Home – Home – Jornals – "Philosophy of Education" 2010 number 2

We present results of a complex study of evaporite sediments from one of the small saline lakes with carbonate sedimentation in the Ol’khon area and substantiate their high significance for paleoclimatic reconstructions. The mineral composition of the bottom sediments was studied by XRD analysis, IR spectroscopy, scanning electron microscopy, elemental analysis (SR-XFA), etc. By decomposition of the complex XRD profiles of carbonate minerals into individual peaks by Pearson VII function, we identified carbonate phases in each sample and determined their proportions. A high-resolution carbonate record has been obtained for the first time for the lacustrine sediments. It bears the information about the stratigraphic distribution of Mg-calcites (a continuous series of structurally disordered low- to high-Mg calcites, up to Ca-dolomites), in which the amount and proportions of phases with different Mg contents are controlled by Mg/Ca, salinity, and total alkalinity of the lake water changing depending on the climatic cycles and lake level fluctuations. Comparison of the carbonate record for the Holocene section dated by the radiocarbon (¹⁴C) method with results of lithological, diatom, and palynological analyses, data on stable isotopes (δ¹⁸ O and δ¹³ C), and the distribution of some geochemical indicators of climatic changes permitted the reconstruction of the intricate evolution of the Lake Tsagan-Tyrm basin, which was controlled by the regional climate from the Atlantic period to the present time. The directed change in various characteristics of essentially carbonate sediments evidences that the Ol’khon regional climate has become more arid in recent 6.5 kyr. Moreover, drastic frequent changes of climate and, correspondingly, the Lake Tsagan-Tyrm water level in different periods of its existence have been revealed. The widespread saline and brackish lakes in southern East Siberia, Mongolia, and North China and the highly informative (in terms of paleoclimate and paleolimnology) carbonate sediments might help to recognize the general tendencies of paleoclimate changes and local fluctuations in Central Asia.

In 1950, D. Korzhinskii hypothesized that minerals in metamorphic reactions can be in local equilibrium. Proceeding from this idea, G. Fisher and R. Joesten later developed a realistic model of metamorphism kinetics. The model included diffusive mass transport in intergranular fluid controlled by the concentrations of components and chemical potential gradients, local-equilibrium reactions between minerals and pore fluid, mass balance of components, etc. The Korzhinskii–Fisher–Joesten model can provide clues to the duration of metamorphic events as inferred from mineral chemistry, free energy of phases, and rock textures and structures. The respective modeling of metamorphic reactions, with regard to spatial distribution of mineral grains, has implications for the transport and balance of chemical components. The balance of components (except volatiles) is restricted to domains of hundredth fractions of a cubic millimeter to several cubic meters. This may be the minimum size of an elementary domain in which minerals are in local equilibrium.

Many gold fields host scores of discovered gold ore occurrences with unclear prospects because of their insufficient geological exploration. Since exploration is expensive, the occurrences should be first appraised by low-cost methods. Studying the typomorphic features of minerals from the gold fields of the Upper Yana–Kolyma region, we have established a relationship between the contents of isomorphic impurity elements (IIE) and the degree of solution supersaturation (DSS). Preliminary studies show that, based on this relationship, criteria can be developed for revealing “concealed” mineralogical-geochemical zonation and predicting mineralization to depth.
The determining factor for the behavior of IIE, depending on the DSS, is their distribution coefficient ( K ) with respect to the host element. If K > 1, the content of these elements decreases with increasing DSS during ore deposition; if K < 1, it increases. When a solution contains IIE with K > 1 and K < 1, they behave according to their distribution coefficients. In other words, when the DSS increases during ore deposition, IIE with K >1 will be typical of early mineral segregations, and IIE with K < 1, of late ones. If the crystallization front migrates, this must give rise to a vertical zonation in the content of both groups of elements. The content of elements with K >1 will decrease upsection, and that of elements with K < 1 will increase (“concealed” mineralogical-geochemical zonation).
In connection with this subject, the paper reports data using native gold as an example. The behavior of Ag, Sb, Hg, Cu, Ni, and Co is discussed depending on the depth of deposit formation from the paleosurface (deep-seated → shallow); in the vertical section of individual deposits; depending on mineralization stages; in the cross-section of individual crystals with a zonal structure. The behavior of Ag, Sb, and Hg has been shown to be opposite to that of Cu, Ni, and Co in all these aspects. With respect to Au, the first group of elements has K < 1, and the second one, K > 1. Copper and antimony are of particular interest. In the vertical section of individual deposits, the Cu content of gold increases with depth and the Sb content decreases. The Cu/Sb ratio can be used to estimate the erosional truncation level of deposits and thus predict their extension to depth. Examples of well-explored deposits are given.

Kerogens from the Lower and Middle Cambrian deposits of the Kuonamka Formation in the northeastern Siberian Platform have been analyzed by modern methods. We have determined the pyrolytic characteristics of insoluble organic matter and the contents of C, H, S, N, O, and the stable C isotope. The type and catagenesis of organic matter have been estimated, as well as the generating potential of oil source rocks. It has been found that the composition of kerogens taken from the Molodo River outcrops was affected by supergene processes and that the degree of their alteration is related to the organic content of rocks and their structure.

We generalized experimental data on the structural group composition and macrostructural characteristics of high-molecular compounds (HMCs) — hydrocarbons, resins, and asphaltenes — from more than 180 crude oil samples extracted from different oil fields of Eurasia.
Most of oil resin molecules contain 1–3 structural blocks, each consisting of 0–3 aromatic and 0–5 naphthenic rings in different combinations, with the total number of rings in each block not exceeding 5–6. The average molecular weights of resins are no more than 100–1500 a.m.u. Asphaltenes differ from resins from the same source in the larger number of structural blocks (mainly tri- or tetracyclic aromatic) in molecule (up to five), lower degrees of substitution of aromatic cores, and smaller portions of carbon atoms in saturated fragments. The average molecular weights of asphaltenes measured by naphthalene cryoscopy do not exceed 2500 a.m.u.
Owing to intermolecular interactions, HMCs form various associates and polymolecular particles, including quasi-crystalline “batches” and multibatch aggregates. Spontaneous disintegration and formation of such particles make the oils dynamically equilibrium polydisperse systems.
We have developed the main regularities of compositional and structural changes of HMCs depending on the depth of occurrence, age, and lithologic composition of oil-bearing deposits.
Being chemically labile heteroatomic substances, petroleum HMCs are more rapidly subjected to compositional and structural transformations than hydrocarbons, i.e., are more responsive to changes in strata conditions.

Naphthene-benzenes, naphthene-naphthalenes, and naphthene-phenantrenes have been extracted with methanol from mono-, bi-, and triarene fractions of oils of different genetic types from the West Siberian, Timan-Pechora, North Caucasian, and Pannonian (Serbia) oil-and-gas-bearing basins. The hydrocarbon composition and molecular-mass distribution (MMD) of naphthene-arenes have been determined by mass spectrometry. Naphthene-benzene and naphthene-naphthalene molecules contain one to six naphthenic cycles, whereas naphthene-phenantrene molecules contain one to three haphthenic rings. The number of carbon atoms in the alkyl groups of naphthene-benzenes, naphthene-naphthalenes, and naphthene-phenantrenes reaches 38, 20, and 19, respectively. Distinctive features of group compositions and MMD of naphthene-arenes have been revealed in oils generated by different organic matter.

Specific deformation patterns in sediments associated with small-amplitude strike-slip faults in the basement have been recognized over a large territory of the West Siberian basin due to 3D seismic exploration advance. These patterns represent shear structures which turn to be a phenomenon beyond the classical views of the regional basin architecture. Many densely faulted oil and gas fields of a complex geometry in reservoir rocks of a wide stratigraphic range fall in zones of shear structures. Prospecting, test drilling, and oil enhancement activities in these fields are risky without a solid mechanic and kinematic background based on simulation of sedimentary fracture patterns which are associated with basement-involved strike-slip faults and may govern hydrocarbon migration as structure controls, fluid channels, or screens.

The harmonic electromagnetic field of a vertical magnetic dipole above an anisotropic half-space has been simulated using a forward algorithm for layered conductive media with inclined anisotropy. Inclined anisotropy has been found out to change the typical behavior of frequency and transient responses. Qualitative interpretation of FD loop-loop responses of a conducting earth with inclined anisotropy requires taking into account the receiver azimuth dependence of apparent resistivities. In the case of time-domain measurements, this dependence is absent but the apparent resistivities are higher at late times.

In the course of scientific collaboration, we were involved in discussion on the capacity of a vertical loop configuration to resolve thin high-resistivity layers, which is quite an interesting and largely debated point. We report a small forward modeling study including an algorithm based on an analytical solution by separation of variables and a respective program for computing the time-domain TEM field of a horizontal magnetic dipole. We infer that the subsurface vertical loop system shows no critical advantage in resolving thin insulating inclusions.

We have studied Jurassic sections in the Predyenisei subprovince of the West Siberian petroleum basin, which were penetrated in the Vostok-1, Vostok-3, and Vostok-4 stratigraphic wells. The Urman, Togur, Ilan, Peshkovo, Tyumen’, Naunak, and Mar’yanovka Formations are described from a detailed comprehensive core analysis and log data. The depositional environment for these sediments was predominantly continental. There is evidence for short transgressions in the Ilan (Lower Toarcian) and Peshkovo (Upper Toarcian) Formations, as well as the Upper Urman (Upper Pliensbachian) and the Upper Tyumen’ (Bajocian) Subformations. In the Upper Naunak Subformation (Oxfordian), there was a change of facies from continental to littoral continental and littoral marine. The Mar’yanovka Formation developed in normal marine shallow- or moderately deep-water environments. Although good reservoirs are common throughout the Jurassic section in the southeast of West Siberia, only small, lithologically screened deposits are predicted here.

New data have been obtained on the paleogeographic and stratigraphic assignment of Neopleistocene morpholithogenesis in the Chuya basin. They were derived from analysis of topographical maps, digital elevation models, and medium- and high-resolution satellite images as well as a textural and facies characteristic of Quaternary sections. Near the basin side, a paragenetic association of sediments is widespread. These sediments, laid down by fluid debris flows and mudflows, formed a ridge terrain during the emptying of a Late Quaternary paleolake. A diluvial–erosional origin of a series of small parallel scarps has been suggested. They are usually interpreted as wave-cut benches, which mark temporary levels of a glacier-dammed lake. We have examined geological evidence for a high glacial dam with an age of maximum glaciation inside the Chuya basin. Because of the dam, glacial floods during the Middle Neopleistocene were larger than those during the Late Neopleistocene.

The phase state of fluid in the system H₃BO₃–NaF–SiO₂-H₂O was studied at 350–800 °C and 1–2 kbar by the method of synthetic fluid inclusions. The increase in the solubility of quartz and the high reciprocal solubility of H₃BO₃ and NaF in water fluid at high temperatures are due to the formation of complexes containing B, F, Si, and Na. At 800 °C and 2 kbar, both liquid and gas immiscible phases (viscous silicate-water-salt liquid and three water fluids with different contents of B and F) are dispersed within each other. The Raman spectra of aqueous solutions and viscous liquid show not only a peak of [B(OH)₃]⁰ but also peaks of complexes [B(OH)₄]^–, polyborates [B₄O₅ (OH)₄]^2-, [B₃O₃ (OH)₄]^–, and [B₅O₆ (OH)₄]^–, and/or fluorborates [B₃F₆O₃]^3-, [BF₂ (OH)₂]^–, [BF₃ (OH)]^–, and [BF₄]^–. The high viscosity of nonfreezing liquid is due to the polymerization of complexes of polyborates and fluorine-substituted polyborates containing Si and Na. Solutions in fluid inclusions belong to P–Q type complicated by a metastable or stable immiscibility region. Metastable fluid equilibria transform into stable ones owing to the formation of new complexes at 800 °C and 2 kbar as a result of the interaction of quartz with B-F-containing fluid.
At high concentrations of F and B in natural fluids, complexes containing B, F, Si, and alkaline metals and silicate-water-salt dispersed phases might be produced and concentrate many elements, including ore-forming ones. Their transformation into vitreous masses or viscous liquids (gels, jellies) during cooling and the subsequent crystallization at low temperatures (300–400 °C) should lead to the release of fluid enriched in these elements.

⁴⁰Ar/³⁹Ar dating yielded the reliable ages of andesite from the Unerikan complex (102.1 ± 1.4 Ma) and basaltic andesite from the Burunda complex (107.3 ± 2.4 Ma). The established age of volcanism is close to one of the stages of formation of the Khingan-Okhotsk volcanoplutonic belt. The petrography and geochemistry of basic, normal-basic, and normal rocks point to their dual character: They combine features specific for tholeiitic and calc-alkalic rocks. Most likely, these rocks formed in the setting of transform continental margin.

Published and new data on the Earth’s past magnetic field have been interpreted in terms of its links with the frequency of magnetic polarity reversals and with tectonic events such as plume-related eruptions and rifting. The paleointensity and reversal frequency variations show an antiphase correlation between 0 and 160 Ma, and the same tendency, likely, holds for the past 400 Myr. The geomagnetic field intensity averaged over geological ages (stages) appears to evolve in a linearly increasing trend, while its variations increase proportionally in amplitude and change in structure. Both paleointensity and reversal frequency patterns correlate with rifting and eruption events. In periods of high rifting activity, the geomagnetic field increases (15 to 30%), and the reversals become about 40% less frequent. Large eruption events between 0 and 150 Ma have been preceded by notable changes in magnetic intensity, which decreases and then increases, the lead being most often within a few million years.

Rock complexes in Mongolia experienced two remagnetization events. Almost all secondary remanence components of normal polarity were acquired apparently in the Cenozoic, after major deformation events, and those of reverse polarity were associated with intrusion of bimodal magmas during the Late Carboniferous–Permian reverse superchron. Active continental-margin sequences in some areas of Mongolia were folded prior to the Late Carboniferous–Permian magnetic event. The primary origin of magnetization in Late Paleozoic and Mesozoic rocks has been inferred to different degrees of reliability. According to paleolatitudes derived from most reliable paleomagnetic data, the analyzed rocks were located far north of the North China block throughout the Late Paleozoic and Early Mesozoic. Mongolia, as well as Siberia, moved from the south to the north in the Paleozoic, back from the north to the south between the latest Triassic and the latest Jurassic, and remained almost within the same latitudes in Cretaceous and Cenozoic time. These paleolatitudes show no statistical difference from those for the Siberian craton at least since the latest Permian (275–250 Ma). Older Mongolian complexes (with ages of 290, 316, and 330 Ma) likewise might have formed within the Siberian continent, which makes their paleomagnetic determinations applicable to calculate the polar wander path for Siberia. The paleolatitudes of Early Carboniferous sediments in Mongolia differ significantly from those of Siberia, either because of overprints from the reverse superchron or because they were deposited away from the Siberian margin.

Chloroform extracts of coals of different genetic groups and different ages have been studied by chromato-mass-spectrometry, namely, Devonian liptobioliths from the Barzas region (Kuznetsk Basin) and Lower Cretaceous humites and sapropelites from the Kangalas and Taimylyr deposits, respectively (Lena Coal Basin). It has been established that the most ancient Devonian liptobioliths formed in coastal environments. Lipids of different biotas of marine and continental genesis, including resins of early Conifers, were the source of biomarker molecules. The Mesozoic humic and sapropelic coals differ little in chemofossil biomarkers, which might be related to their significant bacterial transformation and biosynthesis of chemofossils mainly by prokaryotes.

It is suggested to estimate the Pliocene–Quaternary fault activity in a formalized way from synthesis of different data. The respective database consists of two main sections: general information and basic fault parameters and geomorphic, structural, paleoseismic, seismological, geophysical, geodetic, engineering-geological, hydrological, and meteorological data. The fault characteristics are scored according to their significance, and the cumulative score measures the fault activity. With this approach, the faults in the Barguzin and Tunka rift basins and in the northeastern flank of the Baikal Rift system have been divided into five activity classes (low, medium, relatively high, high, and very high activity) and mapped correspondingly. It has been recommended that the concept of a hazardous fault, as updated with regard to the activity rating, refer to faults of relatively high, high, and very high activity. Thus identified hazardous faults within the study area are quite few (4–8 %), though this percent may increase slightly as more input data become available. The underestimation cannot be dramatic because all known seismological and structural characteristics of faults essential for the activity rating have been already taken into account. The new approach may be useful in seismic risk assessment and in choice of sites for instrumental monitoring of seismicity.

The article discusses the effect on the measured signals of a multicoil electromagnetic tool offset with respect to the borehole axis. The tool is a nonconductive cylindrical body with several coaxial coils. It is assumed that the borehole is vertical and the medium is axisymmetric with respect to the borehole axis.
A number of computations based on the finite-element method were carried out. Simulations took into account the tool body and finite sizes of coils. A wide range of transmitter-receiver spacings (0.18–1.0 m) was studied. The operating frequency was 1.75 MHz. Different drilling muds and values of the tool offset were examined. It was shown that, for highly conductive drilling muds, the type of dependence between apparent resistivity and eccentricity varies greatly with the array length. It was discovered that increasing the contrast between invaded zone resistivity and mud resistivity also increases the eccentricity effect. The eccentricity effect increases with the decrease in mud resistivity and decreases as the array length increases. Also analyzed was the effect of the tool offset on electromagnetic field pattern.

This is a snapshot of the today's views of the Earth with its geospheres and terrestrial and extraterrestrial triggers of its dynamics and energy sources. Along with the presented brief historic outline of the planetary evolution, these data can make a basis for creating in the future a truly global model of the Earth's dynamics and evolution.

The paper is a synthesis of models for basic geodynamic processes (spreading, subduction transient into collision, mantle plumes) in relation with the Earth's evolution and regularly changing geodynamic parameters. The main trends and milestones of this evolution record irreversible cooling of the Earth's interior, oxidation of the surface, and periodic changes in geodynamic processes. The periodicity consists of cycles of three characteristic sizes, namely, 700-800 Myr global cycles, 120, 90, and 30 Myr smaller cycles, and short-period millennial to decadal oscillations controlled by changing Earth's orbital parameters and, possibly, also by other extraterrestrial factors. Major events and estimates of mantle and surface temperatures, heat flow, viscosity, and the respective regimes of convection and plume magmatism have been reported for the largest periods of the Earth's history: Hadean (4.6-3.9 Ga), Early Archean (3.9-3.3 Ga), Late Archean (3.3-2.6 Ga), Early Proterozoic (2.6-1.9 Ga), Middle Proterozoic (1.9-1.1 Ga), Neoproterozoic (1.1-0.6 Ga), and Phanerozoic with two substages of 0.6-0.3 and 0.3-0 Ga.
Current geodynamics is discussed with reference to models of spreading, subduction, and plume activity. Spreading is considered in terms of double-layered mantle convection, with focus on processes in the vicinity of mid-ocean ridges. The problem of mafic melt migration through the upper mantle beneath spreading ridges is treated qualitatively. Main emphasis is placed on models of melting, comparison of experimental and observed melt compositions, and their variations in periods of magmatic activity (about 100 kyr long) and quiescence. The extent and ways of interaction of fluids and melts rising from subduction zones with the ambient mantle remain the most controversial. Plume magmatism is described with a "gas torch" model of thermochemical plumes generated at the core-mantle boundary due to local chemical doping with volatiles (H₂, CH₂, KH, etc.) which are released from the metallic outer core, become oxidized in the lower mantle, and decrease the melting point of the latter. The concluding section concerns periodicities in endogenous processes and their surface consequences, including the related biospheric evolution.

The Jinping-Song Da rift structure joining the Emeishan Large Igneous Province is composed of Permian high- and low-Ti volcanic and volcanoplutonic ultramafic-mafic associations of different compositions and genesis. High-Ti picrites, picrobasalts, basalts, and dolerites are enriched in LREE and depleted in HREE and show low Al₂O₃/TiO₂ ratios (~4), commensurate ε_Nd (T) values (+0.5...+1.1) and low (Th/Nb)PM ratios similar to those of OIB-enriched mantle source. The established geochemical characteristics evidence that the parental melts of these rocks were generated from garnet lherzolite at the depths of garnet stability (~200 to 400 km). Later, high-Mg low-Ti volcanics (komatiites, komatiitic basalts, and basalts) and associating small peridotite-gabbro massifs and komatiite-basalt dikes were produced as a result of ~20% partial melting of depleted water-poor (?0.03 wt.% H₂O) peridotite substratum from the hottest upper part of mantle plume at relatively shallow depths (100-120 km). The LREE-depleted komatiites and komatiitic basalts are characterized by low (Ce/Yb) _CH values, ¹⁸⁷Re/¹⁸⁸Os = 0.05-1.2, ⁸⁷Sr/⁸⁶Sr = 0.704-0.706, positive ε_Nd (T) values (+3...+8), γ_Os = -0.5...+0.9, and strong negative anomalies of Ba, K, and Sr on the spidergrams. The scarcer LREE-enriched komatiites, komatiitic basalts, and basalts vary greatly in chemical composition and values of ε_Nd (T) (+6.4...-10.2), ⁸⁷Sr/⁸⁶Sr (0.706-0.712), and γ_Os (+14.8...+56), which is due to the different degrees of crustal contamination of parental magmas. The Rb-Sr isotopic age of basaltic komatiite is 257 ± 24 Ma. The Re-Os age determined by analysis of 12 komatiite samples is 270 ± 21 Ma. These data agree with the age of flood basalts of the Emeishan Large Igneous Province. The komatiite-basalt complex of the Song Da rift is still the only Phanerozoic PGE-Cu-Ni-complex of this composition. The geochemistry of accompanying Cu-Ni-PGE-ores confirms their relationship with komatiite-basaltic magmatism.

The paper reports the results of integrated geological, petrological, geochemical, and geochronological studies of the Tastau igneous ring complex in the Zaisan orogen of eastern Kazakhstan. Interaction between felsic and mafic magmas has been studied. Hybrid rocks are represented by gabbros and diorites injected into a granitic magma chamber. They occur as dikes and pillow-like and globular mafic bodies variously disintegrated and mixed with host granitoids. The age of synplutonic rocks is 242±20 Ma (U/Pb zircon dating), which is, with regard to analytical error, substantially younger than it was presumed.
Mechanisms of interaction between felsic and mafic magmas have been studied. They include mechanical (mingling) and chemical (mixing) inreractions, which produce composite mixtures and hybrid rocks. The ratios of mafic to felsic components involved in the formation of intermediate rocks were calculated from major elements by regression analysis and tested with regard to rare and trace elements. The model for mingling includes quenching of the mafic melt when it is injected into the granitic magma chamber, decomposition of crystalline fragments, dispersion of fragments and crystals in the magma chamber under conditions of rapid turbulent flow, and enrichment of felsic magma with femic components to produce monzonitic magmas.

In this paper I present results of IR spectroscopic measurements of water solubility in Al-bearing periclase and ferropericlase (Mg# = 88) synthesized at 25 GPa and 1400-2000?C. The IR spectra of their crystals show narrow absorption peaks at 3299, 3308, and 3474 cm^-1. The calculated H₂O contents are 11-25 ppm in periclase (Al₂O₃ = 0.9-1.2 wt.%) and 14-79 ppm in ferropericlase (Al₂O₃ = 0.9-2.9 wt.%). Ferropericlase contains more H₂O and Al₂O₃ than periclase at 1800-2000?C. I suggest that addition of Al₂O₃ does not influence the solubility of water in ferropericlase but can favor the additional incorporation of Fe₂O₃ into the structure. The incorporation of Fe³⁺ into ferropericlase increases water solubility as a result of iron reduction to Fe²⁺. It is shown that water has limited solubility in ferropericlase from mantle peridotite; therefore, ferropericlase cannot be considered an important hydrogen-bearing mineral in the lower mantle.

This work is a review of the modern concepts of the accumulation of Fe and Mn in the Baikal bottom sediments and the regularities of formation of iron-manganese (including phosphate-bearing) nodules in the lake. Special attention is given to the probable participation of hydrothermal water in this process and the genesis of ancient nodules deeply buried in the Baikal sediments. The possible relationship between the shore ores and the nodules in the bottom sediments in the adjacent Baikal regions has been first shown.

Gold ore districts in the Siberian (North Asian) craton and bordering terranes have been studied. Studies showed the long duration of gold concentration processes (Early Cambrian to Late Mesozoic and Cenozoic) and the influence of structural geologic, magmatic, and metallogenic factors on the formation of ore districts. The largest Late Mesozoic (J-K) accumulations of gold deposits in southeastern Russia were discovered in the Aldan-Stanovoi Shield and on the northern margin of the Argun superterrane in the Aldan (Yakutia), Balei (Transbaikalia), and Gonzha (Upper Amur area) ore-placer districts.
The geologic-geophysical positions of these three districts have been compared. All of them are situated in zones of influence of variously trending long-lived deep faults, bordered by large Precambrian uplifts, and spatially (paragenetically) related to local magma chamber domes of Late Mesozoic (J-K) intrusive, subvolcanic, and extrusive-effusive bodies, dikes, and terrigenous-pyroclastic blankets. The areas of Jurassic-Cretaceous volcanoplutonic rocks are related to the influence of the East Asian sublithospheric "superplume".
All this confirms the important ore-controlling role of large long-lived deep faults (in the form of global and regional gravity gradient zones) in the distribution of highly productive precious-metal ore-magmatic systems. This suggests that the junctions between gravity gradient zones of different trends and ranks are important to the identification of gold prospects in metallogenic prediction studies and small-scale prospecting. The Archean-Proterozoic age and the great occurrence depth of the tectonic zones suggest that extensive long-lived mobile zones (before the post-Cambrian breakup of the Siberian craton) significantly affected further evolution of the orogenic belts bordering the craton and their metallogeny, including the distribution of precious-metal deposits.

The former stratigraphic chart of the Cambrian in the Turukhansk-Irkutsk-Olekma region of the Siberian Platform was compiled in 1986 and approved in 1988. Large amounts of data were obtained from new wells drilled in the western and northern parts of the region during the preceding 20 years. Modifications necessitated by new data entail an indefinitely continuous series of revised facies zonation, recognition of new facies areas, regions and zone, as well as definition of a regional early Mayan stratigraphic hiatus. A new local stratigraphic division is the Olenchima Member (base of the Evenk Formation) underlain by a hiatus. The term Kochumdek Formation is no longer used in the Bakhta region, and its lithologically distinct subformations (Yasenga, Moktakon, Mara, and Abakun) were raised to formation rank. The Olenchima Formation is no longer used in the Baikit zone; but instead, the Litvintsevo Formation was established here by correlation.

The paper discusses the evolution of the order Stromatoporoidea in the epicontinental sedimentary basin of the Siberian Platform and Taimyr during the Ordovician and Silurian. Specimens of the oldest genus, Priscastroma , were found in the middle of Middle Ordovician sediments. This genus is represented by the species Priscastroma . gemina Khrom., which has two forms, A and B. Tracing the emergence of new genera over time, we identified two distinct branches in stromatoporoid evolution.
The ancestor of the first branch is P. gemina f. A., which gave rise to the genus Cystostroma . The latter is the ancestor of two subbranches with predominant horizontal skeletal elements. The subbranches differ only in tissue microstructure. The genera Stromatocerium, Dermatostroma , and Aulacera display dense fibrous microstructure, whereas the genus Rosenella and its descendants display dense microstructure. The genus Lophiostroma , with a lamellar-fibrous tissue, may be a dead branch of evolution.
The ancestor of the second branch is P. gemina f. B., which gave rise to the genus Labechia and its descendants. This branch has a dense tissue, with predominating vertical skeletal elements.
Ordovician stromatoporoids from Siberia were compared with those from other basins of the world. Comparison shows that all the Ordovician genera from the epicontinental basin of the Siberian Platform and Taimyr originated here. Thus, this basin was one of the centers of stromatoporoid origin.

The three-dimensional shear velocity lithospheric structure at depths from 0 to 70 km beneath the southern Baikal rift system and its surroundings has been imaged by inversion of P -to-SV receiver functions from 46 digital stations operated in two teleseismic international projects in southern Siberia and Mongolia. The receiver functions were determined from teleseismic P waveforms and inverted to obtain depth dependences of S velocities at each station, which were related to tectonic structures. The computed vertical and horizontal sections of the 3D shear velocity model imaged a transition from relatively thin crust of the southern Siberian craton to thicker crust in the folded area south and southeast of Lake Baikal, with a local zone of thin crust right underneath the South Baikal basin. The velocity structure beneath the Baikal rift, the mountains of Transbaikalia, Mongolia, and the southern craton margin includes several low-velocity zones at different depths in the crust. Some of these zones may record seismic anisotropy associated with mylonite alignment along large thrusts.

A numerical experiment has been applied to explore the potentialities and the limitations of the inversion of IP-affected TEM responses of a two-layer earth with a polarizable layer above (Model 1) or below (Model 2) a nonpolarizable layer. The IP effects have been incorporated into the models via a Cole-Cole complex frequency-dependent conductivity. One of us computed synthetic in-loop and coincident-loop transient responses with added Gaussian noise, and the other performed single and joint inversion of the two sets of pseudoexperimental data. Model 1 turns out to be advantageous over Model 2 in TEM applications and gives a good fit of the Cole-Cole parameters (chargeability, IP time constant, and exponent) even in the absence of a priori information. In the case of Model 2, the lack of a priori information causes problems as to recognize which layer is polarizable, and the fit of the Cole-Cole parameters is generally worse. The layer thicknesses and resistivities are rather accurate in both groups of models, irrespective of whether a priori information is available. As the upper layer increases in thickness ( H ₁), the fit of its parameters ever improves in both models, while the parameters of the lower layer, on the contrary, contain a greater error. Joint inversion of in-loop and coincident-loop transients improves the fit in most cases.
Relative rms error (σ_rel) does not depend on the upper layer thickness for Model 1 but decreases as H ₁ increases in the case of Model 2. The error in joint inversion is times that in single inversion, which means that additional criteria other than σ_rel may be useful to estimate the inversion quality.

The paper explores the whole set of epistemological theoretical positions which reveal the essence of cognitive (informational) processes. The basic thesis is the thesis about the value of awareness as the means of increasing the instrumental variety of cognitive processes and the efficiency of thought. The obligatory components of rational (logic-verbal) thought are the ability to concentrate, focus attention on the object and reveal what is different and what is the same in the representing system. A necessary condition of the rational thought development is awareness and mastering the principles of ordering. The mentioned capabilities are formed and acquired in the process of mastering the study material of the course of logic. The significance of the results obtained in the process of studying logic is conditioned by their universal character and high degree of applicability.

The global character of education is directly connected with international relations, in which the basic intellect of the population of every country is manifested. This basic intellect corresponds to the traditions of the country and the global social life conditions in the modern world. In the article, there is studied the problem of the basis intellect as a consciously formed part of the mentality of the population, country and humanity as a whole. There is substantiated the key fundamental role of education in the development of basic intellect. There is ascribed even greater significance to the basic intellect in education, which reflects national, international, global, and regional characteristic of the people's consciousness. The tasks of Russian education on the international arena are preservation of the national identity in the structure of basic intellect and also fruitful international collaboration in the educational sphere.

The goal of the research is to analyze the category of activity. The research reveals that the socio-historical dimension of activity is studied from various scientific positions. The authors indicate that the philosophical research of activity was conducted beginning from the period of antique philosophy, more precisely, beginning from Aristotle's studies. However, the true scientific solution of the activity problem became possible only on the basis of the materialistic understanding of history. It is shown that the activity approach presupposes studying the human world as an activity world in the unity of all aspects of its development and realization. The authors consider the activity category in the perspective of the educational theory and practice. Within its framework they formulate an integral characteristic, competence, which is adequate to modern realities. The paper describes the specific competences corresponding to each type of activity, each competence being characterized by the set of the corresponding personal and job competences.

The paper deals with the argumentational nature of philosophical knowledge, the place and role of the argumentational procedures in philosophical education. The key issue of the paper is teaching philosophy through the prism of the theory of argumentation and its main principles. Some tools of the evolutional epistemology are involved in the research. The author has tried to study the argumentational component of education, taking into account the argumentational character of philosophical discourse.

The scientific heritage of N. N. Vorozhtsov is first of all the development of all the research directions that were laid by him in the foundations of the Institute. This review deals with the analysis of the main results obtained in these areas, mainly during the recent years. These works are connected with the chemistry of aromatic and heterocyclic compounds, mechanisms of the reactions of nucleophilic and electrophilic substitution, chemistry of perfluoroarenes, chemistry of natural compounds, and synthesis of functional materials.

New supramolecular adducts of cucurbit[6]uril with triangular cluster chloroaquacomplexes of Mo and W with mixed sulfido-selenido bridging ligands, {[W₃S₃Se(H₂O)₇Cl₂]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₂·15H₂O (1), {[W₃S_1.5Se_2.5Cl_1.5(H₂O)_7.5]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₅·18.5H₂O (2), and {[Mo₃SSe₃(H₂O)_7.5Cl_1.5]₂×(C₃₆H₃₆N₂₄O₁₂)}Cl₅·11H₂O (3) are obtained treating the mixture of products in Mo-S-Se-Br and W-S-Se-Br systems, isolated, and structurally characterized. In all compounds, the supramolecular structure is based on hydrogen bonded associates of cucurbit[6]uril molecule with two cluster cations.

In the crystal of K₄[Zn(Citrate)₂], two citrate anions coordinate Zn(II) cation with octahedral geometry in the [Zn(Citrate)₂]^4- complex anion, and the charge is balanced by four potassium ions. Crystal dat a: monoclinic, P2₁/c, a = 8.502(2) Е, b = 13.210(3) Е, c = 8.942(2) Е, І == 113.132(4)°, V = 923.5(4) Е³, Z = 2, R = 0.0229.

Two new zinc(II) complexes have been synthesized and studied by single crystal X-ray diffraction method: [Zn(L1)Cl₂]·2DMF (1) and [Zn(L2)Cl₂]·DMF (2) (L1 = 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine, L2 = 3,3′-bis[2-bis(2-ethylbenzimidazolyl)]-2,2′-dipyridine). Compound 1 is monoclinic, C2/c, a = 23.142(3), b = 11.845(1), c = 14.735(3) Å; compound 2 is orthorhombic, C222₁, a = 12.140(7), b = 16.283(9), c = 16.51(1) Å. In both compounds, Zn(II) cations are coordinated by two chlorine atoms and two benzimidazole nitrogen atoms in a slightly distorted tetrahedron fashion. Structural features responsible for fluorescent properties of the complexes are discussed.

2-(2-p-Tolyloxyethoxy)ethylchloroacetate is synthesized and its single crystal X-ray diffraction analysis is performed.

The synthesis of methyl-10,14,19,19-tetramethyl-4-oxo-20-oxahexacyclo[15.3.1.1^6.18.0^6.15.0^9.140^17.21] docosane-10-carboxylate III is performed and its molecular structure is determined. Compound III С₂₇H₄₀O₄ crystallizes in the monoclinic system with the cell parameters as follows: а = 12.8081(11) Å, b = 7.0384(6) Å, c = 12.8904(12) Å, β = 105.828(2)°, P2₁ space group, Z = 2, d = 1.273 mg/m³.

The crystals of 2-(6-chloro-4-(p-tolylamino)pyrido[3,2-d]pyrimidin-1-ium-1-yl)acetate (zwitterionic form) oxonium bromide, C₁₆H₁₃ClN₄O₂·Br^-·H₃O⁺ (I) were prepared and studied by single-crystal X-ray diffraction method. The compound crystallizes in the triclinic space group P-1 with a = 8.3121(8), b = 9.3885(8), c = 13.2903(12) Å, α = 106.788(2), β = 95.204(3), γ = 110.871(2)°, V = 905.81(14) ų, Z = 2; final R = 0.053, wR2 = 0.150. It is interesting that methylene C in the BrCH₂COOH molecule binds to the N1 of the pyrimidine ring. In the crystal studied, two neighboring organic molecules are connected by hydrogen bonds through carboxylate oxygen, oxonium and bromide ions to form a dimer.