Role of field-aligned currents in generation of high-latitude magnetic disturbances

The distant effects of the field-aligned currents (FAC) observed by TRIAD are computed for conditions of low and moderate activity. The systems of total ionospheric currents (both Hall and Pedersen) generated by corresponding FAC are also examined and the contribution of the distant effects and the ionospheric currents into the total equivalent current system is estimated. The conclusions are as follows. In cases of low magnetic activity the magnetic effects produced by Pedersen currents are mainly cancelled by the FAC distant effect in accord with Fukushima's theorem. In cases of moderate activity when the zone of high ionospheric conductivity and the two-sheet FAC structure are present the FAC distant effect is too small to cancel the effect of Pedersen currents. For these conditions the system of total ionospheric currents shows the best correspondence with the experimental equivalent current system. Effects produced by the IMF azimuthal component are also analysed.     

Studying large-scale traveling ionospheric disturbances according to the data of oblique-incidence sounding

The morphological features of wave-like ionospheric disturbances with periods of 1–2 h and the spatial extent exceeding 1000 km are studied. Oblique-incidence sounding data of the ionosphere, obtained in eastern Siberia during several continuous monthly experiments on three radio paths from 2006 to 2010, have been used. Large-scale traveling ionospheric disturbances generated during magnetic storms and large-scale wave-like ionospheric disturbances registered during geomagnetically quiet periods are considered. Small-scale ionospheric structures were also observed against a background of large-scale traveling iono-spheric disturbances considered in this study.     

The thermodynamics of arsenates,selenites, and sulfates in the oxidation zone of sulfide ores. XI. Solubility of synthetic chalcomenite analog and zinc selenite at 25°C

The aim of this study is the synthesis of CuSeO₃·2H₂O (chalcomenite analog), ZnSeO₃·2H₂O, and ZnSeO₃·H₂O and the investigation of their solubility in water. CuSeO₃·2H₂O has been synthesized from solutions of Cu nitrate and Na selenite, while Zn selenites were synthesized from solutions of Zn nitrate and Na selenite. The samples obtained have been examined with X-ray diffraction and infrared and Raman spectroscopy. The solubility has been determined using the isothermal saturation method in ampoules at 25°C. The solubility has been calculated using the Geochemist’s Workbench (GMB 9.0) software package. Solubility products have been calculated for CuSeO₃·2H₂O (10^–10.63), ZnSeO₃·2H₂O (10^–8.35), and ZnSeO₃·H₂O (10^–7.96). The database used comprises thermodynamic characteristics of 46 elements, 47 base particles, 48 redox pairs, 551 particles in solution, and 624 solid phases. The Eh–pH diagrams of the Zn–Se–H₂O and Cu–Se–H₂O systems were plotted for the average contents of these elements in underground water in oxidation zones of sulfide deposits.     

Physical conditions in the plasma tail of comet C/1987 P1 bradfield

Photometric measurements of photographic images of comet C/1987 P1 Bradfield have been carried out with a flat-bed scanner equipped with a slide module. Lengthwise and transverse photometric profiles of the cometary plasma tail have been obtained. Magnetic field induction and some other physical characteristics of the cometary plasma tail observed in November 1987 have been estimated with the use of the diffusion model for a cometary tail by Shul’man and Nazarchuk (1968). It has been shown that the scanned images of comets can be used for estimating the physical characteristics of cometary tails.     

Granitoids of the Kongo Magmatic Zone of the Omolon Massif (Northeastern Russia): Rock Composition,Age, and Geodynamic Setting

Geotectonics - In our study we analyzed the composition of granitoid rocks within the Kongo magmatic zone of the Omolon median mass. The studied calc-alkaline granitoids cut through the Early...     

Metal Concentrations in the Ecosystem and Around Recreational and Fish-Breeding Pond Bugach

Data of two field studies were used to analyze the concentrations of Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Al, Cr, Ni, Cd, and Pb in the water, bottom deposits, zoobenthos, fish, and macrophytes of the Pond Bugach and in the soils near the pond. It was established that the majority of metals in the soils and bottom deposits correlate and their concentrations are governed by the universal geochemical factors of the region. The heavy metals were recognized that originate from anthropogenic sources and their concentrations were found to exceed the maximum admissible values for different components of the ecosystem. Five types of heavy metals migration were recognized in the soil–bottom deposits–zoobenthos–fish chain and in macrophytes. Statistically significant difference was found to exist between the concentrations of some heavy metals in the muscles of fish species with different food types (crucian carp and perch) as well as between the correlations of metals. The recorded concentrations were compared with the concentrations of metals measured in the last decade in other limnetic ecosystems in Siberia, Europe, North America, and China.     

Assessing the accumulation of sorbed isotope <Superscript>137</Superscript>Cs within the upper components of the fluvial network in the zone of Chernobyl contamination

We examine the use of two alternative techniques for assessing the redistribution volumes of sorbed ¹³⁷Cs within the upper components of the fluvial network, based on the concept of catchment as a lithodynamical system. In terms of one of them, we made a substantive analysis of changes in reserves on accumulative positions where the ¹³⁷Cs distribution curves showed a significant increase in radionuclide content levels. We carried out a typization o the accumulation surfaces in order to extrapolate data, obtained for a group of soil profiles, to the territory of the entire catchment and to make a direct assessment of the increases in accumulation. An alternative technique was used to assess the volumes of accumulated sediment loads on accumulative positions by analyzing the ¹³⁷Cs distribution curves, and to correlate with denudation zones in the drainage area under consideration. Values of the wash-out rates for the period 1986–2012 have been obtained, which are necessary for the formation of the accumulative layer observed. We calculated the volume of ¹³⁷Cs swept away during 26 years after the Chernobyl accident, based on information regarding the volumes of initial reserves in the denudation zones and a correlation between the erosion rate and a specific reduction in reserves. It is established that the technique on the basis of analyzing the wash-out zones featuring high economical efficiency can be used in assessing ¹³⁷Cs migration for larger territories with relatively low labor-consuming effort.     

The phosphate-containing interlayers of the Bazhenov Formation as potential reservoirs

The possible reservoir type of the Bazhenov Formation relative to the intervals enriched in phosphates (apatite varieties) is described in this work. The phosphate rocks are characterized by a highly developed pore space; their porosity can reach up to 14%. Along with this, these rocks have explicit geochemical characteristics of oil-reservoir rocks in comparison with other rock samples in the well. As an example, the productivity index and oil-saturation index for phosphates are twice as high as the background values. The composition of such rocks can slightly vary: fluorine can be observed in phosphate minerals, while the rock is always enriched in organic matter (>8 wt %).     

Concentrically zonal textures in a sample of the Kaidun meteorite

The paper reports the results of the textural and mineralogical studying of clast Kaidun #d6A. The principal minerals of the clast are phyllosilicates, carbonates, and sulfides, but the clast contains no anhydrous silicates. The clast is characterized by extremely high concentration of inclusions, which broadly vary in size, composition, and texture, from completely remelted to practically unchanged when brought to the parent body. The latter group includes two inclusions having a concentrically zonal texture, which have never before been found in meteorites. One of the inclusions consists of serpentine replaced by talc in the margins. The inclusion was formed in relation to silification under the effect of silicon-bearing aqueous fluid at a temperature of more than 300°C. The other inclusion consists of alternating Ca carbonate and phyllosilicate zones. The texture and composition of the inclusion suggest that its genesis was related to the metasomatic alteration of carbonates under the effect of silicon- and alumina-bearing aqueous fluids at temperatures of about 400–500°C. These processes are typical of large differentiated planets, and there are no reasons to expect them in the parent bodies of carbonaceous chondrites, such as Kaidun. Our results obtained on clast #d6A are in good agreement with the hypothesis that the parent body of the Kaidun meteorite was Phobos [1]. Correspondingly, inclusions #d6Aa and #d6Ab likely originated from Mars, as previously examined alkali-rich clasts did. The clast described in this publication seems to originate from the surface regolith of Phobos, which was compacted in the process of the aqueous alteration of the material and subsequently buried at a greater depth.