Home – Home – Jornals – Chemistry for Sustainable Development 2006 number 1

Siberian geologists in general and Academician V.A. Kuznetsov in particular made a considerable contribution to metallogeny. To follow them, we consider regularities of location and formation of gold deposits. Analysis of topical problems of gold metallogeny reflects general problems of state-of-the-art metallogeny. The analysis is based on concepts of geologic-genetic types of gold deposits and metallogenic specialization of geodynamic-geotectonic regimes and settings. The types of endogenic-polygenic gold ore and gold-bearing deposits restricted to certain settings - among which, in addition to traditional ones, intracratonic basins have been established - are characterized by depressions and heterochronous areas of rift and plume tectonomagmatic activity.

Based on data on the composition of ore-bearing hydrothermal solutions and parameters of ore-forming processes at various antimony and antimony-bearing deposits, which were obtained in studies of fluid inclusions in ore minerals, we investigated the behavior of Sb(III) in the system Sb-Cl-H₂S-H₂O describing the formation of these deposits.
We also performed thermodynamic modeling of native-antimony and stibnite dissolution in sulfide (m _HS^- = 0.0001-0.1) and chloride ( m _Cl^- = 0.1 - 5) solutions and the joint dissolution of Sb⁰_(s) and Sb₂S _3(s) in sulfide-chloride solution ( m _HS^- = 0.01; m _Cl^- = 1) depending on Eh, pH, and temperature. All thermodynamic calculations were carried out using the Chiller computer program. Under the above conditions, stibnite precipitates in acid, weakly acid to neutral, and medium redox solutions, whereas native antimony precipitates before stibnite under more reducing conditions in neutral to alkaline solutions.
The metal-bearing capacity of hydrothermal solutions (200-250

The large hydrocarbon basin of South Caspian is filled with sediments reaching a thickness of 20-25 km. The sediments overlie a 10-18 km thick high-velocity basement which is often interpreted as oceanic crust. This interpretation is, however, inconsistent with rapid major subsidence in Pliocene-Pleistocene time and deposition of ~ >10 km of sediments because the subsidence of crust produced in spreading ridges normally occurs at decreasing rates. Furthermore, filling a basin upon a 10-18 km thick oceanic crust would require twice less sediments. Subsidence as in the South Caspian, of ≥20 km, can be provided by phase change of gabbro to dense eclogite in a 25-30 km thick lower crust. Eclogites which are denser than the mantle and have nearly mantle P velocities but a chemistry of continental crust may occur beneath the Moho in the South Caspian where consolidated crust totals a thickness of 40-50 km. The high subsidence rates in the Pliocene-Pleistocene may be attributed to the effect of active fluids infiltrated from the asthenosphere to catalyze the gabbro-eclogite transition. Subsidence of this kind is typical of large petroleum provinces. According to some interpretations, historic seismicity with 30-70 km focal depths in a ~100 km wide zone (beneath the Apsheron-Balkhan sill and north of it) has been associated with the initiation of subduction under the Middle Caspian. The consolidated lithosphere of deep continental sedimentary basins being denser than the asthenosphere, can, in principle, subduct into the latter, while the overlying sediments can be delaminated and folded. Yet, subduction in the South Caspian basin is incompatible with the only 5-10 km shortening of sediments in the Apsheron-Balkhan sill and south of it and with the patterns of earthquake foci that show no alignment like in a Benioff zone and have mostly extension mechanisms

Trachybasalt-alkali trachyte volcanism in the Yenisei Ridge was found out to be synchronous with deposition of coarse tilloids and flysch of the Chivida Formation of the Neoproterozoic Chingasan Group. New 703 ± 4 Ma ⁴⁰Ar/³⁹Ar biotite and titan-augite ages of subalkaline basalts in the Chivida Formation indicated that they erupted in the Late Neoproterozoic. According to microfossil evidence, the Chingasan sediments correlate with Late Neoproterozoic strata in the type sections of the southern Siberian craton. The Chingasan deposition apparently lasted no longer than 30 Myr judging by the isotope ages obtained for the underlying Upper Vorogovka Group and subalkaline basalts in the Chivida Formation. The fault-parallel position of grabens and coarse grain sizes and variable thicknesses of their lithological complexes, as well as syndepositional trachybasalt-alkali trachyte volcanism provided evidence that the volcanosedimentary rocks of the Chingasan Group formed in an environment of active rifting.

We present new data on the age and geochemistry of the Veselyi and Petropavlovsk ultramafic-mafic massifs of the Selenga-Stanovoy (West Stanovoy) superterrane on the southeastern framing of the North Asian craton. The massifs are composed of rocks of peridotite- websterite-gabbro and peridotite-gabbro-monzodiorite associations, respectively. The latter combine normal, subalkalic, and alkaline rocks and thus are of diverse composition: from ultrabasites and pyroxenites through gabbroids to monzodiorites. The U-Pb zircon age of these massifs is 154±1 and 159±1 Ma, respectively, which permits them to be referred to as the youngest rocks of ultramafic-mafic complexes on the southern framing of the North Asian craton. The rocks of the studied massifs are enriched in LILE (K, Rb, Sr, Ba, LREE) and are depleted in HFSE (Zr, Nb, Hf, Ta). These rocks formed, most likely, in the rear of subduction zone or in the setting of the subducting-slab detachment.

The structure of convection currents was experimentally studied in the model system layered intrusion-feeding conduit-parental magma chamber. Persistent hydrodynamical and thermophysical interaction between interrelated melts of the parental magma and intrusive body occurs through the feeding conduit. Being associated, they control the structure of convection currents and mechanisms of heat and mass transfer in the intrusive, conduit, and magma chamber. The existence of two convection countercurrents in the conduit has experimentally been established: inner central lifting jet and outer annular downward current along the conduit walls. At the top of the conduit, the downward current has the lowest temperature and appears to be quite in equilibrium with the earlier precipitated crystals. Moving downward along the conduit wall, the annular descending current interacts with the lifting jet and, as a result, becomes hotter and undersaturated relative to the crystals that formed before. Thus, there is no possibility for heterogeneous crystallization to occur on the walls of conduit. The experimentally simulated mechanism of melt interaction in a whole natural system rules out the possibility of formation of a zone of immobile melt with stable steady-state temperature stratification anywhere in the chamber's volume.

We analyzed oils, gases, and bitumens of bottom sediments from natural shows on the southeastern shore of Lake Baikal, in the mouth of the Stvolovaya River near Capes Tolstyi and Gorevoi Utes. Based on a set of geological data, we have established that: (1) the lake oils underwent biodegradation to a variable degree:

Mathematical modeling was applied to study attenuation of a nanosecond pulse that propagated in an oil-bearing formation and was reflected from the oil-gas or oil-water interfaces. The problem was formulated and solved for propagation of a short electromagnetic Gaussian pulse in a layered hydrocarbon reservoir in the case of excitation by a long electric line. Complex permittivity of oil-bearing rocks was calculated using a refractive mixing dielectric model for oil, saline water, methane, quartz, and bentonite in each layer. We obtained and analyzed space-time diagrams of wave propagation and reflection and estimated effective attenuation for both cases.

We discuss the results of bottom temperature monitoring run in October through December 2005 in the deepwater basin of Lake Teletskoe at a lake depth of ~320 m using an autonomous recorder. The obtained temperature patterns of water and sediments to a depth of ~1.4 m show sudden large changes. Bottom water temperature fluctuated between 2.9 and 4

The problem of image reconstruction is considered for the case when the right-hand side of the 2D integral equation and the point-spread function (the integral equation kernel) are given with random errors. A stable image reconstruction algorithm is proposed. It is a combination of a regularizing algorithm for solving an integral equation (frequency filtering) and a local nonlinear filter (spatial filtering). Characteristics of the 2D point-spread function of the regularizing algorithm are introduced. The regularization parameter is chosen according to the required regularizing algorithm resolution. For eliminating the random reconstruction error, the regularized solution is subjected to nonlinear local filtering that preserves high-frequency information components of the image.

Synthesis and analysis of maximum likelihood algorithms for estimating the velocity of a spatially extended object image under different contents of a priori information on the background and object image intensities are carried out. The efficiency of the algorithms and the scope of applicability of the found asymptotical expressions for the velocity estimate characteristics are determined by statistical computer modeling.

A method for microwave tomography with a synthetic aerial aperture and a monochrome probing signal is proposed. A mathematical description of aerial aperture synthesis with regard to wave propagation in two media is presented. The velocity of wave propagation inside the object is assumed to be six times smaller than in the open space. Results of practical microwave object tomography with an aerial aperture synthesized by the proposed approach are given.

The nonparametric estimates of a density and its derivatives are considered within the scope of the L₂-approach. New sets of weight functions with a bounded support are proposed for constructing admissible (unimprovable in the space metric L₂(-∞, ∞)) estimates of the density itself and its derivatives to the third order, inclusive.

A cellular automata model is proposed for investigating the process of formation and percolation of gas or fluid flows through interstices in solid media. The model is a cellular automata analogy of a convection-diffusion equation in partial derivatives. The advantage of the model is that it allows a simple representation of boundary conditions and, thus, makes it possible to investigate properties of media with a complex pore configuration. Moreover, using probabilistic transition rules makes it possible to adapt to the properties of the boundaries between liquid and solid phases. A formal representation of the model is given. Results of experimental investigation for a medium with hydrophobic, hydrophilic, and neutral pores are presented.

Numerical realization of the model of unstable 3D processes in gravitating gas systems with a self-consistent field in the Cartesian coordinates is considered. Evolution of the disk gas component is described by a system of equations of gas dynamics with regard to the equation for temperature, and Poisson-s equation for gravity potential. A modified rotation-invariant fluids-in-cell method for numerical realization of equations of gas dynamics is considered. Results of applying the numerical model in a spatial case are presented.

A problem of extracting and analyzing knowledge oriented to expert-s individual goals is discussed. The information is represented as texts in a natural language. The system architecture, the main modules and algorithms, and also program functionality and perspectives of the approach are described.

A numerical formulation of the incident wave source conditions for a two-dimensional domain enclosed in a nonuniform envelope within the scope of the TF/RF technique (a special case of the TF/SF technique) is proposed. Comparison with traditional approaches to defining the incident wave source conditions is presented. Benefits of the proposed approach are shown.

A multibeam interferometer with oscillating mirrors is theoretically investigated. Transfer functions are presented and analyzed for two extreme cases, namely, for an interferometer with stationary mirrors and an interferometer operating in the mode of -superslow- mirror oscillations.

Peculiarities of forming a temperature track in circular laser writing in chromium films on glass substrates are studied. The temperature field is calculated for a wide range of writing diameters (20-150 mm). Dynamics of heating a chromium film on a quartz substrate upon switching on the beam in the course of movement for cases with temperature-dependent and independent thermophysical coefficients of the film and substrate is considered. Calculation results show the difference in the form (asymmetry) of the temperature track for an on/off writing beam. A method for correcting the procedure of choosing the writing beam power for producing small (about several microns) grooves is proposed. Calculated and experimental data are compared. The difference between images of synthetic microstructures in transmitted and reflected light is discussed.

The width and spectral dependence of the complex refractive index of upper layers in thin-film MBE-grown GaAs structures can be measured by means of spectral ellipsometry, that is, a nondestructive noncontact optical method, using an oscillatory model of dielectric function.

Methods for evaluating readiness of mining technologies to robotization and expediency of mining robotization are proposed.

For Lower Amur region as example, the features of bird distribution over various habitats from undisturbed to urban ones are described on the basis of the results of long-term investigations. The trends of territorial changes in overall characteristics of bird complexes are determined. The spatial-typological structure of bird complexes and the main structure-forming environmental factors are revealed, their role in the organization of bird communities in the Lower Amur Region is estimated.

The main bird communities of the Norsk reserve are considered. The highest density of bird population (150

A reliable decrease in the number of synanthropic and bush-forest birds, an increase in the number of polyphages and air-soaring birds were demonstrated on the basis of accounting of birds in Novosibirsk in the years 1978

Season

Distribution of millerbirds over the territory of the upper Don is limited to a small number of near-water biotopes. In this connection, a special rope is played by anthropogenically transformed territories. Works performed in 1999

To evaluate inter- and intrapopulational divergence of the Siberian White crane (Grus leucogeranus Pallas), a phylogenetic analysis of mitochondrial DNA D-loop fragment (512

Demographic characteristics (age structure, increase in population, female prolificacy) of sables in the Trans-Ural region are investigated on the basis of the data collected during the years 1951-1968 and 1978-1990. The revealed statistically valid differences in the parameters allow concluding that a substantial intensification in the reproduction process in sables occurred in the region in the end of the XX century, and the cyclic character of number dyn

Measurements of the length of otoliths extracted directly from salmon-like fish (SF), which are a component of the diet of Baikal seal (Pusa sibirica Gm.), and from the alimentary tract of the animals were carried out. It was calculated on the basis of the analysis of the content (otoliths) of the alimentary tract of seal and the obtained regression equations that the modern population of seal annually consumes ~ 9,3 mln of SF individuals mainly of the medium size for the species. The biomass of consumed fish is estimated to be 1772 t/year (lim 1393

The structure of 756 summer and 169 winter nest burrows belonging to different age groups of male and female Daurian souslik individuals was investigated at the northern outlying regions of the natural habitat during seasonal and all-year-round stationary investigations in 1980

Comparison of the data characterizing the population structure of mole voles in the central part of the natural habitat (The Ural Region) and at its north-eastern periphery (Novosibirsk Region) shows that habitation under ecologically pessimal conditions does not affect the density of populations and number of members in separate families, but causes a decrease in the lifetime of individuals and, as a consequence, an increase in the reproductive output at the level of a population due to an increase in the number of reproducible females. The features of changes in the occurrence of differently colored phenotypes in the geographic gradient revealed at the north-eastern periphery of the species habitat are similar to those in the central part of the habitat

Data obtained on the reproductive features, life duration, specificity of morphogenesis and genetic structure, trophic links, some physiological indices, bioaccumulation of moor frog inhabiting the territory of East Ural radioactive trace are generalized. It is shown that the stability of R.arvalis population existing for a long time under the conditions of radionuclide contamination is sustained due to the selective survival probability of the individuals with high stability of morphpgenesis and inherent physiological features.

Kinetics and equilibrium of the sorption of Cu(II), Zn(II) and Cd(II) ions on a natural cellulose-containing material

A direct atomic emission method developed for measuring mercury content in powder carbon adsorbents is shown to perform the simultaneous analysis of nuisance admixtures. It provides an express control of mercury content in carbon based modified adsorbents (CMA) used for mercury removal from wastewaters. Analysis accuracy is improved due to simultaneous calculations using several analytical lines of the element, mercury content range being 0.0001

Sorption properties of various kinds of hydrolytic lignin

Indirect electrochemical oxidation of phenol is studied in acid (pH 2

Inversion voltammetry method applying glass carbon electrode was developed for the case specific mercury control. Mercury concentration was measured in the lithium-containing solvents and in modified carbon adsorbents (MCA). In MCA mercury content was measured after weighted sample burning and mercury stripping by the H2O2 containing 1 M HCl solution. Diapason of mercury concentration measurement was 0.2

Experimental data on the dissolution of calcite in water and in the solution of sulphuric acid were treated with the help of the generalized equation of heterogeneous kinetics. The possibility of using this method to determine the kinetic characteristics of the process was demonstrated. The data on the limiting stage were obtained; rates constants of calcite dissolution under different conditions were calculated.
A procedure to calculate technological parameters of the process leading to a decrease in the level of acidation of natural water was proposed.

Nanocrystalline tin oxide films were obtained on glass and metal substrates by immersing into the solution of tin carboxylate, centrifuging of the substrate with the solution, followed by thermal treatment. A distinguishing feature of the proposed method is the use of extraction for the synthesis of precursors, which allows us to obtain the precursor material free from any impurities. It was established that the sensitivity of tin oxide films to the gases depends on pyrolysis temperature and is maximal for the films pyrolyzed at 400 oC.

Dynamics of the accumulation of oxygenated groups during coal ozonation in chloroform is investigated. It is shown that the oxygen content of the organic matter of coal is determined by the availability of reaction centres for ozone molecules. High-molecular water-insoluble acids prevail among coal ozonation products.