Home – Home – Jornals – Thermophysics and Aeromechanics 2007 number 2

Complex study and comparative analysis were carried out for two gold deposits, Vodorazdel'noe and Ondol'toi, localized among carbonate and siliceous-carbonate rocks of the Il'chir Formation in southeastern East Sayan. The Vodorazdel'noe deposit is of gold-quartz-sulfide type; it formed at 275-300

Spinel-anthophyllite rocks that may be classified as ultrabasic low-Ca spinel amphibolites have been first discovered in the Kokchetav collision zone (northern Kazakhstan). They outcrop 2 km west of Enbek-Berlyk Village among schists and quartzites and are closely associated with spinel harzburgites and garnet pyroxenites. The main hosted minerals are spinel (hercynite) and anthophyllite. The rocks bear magnetite-hornblende-spinel-anthophyllite pseudomorphs with rounded and polygonal sections, which might have been resulted from the replacement of garnet grains. The prismatic anthophyllite crystals and scarce olivine relics contain elongate parallel spinel inclusions resembling spinel-olivine syntactic intergrowths in the Enbek-Berlyk spinel harzburgites. The spinel-anthophyllite rocks are similar to the associated spinel harzburgites in CaO, MnO, SiO₂, and Al₂O₃ contents but are richer in FeO and poorer in MgO ( F = FeO/(FeO + MgO) = 57% against 35% in the harzburgites). Geological, mineralogical, and geochemical data suggest that the spinel-anthophyllite rocks formed during the isochemical contact metamorphism of garnet-bearing spinel harzburgites, which contained more FeO and less MgO than garnet-free harzburgites of the same area. Variations in FeO and MgO contents in both types of harzburgites seem to be due to different chemical compositions of the chlorite protoliths of these rocks.

The relief of a vast area of western China and southern Mongolia was analyzed by methods of specialized morphometry to reveal structural and morphological features of recent tectonism. The tectonic relief of some part of the collisional system of Inner Asia, including the eastern Tien Shan, Govi Altay, and Bei Shan, is characterized by a general decrease in heights from west to east and a complicated system of domal ridges and intermontane troughs controlled by lenticular-rhombic faulting in the upper lithosphere. Submeridional transverse linear lows play an important role in the structure of the tectonic relief. It is likely that they are due to an irregular longitudinal flow of lithosphere blocks in the process of submeridional transverse compression. The structural signature of collisional geodynamics is traced eastward to the Ordos Province in a large meander of the Huang He and northward to the Hangayn Mountains, Tuva, and southern Gorny Altai. The predominance of domal deformations in young uplifts and no signs of their block desintegration suggest a crucial role of vertical tectonic motions largely responsible for the recent tectonic style of the eastern Tien Shan and Altay.

The Bohai Gulf basin is the largest petroliferous basin in China. Its Carboniferous-Permian deposits are thick (on the average, ca. 600 m) and occur as deeply as 5000 m. Coal and carbonaceous shale of the Carboniferous Taiyuan Formation formed in inshore plain swamps. Their main hydrocarbon-generating macerals are fluorescent vitrinite, exinite, alginite, etc. Coal and carbonaceous shale of the Permian Shanxi Formation were deposited in delta-alluvial plain. Their main hydrocarbon-generating macerals are vitrinite, exinite, etc. The carbonaceous rocks of these formations are characterized by a high thermal maturity, with the vitrinite reflectance R⁰ > 2.0%. The Bohai Gulf basin has been poorly explored so far, but it is highly promising for natural gas.

The study aims at developing petroleum potential criteria for reservoirs at the Paleozoic-Mesozoic boundary in West Siberia, by the example of the Chuzik-Chizhapka regional oil and gas accumulation in the Parabel District (Tomsk Region).
Oil and gas accumulations in formations of the Paleozoic-Mesozoic boundary were discovered in the Archa, Urman, Gerasimovka, Kalinovoe, North Kalinovoe, Tambai, Ostanino, North Ostanino, and other fields within the Chuzik-Chizhapka zone. Hydrocarbons are hosted by reservoirs of different lithologies and ages, including Devonian and Carboniferous organic, dolomite, and siliceous limestones and argillaceous-siliceous rocks.
Synthetic interpretation of seismic profiling and log data was used to model the geological structure of the Chuzik-Chizhapka regional accumulation, to develop potential criteria for reservoirs of the Paleozoic basement and weathering zone, and to suggest methods for detection of complex traps in upper Paleozoic strata.

The paper summarizes twenty years of studies in crustal sensitive zones. Sensitive zones show prominent geophysical responses to stress and strain changes and high-amplitude and distant preseismic and postseismic effects. Four sensitive zones are known today in Turkmenistan, Uzbekistan, Armenia, and northeastern China, which occur at junctions of large crustal blocks. High-amplitude and distant responses are due to deformation and high strain sensitivity of geophysical parameters along block boundaries. Data from sensitive zones are used to investigate earthquake-related effects as controlled by crustal heterogeneity and nonlinearity. These effects act also outside sensitive zones and should be taken into account when interpreting precursor signals. The knowledge of sensitive zones has important implications for active deformation along block boundaries.

The study addresses the space distribution of lithospheric density contrasts in 3D and 2D surface (spherical) sources of gravity anomalies to depths of 120 km below the geoid surface and their relationship with shallow deformation and Archean, Early Paleozoic, and Late Mesozoic geodynamic environments. The lithospheric section in northeastern Transbaikalia and the Upper Amur region includes two layers of low-density gradients attendant with low seismic velocities and low electrical resistivity. The lower layer at depths of 80-120 km is attributed to an asthenospheric upwarp that extends beneath the North Asian craton from the Emuershan volcanic belt and the Songliao basin. The concentric pattern of density contrasts in the middle and lower crust beneath the Upper Amur region may be produced by the activity of the Aldan-Zeya plume, which spatially correlates with the geometry of the asthenospheric upwarp as well as with the regional seismicity field, magnetic and heat flow anomalies, and stresses caused by large earthquakes and recent vertical crustal movements. The relationship between shallow and deep structures in the crust and upper mantle bears signature of horizontal displacement (subduction) of the lower crust of the Baikal-Vitim and Amur superterranes beneath the North Asian craton.

System As-Na-S-Cl-H-O was studied. The research was carried out in three stages: (1) selection of the most likely complexes resulting from arsenic sulfide dissolution, (2) calculation of their thermodynamic constants, and (3) comparison of calculated data with thermodynamic database obtained in tests with the solution of inverse thermodynamic problems using the Selektor program complex. The system As-Na-S-Cl-H-O included more than 230 dependent components, which were divided into two groups, base and functional. The former group includes components of the solution (NaCl, NaOH, Na₂S, NaHS, HCl, H₂S, H₂SO₄, sulfates, H₂SO₃, sulfites, thiosulfates, Na⁺, Cl^-, HS^-, S^2-), gas phase (43 components), and solid phase (orpiment, red arsenic, arsenolite, claudetite, arsenic, sulfur, sodium salts). Thermodynamic constants of the base components are contained in the Selektor database (they were borrowed from reference-books). The latter group includes 77 complexes labile in the solution but determining the solubility of arsenic and stability of its solid phases. Physicochemical modeling was performed in H₂S (≤0.01 m, pH = 1-10), Na₂S, and NaHS solutions at 25-250

A simple, reliable, and high-performance method has been proposed for direct determination of the isotopic composition of authigenic uranium in silica lacustrine sediments. The method is based on studying the kinetics of the selective extraction of authigenic uranium from sediments with weak solutions of ammonium hydrocarbonate followed by the ICP-MS analysis of the nuclides. To estimate the contamination of authigenic uranium by terrigenous one, the contents of ²³²Th and some other clastogenic elements in the extracts were measured simultaneously. The selectivity of extraction of authigenic uranium from the sediments treated with a 1% NH₄HCO₃ solution appeared to be no worse than 99%. The method was used to analyze the isotopic composition of authigenic uranium at several key horizons of a core dated before. The measurements directly prove that the ²³⁴U/²³⁸U values in Baikal water varied depending on climate, which contradicts the previous statements. The measured ²³⁴U/²³⁸U ratios in paleo-Baikal water match the values reconstructed from isotopic data for total uranium in the sediments on the supposition that the U/Th ratio is constant in the terrigenous part of the sediment. Direct experimental determination of total and authigenic nuclides in sediments enhances the potentiality of the method for absolute ²³⁴U-²³⁰Th dating of carbonate-barren lacustrine sediments, including those from Lake Baikal, within the intervals corresponding to the periods of glaciation, where the sediments contain a large fraction of terrigenous component. Given the fractions of terrigenous and authigenic uranium are accurately determined, we have an opportunity to study the variability of the sources of terrigenous matter and to refine the previous model for reconstructing the climate humidity in East Siberia.

Pegmatoid segregations containing three polymorphous Al₂SiO₅ modifications have been revealed in metamorphic rocks of the Tsel block localized in the Hercynian belt on the southern flank of Mongolian Altay. Petrographic study showed a successive substitution of polymorphs in the sequence: andalusite-kyanite-fibrolite-sillimanite. Estimated parameters of the host-rock metamorphism indicate that the mineral assemblage of pegmatoid veins formed at two successive stages of metamorphism: andalusite-sillimanite and kyanite-sillimanite. It is suggested that the transformation of Al₂SiO₅ from one to another polymorphous modification occurs by the ion exchange mechanism with the participation of muscovite.

The modern distribution of biogenic silica (SiO_2biog ) in Baikal surface (0-0.2 and 0-0.5 cm) sediments, its mass accumulation rates (MAR), and the processes responsible for this distribution were studied. The contents of SiO_2biog were determined in samples from 87 stations evenly distributed throughout the lake water area. These data were used to calculate the MAR of SiO_2biog and compile SiO_2biog and MAR distribution maps. The maps showed that the MAR varies significantly throughout the study area. Its highest values have been established in North Baikal. In Central and South Baikal the MAR values are much lower, and the minimum values are observed in the Selenga shoal. This MAR distribution pattern is consistent with the distribution of frustules of Aulacoseira baicalensis endemic diatoms throughout the surface sediments. Compared with other modern diatom species, this one has the most massive and heaviest frustules, which undergo the least dissolution when settling. This suggests that the above species plays a leading role in the accumulation of biogenic silica in modern Baikal bottom sediments, whereas the role of thin-walled species is minor because of their small mass and partial or complete dissolution in water on settling. Dilution of the sediments with terrigenous material is less significant for the SiO_2biog accumulation.

Facies zonation of the Paleozoic basement of West Siberian geosyncline and its surroundings is presented. Facies megazones are distinguished according to types of sedimentation. Analysis of lateral and successive sedimentary sequences shows that the available data are insufficient to map the facies distribution over the whole territory of the geosyncline for short time slices. Only the Late Devonian section is supported by data sufficient for the proposed facies zonation. Five megazones, I, II, III, IV, and V, are distinguished in the westward direction. First three megazones make up a single lateral facies succession and represent sedimentary environments on and around the Siberian continent. Megazone IV includes shallow-water volcanic and sedimentary rocks that compose the Kazakhstan continent bounded by Early and Middle Carboniferous sutures in the west and east. Megazone V comprises fold-thrust (island arc) complexes of the eastern Urals.
The main events in the geologic history of the region were associated with the interaction of two major crustal masses (Siberian and East European continents) and the young Kazakhstan continent in the oceanic space called the Paleoasian ocean. Only few fragments of this space occur in the present-day framework of the territory, the greatest part being sunk in subduction zones, especially in the large zone of the Main Uralian Fault.
Production and accumulation of organic matter in pre-Mesozoic deposits occurred on continental shelves, which are most promising for Precambrian and Paleozoic oil and gas.

The first catalogue of active regional faults of Cuba is presented. The seismotectonic map of Cuba is a base for studying the seismicity in this region. Of the 30 faults studied, only twelve are active. The main seismotectonic structure is the Bartlett-Cayman fault system, which borders the eastern and southeastern seismotectonic units in this region. Approximately 70% of Cuban seismicity is concentrated here. The Cauto-Nipe, Cochinos and Nortecubana faults border other seismotectonic units. The Nortecubana fault is the only one associated with a tsunami. All the faults are segmented. The faults described are related to the current tectonic stress regime of the Northern Caribbean. All the available information (maps, sections and profiles, photos, geological and neotectonic data on seismicity and focal mechanisms) is supported by a GIS.

We investigated the electromagnetic filed of a current loop in a conducting ferromagnetic cylinder for applications of casing monitoring in petroleum wells. We tested different transmitter-receiver configurations for excitation and recording of TEM and stationary magnetic fields, studied the responses to changes in electromagnetic and geometrical parameters of casing strings, and determined the intervals of highest sensitivity.

Being of global ecological significance, boreal forests of Siberia located at high latitudes of the Northern Eurasia represent the unique source of genetic, species and ecosystems diversity. Previously conducted research revealed a wide range of scientific problems regarding the studies on intraspecific diversity of woody species, estimation of the structure and current state of forest ecosystems, as well as their ordination and classification.
The use of the modern information technologies (the databases, species diversity indices, GIS) can promote the knowledge on Siberian boreal forests to the new high stage.

Diversity of algae, lichens, mushrooms, Bryophyta and higher vascular plants over the territory of West and Middle Siberia is considered. Their spatial arrangement is presented at the level of plain and mountainous territories, vegetation zones and sub-zones, altitudinal belts and the most widespread ecosystems.

Successions of the burnt areas of the northern and the southern taiga borders exhibit both common same and opposite features. The recolonization takes place fastly, during several weeks. The post-fire succession may be divided into three stages, with the typical peculiarities of the arthropod population. The community of the initial stage (1

The background and prospects of the terrestrial biodiversity investigations in the Baikal region are briefly overviewed. The most well studied spheres and

The main contribution into the greenhouse effect is made by CO2 and CH4 (60 and 15-18 %, respectively). The territory of the former Soviet Union accounts for the mean values of 11% of the global flux of

On the basis of the climate and vegetation database at the territory of Siberia, cluster analysis helped to reveal four clusters, i.e. geographic and climatic versions of the light coniferous grass forests (subtaiga). The leading climatic factors determining the boundaries between the clusters were revealed, the intracluster community and differences between clusters in the composition of forest-forming species were investigated. The revealed clusters were compared with the previously proposed versions outlined on the basis of vegetation.

Evaluation of the quality of underwood in the sub-tundra forests of Middle Siberia is made on the basis of analysis of its absolute and relative biometric indices. It is revealed with the help of factor analysis and descriptive statistics method that the vital capacity of underwood in the Extrteme North is characterized by apical growth and crown habitus.

Nitrogen resources in the biomass of phytocenosis, mortmass and humus of soil in n

A new approach to the understanding of the fungal community and to its an

This paper reveals the influence of catastrophic fires, 1998

Conducting the complex biological monitoring of large regions requires a choice of the necessary minimum of reference-point plots for observation that would fully enough reflect the state of biota at the species, population and cenosis levels. On the basis of an original cartographical method for the model territory

Changes in the parameters of carbon budget are considered in the following series of ecosystems: green subshrub larch forest unaffected by strong fire within the last 400 years

Results of the analysis of the vertical distribution of moss species in the high-mountain regions of the Khamar-Daban Ridge and their coenotic distribution are considered.

Species of genera Oxytropis DC. and Astragalus L. of alpine, mountain

A correlation between the high values of photosynthesis intensity in Pinus sylvestris L. and Picea obovata Ledeb. and definite combinations of weather conditions is investigated. It is shown that under the conditions of Baikal Siberia the maximal intensity of photosynthesis in conifers is observed under optimal soil wetting in early spring and during summer. The early spring maximum, which is observed at low soil temperature and high amount of accumulated water, can be much higher than the intensity of photosynthesis in summer. The summer maximum is observed after rains and heating of the lower soil horizons. The types of localization of the maxima of photolynthesis intensity observed under vegetation periods with different weather conditions are graphically marked out and characterized.

Resutls of the investigation of recreation transformation of oak forests of Belarussian Polesye are reported for oxalis and ashweed oak forests as examples. Indicators of recreation distortions are various characteristics of the forest synfolium (composition, density, dead-wood), underwood (composition, density), ground cover (species composition, projective cover, constancy of separate species). Complex indicators are the spectrum of vital forms and synanthropization indices. The changes in synanthropization of the oak forest flora over the gradient of recreation impact are considered.

The intraspecific variation of 26 qualitative and 37 quantitative characters of the generative sphere of Ribes atropurpureum C. A. Meyer and R. hispidulum (Jancz.) Pojark. growing on the Salair Ridge and introduced in CSBG was studied. Two taxonomixally significant characters were clarified and 5 new ones were determined. The levels of quantitative character variation were studied, 11 most stable characters were established for both species, 3

Comparative results of the investigation of the reserves of the top phytomass of lichen communities of aride, semi-aride and semi-humide areas of Tuva are presented. The dependence of the reserves of the top phytomass on the relief, climate and vital forms of dominating kinds is revealed.

The density of solid and liquid indium antimonide was studied by irradiating the samples with a narrow beam of monochromatic gamma-radiation in the temperature range of 293- 1950 K, including the range of melting

Thermal conductivity of gaseous refrigerant R404A was studied by the method of coaxial cylinders within the ranges of thermodynamic parameters 309

Conventional mechanical alloying (MA) is used to process mixtures of powders and generates a product that is also in powder form. MA can also be adapted to the preparation of coatings. For example, if a plate is attached to the wall of the milling container, the impacts by the milling balls activate the surface of the plate, deliver particles from the powder charge and pound them onto or into the surface. The structure and properties of the coating depend on the milling conditions and the properties of the components. In this paper, some aspects essential to the preparation of coatings are discussed. In particular, the importance of the relative hardness of the components is demonstrated by comparing the deposition of aluminium on steel and nickel on aluminium. Mechanical deposition is a promising method that may be utilized to produce a variety of coatings, but its successful application requires detailed understanding and control of the process.

M₃H(SO₄)₂ (M = Na, K, Rb) crystals, which are known to undergo superprotonic phase transition in the case of M = K and Rb, were prepared via mechanochemical process from equimolar M₂SO₄ and MHSO₄. The phase transitions of M₃H(SO₄)₂ prepared by mechanical milling using a high energy ball mill apparatus were confirmed from DTA-TG and conductivity measurements, although the phase transition temperatures were slightly lower than that of M₃H(SO₄)₂ prepared via solution process. The Rb₃H(SO₄)₂ prepared by mechanical milling showed reproducible ionic conductivity of 1×10^-3 S/cm at 230 ^oC under dry N₂ atmosphere.

Bismuth vanadate (BiVO₄) can be synthesized by mechanochemical reaction between bismuth oxide (Bi₂O₃) and vanadium oxide (V₂O₅) by using a planetary ball mill at ambient temperature. The following solid state reaction takes place mechanochemically during the milling: Bi₂O₃ + V₂O₅ ® 2BiVO₄. The particles of the sample look like agglomerates of fine grains with sizes less than 200 nm, and the agglomerates seem to be consisting of primary particles with several microns. The mechanochemical reaction ratio between Bi₂O₃ and V₂O₅ is saturated around 90 %. Heating treatment above 300^oC leads to the formation of homogeneous BiVO₄ with an increase in reaction ratio up to about 99.4 %. The mechanochemical method enables us to synthesize other bismuth complex oxides (BiAO₄; A = P, Nb and Sb).

We developed a method for narrowing the band gap in an oxide powder such as ZnO by doping other components such as S (sulphur) and N (nitrogen). The method consists of grinding a mixture of ZnO powder and non-metal element in air, followed by heating the milled sample at 400 ^oC. The former enables us to cause mechanochemical reaction between the components, and the latter allows us to enhance the bonding strength, as well as to remove the unreacted starting samples away from the surface of the oxide particles. The temperature has to be chosen in the heating operation so as to avoid any decomposition of the doped sample. The detailed information on doping S and N into ZnO powder, as well as its photo-catalytic reactivity, is shown in this report.

The objective of the present work was to show the beneficial effects of mechanochemical treatment of CuO-Al system for fabrication of composites consisting of Cu(Al) solid solution and Al₂O₃ ceramic with ultrafine grain microstructures. In particular, our research focused on explanation of the mechanism and kinetics of mechanochemically induced reactions in metal oxide-active metal system.

In the present investigation, the powder mixture of Al (70 at. %), Ni (15 at. %) and Cu (15 at. %) was mechanically milled in an attritor ball mill for 10, 20, 40, 60, 80 and 100 h in hexane medium at 400 rpm. The isothermal annealing of 100 h mechanically milled powder was done at 700 ^oC for 20, 40 and 60 h. The powders were characterized using X-ray diffraction, differential thermal analysis and transmission electron microscopy techniques. It was observed that mechanical alloying led to the formation of nano vacancy ordered (t₃) phase after 80 h of milling. In the case of 100 h mechanical milling (MM) and subsequent annealing at 700 ^oC for 20, 40 and 60 h, powder exhibited the formation of ordered and perfect t₃ phase with larger grain sizes. The phase formation and transformations in the above systems were discussed.