Home – Home – Jornals – Russian Geology and Geophysics 2017 number 12

Middle-Late Paleozoic geodynamics and structure of Gorny Altai are studied with reference to gravity data. The northern and central parts of the area belong to the Gorny Altai terrane consisting of Late Precambrian-Paleozoic rocks originated in different tectonic settings on the Siberian continental margin, including Devonian active-margin volcanoplutonic complexes. In the south and east, the Gorny Altai terrane borders the Altai-Mongolia terrane along the Charysh-Terekta-Ulagan shear zone. The Altai-Mongolia terrane is composed of Early Paleozoic turbidites of the Kazakhstan-Baikal continent, Middle Paleozoic collisional garnet-disthene-andalusite schists, and Late Paleozoic zoned andalusite-cordierite schists, with granitic plutons on their periphery. The pattern of these complexes is similar to that of Cenozoic volcanoplutonic and metamorphic domes in the Kamchatka and Chukchi Peninsulas. The Devonian volcanoplutonic complexes from the Gorny Altai terrane and the Middle-Late Paleozoic metamorphic complexes from the Altai-Mongolia terrane are well evident in the gravity field. In general, gravity anomalies in the two terranes strike in different directions: NW in the Gorny Altai terrane and W-E in the Altai-Mongolia terrane, which highlights the structural heterogeneity of the Gorny Altai region. New dates have been obtained for magmatic detrital zircons from Paleozoic sedimentary rocks of the Anui-Chuya basin in the Gorny Altai terrane. The inferred source areas of zircon hosts are igneous rocks of the Precambrian craton basement and the Vendian-Early Ordovician Kuznetsk-Altai island arc. Early Neoproterozoic (1.00-0.75 Ma) detrital zircons are abundant in the Early Paleozoic turbidites of the Altai-Mongolia terrane but are absent from samples of the Gorny Altai terrane. Populations of detrital zircons in the the Gorny Altai terrane contain Devonian and Early Neoproterozoic specimens. The reported data prove that the Kazakhstan-Baikal and Siberian continents amalgamated in the Middle-Late Paleozoic. The resulting Gorny Altai tectonic framework of that time is recorded in the gravity field and in the provenance of detrital zircons.

Tholeiitic melts from the Bouvet triple junction (BTJ) of rift zones in the South Atlantic are moderately enriched rocks with specific lithophile-element patterns. The high (Gd/Yb) n values (up to 2.5) in some tholeiite compositions suggest the presence of garnet in the mantle source of primary BTJ melts. The high Ni and low Mn contents of the most magnesian olivines determined by high-precision probe microanalysis suggest the presence of pyroxenite, along with typical peridotite, in the melting source. The unusually wide within-sample variation in the proportions of pyroxenitic component in the source region ( X Px Mn/Fe = 0-90%) indicates different degrees of mantle heterogeneity beneath the spreading zone. Based on geochemical data, this component is a silica-oversaturated eclogite, reacting with peridotite to form olivine-free pyroxenite in the melting source. This component is probably represented either by subducted and recycled oceanic crust or by fragments of the ancient continental lithosphere buried into the mantle after the Gondwana breakup. The observed global and local mantle heterogeneities might have been developed during the complex geodynamic evolution of the Southern Ocean, whose opening was affected by the activity of the Mesozoic Karoo-Maud-Ferrar plume and multiple jumps of the spreading axes, which led to the involvement of fragments of the early oceanic lithosphere in the melting process.

We studied the Sm-Nd, Rb-Sr, and Re-Os isotope compositions of mantle xenoliths (eclogites and peridotites) from diamondiferous kimberlites of the Catoca cluster of the Kasai Craton. In the eclogites, the primary strontium isotope composition 87Sr/86Sr varies from 0.7056 to 0.7071, and the neodymium isotope composition εNd, from 1.8 to 2.6. The 187Re/188Os and 187Os/188Os ratios range from 135 to 80 and from 1.3110 to 1.9709, respectively, which indicates a significant portion of radiogenic 187Os: γOs = 129-147. These isotope values exceed the values assumed for model reservoirs (primitive upper mantle (PUM) and bulk silicate Earth (BSE)) and those of chondrites. The isotope composition of the studied systems indicates the formation of eclogites from a rhenium-enriched source, namely, the subducted oceanic crust transformed as a result of metasomatism and/or melting under upper-mantle conditions.

This paper describes a thermomechanical mathematical model of magma mingling and mixing during the formation of complex intrusions and presents the first results of numerical modeling. The model considers one-pulse intrusion of mafic or intermediate melts into a granitoid magma chamber. The model is based on literature data on the composition and structure of two polychronous intrusions: the Burgas quartz syenite massif and the Magadan granitoid batholith. The modeling shows that the main parameter controlling the convection regime is the density difference. The density and viscosity contrasts of interacting magmas during mingling and mixing are estimated. Depending on the density difference, one of the possible processes dominates: In the case of a small difference (less than 30-40 kg/m³), magma mixing and hybridization in a small contact zone takes place; in the case of a large difference (100 kg/m³ or more), magma mingling predominates. The viscosity contrast, in turn, determines whether interpenetration of melts or fragmentation of melts in the form of drops, spheres, etc. occurs. There is a limiting viscosity of salic magma (108 Pa·s) at which the flows freeze in the chamber and further cooling occurs with a slowly moving fluid. The time of formation of mingling structures is estimated to be several days to several hundred years, depending on the initial melt viscosity.

Garnet-bearing aluminous gneisses in the Vasil’kovka area of the Orekhov-Pavlograd zone of the Ukrainian Shield were studied using the THERIAK-DOMINO, THERMOCALC, and WINTWQ software and mineral geothermobarometry methods. The stability fields of parageneses formed at the initial, peak, and post-peak metamorphic stages have been estimated: T = 500-650 ºC and P > 7 kbar, T = 800-850 ºC and P ≈ 8 kbar, and T = 600-670 ºC and P = 4.0-5.5 kbar, respectively. A «clockwise» PT path has been established. Based on the aluminous gneiss, the age of metamorphism is determined as Paleoproterozoic (2014 ± 11 Ma). Unique regularly oriented acicular goethite microinclusions were described in garnet. In contrast to other known oriented Ti-bearing mineral inclusions in garnet, these goethite inclusions suggest not only extremely high P and T values (necessary for the formation of oriented Ti-bearing inclusions) but also a high oxygen fugacity. The obtained data broaden the concepts of the ways and conditions of formation of regularly oriented mineral phases in garnet.

The barite deposits that emerge as veins and lodes within or along the contact zones of recrystallized limestone and dolomite units of Cambrian Degirmentas Formation are of epigenetic character. Depositional styles, paragenesis, host rock alteration styles, and high SrO contents of the barites suggest a hydrothermal origin for their formation. However, considering their rare earth element compositions, barite samples surround the field for seawaters when plotted on Ce _N / Yb _N -Yb _N and Ce _N /Sm _N -Ce _N /Yb _N diagrams. Fluid inclusion data obtained from the barites indicated a formation from a fluid with low salinity (0.9-1.6 wt.% NaCl eq.) at homogenization temperatures between 78 and 190°C. Sulfur isotopic compositions of barites vary between +32.2 and +36.3‰, and their ⁸⁷Sr/⁸⁶Sr values range between 0.709885 and 0.749652. Depositional styles, parageneses, trace element compositions, fluid inclusion data as well as δ³⁴S and ⁸⁷Sr/⁸⁶Sr isotopic data indicate a model in which hydrothermal fluids were possibly derived from a buried intrusion mixed with meteoric and marine waters, further interacting with the Precambrian - Phanerozoic metaclastic and Cambrian carbonate rocks to form barite deposits.

The Panimba gold deposit lies in the rocks of the epidote-amphibolite metamorphism facies and is confined to the exocontact zone of the Chirimba granitoid massif. Fluid inclusions in quartz and sulfides of two sites of the deposit, Mikhailovka and Zolotoi Brook, were studied by thermobarogeochemistry, gas chromatography, and chromatography-mass spectrometry. We have established that gold-quartz veins of the deposit were formed by metal-bearing Mg-Na-Cl-containing water-carbon dioxide-hydrocarbon fluids with salinity of 8-23 wt.% NaCl eq. at temperatures of 180 to 410 ºC and pressures of 0.2 to 3.3 kbar. Hydrocarbons and nitrogen- and sulfur-containing compounds of the fluids can transport gold and might be positive indicators of the gold presence in quartz veins. Fluids with salinity of >30-40 wt.% and sulfur isotope values (δ³⁴S) of 0.9 to 6.7‰ of sulfides are the result of the action of postmagmatic solutions of the nearby Chirimba granitoid massif. The age of hydrothermal gold-sulfide mineralization of the Panimba deposit is within 817.2 ± 5.3-744 ± 17 Ma and falls in the time interval of crystallization of the Chirimba intrusion, 868.9 ± 6.5 to 721.4 ± 1.6 Ma, but it is considerably younger than the age of the regional metamorphism (996 ± 32-889 ± 26 Ma).

We summarize the results of our long-term research into the composition of alkyl derivatives of mono-, bi-, and tricyclic aromatic hydrocarbons of 113 crude oils from the Cenozoic (Sakhalin, Pannonian Basin (Serbia), China, and Vietnam), Cretaceous (West Siberia, Mongolia, China, and Saxony), Jurassic (West Siberia and Saxony), and Paleozoic (West Siberia, East Siberia, and Timan-Pechera and Volga-Ural petroliferous provinces) deposits localized at depths from 200 to 4500 m. To identify compositional similarities and differences of crude oils from deposits of different ages, we processed the obtained data on the individual composition of alkanes, alkyl benzenes, alkyl naphthalenes, and alkyl phenanthrenes by principal-component analysis. The analysis has revealed the regularities of changes in the content and composition of alkyl aromatic hydrocarbons in crude oils depending on the age of the enclosing deposits.

Sediments of intracontinental closed lakes are unique natural archives that store climate history records. We study Late Holocene carbonate-bearing sediments of Lake Dolgoe, a small saline lake in the Eravnoe basin on the Vitim Plateau (western Transbaikalia). Sediment samples have been analyzed by several methods: powder X-ray diffractometry, Infrared spectroscopy, stable isotope (18O and 13C) determination, laser diffraction particle size analysis, XRF elemental analysis, etc. The mineral phases of bottom sediments include clastic and carbonate components and hydromagnesite at the section top; carbonates are authigenic varieties of the calcite-dolomite series. Modeling of complex XRD profiles reveal Mg-calcite with various Mg contents and excess-Ca dolomites which are mixed-structure crystals compositionally close to stoichiometric dolomite. The crystal structure and relative percentages of carbonates from the dated sedimentary section controlled by climate and lake level changes allow reconstructing the Holocene history of Lake Dolgoe.

In March 2014, the Lake Baunt bottom sediments were drilled in the deepest part of the lake basin (33 m). The penetrated interval is 13.7 m thick, with the age of the base being evaluated at 28-30 ka. Lithological study of the penetrated sediments demonstrates the upper part of the section dominated by diatom ooze, whose concentration decreases gradually downward the section, up to the replacement of the ooze by silty clay. The obtained data on variations in petromagnetic parameters, concentration of biogenic silica, and sediment compaction indicate considerable variations of sedimentary environments during the Late Pleistocene and Holocene. Being compared with the previously reconstructed landscape and climate dynamics for the sedimentary succession of Lake Kotokel for this time interval, the above parameters reveal that the Lake Baunt bottom sediments reliably fix the regional paleoclimate signal. For the first time for lakes of the Baikal region, Gothenburg and Mono Lake magnetic excursions are identified in the paleomagnetic record of the Lake Baunt section.

Predictive models for the localization of soil liquefaction for seismic events with magnitudes MS = 7.5 and 8.0 were constructed based on available data on a possible earthquake in the zone of the Main Sayan Fault. It has been established that for MS = 7.5, liquefaction will extend over a distance of 40 km from the causative seismogenic fault. For MS = 8.0, the limiting distance from the activated segment of the Main Sayan Fault will be 112 km. The calculation models take into account the effect of faults on the predicted process, which allows a more accurate identification of areas with different probabilities of this event. Zones of possible liquefaction at MS = 7.5 include the towns of Kultuk, Sludyanka, Baikal’sk, Arshan, and Podkamennaya. At MS = 8.0, the liquefaction process will spread over a large area including the cities of Usol’e-Sibirskoe, Angarsk, and Irkutsk, especially localities near the Angara River and its major tributaries. Similar evaluation can also be made for other natural situations with known seismogenic faults, fault-block divisibility of the Earth’s crust for the Pliocene-Quaternary stage of tectonism, earthquake magnitude, and potentially liquefiable soils within the model area.

The paper presents the results of paleoseismological studies in the epicentral area of the Tuva earthquakes of 2011 ( M = 6.7) and 2012 ( M = 6.8). Their seismotectonic position and seismic history over the last millennia has been studied. The results are of great importance because these earthquakes are the strongest in the history of seismological observations in Tuva and are thus the first well-studied strong earthquakes in this region. The data show that relatively weak events similar to the 2011-2012 Tuva earthquakes recurred every 300-500 years in the past millennium, while catastrophic earthquakes with M = 7.0-7.2 and higher occur approximately every thousand years.

This paper presents induced polarization (IP) data on a number of gold deposits and occurrences in the Magadan Region. Geophysical works are effective for the study of gold-quartz deposits of different morphological types (vein, veinlet-vein, and veinlet-disseminated). It is shown that multifrequency IP sounding reliably identifies zones of carbon metasomatism, a reliable indicator of potential gold mineralization areas in northeastern Russia. Carbon metasomatism is the typical shape of phase frequency response curves for graphite and graphitized rocks.

Neutron tomography is considered as an alternative to X-ray tomography in the study of paleontologic and geologic objects. Based on experimental data, a contrast scale of minerals and rocks, including those present in paleontologic objects, has been constructed for neutron tomography. Examples of application of neutron tomography of geologic objects are given, and the potentialities of the above methods are compared.

A new algorithm is proposed to compute magnetotelluric (MT) curves for a horizontally layered earth with laterally inhomogeneous conductivity. It is fast and ensures correction of induced eddy currents and galvanic distortions of MT curves produced by 3D inhomogeneities. The computation time is short (~1 min) due to the use of the perturbation method for solving Maxwell’s equations. The suggested algorithm has a better performance than the more costly classical Trefftz method but has an applicability limitation.

This study describes a new method for quantification of hypothetical oil and gas resources, which is considered to be an alternative to conventional estimates by analogy to geologically similar plays and is most appropriate for maturely explored provinces. This method is based on the size-frequency distribution of oil accumulations in sedimentary basins and has never been applied to petroleum exploration. The new approach makes it possible to assess the oil resources concentrated in small and smallest oil fields, which may become the main targets for petroleum exploration. This study reviews the discovery and exploration history of the Volga-Ural province and provides estimates of initial and hypothetical oil resources and the size distribution of undiscovered field and the number of their pools. It was shown that given the volume of exploratory drilling of 500-550 thousand m per year, it is expected that more than three billion tons of oil would be produced from small and smallest fields of this province by the mid-21st century, with a stable annual production of 40-50 million tons. It was shown that the development of small and smallest oil fields is performed by small and medium-sized oil companies, which can be delivered through a dedicated government program.

Deposition environments in the Chukchi Sea and adjacent areas of the Arctic Ocean are studied by the Q -cluster analysis of compositions, particle sizes, and other properties of surface bottom sediments. Analysis of more than 4700 numeric values allowed mapping fifteen clusters distributed over the seafloor according to deposition environments. Chemical and statistical data confirm the predominance of clastic sedimentation and mainly mechanic sorting of sedimentary material. At the same time, the major-element composition trends correspond to Si decrease and Al increase seaward. Biogenic deposition is of inferior scale and shows up as relative enrichment in total organic carbon, Ca, Mg, Ba, Sr, and some other biogenic and chemogenic components in sediments. Clastic and biogenic deposition, with accumulation of Fe, Mn, V, Ni, Cr, Co, and other elements, as well as precipitation of authigenic growths, occurs within areas of seafloor having particular water chemistry, such as the Herald Canyon, the outer shelf, and the deepwater Arctic Ocean.

The results of numerical simulation of self-action in air of a sequence of ultrashort laser pulses with a carrier in the near and mid-IR regions are presented. We show that the use of a 10.6-mm pulse train allows appreciable elongation of the plasma channel generated during pulse filamentation and enhancement of its spatial connectivity. The filamentation of a submicron pulse train does not visibly change the filamentation region characteristics.

Estimates of the radius of coherence of a laser beam and the possible beam broadening in the atmospheric boundary layer under the effect of random inhomogeneities of the refractive index, determined from experimental data of remote acoustic sounding, are presented. The possibility of significant loss of coherence and marked broadening of the laser beam due to turbulence in nighttime conditions is noted.

Study of ecological state of marine coastal regions often requires operative acquisition of detailed data. In this work, the measurements of the sea radiance coefficient spectra are analyzed, which were made with a new three-channel passive optical complex for ecological monitoring of marine aquatoria (EMMA) developed by us, which operates semiautomatic from board a moving ship. The measurements were carried out at the Brazilian coast in the area of the Rio Grande river mouth. The spectra obtained were processed using an original technique based on intrinsic properties of the pure sea water absorption spectrum (WASM - water absorption step method) modified for the eutrophic type II waters. This enables us to estimate the absorption indices of the suspended matter and colored organic matter. The comparison of these remote estimates with the estimates retrieved from the water samples taken at special stations shows their high correlation. Using remotely obtained data the distributions of the suspended matter and colored organic matter were constructed and compared to the satellite image in the aquatory under exploration.

Absorption spectra of methane in the 11000-11400 cm^-1 region were recorded at a IFS-125M Fourier spectrometer at pressures from 11 to 100 mbar, room temperature, and spectral resolution of 0.03 cm^-1. A multipass cell 60 cm long and 44 passes were used, which provided a total path length of 2640 cm and threshold sensitivity to absorption on an order of 10^-8 cm^-1. Voight contour parameters (line center, intensity, self-broadening and self-shift coefficients) were determined.

Adsorption and desorption of atmospheric gases (N₂, O₂, Ar, CO₂, and H₂O) in silica aerogel is studied. Static parameters of adsorption and kinetic parameters of adsorption and desorption are determined based on pressure vs time dependence P(t) in the buffer vacuum chamber of the experimental setup during adsorption and desorption of gases by a SiO₂ aerogel sample of V = 42.8 cm³ in volume and ρ = 0.34 g/cm³ in density. The ratios of adsorbate molecular density to aerogel molecular density at the room temperature T = 293 K and equilibrium pressure P_р ≈ 1 bar are found: γ(N₂) = (9 +- 3)% (9 molecules of N₂ adsorbed by pore surface to 100 N₂ molecules in the gas at equilibrium), γ(O₂) = (7 +- 3)%, and γ(CO₂) = (222 +- 8)%; for water vapour, γ(H₂O) = (5.9 +- 0.3) x 10⁴% at the pressure P_р = 5.7 mbar. It is ascertained that argon atoms are not adsorbed by the aerogel. It is suggested to use argon as a “zero” gas in spectroscopy of molecules adsorbed by SiO₂ aerogel to determine the amount of adsorbate in a sample. A sum of two exponents with kinetic parameters τ₁ and τ₂ is used to fit P(t) dependence. The τ₁ and τ₂ values are estimated during adsorption and desorption of each gas under study.

Temporal variability of PM_2.5 surface concentrations in Moscow and its dependence on other atmospheric parameters, such as trace gas concentrations, aerosol optical thickness (AOT), surface air temperature, humidity, and wind speed have been considered. Data rows of PM_2.5 and SO₂, NH₃, NO_x, CO, and O₃ obtained during continuous measurements in 2011-2013 have been analyzed. Daily and seasonal variations in PM_2.5 and trace gas concentrations as well as correlations between them have been studied. The variability of PM_2.5 concentration has been considered in relation to trace gases participating in atmospheric aerosol formation and to meteorological parameters. Data on PM_2.5 surface concentrations have been compared with aerosol optical depth (АОТ₅₀₀) measured at the same site.

The vertical distributions of gas and aerosol compositions of air over the Kara Sea and coastal areas of the Russian Arctic, measured by Tu-134 Optic airborne laboratory in October, 2014, are analyzed. Features of the altitude distributions of CO₂ and aerosol over the Kara Sea that differ them from continental conditions are revealed. No considerable deviations from continental distributions are found for CH₄, CO, and O₃.

Analysis of Aura MLS data showed that the temperature in the stratosphere of Arctic was much lower than normal during the entire period of January-March 2011 in the altitude range 20-35 km. This had led to a considerable spread of polar stratospheric clouds (PSCs) that formed most intensely in periods and at altitudes of minimal temperatures (maximal temperature drops below PSC formation threshold). The main ozone losses were observed in March. They were due to a photochemical release of chlorine that avoided deactivation in view of nitrogen deficit caused by denitrification in the course of frequent dehydration events indicated by oscillations of the altitude of maximal humidity deviation from multiyear norm. Elevated humidity in the stratosphere had increased the threshold temperature of formation of PSCs that persisted until late March; this raised the threshold of chlorine activation and, thereby, delayed the chlorine deactivation, resulting in even higher level of overall ozone losses during March 2011.

Series of temperatures measured at 818 weather stations in the Northern hemisphere and one series of Wolf numbers for the period from 1955 to 2010 are considered. The sun effect on the surface temperature is estimated by the cosine of the angle between the two vectors determined by the series under consideration using the cyclic time. The technique is effective because it provides a broad common frequency band of the series under study. The sun effect has a monotone approximated dependence on the monthly average temperature and reflects the climate geography, including the effect of warm ocean streams. The approach suggested is expedient for applications in the development of observational data analysis, analytical transformations, and climate simulations.

Stationary lidar “LOSA-S” is intended for the study of aerosol fields in the boundary layer of the troposphere in the altitude range 0.05-15 km, as well as for the study of crystal clouds using the polarization unit with linear and circular radiation polarization. The scheme of simultaneous observation of elastic and Raman scattering signals when irradiating the medium at wavelengths of 1064, 532, and 355 nm is implemented in the lidar. The lidar is based on a LOTIS-2135 Nd:YAG laser and a Cassegrain receiving specular telescope with a diameter of 300 mm. In addition to the return signals of elastic scattering recorded in the analog mode, the lidar records Raman scattering signals on molecular nitrogen (387 and 607 nm) and water vapor (407 nm) in the photon counting mode. To cover the aforementioned altitude range, two receiving telescopes are used in the lidar for near and far zones; the signals are recorded by the same photodetectors.

A technique is suggested for enhancement of the pumping efficiency of a CuBr laser by means of modifications of the discharge circuit with a cable pulse autotransformer. The results of using four different discharge circuits are described. The experiments were carried out under similar operating conditions of the active element and at a constant input power of the pumping source. The output power increases from 14 to 21 W with the use of autotransformer and peaking capacitor. The power increase is a result of a delay between GDT current and pumping voltage and different volume-temporal characteristic of the energy input into a charge. The technique suggested can be used in different applications.

For the first time polymorphisms in Kodar snow sheep, KOD ( Ovis nivicola kodarensis ) nuclear DNA were studied. KOD is a representative of small isolated population of Asian snow sheep ( Ovis nivicola Eschscholtz, 1829) inhabiting the Kodar Ridge (Irkutsk Oblast, Transbaikal Krai). We compared KOD with its geographically closest Yakut subspecies ( Ovis nivicola lydekkeri ). Genome-wide study of single-nucleotide polymorphisms (SNPs) was performed using the Illumina OvineSNP50 BeadChip (Illumina Inc., San Diego, CA, USA). The final set of markers for analysis included 1030 SNPs. We found that Kodar snow sheep had almost 10 times lower level of genetic diversity evaluated by multilocus heterozygosity - MLH (0.027 for KOD - 0.215-0.270 for individuals of Yakut subspecies) and standardized MLH - stMLH (0.116 against 0.910-01.147). The results of multidimensional scaling (MDS), Nei distances calculations ( DN ) and STRUCTURE analysis showed a clear genetic differentiation of Kodar snow sheep from Yakut subspecies. Our data represent the first step to understanding of the demographic history of the original Kodar population of snow sheep.

We studied brown bear ( Ursus arctos ) land use using satellite collars deployed on four animals in Kamchatka in 2005-2006 and three animals on Sakhalin Island in 2011-2012. The annual home range sizes ranged from 6.09 to 27.58 km2 for females and was 153.12 km2 for male. The sizes of annual core area of home range did not exceed 1.68 km2. Seasonal home range sizes were the highest in August and September and the lowest in May. Home ranges of two females in Kamchatka significantly overlapped, while a lower degree of overlap was found for two females in Sakhalin. Habitat use by bears depends on the seasonal distribution of food, in particular salmon.

Ranges of three studied alien fish species (rotan Perccottus glenii , sunbleak Leucaspius delineaus , and bleak Alburnus alburnus ) in the Ob River basin, West Siberia, have expanded. Our data prove the expansion of rotan and sunbleak ranges to the north. In particular, for the first time populations of rotan have been reported from the lower section of the Ob. We also present new data on range expansion of the studied fish species southward. All three species have probably reached southern limits of their possible distribution in the Upper Ob system getting into potamon/rhithron transition zone because the species under study prefer lowland waters. Spatial-temporal dynamics of their expansion reveals the role of the Ob River as the main invasion corridor enhancing their distribution mostly in meridional direction. In the system of the Upper Ob, rotan and sunbleak were found by us in isolated ponds and lakes as well as in floodplain and river systems. This is in agreement with the concept of two invasion vectors: translocation of fish by humans between water bodies and self-distribution along the river courses.

In order to compare the impact of alien common carp ( Cyprinus carpio ) and native bream ( Abramis brama ) on water chemistry, phyto- and zooplankton, and macrozoobenthos, nine enclosures, 9 м² each, were placed in the littoral zone of Lake Obsterno (Republic of Belarus) at a distance of 60 m from the shore. Feeding behavior of carp, characterized by extensive burrowing in the sediment, led to the change in the phytoplankton community structure. But the significant differences in algae biomass between control and fish enclosures were received only for diatoms algae. Carp had a more pronounced effect on abundance of large-bodied species of zooplankton ( Diaphanosoma brachyurum ) than bream did. For both fish species an increase in abundance of small-bodied Bosminа longirostris was recorded. Decreased abundance and biomass of macrozoobenthos occurred at a much higher rate within the carp enclosures, with the strongest impact on ephemeropterans. There was no difference in the consumption of chironomids and oligochaetes regardless of fish species.

Based on materials collected in 1963, 1998 and from 2009 to 2016, the subzonal changes in the population of the small mammals of the Prealtai plain are described, its classification and spatial-typological structure are given, the strength of the connection between nonuniformity of communities depending on environmental factors are estimated. The results of the analysis of the spatial inhomogeneity of the population of the West Siberian and Prealtai plains and mountain provinces of the Altai are compared.

The results of the study of taxonomic, ecological and phytocenotic structure of plant communities formed in the initial stages of overgrowing the anthropogenic sandy outcrops within the forest-tundra zone and the subzone of the northern taiga forests of West Siberia are presented. At the pioneering stages of vegetative cover restoration, there are two to eleven species growing into sparse communities of the Loiseleurio-Vaccinietea, Artemisietea vulgaris and Koelerio-Corynephoretea classes. The participation in the recovery succession on the sandy outcrops of some meso-xerophitic forest-tundra, meadow-margin and weed herbaceous plant species and dwarf shrubs mostly with ruderal and stress-tolerant eco-phytocenotic strategies, as well as with secondary strategies - violent-ruderal and ruderal-stress-tolerant strategies are shown. The primary succession begins at the bottom and slopes of the quarry ditches, as well as on the surface of the sand dunes, and proceeds on an accelerated scenario. In the initial stages of succession participate hygro-, meso- and xerophilous species, predominantly oligo-mesotrophic rhizome and densely turf grass plants and shrubs of the native flora as well as ground lichens.

Sizes of bushes, leaves, seeds and flower elements of Nitraria sibirica Pall. and N. schoberi L. were studied in 19 Siberian populations. It has been revealed that larger bushes 150-170 cm high, leaves 15-30 cm long and 5,7-8,8 mm wide, seeds up to 10 mm long, wider corolla petals about 2,5 mm and larger (by 1,2-1,5 times) anthers are typical of N. schoberi . Height of N. sibirica bush does not exceed 80 cm, length of a leaf blade varies from 8 to 15 mm; length of stones amounts to 3,7-7,4 mm; length of petals is somewhat more than 3,5 mm and that of anthers - 0,5-1 mm. Rather high constancy of metric characters typical of both species regardless of habitat conditions is shown. Climatic dependence is only followed by bush height in N. sibirica which is a trailing plant in the continental regions, especially in the high mountains of the Altai Republic. The vegetative organs (leaf blades and young stems) of N. sibirica are always more pubescent compared to those of N. schoberi .

The present paper is devoted to the results of study of ontogenesis and structural-morphological pattern of Nepeta pulchella individuals of different life forms. Ecological-coenotic conditions of the species habitats within Aksu-Zhabaglinsky Nature Reserve are characterized. N. pulchella occurs from the middle part of the mountains to the subalpine belt. Status of coenopopulations in two types of plant communities has been assessed. Depending on various ecological-coenotic conditions N. pulchella individuals have two life forms: taprooted caudex and short-rooted- taprooted. Individuals of these biomorphs pass complete complicated ontogenesis. The following morphogenetic phases are described for the first biomorph: primary shoot -> main axis -> primary bush -> clone and for the second one - primary shoot -> main axis -> primary bush -> tillering particle -> not tillering particle. The coenopopulations studied are normal, transitional to mature, resistant and incomplete. Ecological-coenotic and structural-morphological analyses have made it possible to reveal in N. pulchella individual morphogenesis a number of characters indicative to phylogenetic link with сlosely related taxa.

It is established that in the conditions of cold humid climate the change in the chemical composition of soils after the arrival of volcanic ash in them depends on the granulometric and petrochemical composition of the products of eruptions, the method and the forms of chemical elements entering the soils, the season and the meteorological conditions of the ash falls. Petrochemical composition of ash determines, mainly, the nature of changes in the gross composition of soils. Transformations of soils in the part of the contents of mobile forms depend more on the time of year and the meteorological conditions of ash falls. The overwhelming part (up to 99.3 %) of the mobile forms of most elements enters the soils at ash falls not in the composition of ash particles, but in gas and water-soluble forms directly from the dispersion medium of volcanic aerosol. In 25 km from the centers of eruptions in soils are established: in winter conditions - growth of gross contents of elements and removal of their mobile forms; in the summer period - the accumulation of mobile forms of elements against the background of a fall in the content of their gross forms, acidification of soils is observed here with a significant (about 1.5-fold) decrease in the degree of saturation of soils with bases.

The new data on the small mammal communities in the industrial area near Pavlodar (Northern Kazakhstan) are presented in this article for the first time. The comparative analysis of the diversity characteristics of the small mammal communities in the areas of technological environmental impact, and the reference area was performed. It is shown that the total abundance increases with the distance from the pollution sources. The community of small mammals in a territory with a significant anthropogenic pressure is characterized by depleted species composition and the monodominant structure. With a moderate intensity of anthropogenic load, species diversity increases, but the number of individual species decreases due to fragmentation of habitats.

The present paper deals with data on abundance and habitat use of four arctic breeding species of loons in the plains and surrounding mountains of western Chukotka, Russia. Loon species differed in their use of the four lacustrine habitat types within the study area. In yedoma habitat, the Yellow-billed Loon ( Gavia adamsii ) was the most abundant (0.593 birds/km2); on fluvial plains Pacific loons ( G . pacifica) outnumbered other loons (0.701 birds/km2); mountain valleys were inhabited similarly by G . pacifica (0.354 birds/km2) and Red-throated loons ( G . stellata ; 0.307); and maritime tundra was used only by G. pacifica (1.13) and Arctic loons ( G . arctica ; 0.553). G. adamsii was not observed in mountain valleys or maritime tundra. Mountainous portions of rivers were predominantly occupied by G. stellata and G. pacifica , and lowland rivers by G. stellata , G. pacifica and G. arctica .