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The lithologic composition of basalts from the most complex sections of the Koltogory-Urengoi Rift is considered, and their ⁴⁰Ar/³⁹Ar ages are given: basalts from the lower section of Nikol'skaya BH-1 (Bergamak Formation) - 272.9 ± 10.5 and 249.5 ± 3.0 Ma, basalts from the uppermost section (Voinov Formation) - 247.5 ± 2.9 Ma, and basalts from the lower section of Tyumenskaya SDB-6 (Korotchaevo Formation) - 251.2 ± 2.0 Ma. According to these and the paleomagnetic data, trap magmatism began in the Koltogory-Urengoi Rift in the Permian and ended in the Early Triassic, whereas the paleontological data suggest its beginning in the Early Triassic and its termination in the late Middle Triassic.
In Tyumenskaya SDB-6 we have recognized both low-K tholeiitic and medium- to high-K subalkalic and calc-alkalic basalts, which form large alternating packets up to 480 m thick. This section is juxtaposed to the anomalous sections of the Siberian Platform trap formation near the margins of the Tunguska syneclise. The section of Nikol'skaya BH-1 is composed mainly of medium- and high-K subalkaline basalts with scarce flows of low-K ones. The low-K basalts differ from the medium- and high-K varieties in having lower contents of TiO₂, P₂O₅, Ba, Rb, Th, and ΣLREE.
The Tyumenskaya SDB-6 basalts are characterized by paleohypergene alterations, up to the development of more than five levels of alumina-ferruginous cuirasses, as well as superposed chloritization, sericitization (hydromication), carbonatization, zeolitization, silicification, and epidotization, whereas the Nikol'skaya BH-1 basalts are subjected mainly to carbonatization, chloritization, and hydromication.
We have concluded that the existence of a vast mega-arch above the superplume within the West Siberian geosyneclise in the Permo-Triassic was complicated by the Koltogory-Urengoi Rift. The Triassic rift deposits are both continental and marine sediments (sandstones and siltstones with glauconite, coccolith oozes, spherulitic lavas, and hyaloclastites). The basic volcanism within the rift showed the features of both rift and flood basalts as well as E-MORB.

In the northwestern part of the Sharyzhalgai uplift of the Siberian craton (Bulun block), the earliest sialic crust (grey-gneiss complex) is composed of plagiogneisses, their migmatized varieties, and subordinate plagiogranitoids. The petrochemical, trace-element, and Sm-Nd isotope compositions of rocks were studied, and U-Pb dating of zircons (SHRIMP II) was performed. Plagiogneisses and plagiogranitoids of trondhjemite and, more seldom, tonalite compositions are predominant; their compositions are typical of rocks of Archean tonalite-trondhjemite-granodiorite (TTG) complexes (Al₂O₃ ≥ 15%, Mg# = 28-38, (La/Yb) _n = 23-66, Sr/Y = 27-135, Eu/Eu* = 0.7-1.1). Plagiogneisses of meta-andesite-rhyodacite association are subordinate (SiO₂ = 59-69%, (La/Yb) _n = 7-32, Sr/Y = 11-24, Eu/Eu* = 0.5-0.7). Cathodoluminescent study of zircons revealed

The meteoritic-material-normalized REE patterns of rare-metal granite intrusions of the ore-bearing Kukul'bei complex (J₂-J₃), eastern Transbaikalia, were studied. It is shown that the intrusions were initially enriched in granitophile volatiles and trace elements (rare metals), i.e., this phenomenon is not related to the differentiation of their parental magma chambers. On the differentiation of the Kukul'bei rare-metal intrusions, the REE contents decrease in passing from granites of the main intrusive phase (MP) to late leucocratic differentiates (muscovite and amazonite granites), the differentiates become more enriched in granitophile elements, and their rare-metal contents drastically increase as compared with the MP granites. The ore-bearing bodies of muscovite and amazonite granites have extremely low REE contents and the highest contents of granitophile (including ore-forming) elements.
The REE patterns of the Kukul'bei intrusive differentiates are not universal among rare-metal intrusions. By the example of highly ore-bearing rare-metal granite intrusions of the Erzgebirge, Central Europe, it has been established that their late deep-seated differentiates (ultrarare-metal lithionite-zinnwaldite Li-F-granites) accompanied by highly productive Sn-W mineralization concentrate both granitophile elements and REE (particularly HREE). Among the studied Transbaikalian rare-metal intrusions of the Kukul'bei complex, only the differentiates of the most ore-bearing Sherlovaya Gora intrusive system belong to the above type. The analysis of the REE patterns of the Kukul'bei granites confirmed the earlier conclusions on the low ore potential of the rare-metal mineralization of the studied intrusive complex.

Metamorphism in the northern sector of the Main Uralian Fault (MUF) area, northern Urals, is considered by the example of the Salatim glaucophane-schist and Belokamenka kyanite-staurolite complexes. New isotope-geochronological dates for metamorphic rocks of the MUF area are presented. The obtained data evidence the existence of two metamorphic events, of Early and Late Devonian ages, which apparently correspond to the wedging-up of subduction paleozones.

Numerical experiments are applied to simulate propagation of broadband pulses which are transmitted by an electric dipole and travel in a uniform oil-bearing formation or in a layered reservoir with an oil-water interface. We calculate the frequency responses of the oil- and water-saturated layers as low-frequency filters for the propagating waves and find the respective cutoff frequencies. Attenuation rates are analyzed in the cases of incident nanosecond and picosecond pulses in uniform oil-bearing formations and those reflected from the oil-water interface. The low frequency filtering of pulses is investigated in terms of its effect on wave energy attenuation during propagation in oil-bearing rocks.

We suggest a new inversion method for frequency induction data implying the use of a new parameter, which has a simple analytical form in the case of a uniform subsurface. The new parameter is found from induction numbers measured in the field of a vertical magnetic dipole or a vertical magnetic dipole combined either with a horizontal electrical dipole or with a horizontal magnetic dipole. Compared with the classical methods, the new technique provides better resolved resistivity curves and faithful images of the subsurface at higher frequencies and smaller transmitter-receiver separations. The inversion algorithm is applied to amplitude and amplitude-phase data and provides reliable depth assignment of the detected resistivity layers in the latter case.

We report a new paleomagnetic determination of Paleoproterozoic rocks from the Siberian craton which showed a positive baked contact test and a stable age of the high-temperature NRM component. The mean paleomagnetic pole of Siberia for ~1730 Ma located at 42.9

We report a macroseismic study of a ruined medieval building, a small caravanserai located along the caravan way from the Talas valley to the Chatkal and Fergana valleys in Kyrgyzstan. The ruins document several events in which the caravanserai was destroyed, apparently during earthquakes, and was rebuilt or repaired. The earliest earthquake occurred soon after the building was put up, about 400 years ago, according to radiocarbon dating of charcoal, and another event shook the area between 400 and 50 years BP. After being damaged in the ultimate earthquake, in the middle of the 20th century, the building was eventually abandoned.

We consider the general and specific features of the evolution of the composition of fine-grained terrigenous rocks in the Riphean sedimentary megasequences of the Southern Urals, Uchur-Maya region, and Yenisei Ridge. It has been established that the crust on the southwestern (in the modern frame of references) periphery of the Siberian craton was geochemically the most mature segment of the Riphean continental crust. For example, the fine-grained clastic rocks and metapelites of all Riphean lithostratigraphic units of the Yenisei Ridge have higher median contents of Th than the most mature Paleoproterozoic crust, and in median contents of Y and Cr/Th values they are the most similar to it. In the Southern Urals and Uchur-Maya region, some units of the Riphean sedimentary sequences show median contents of Y and Th and Cr/Th values close to those of primitive Archean crust. Analysis of Cr/Th variations in the fine-grained terrigenous rocks of all three megasequences shows that the minimum Cr/Th values, evidencing a predominance or the abundance of felsic rocks in provenances, are typical of the Riphean argillaceous shales and metapelites of the Yenisei Ridge. The distinct Cr/Th and Cr/Sc increase in the fine-grained clastic rocks of the Chingasan Group of the ridge reflects the large-scale destruction of continental crust during the formation of rift troughs as a result of the Rodinia breakup in the second half of the Late Riphean. The Cr/Th variations in the Lower and Middle Riphean argillaceous shales and mudstones of the Bashkirian mega-anticlinorium and Uchur-Maya region are in agreement, which evidences the subglobal occurrence of rifting in the early Middle Riphean (so-called

Approaches to the construction of thermodynamic models for sorption of trace-element cations on carbonates are considered. To calculate thermodynamic equilibria by the method of Gibbs free-energy minimization, the existing database of reaction constants and thermodynamic potentials was extended. Different types of models are illustrated by the example of precipitation of Cd, Cu, Pb, and Zn from the water of a drainage stream flowing out of the impoundment of barite-polymetallic ore-dressing wastes. It is shown that the mobility of metals in such cases can be controlled by their sorption by calcite present in bottom sediments and suspension. Any approach can be successfully applied to both the modeling of experimental data on cation sorption and the prediction of the ecologo-geochemical situation in the districts of dressing works.

Density sections of the Upper Proterozoic-Paleozoic cis-Yenisei sedimentary basin were numerically modeled to show that the gravity mechanism was sufficient to bring about linear deformation structures. The main conditions of their formation and development have been determined. Comparative analysis of the results of modeling with variations in initial parameters shows an important role of dolomite interbeds in the formation of structures in the section of Cambrian evaporates. The specific evolution of the structures was related to the specific basin sedimentation and the subsequent tectonic evolution of the region as a whole. The conclusion has been drawn that the tectonic influence of neighboring folded zones might have triggered salt tectogenesis.

The Altai lithospheric structure has been generally understood due to available high-resolution digital models. As a further step in modeling, we have simulated the structure of southeastern Altai as interaction of eight blocks which comprise or surround the Chuya and Kurai basins, proceeding from the basic configuration of blocks and earthquake mechanisms. Should the stresses in the system remain invariable, the western periphery of the Kurai basin will deform to let the Uimen-Sumulta fault join the Chuya (western end of Tolbonur) fault and evolve further as a single shear zone. The best fit model was one with slip along a single border fault in the middle of the area between two rheologically different terranes. This setting corresponds to a fault boundary between the more plastic Gorny Altai and more rigid Teletskoe-Chulyshman domains, which is consistent with current crustal movements from GPS data. In addition to scientific significance, models of this kind have practical applications as they highlight areas of stress buildup prone to release in large earthquakes. The new approach was applied to simulate the stress and strain patterns of central and southeastern Gorny Altai, and the models were tested against available geomorphological and seismotectonic data.

Years-long data series of Earth's natural pulse electromagnetic fields (EPEMF) from the Talaya station near Lake Baikal indicates their mainly terrestrial origin and includes a component of poorly understood stable diurnal and annual crustal rhythms. The short-period crustal motion may drive mechanic-to-electric conversion in rocks and be responsible for diurnal and annual VLF electromagnetic pulses.
The lithospheric rather than atmospheric origin of many recorded EPEMF signals is supported by their links with nucleation of earthquakes and respective perfect match of the EPEMF and seismicity diurnal patterns. Joint spectral analysis of the Talaya EPEMF and seismicity time series and comparison with the known spectra of lunar and solar tides shows no direct correlation between the short-period rhythms and the gravitation effects.
We suggest that the diurnal and annual EPEMF periodicity may be associated with differential motion of the core and lithosphere and use this hypothesis to model an annual core path. As the model predicts, the inner solid core is never at the Earth's geometric center but moves relative to the latter along a closed orbit; the plane of the core orbit is normal to the equatorial plane and tilted 45

We have applied the method of one temperature log suggested by Kutasov in 1987 to process an unsteady temperature log of the 674 m deep submarine borehole BDP-98-2 (Akademichesky Ridge, Lake Baikal) and found it suitable to reconstruct the primary steady thermal gradient not disturbed by drilling. The steady gradient we derived using a special formalism, with reference to drilling conditions and measured thermal properties of sediments, was 63 mK/m, more than two times the unsteady gradient at different depths. Heat flow calculated with this gradient and a mean thermal conductivity of 1.1 W/(m·K) was 70 mW/m², which is consistent with earlier geothermal data from the same area. Thus, the one-log procedure is a useful tool to predict the original undisturbed thermal gradients and estimate approximate heat flows if a single unsteady temperature log is available.

A numerical experiment was applied to explore the potentialities and limitations of joint inversion of IP-affected transients measured with different loop configurations above a uniform half-space with a Cole-Cole complex conductivity. One of us calculated 200 m × 50 m and 50 m × 50 m loop responses of a uniform polarizable conductor with varied Cole-Cole parameters and imposed synthetic Gaussian noise that simulated measurement errors. Then the generated pseudo-experimental data passed to the other co-author who performed single and joint 1D inversion twice: first being unaware of the

The concepts of the role of catastrophic breakthroughs of ice- and rock-dammed and thermokarst lakes in West Siberia in the Late Neopleistocene-Holocene are systematized. The Late Neopleistocene glacial maximum in the mountains and on the plain was obviously at the same time, at 90-60 ka. It has been revealed that the basal part of the Late Quaternary cyclic three-stage upper Ob' River terrace is formed by catafluvial sediments including boulder-gravels, which descend from the valley edge beneath the water line. The Early Karginian (Kharsoimian) marine layers are spatially related to the valleys of the rushed waters of ice-dammed Lake Ermakovskoe. Substantiation is given to the concept of catastrophic flows that arrived at the plain from the Pamir and Tien Shan mountains in the Holocene Optimum and carried the Aral microfauna through the Turgai trough into the Lake Chany area. Floods resulted from the breakthrough of thermokarst lakes in the north of the West Siberian plain were typical in Karginian and Holocene time. The breakthroughs of moraine-dammed basins in the Altai Mountains took place mainly in Karginian time, whereas the breakthroughs of rock-dammed lakes, in the Sartan and Holocene epochs.

We consider the applications of existing mathematical models to heat and mass transfer dynamics in different zones of mantle-crust magmatic systems and discuss problems concerning quantitative modeling of mineralization associated with fractional crystallization of mafic melts in magma chambers, with or without crustal contamination.

Gold mineralization of the Tardan deposit is of different spatial occurrences and is related to different hydrothermal-metasomatic formations, the main ones being skarn-magnetite bodies, metasomatites of mineralized crush zones, and metasomatites of argillizitic-rock association. The formation of gold mineralization was a multistage process related to the repeated magmatism of the Tannu-Ola complex. It took place in a wide temperature range (400-150

The Borehole Vostok 3 drilled in the east of the West Siberian Plate (Tomsk Region) revealed a Vendian section in the depth range 5002-3870 m, which was subdivided into the Poiga, Kotodzha, and Raiga Formations based on geological, geophysical, and paleontological data. In the Kotodzha and Raiga Formations, typical Upper Vendian fossils of Cloudina hartmanae and Namacalathus sp. were found along with diverse Platysolenites, which are commonly considered to be of zonal significance in Lower Cambrian strata. Hence, the stratigraphic interval with abundant diverse Platysolenites has a wider stratigraphic range than it was believed earlier and seems to cover the Upper Vendian and Lower Cambrian deposits. The Borehole Vostok 3 is the first Siberian occurrence of the fossils Namacalathus , the world's fourth occurrence of the Cloudina-Namacalathus association, and the first site where coexisting Platysolenites and typical Vendian organisms have been found. Therefore, the borehole provides one of the most informative (in paleontological context) Upper Vendian sections.

Eleven new estimates of heat flow ( q ) from the southern Altai-Sayan Folded Area (ASFA) have provided update to the heat flow map of Gorny Altai. Measured heat flow in the area varies from 33 to 90 mW/m², with abnormal values of >70 mW/m² at four sites. The anomalies may have a deep source only at the Aryskan site in the East Sayan (q = 77 mW/m²) while high heat flows of 75-90 mW/m² obtained for the Mesozoic Belokurikha and Kalguty plutons appear rather to result from high radiogenic heat production in granite, which adds a 25-30 W/m² radiogenic component to a deep component of 50-60 mW/m². The latter value is consistent with heat flow estimates derived from helium isotope ratios (54 mW/m² in both plutons). Heat flow variations at other sites are in the range from 33 to 60 mW/m². The new data support the earlier inferences of a generally low heat flow over most of ASFA (average of 45-50 mW/m²) and of a

We have discovered a 2-4 year periodicity in geomagnetic secular variation (SV) from data of 110 world magnetic observatories. The periodicity in the horizontal component ( H ) is most prominent and appears to be globally uniform in different regions, on all continents, and in both hemispheres. The quasi-periodic short-wavelength variations show up in the vertical component ( Z ) as well but locally superpose on long-wavelength regional anomalies. We presume that the short-period fluctuations may be produced by instability of the eccentric dipole (ED) axis proceeding from the analysis of the SV field and optimization modeling of the dipole field with varied ED parameters.

An improved technique is suggested for quantifying seismic activity over averaging areas of an arbitrary size. The example of the Altai-Sayan seismic zone is used to substantiate the choice of a 1

Relations between indoor and soil gas radon were experimentally studied in villages of the Baikal region. On the basis of the obtained data, the soil-to-indoor radon ratio was calculated, which can be used for prediction of radon pollution in buildings of the same kind.

Climatic changes in southeastern Transbaikalia in the Middle and Late Holocene and their influence on alluvial sedimentation environments are reconstructed from the results of study of the Ilya floodplain sediments (Alkhanai National Park). At the beginning of the Subboreal period, the regional climate became more arid, which led to a significant increase in steppe species communities in the landscapes. Intense climate aridization also took place at the beginning and at the end of the Subatlantic period of the Holocene. The alluvial-sedimentation rate increased during the weakening of aridization and decreased during cooling and the intensification of aridization. The obtained regional data are compared with data on the adjacent areas and the global climatic changes in the Northern Hemisphere.

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