densely populated cities or indoor environments, limited accessibility to satellites and severe multipath effects significantly decrease the accuracy and reliability of satellite-based positioning systems. To meet the needs of "seamless navigation" in these challenging environments, an advanced terrestrial positioning system is under development. A new principle of mobile robot navigation capable of working in a complex unknown landscape (another planet or just on a cross-country terrain) is proposed. The optoelectrical method proposed has a good spatial domain resolution and immunity to multipath, as well as new optical means for "technical vision" realization. Two related problems are solved: creation of a technical vision system for recognition of images of an unfamiliar landscape and determination of the direction to the initial point of the movement trajectory of the mobile transport robot. Issues of principle design and also of functioning and interaction of system units and elements are described. A mathematical apparatus for processing digital information inside the system and for determining the distances and angle measurements in the system proposed is developed. Some important parameters are analytically determined: expected accuracy, functioning speed, range of action, power issues, etc.

The most essential constraints of conventional technologies of processing multispectral data of remote sensing of the Earth in solving the problem of searching for man-made objects are analyzed. Several methods using structural features of images of man-made objects are modeled and studied. The efficiency of approaches based on classification of fragments with the use of the Harris detectors is demonstrated.

A histogram-based clustering algorithm is proposed that takes into account features of the collection of image texture statistics. The algorithm allows the addition of the false clusters occurring on the boundaries of objects with different textures, thus significantly reducing their number. The clusters are analyzed by estimating their separability in the multidimensional vector space of features and the image context. The application of the algorithm to the automated recognition of types of land cover from aerial photographs of forest landscapes is considered. A comparison of cluster maps and schematic map of ground survey shows their good agreement.

An approach to choosing the composition of a multivariate nonlinear relationship based on pair functions is considered. The approach is based on an analysis of the elements of decomposition of a multiple variance ratio (MVR) into pair variance ratios (PVRs), variance-correlation ratios of coupling effects (VCRCE), and variance ratios of interaction effects (VRIE). It is shown that if such a decomposition contains only PVDR, an additive composition of pair nonlinear functions is recommended. In a decomposition dominated by VRIE, a multiplicative combination is proposed. In a mixed set of variance ratios, mixed combinations are preferred. VCRCE participate in the selection of dominant variables. The identity of the models is determined by MVR. An example illustrating the various combinations of multivariate relationships is given, and variance ratios are analyzed.

A method of using the function of rival similarity (FRiS function) to solve the problem of predicting variables measured on strong (quantitative) scales is proposed. The FRiS-Pro prediction algorithm and the experience of its use in solving problems of predicting a target attribute, measured on the absolute scale (customer demand) at the international competition Data Mining Cup 2009

A method of electronic calibration of measurement channels of multichannel analyzers of atomic emission spectra is developed for reducing nonlinearity of the dependence of the photoresponse of each channel on input radiation intensity, which is provided by obtaining measurement channel characteristics, their approximation by Chebyshev polynomials, and subsequent application of the calculated polynomial coefficients for output signal correction. A specialized unit of electronic registration and corresponding software are developed for such calibration. It is experimentally demonstrated that the measurement signal nonlinearity can be substantially reduced by using the electronic calibration. In this case, the residual nonlinearity of the photoresponse dependence on the number of photons incident onto the photodiode during the exposure time is within 1%.

Possible ways of improving laser image generators based on the circular scanning principle are analyzed. The most important sources of errors induced by the system of radial displacements and by the rotation unit are studied. Principles of decreasing the main components of instability of operation of image generators with circular scanning are described. Owing to the use of some principles, the prototype of such a generator can be put onto the second place in the worldwide rating of systems used by various companies to form structures providing high-accuracy measurements of angles (scales, limbs, rasters, etc.).

This paper describes an absolute ballistic laser gravimeter of a new generation developed at the Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences. The device is intended for use under field conditions and has small dimensions and weight. The light source in the gravimeter interferometer is an optical standard with a wavelength λ = 532 nm consisting of a traveling-wave Nd :YAG laser with intracavity frequency doubling and with a stabilization system for the saturated absorption resonances in molecular iodine. The instrumental standard error in measuring the absolute gravity by the gravimeter does not exceed ±5 · 10⁻⁸ m/s² (or 5 μGal).

The use of chalcogenide glassy semiconductors as an inorganic vacuum photoresist to obtain periodic relief structures on substrates of various compositions is investigated. It is shown that a chalcogenide resist can be successfully used in combination with interference lithography (including the immersion one) to form one- and two-dimensional submicron-size periodic structures with a spatial frequency of 300 to 8000 mm⁻¹. Technological processes of obtaining relief structures and lithographic masks with submicron sizes of elements on semiconductor, dielectric and metal substrates are developed, and their possible applications are described.

A new optical method of measuring noncircularity of cylinders is experimentally justified. The method is based on measuring the horizontal projection of velocity of a rolling circular body and calculating the maximum deviation of the local radius periodically repeated in the course of motion. Results measured by the proposed method are compared with direct measurements by a micrometer. The new method allows estimating tolerances of noncircularity in the case of defects of cylinder generatrices and the maximum variations of the radius in the case of guideline noncircularity. The noncircularity measurement error (~1 µm) is experimentally verified.

Simulation of an intelligent linear sensor for email monitoring based on theWin32 platform in the Windows XP environment is considered. The sensor emulation software of the device reads packets from a communication line, parses them, extracts email information, and sends it to a control unit. The features and limitations of the Win32 platform for designing devices of this type when using a multithreading mechanism in the emulation program are studied

A method for processing observation data based on their discretization and graphical analysis is proposed. The purpose of the processing is to determine and model the functional relationship between the inputs and output of an experimental object. The case of a series of experiments is considered.

The paper describes the socio-economic situation in Russian regions over 2000-2007 - the period of the crisis-free development - through our analyses of such indicators as the comparative indicators of regional growth, transformation of the territorial structure, basic indicators of regional development, comparative consolidated indices of the situation in the units of the Russian Federation, and lists of regions-leaders and regions-outsiders.

In the second part of review, we have considered the problems related to momentum and heat transfer in nanofluids. Results on hydrodynamic friction, forced and free convection in the laminar and turbulent flows are analysed; heat transfer at boiling is considered. The available models describing heat transfer intensification and suppression in nanofluids are studied. It is shown that for some problems on convective heat transfer there is a contradiction in data of different authors; possible reasons for this contradiction are analysed

Experimental heat-transfer data for a small-diameter hot wire have been obtained and generalized in a wide range of Reynolds numbers typical of hot-wire anemometry. The experiments were carried out using an IRVIS-TA5 digital hot-wire anemometer and standard critical nozzles used for regulating the flow in the test section of the Eiffel chamber in which the hot-wire sensor was installed. Approaches to carrying out hot-wire anemometric measurements without a labor-consuming calibration procedure for the hot-wire sensor are substantiated.

Time dependences of temperature distributions in a thin metal wall were studied experimentally under two conditions of convective heat transfer in a tank model. In the first case, the vertical working wall was heated from within due to a convective heat flux from the opposite wall heated monotonously, and it was cooled due to heat transfer to the ambient medium. Dependence of the temperature field on a thin wall at the stage of convective flow development was retraced with the help of the thermographic camera and thermocouple sensors. In the second case, the tank wall was heated uniformly by IR radiation from the outside, and nonstationary convective flow and volumetric liquid heating were formed inside. Time dependence of temperature distribution over the wall height is studied. It is shown that the flow structure and convective heat transfer in a fuel layer with free boundary are subjected not only to the buoyancy force, but also to the thermocapillary effect. The local features of the flow affect temperature distribution in a thin wall.

The dynamics of phase fronts in a hydrothermal solution filtering through the fluid-conductor pores upwards to the earth surface was investigated on the basis of the model of volcanogenic orthomagmatic fluid systems. The problem was solved with regard for the rise and gradual extinction of the source of a fluid related to the crystallization of water-saturated basite magma in a shallow intrusion chamber. The influence of the porosity and permeability of supra-intrusion rocks as well as the heat-exchange conditions at their boundaries on the evolution of the orthomagmatic fluid system was investigated.

Density of low-temperature eutectic in magnesium−lead system (83.06 at. % Pb) has been measured by gamma-raying of the samples with narrow beam from cesium-137 isotope over the temperature range 293−1000 K of solid and liquid states. Approximation density dependences have been obtained and data of this work and other authors have been compared. Reference tables of temperature dependences of the alloy thermal properties have been compiled for the entire range of measurements and their errors estimated. It is shown that differences in the values of volumetric changes obtained during melting and crystallization are bound with the metastable β′-phase formation.

The process of heating a moving medium by an electromagnetic radiation in high-frequency range is considered in the presence of heat exchange with the ambient medium in the approximation of a thermally thin layer. The existence of temperature profiles in the form of auto-waves is established. The analytic and numerical solutions are compared.

The one-phase Stefan problem was simulated numerically in a layer of semitransparent medium with different emissivity factors at the right moving boundary. The effect of optic properties of irradiated surface on formation of temperature fields and radiation flux densities was demonstrated.

The dynamics of planar one-dimensional shock waves applied to the available experimental data for the water−Freon system is studied on the basis of the theoretical model of the bubbly liquid refined with regard for a possible hydrate formation. A scheme is proposed for considering the fragmentation of bubbles in the shock wave, which is one of the main factors of the intensification of the hydrate formation process with the growth of the shock wave amplitude.

The unobvious effect of the limiting wetting angle on heat transfer intensity at boiling is shown. The purposeful experiments allow us to develop the mathematical model, which describes properly the results of experiments on determination of the role of limiting wetting angle: sometimes this role is obvious, sometimes it is ambiguous.

Experiments are performed to study the possibility of decreasing the net drag of a flat plate with the use of streamwise-oriented vertical elements mounted normal to the surface in an incompressible equilibrium turbulent boundary layer. The Reynolds number based on the boundary-layer momentum thickness in the section where the vertical elements are placed is 820. It is demonstrated that vertical large eddy breakup elements with the geometry used do not reduce the drag of a flat plate in the major part of the range of Reynolds numbers Re_{х examined. It is only at extremely low values of Reх that a certain gain in the net drag is reached, as compared with the value for a non-modified flow.}

In the present study, we examined, both experimentally and theoretically, the influence of surface permeability on the stability and laminar-turbulent transition of supersonic boundary layer at free-stream Mach number М_∞ = 2. A satisfactory agreement was obtained between the data calculated by the linear theory of stability and the data obtained in experiments with natural disturbances performed on models with different porous inserts.

Flow of two high-lift devices is studied on the basis of the solution to two-dimensional Reynolds equations with the Spalart - Allmaras one-equation turbulence model. Computation results are compared with the experiment under the conditions of airfoil flow in the low-speed wind tunnel with open test section. It is shown that such approach is the most correct for this comparison.

Presented below are the results of tests of turbine vanes with vertical rotation axis aimed at determination of their aerodynamic characteristics. Three types of vanes with the profiles in the form of semicylinder, semiellipse, and semiellipse with stabilizing plane have been tested. The last type of vane has been tested with stationary and rotary stabilizing planes.

The dependence of the flow patterns around two prism bodies with square cross sections on the distance between them has been studied. The specific structures arising around two bluff bodies have been obtained and divided into four main types. The thermoanemometer probing in aerodynamic wake of the same two bodies has been performed and resulted in the presented dependence of Strouhal numbers on the relative distance between the investigated prisms.