Uranium Concentration in Altered Brown Coals Located under Burnt Rocks from the Kansk-Achinsk Basin, West Siberia     

Vsevolod M. Gavshin  Leonid V. Miroshnichenko 《Geostandards and Geoanalytical Research》2000,24(2):241-246

West Siberian brown coals from the Kansk-Achinsk basin and their combustion products are generally characterized by a low uranium content. In some places where brown coal has been altered (losing density, becoming cracked or friable), the uranium content has increased by concentrations ranging from 1001000 μg g⁻¹. At these locations distinct signs of underground fires are visible. The uranium distribution patterns suggest that the burnt organic matter was a source of uranium and altered varieties of coal serve as a geochemical barrier to uranium transport.  相似文献   

Reindeer husbandry/hunting in Russia in the past, present and future     

Leonid M. Baskin 《Polar research》2000,19(1):23-29

The dynamic state of reindeer husbandry in northern Russia during the 20th century was studied as a basis for predicting the consequences of the current drastic changes taking place there. Similar forms and methods of reindeer husbandry were used with different frequencies and effectiveness throughout the century. In the future reindeer husbandry will conform to market requirements, landscape features and national traditions. In some areas, the more sophisticated methods of management developed in conjunction with large-scale, highly productive reindeer husbanry, could be lost and a subsistence economy, including hunting, could predominate.  相似文献   

Environmental evolution of the southern Chukchi Sea in the Holocene     

E. A. Gusev  N. Yu. Anikina  L. G. Derevyanko  T. S. Klyuvitkina  L. V. Polyak  E. I. Polyakova  P. V. Rekant  A. Yu. Stepanova 《Oceanology》2014,54(4):465-477

The molluscan shells from three drill and two piston cores obtained in the southern Russian sector of the Chukchi Sea are dated by the AMS ¹⁴C measurement method back to 0.8–3.5 and 9.2–10.5 ka. The period of 9–10 ka was marked by increased sedimentation rates related to the transgression onset. The fossils in the lower Holocene section exhibit the successive upward replacement of brackish-water organisms by their marine counterparts. After the opening of the Bering Strait in the middle Holocene, the sedimentation was under influence of the increased bioproductivity of the waters. The climatic optimum in the Chukotka region corresponds to the early Holocene, while the late Holocene was characterized by the wider development of the ice cover on the shelf.  相似文献   

High-temperature Raman spectroscopy and quasi-harmonic lattice dynamic simulation of diopside     

Varghese Swamy  Leonid S. Dubrovinsky  Masanori Matsui 《Physics and Chemistry of Minerals》1997,24(6):440-446

We investigated the lattice vibrational properties and lattice dynamical behaviour of diopside by combining laser micro-Raman spectroscopic measurements with quasi-harmonic lattice dynamic simulation using a transferable interatomic potential. We obtained polarized Raman spectra from a Fe-poor natural diopside and the temperature dependencies of the Raman modes to 1125?K from high-temperature Raman spectra of a Fe-poor and a Fe-rich natural diopside. The various modes display different temperature dependencies: from ?0.021?cm^?1/K to ?0.004?cm^?1/K. The temperature shift of low frequency modes is generally higher. A comparison of experimentally determined frequencies and symmetries of vibrational modes of the optical type (Raman and infrared) obtained in this and earlier studies with those calculated by us suggests that a consistent characterization of the vibrational properties was achieved. The good agreement between the experimental and simulated data on the temperature-dpendencies of the Raman modes (within 5%), crystal structure (2%), bulk modulus (5%), volume thermal expansivity (6%), and constant volume heat capacity (0.2%) testifies to the applicability of the transferable interatomic potential and the lattice dynamic model to predicting the vibrational, physical, and thermodynamic properties. The simulated properties from the lattice dynamic calculations are very similar to those obtained by molecular dynamic calculations with the same potential model.  相似文献   

The Growth rate of upper-hybrid waves and dynamics of microwave zebra structures     

Yasnov  Leonid V.  Karlický  Marian 《Solar physics》2004,219(2):289-299

The growth rate of the upper-hybrid waves with different velocities of superthermal electrons is computed considering a finite temperature of the background plasma and relativistic corrections. Based on these computations two examples of high-frequency zebra structures are interpreted. The sequence of the continuum, zebra structure, and continuum observed in the 29 October 2000, event is explained as an increase and following decrease of the velocity of superthermal electrons in the range of v=0.1–0.3 c. On the other hand, the zebra structure observed during the 18 March 2003 event represents an example with fast electron acceleration.  相似文献   

New limits on the generation of magnetic fields     

Leonid Chuzhoy 《Monthly notices of the Royal Astronomical Society》2004,350(2):761-762

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Fast Variations of Spectra of Comet Halley     

Borysenko  Sergiy  Nazarchuk  Halyna  Shulman  Leonid 《Earth, Moon, and Planets》2002,90(1-4):205-215

Results of the analysis of the Comet Halley spectrophotometry,which has been carried out by H.K. Nazarchuk in 1985 with the TVscanner of the 6-meter telescope (SAO, Russia) are presented. Timevariations in the intensities of the CN, CH, C₂ and NH₂bands were investigated using the series of spectra obtained inthe spectral region λλ=410÷ 510 nm. Theauto-correlation functions for all the bands, thecross-correlation functions for C₂ lines and their Fouriertransformations are calculated to determine the frequencies andperiods of the variations. A possibility is considered thathigh-amplitude fast variations of spectral lines in Comet Halleyare caused by solar flares. The daily numbers of solar spots andproton fluxes with energies of more then 1 MeV are compared withthe spectral variations of these lines. It is shown that in theobservation periods the comet was projected onto an active regionof the Sun, but, among all the kinds of solar activity, mainlythe solar proton flux with energies less than 4 MeV coincides intime with fast intensity variations in the spectral lines. Analgorithm of cross-correlation analysis of discrete samplingseries with gaps is built, and average cross-correlation coefficientsare calculated.  相似文献   

Isotope-Geochemical Features and Genesis of Gases in the East Carpathian Region     

B. G. Polyak  A. L. Cheshko  O. E. Kikvadze  I. L. Kamensky  E. M. Prasolov 《Lithology and Mineral Resources》2018,53(5):380-393

The paper presents data on the composition of a gas phase of underground fluids in the East Carpathian region, including ³He/⁴He, ⁴⁰Ar/³⁶Ar, and ⁴He/²⁰Ne ratios. The argon isotope composition of these gases was used to estimate the fractions of atmospheric Aratm and radiogenic ⁴⁰Ar_rad formed in the rocks, N₂/Aratm ratio, and to reveal the admixture of nonatmogenic (“excess”) nitrogen in most samples. The CO₂ content in gases positively correlates with the fraction of mantle component in fluid helium. At the same time, the CO₂ content shows a negative correlation with the total helium (and light ³He enriching mantle derivatives), thus excluding the simultaneous influx of CO₂ and helium from a common mantle source in the fluids. A wide spectrum of ³He/⁴He = R in gases of the region spanning three orders of magnitude confirms the concept of mixing of the crustal and mantle components in the helium. However, even gases with similar R values show a wide scatter of He concentrations. This is mainly caused by the additional influx of other gases: CH₄ formed during OM transformation or CO₂ released during the thermal metamorphism of carbonate sequences. Correlation of the CH₄/³He ratio and the helium isotope composition in the Carpathian gases indicates the crustal origin of hydrocarbons, which formed economic gas pools in the Ciscarpathian Trough and the adjacent part of the Folded Carpathians. Lateral chemical and isotope variations revealed in the underground fluids are related to the tectonic zoning of the region. The helium isotope variations are also consistent with the geodynamic setting of the region (thinning of the crust and lithosphere towards the Pannonian Basin, growth of the background conductive heat flow and corresponding ascent of isotherms). In combination with geothermal data, they reflect specifics of the mantle heat-and-mass flow discharge.  相似文献   

Hydrochemistry of Salt Lakes in Southeastern Transbaikalia(Russia) in the Time of Arid Phase of Climate Change at the Beginning of the XXI Century     

Leonid V.ZAMANA  Irina L.VAKHNINA 《《地质学报》英文版》2014,(Z1)

正1 Introduction In the south of Eastern Transbaikalia in the border area with China and Mongolia,there are at least 300 saline without outlet lakes.They are confined to the semi-arid zone Daurian steppes with pronounced continental salinization processes and are mostly located on the bottoms of the intermountain basins.Their origin is related to evaporative concentration of fresh waters lakes filling.  相似文献   

Thermodynamic Evaluation of Mineral Balance in Water Thickness of the Soda Lake Doroninskoe(Eastern Transbaikalia,Russia)     

Svetlana V. BORZENKO  Leonid V. ZAMANA  Daria S. SUVOROVA 《《地质学报》英文版》2014,88(Z1):123-124

正In recent years,lakes,including salted,attract the attention of researchers,also when reconstructing last climate changes using the bottom sediments(Solotchina et al.,2008,et al.).In this case the different geochemical  相似文献