Home – Home – Jornals – Russian Geology and Geophysics 2007 number 4

New data on the geochemistry and isotopic composition of chloride brines of the Siberian Platform are presented. The distribution of stable isotopes (²H, ¹⁸O, and ³⁷Cl) in brines of the Tunguska, Angara-Lena, western part of the Yakutian and Olenek artesian basins and ⁸⁷Sr/⁸⁶Sr in brines of the western part of the Olenek artesian basin was studied in the context of the problem of genesis of highly mineralized groundwaters. Results of the study and comparative analysis of the geochemical and isotopic peculiarities of the Siberian Platform brines conform to the theory of brine formation through the interaction of connate waters with enclosing rocks.

We discuss the redox environments and the compositions of bottom sediments and sedimentary pore waters in the region of a hydrothermal vent in Frolikha Bay, Lake Baikal. According to our results, the submarine vent and its companion nearby spring on land originate from a common source. The most convincing evidence for their relation comes from the proximity of stable oxygen and hydrogen isotope compositions in pore waters and in the spring water. The isotope composition indicates a meteoric origin of pore waters, but their major- and minor-element chemistry bears imprint of deep water which may seep through permeable faulted crust. Although pore waters near the submarine vent have a specific enrichment in major and minor constituents, hydrothermal discharge at the Baikal bottom causes a minor impact on the lake water chemistry, unlike the case of freshwater geothermal lakes in the East-African Rift and North America.

The Middle Cenozoic evolution of magmatism in the Schmidt Peninsula between 37 and 25 Ma began with eruptions of subalkaline and moderately alkaline andesite, latite, trachyandesite, and trachyrhyolite lavas and ended with subvolcanic intrusions of highly alkaline strongly undersaturated essexites. According to trace-element data, magmatism evolved from melting of a mantle source in the zone of ocean-continent plate convergence to small-degree partial melting in lithospheric mantle at the final stage. This succession is generally typical of Late Cenozoic continental-margin magmatism in southeastern Russia. The similarity in the Middle and Late Cenozoic stages of magmatism is evidence for their individual significance.

We suggest a new approach to study apparently chaotic jointing near faults of different geometries. It implies matching jointing stereograms to standard patterns developed for strike-slip, reverse, thrust, and normal faulting. The standard patterns correspond to joint triplets that regularly initiate in small rock volumes under second-order stress fields during the formation of fault zones. The approach was tested for the cases of failure in bedrock and unconsolidated sediments and showed up as an efficient tool for investigating the origin, structure, and evolution of faults.

This study is concerned with the eolian deposits on the Baikal shore. It has been established that (1) the eolian sands are distinctly divided into two sequences: Khuzhir (Late Pleistocene) and Peschanka (Holocene); (2) the ilmenite enrichment of the sands is due to the removal of sand grains (containing mainly light minerals) by strong winds up the shore, first, from a dewatered beach zone, and then, from zones of psammitic-material transition. This leads to the concentration of ilmenite and other heavy minerals, first, within the beach zone, and then, within the zones of prevailing eolian-sand transition. The accumulation-transition zones are most enriched in heavy minerals, including ilmenite; (3) the ilmenite content in the study Ti-ore placer deposit shows a high correlation ( R = 0.89) with the total content of heavy minerals.

Using the ICP-MS method we have studied the isotope systematics of Sr and Nd as well as trace element composition of a representative collection of kimberlites and related rocks from the Siberian Platform. The summarized literature and our own data suggest that the kimberlites developed within the platform can be divided into several petrochemical and geochemical types, whose origin is related to different mantle sources. The petrochemical classification of kimberlites is based on persistent differences of their composition in mg# and in contents of indicator oxides such as FeO_tot, TiO₂, and K₂O. The recognized geochemical types of kimberlites differ from one another in the level of concentration of incompatible elements as well as in their ratios.
Most of isotope characteristics of kimberlites and related rocks of the Siberian Platform correspond to the earlier studied Type 1 basaltoid kimberlites from different provinces of the world: Points of isotopic compositions are in the field of primitive and weakly depleted mantle. An exception is one sample of the rocks from veins of the Ingashi field (Sayan area), which is characterized by the Sr and Nd isotopic composition corresponding to Type 2 micaceous kimberlites (orangeites).
The most important feature of distribution of isotopic and trace-element compositions (incompatible elements) is their independence of the chemical rock composition. It is shown that the kimberlite formation is connected with, at least, two independent sources, fluid and melt, responsible for the trace-element and chemical compositions of the rock. It is supposed that, when rising through the heterogeneous lithosphere of the mantle, a powerful flow of an asthenosphere-derived fluid provoked the formation of local kimberlite chambers there. Thus, the partial melting of the lithosphere mantle led to the formation of contrasting petrochemical types of kimberlites, while the geochemical specialization of kimberlites is due to the mantle fluid of asthenosphere origin, which drastically dominated in the rare-metal balance of a hybrid magma of the chamber.

Isoferroplatinum mineral assemblage has been first discovered in the Simonovsky Brook gold placer localized in the Egor'evskoe gold-bearing district (Salair Range). It includes isoferroplatinum (Pt₃Fe) grains with inclusions of cuprorhodsite CuRh₂S₄, braggite (Pt,Pd)S, vysotskite PdS, high-Pt rhodarsenide (Rh,Pd,Pt)₂ As, keithconnite Pd₃Te, hollingworthite RhAsS, Cu and Fe sulfides, basic plagioclase, magnetite, epidote, quartz, kaolinite, and leucoxene. The assemblage might have been produced from small gabbroid bodies widespread in the northwestern Salair region, including those of the Uralian platinum-bearing type, or from gabbroids of other complexes.

Microdiamonds (crystals smaller than 1 mm) of octahedral and cubic habit from Udachnaya kimberlite pipe (Yakutia) have been compared in order to distinguish genetic features inferred from carbon isotopic composition and impurity defects. Microdiamonds of cubic habit from the Udachnaya kimberlite pipe have a fibrous internal structure and a high content of nitrogen impurity (400-3000 ppm). Octahedral microdiamonds from the same deposit are distinguished by a low nitrogen content of 0 to 500 ppm and zoning structure. The isotopic composition of carbon (δ¹³C is -4.7

Integrated seismological, structural, and geomorphic studies of the western Tunka system of rift basins show that the historic seismicity reflects the general Late Quaternary evolution trend of structures. Crustal deformation occurs mainly as shear with compression. Compression follows the boundaries of blocks and the mountainous northern periphery of basins, whereas extension acts upon their inner parts, which remain in

Results of investigations of Baikal bottom sediments from a long core (BDP-97) and several short (0-1 m) cores are presented. It has been shown that the Holocene sediments in the Baikal basins consist of biogenic-terrigenous muds, accumulated under calm sedimentation conditions, and of turbidites, formed during catastrophic events. The turbidites can be distinguished from the host sediments by their enrichment in heavy minerals and thus their high magnetic susceptibility. Often, Pliocene and Pleistocene diatom species observed in the Holocene sediments (mainly in the turbidites) point to redeposition of ancient offshore sediments. Our results indicate that deltas, littoral zones, and continental slopes are the source areas of turbidites. The fact that the turbidites occur far from their sources confirms the existence of high-energy turbidity currents responsible for long-distance lateral-sediment transport to the deep basin planes of the lake.

First data on the geologic and geochemical compositions of kimberlites from nine kimberlite pipes of southwestern Angola are presented. In the north of the study area, there are the Chikolongo and Chicuatite kimberlite pipes; in the south, a bunch of four Galange pipes (I-IV); and in the central part, the Ochinjau, Palue, and Viniaty pipes. By geochemical parameters, these rocks are referred to as classical kimberlites: They bear mantle inclusions of ultrabasites, eclogites, various barophilic minerals (including ones of diamond facies), and diamonds. The kimberlite pipes are composed of petrographically diverse rocks: tuffstones, tuff breccias, kimberlite breccias, autolithic kimberlite breccias, and massive porphyritic kimberlites. In mineralogical, petrographic, and geochemical compositions the studied kimberlites are most similar to group I kimberlites of South Africa and Fe-Ti-kimberlites of the Arkhangel'sk diamondiferous province. Comparison of the mineralogical compositions of kimberlites from southwestern Angola showed that the portion of mantle (including diamondiferous) material of depth facies in kimberlite pipes regularly increases in the S-N direction. The northern diamond-bearing kimberlite pipes are localized in large destructive zones of NE strike, and the central and southern diamond-free pipes, in faults of N-S strike.

On the basis of combined (paleomagnetic, lithological, and paleontological) data, a scale of Neogene geomagnetic polarity is proposed for the West Siberian Plate (WSP). It comprises 17 large orthozones of normal and reversed polarity. The scale was compiled by comparing and correlating the Neogene key sections of the Kulunda and Baraba plains, Irtysh regions between Omsk and Pavlodar and near Tara, and Ob' region near Tomsk. The reliability of paleomagnetic data is confirmed by component analysis of natural remanent magnetization and by a possibility of determining its primary component. In the studied Neogene rocks this is a high-temperature component related to magnetite, hematite, and maghemite, which decays at 420-675

The Ogurtsovo section, one of the key sections of the Ob' region near Novosibirsk, has been comprehensively studied using a detailed geological description of deposits, granulometric and petromagnetic analyses. The combined methods allowed us not only to interpret the geologic structure of the Ogurtsovo section in terms of its facies and genesis but also to refine and supplement the Pleistocene geologic history of the region. Emphasis was placed upon relationships between granulometric and petromagnetic parameters. As a result, we have revealed regularities in the behavior of magnetic characteristics and their relationships as a function of granulometry in different lithogenetic types of deposits. On the example of this key section, criteria are proposed for distinguishing facies of the subaerial complex by analytical methods.

We report results of an integrated study of volcanosedimentary rocks of the Middle-Late Miocene Dzhilinda Formation consisting of the prevolcanic sedimentary Lower Dzhilinda and volcanosedimentary Upper Dzhilinda subformations. The section was studied in three wells drilled near Lake Mukhal (Khoigot paleovalley, Vitim upland). The Dzhilinda sediments contain ubiquitous Alveolophora jouseana (Moiss.) Moiss. typical of Miocene environments. Deposition occurred in two main stages represented by different water (diatoms) and land (spores and pollen) plant communities. The upsection successive changes in diatom species are attendant with changes in pollen and spore assemblages. The K-Ar ages of lavas indicate that the mostly sedimentary lower section of the Dzhilinda Formation deposited between 12 and 14 Ma and the more volcanic upper section, with a lacustrine lens at base, formed at about 10.8-9.5 Ma. The isotope dating of volcanic rocks agrees with the ages inferred from the diatom and spore-pollen analyses. The prevolcanic Lower Dzhilinda subformation deposited during the Middle Miocene climate optimum. The stratigraphy, lithology and facies of sediments suggest that the Dzhilinda deposition was associated with the development of a deep freshwater lake in the conditions of active tectonism and volcanism.

We report results of bottom temperature monitoring of 2003-2004 in the deepwater South Baikal basin (Lake Baikal) near active gas-fluid methane vents at lake depths of 1020 and 1350 m. Sediments and water temperatures were measured using an autonomous temperature recorder designed at the Institute of Geophysics (Novosibirsk). Experiments implied short-duration recording and pioneering continuous 350 day-long monitoring near the Staryi vent. Measurements within a 1 m thick layer above and below the bottom showed notable variations in water (up to 0.07

A four-channel point object image filtering algorithm obtained by modifying an adaptive filtering algorithm is proposed. It is shown that the quality of four-channel filtering deteriorates only slightly compared with the adaptive filtering whereas the computational complexity is reduced several times.

Results of computer simulation are presented. They allow evaluating the reconstruction errors of an impulse signal at the multichannel recorder output versus the accuracy of determining the phase shifts between channels and their gain.

The nonparametric approaches to applied spectral analysis of generally stationary discrete-time stochastic processes are reviewed. The classical periodogram estimator of spectral density f(w) of the analyzed stochastic process and the Welch-type estimator are considered in detail. Practical advice on choosing the parameters of both the statistical estimators is presented.

Synthesis of the structure of an adaptive fuzzy controller for multistructure objects is considered. An algorithm for identifying the fuzzy multistructure model defined as a fuzzy relational equation is described

Results of an experimental study of a two-beam laser method of recording and heterodyne detection of elementary microstructures (microgratings) in

An iterative method for designing a field eikonal that creates conditions for light beam focusing to a given 2D region is considered. The eikonal function that ensures focusing from a circular to rectangular region is calculated. Application of the method to design of refractive optical elements is considered. The refractive element that focuses a plane beam with a circular section to a rectangle is designed.

A method for measurement of a surface microprofile with a nanometer resolution is described. The method is based on partial scanning of correlograms in a Linnik white-light interferometer. Experimental results on measurements of thin film thickness are presented. It is shown that a depth resolution of better than 1 nm can be obtained by correlogram scanning in the range from 1 to 2 periods.

A complementary scanning device control system was developed. In the system, the laser beam is displaced by deflectors inside the writing zone confined by the focusing objective field. The deflectors are placed in a scanning head that, in its turn, can move over the entire writing field. Based on the proposed control system model it is shown that the chosen system implementation allows precision image writing on formats that are much greater than the writing field of the focusing objective; the writing speed is primarily determined by the scanning head deflectors. Results of simulating the system behavior and experimental results are presented.

On May 18, 1957, the Soviet Government adopted a decree about establishing the Siberian Branch of the Academy of Sciences (SB AS USSR). The initiative for this historical decision was backed up by several prominent scientists: academicians M.A. Lavrentyev, S.A. Khristianovich, and S.L. Sobolev. They promoted the idea of creating a new territorial division of Academy and supported this idea by personal decision to reallocate it from the capital to Siberia together with their scientific schools.

Sergey Alekseevich Khristianovich is one of the famous Russian mechanical engineers of the 20^th century together with N.E. Zhukovsky, S.A. Chaplygin, N.E. Kochin, and others. He made an immense contribution to some aspects of mechanics, such as aerogasdynamics, rock mechanics, theory of plasticity, filtration theory, and environmental power engineering. All this was preceded by a long, hard, and fruitful life full of outstanding events.

I remember my first encounter with S.S. Kutateladze; this was at the All-Union Conference on Self-Similarity Theory in the conference hall of the Krzhizhanovsky Power Engineering Institute of the USSR Academy of Sciences. The young generation of researchers occupied the balcony places. I remember a bright lecture of young S.S. Kutateladze, who became our

The processes of breaking, solution, and formation of hydrates behind a shock wave of moderate amplitude were studied experimentally in water with carbon dioxide bubbles under different initial static pressures. It is shown that an increase in the static pressure in a gas-liquid medium leads to reduction of critical relative amplitude of the shock wave, corresponding to starting development of Kelvin ¾ Helmholtz instability and bubble splitting into small gas inclusions behind the shock wave front. It is shown that the rates of carbon dioxide solution and hydrate formation behind the shock wave front are close by the value; their dependences on medium and wave parameters are determined. Calculations by the model of gas hydration behind the shock wave are presented.

The dynamics and heat and mass exchange in the pressure wave of a vapor bubble containing a hot particle was investigated parametrically. The influence of the particle size and temperature, of the liquid temperature and static pressure, and the wave amplitude on the dynamics of such a two-phase bubble was studied. A procedure is proposed to estimate the least value of the thickness of a vapor layer around the particle.

Experiments were carried out on ultrasonic cavitation in glycerin. The zone near the emitter has a structure from interacting gas-vapor bubbles; this structure takes the form of fractal clusters. The photometry of passed laser emission was the tool for studying dynamics of fluctuations. In transitive mode, the power spectrum of fluctuation varies by the law inversely proportional to frequency. Distributions of local fluctuations are different from Gaussian and exhibit the property of scale invariance. The qualitative behavior of the frequency dependence of the spectral fluctuation density was tested while varying the power of the ultrasonic emitter. It was demonstrated that the growth of the high-frequency margin of flicker-type behavior evidences for growing instability and can be considered as a forerunner of possible large-scale outbursts.

This paper deals with experimental results on flowboiling heat transfer of liquid moving in an annular channel with unilateral central heating under the conditions of a significant effect of capillary forces on the flow modes and heat transfer . Experiments were carried out on boiling freon R318

Thermal conductivity of liquid ozone-safe refrigerant R404A was studied for the first time in the range of temperatures of 297.9

Wave characteristics of the water film flow over a vertical plate with a heater were studied. Without a heat flux, data obtained perfectly coincide with results of other authors obtained for an isothermal liquid film. When heating the falling liquid, thermocapillary forces form the rivulets and thin film between them. It was found out that an increase in the heat flux causes a rise of the phase velocity and decreases the frequency of 3D waves. It is shown that in contrast to the known data for an isothermal liquid film, the average relative wave amplitude increases with a rise of dimensionless complex Re_loc/at relatively high heat flux densities in the interrivulet. The growth of wave amplitude under the action of thermocapillary forces was revealed in the interrivulet, what corresponds to calculations.

The temperature variations of the density of liquid magnesium-lead alloys were measured by the gamma-method in the temperature range from the liquidus temperature to 950- 1000 K for compositions of 19.11, 33.45, 52.46, and 83.06 at. % Pb. It is shown that within the estimated errors (0.25- 0.30 %), the alloy density depends linearly on the temperature. Approximation dependences r (T) were obtained for every studied composition together with generalizing density-temperature and density-concentration dependences for the range of 0- 100 at. % Pb.

The passive systems for ensuring the thermal regime of space objects, which are in current use, can preserve the temperature at the same level only under a certain orientation of spacecraft and at a constant heat release of the equipment. At a variable orientation of the space object, its temperature may vary due to a possible illumination of the radiator-emitter of the system for ensuring the thermal regime by the solar or planet radiation. At a variable heat release the object temperature changes due to an off-design regime of the radiator operation. To compensate for the given effects the active elements are used ¾ the heaters and coolers. This reduces the reliability of thermal regulation system and, consequently, the reliability of the entire spacecraft.

A comparative analysis of the aerogasdynamics of waveriders designed from two different flow types, namely the axisymmetric conical flows and the flows behind two-dimensional planar shocks, was carried out. Integral aerodynamic characteristics of a configuration with different forms of transverse contours of the lower surface were considered, and the

The questions related to the formulation and numerical realization of boundary conditions on a wall at the computation of turbulent flows on unstructured grids are considered. A technique is proposed for realization of weak boundary conditions assuming a non-zero value of the tangent velocity on the wall at a discretization of the Reynolds-averaged Navier - Stokes equations by the control volume method. The capabilities of the developed approach are demonstrated by the example of computing the flow in the inter-blade channel of a low-velocity compressor. The influence of the near-wall grid step on the accuracy of computations, in particular, the pressure distribution near the profile trailing edge is shown, and the solution grid dependence is investigated when using the method of near-wall functions and weak boundary conditions.

Hot-wire measurements have been undertaken in a turbulent boundary layer which is subjected to an impulse in form of a short roughness strip with the aim of examining its influence on the structure of the turbulent boundary layer. The results indicate that, while the energy containing motion is shifted from low wave number to high wave number near the wall due to the interfering of the roughness strip with the near-wall structure, the reverse is the case in the outer region. While the anisotropy at small scale changes appreciably, there is no discernable change at the large scale when distance from the wall is increased as reflected in the collapses of spectra shear correlation coefficient at the low wave number. It further shows that the roughness strip alters the flow dynamics of the boundary layer as shown in the changes in the mixing length distribution.

Measurement results on turbulent friction are presented for nine single-layer compliant coatings in comparison with a polished solid surface streamlined by the water flow. Three experimental series separated by time passed after coating fabrication were carried out. Results on monitoring of the viscoelastic properties of coating materials are shown; they allow analysing coating aging effect as the instability factor of coating hydrodynamic efficiency.

A complex numerical and experimental investigation of burner devices for a reburning of the anode gas of aluminum production was carried out. The chosen mathematical model of the processes of aerodynamics, heat exchange, and gas burning was identified and adapted on the basis of data of real-scale measurements. Basing on computational experiments the optimization of the design of elements of the system for anode gas detoxication and transport was carried out. A new system was proposed and tested for reburning the anode gases of electrolysis production, which consists of an improved burner device and a dust-sedimenting chamber with a possibility of regulating the amount of gas suction.