Formation of ferriolivine and magnesioferrite from Mg — Fe-olivine: Reactions and kinetics of oxidation     

N. R. Khisina  D. A. Khramov  M. V. Kolosov  A. A. Kleschev  Lawrence A. Taylor 《Physics and Chemistry of Minerals》1995,22(4):241-250

Olivine samples (Fa 11) have been oxidized in air (f _O2 = 0.2 atm) at temperatures ranging from 350–700 °C and examined by Mössbauer spectroscopy, transmission electron microscopy, X-ray powder diffraction and thermomagnetic analysis. Oxidation of olivine was found to result in ferriolivine, magnesioferrite (major oxide phase) and magnetite (minor oxide phase) formation. Ferriolivine forms planar (001) precipitates, 0.6 nm in thickness, in the olivine host; the composition is likely to be Mg_0.5 v _0.5(Fe³⁺)_1.0SiO₄. Magnesioferrite MgFe₂O₄ exsolves as fine-grained precipitates (5–6 nm in size) filling interstices between the ferriolivine planar precipitates. Oxidation kinetic data at 700 °C show two stages of oxidation corresponding to formation of ferriolivine in the first stage and magnesioferrite in the second stage. The linear rate law with a rate constant k _Fol = 1.23 · 10^-3 s^-1 was found for the first stage whereas a parabolic rate-law with a constant of k _oxi = 3.28 · 10^-3 s^-1 was determined for the second stage of oxidation. It was found that ferriolivine is not an intermediate metastable phase in the oxidation process, terminated by magnesioferrite formation. The ferriolivine and magnesioferrite are considered to have formed by independent reactions which do not necessarily proceed simultaneously.  相似文献   

Isotopic Composition of Oxygen and Carbon and Formation Temperature of Accessory Minerals from Evaporitic Sediments in the Pripyat Trough     

Makhnach  A. A.  Kuleshov  V. N.  Pokrovskii  B. G.  Gulis  L. F.  Mikhailov  N. D.  Kolosov  I. L. 《Lithology and Mineral Resources》2002,37(6):536-545

The isotopic composition of oxygen and carbon was studied in accessory carbonates and quartz separated from salts in Upper Devonian halogenous formations of the Pripyat Trough (Belorus). It is established that isotopic characteristics vary in a wide range. Values of ¹⁸O vary in the following range (SMOW): from 18.2 to 29.2 in calcites, from 15.7 to 32.5 in dolomites, and from 17.4 to 27.2 in quartz. Values of ¹³C range from –13.4 to 1.4 in calcites and from –11.1 to 1.7 in dolomites (PDB). Results obtained indicate highly variable isotope-geochemical conditions of sedimentation and early diagenesis during the formation of evaporitic sediments. Accessory minerals were repeatedly formed in a wide temperature range and probably at various stages of the lithogenesis.  相似文献   

Applying Dalton’s law of potential evaporation rate over the territory of Russia and neighboring countries using long-term observation data     

M. D. Korzukhin  P. A. Kolosov  S. M. Semenov 《Russian Meteorology and Hydrology》2011,36(12):786-793

Parameters of the relationship between wind speed W and conductance G, used in Dalton’s law for potential evaporation rate, were estimated from the long-term field monitoring data on potential evaporation at 81 stations of the State Hydrological Institute. Linear dependence onWwas assumed, that is, G(W) = g ₁ + g ₂ W. The estimation yielded g ₁ = 165.2 and g ₂ = 99.9. These parameters were employed for computation of potential evaporation rate from routine meteorological data for locations of 2460 meteorological stations of the former USSR territory. The computed estimates were then compared with some published calculated values and with the data of direct potential evaporation rate measurements at 254 geographical points. The comparison yielded satisfactory results.  相似文献   

Carbon and Oxygen Isotopic Signatures in Albian-Danian Limestones of Cauvery Basin, Southeastern India     

J. Madhavaraju  I. Kolosov  D. Buhlak  J.S. Armstrong-Altrin  S. Ramasamy  S.P. Mohan 《Gondwana Research》2004,7(2):519-529

The Albian-Danian limestones of Cauvery Basin show a wide range of d¹³C and d¹⁸O values (–13.2 to +1.1% and –9.0 to –2.5%, respectively). The cement samples show negative carbon and oxygen isotope values (–18.9 to –3.9% and –9.0 to –4.3%, respectively). The petrographic study reveals the presence of algae, molluscs, bryozoans, foraminifers and ostracods as major framework constituents. The limestones have microspar and equant sparry calcite cements. The pore spaces and vugs are filled with sparry calcite cement. The bivariate plot of d¹³C and d¹⁸O suggests that most of the samples fall in the freshwater limestone and meteoric field, while few samples fall in the marine limestone and soil calcite fields. The presence of sparry calcite cement, together with negative carbon and oxygen isotope values, indicates that these limestones have undergone meteoric diagenesis.  相似文献   

Sources of Dissolved Organic Carbon in Rivers of the Yenisei River Basin   总被引：2，自引：0，他引：2  

A. S. Prokushkin  O. S. Pokrovsky  M. A. Korets  A. V. Rubtsov  S. V. Titov  I. V. Tokareva  R. A. Kolosov  R. M. W. Amon 《Doklady Earth Sciences》2018,480(2):763-766

The spatial and temporal variations in concentrations of dissolved organic carbon in the Yenisei River and its major tributaries are analyzed. The results obtained suggest that the maximal contribution to the flows of dissolved organic carbon in the Yenisei River is made by cryohydromorphic forest landscapes of the Central Siberian Plateau.  相似文献   

Characteristics of the surface and features of the propagation of radio waves in the atmosphere of Venus from data of bistatic radiolocation experiments using Venera 9 and 10 satellites     

M.A. Kolosov  O.I. Yakovlev  A.G. Pavelyev  A.I. Kucherjavenkov  O.E. Milekhin 《Icarus》1981,48(2):188-200

The results of the investigation of two regions of Venus by bistatic radiolocation are presented. The experiments were carried out at wavelength λ₀ = 32 cm. Maps of the distribution of reflectivity were obtained and characteristics of the relief, dielectric permittivity, soil density, and refraction attenuation in the atmosphere were measured. The value of the dispersion of small-scale slopes in the observed regions, γ, varies between 0.4 and 2.2°. There are some features on the reflectivity maps. Some of these features may correspond to mountain slopes with values in the range 2 to 8°. Corresponding changes of relief heights are contained in the interval 0.8 to 2.6 km. The features are found within the region (in the venerocentric IAU system): ?26.5 to 25.0° latitude and 220.0?239.2° longitude. One area was revealed with large values of permittivity in the range 6.5–7.5, and soil density between 2.7 and 2.9 g/cm³. The center of this area is located at ?23.5° latitude and 230.4° longitude. The extent of this region is 80 km. The results of measurements of the refraction angle and the refraction attenuation of radio waves are in good agreement with the parameters of the atmosphere of Venus received from the Soviet landers.  相似文献   

Microfossils in cherts from the Mesoproterozoic (Middle Riphean) Debengda Formation, the Olenek Uplift, northeastern Siberia.     

V N Sergeev  A H Knoll  S P Kolosova  P N Kolosov 《Stratigraphy and Geological Correlation》1994,2(1):19-33

Silicified shallow-water marine carbonate deposits of the Proterozoic Debengda Formation (the Olenek Uplift, northeastern Siberia) contain well preserved microfossils. One or two distinct assemblages consists only of filamentous Siphonophycus microfossils, which are presumably the extracellular sheaths of hormogonium cyanobacteria. The other is dominated by coccoidal microfossils, first by the entophysalidacean cyanobacterium Eoentophysalis. The coccoidal assemblage was recognized in the layered carbonate precipitate structures of a superficially stromatolite appearance. Despite its simple composition, the microfossil assemblage supports the generally accepted Mesoproterozoic (middle Riphean) age of the Debengda Formation. This conclusion corresponds to the available data on isotopic geochronology, and to the composition of columnar stromatolites from the Dehengda Formation. Both the structural features and carbon isotopic composition of its rocks are comparable to those of rocks of known Mesoproterozoic age, but differ from the characteristics of definitely Neoproterozoic deposits.  相似文献   

Microwave radiometry of Mars from the Mars 2 and 3 orbiters (preliminary results)     

A.E. Basharinov  I.B. Drozdowskaya  S.T. Egorov  V.N. Galaktionov  M.A. Kolosov  V.D. Krotikov  N.N. Kroupenio  A.D. Kuzmin  V.A. Lodygin  L.I. Malafeev  E.I. Omelchenko  O.B. Schuko  N.Y. Shapirovskaya  A.M. Shutko  V.S. Troitskiy  Yu.N. Vetukhnovskaya 《Icarus》1972

A 3.4-cm wavelength radiometer aboard the Mars 2 and 3 orbiters observed the brightness temperature due to planetary thermal emission in two orthogonal polarizations as a function of position on Mars. Preliminary results for two orbits of Mars 3 show a correlation between subsurface temperature and dielectric constant, interpreted as an effect of porosity.  相似文献   

Interannual Variability of Atmospheric CO<Subscript>2</Subscript> Concentrations over Central Siberia from ZOTTO Data for 2009–2015     

A. V. Timokhina  A. S. Prokushkin  A. V. Panov  R. A. Kolosov  N. V. Sidenko  J. Lavric  M. Heimann 《Russian Meteorology and Hydrology》2018,43(5):288-294

The interannual variations in the characteristics of the seasonal cycle (annual and seasonal amplitudes, winter emission, dates of annual minimum and maximum, and phase) and in the growth rate of atmospheric carbon dioxide concentration over Central Siberia are analyzed for the period from May 2009 to January 2016. The results are based on the continuous monitoring of CO₂ concentration at the Zotino Tall Tower Observatory (ZOTTO, www.zottoproject.org). It is found that the seasonal amplitude of CO₂ concentration in the atmo spheric surface layer over Western Siberia is 26.4 ± 0.8 μmol/mol (no long-term trend toward its increase was revealed), the annual mean growth rate of CO₂ is 2.34 μmol/mol per year, its variations range from 1 to 4 μmol/mol per year.  相似文献   

Daytime ionosphere of Venus as studied with Veneras 9 and 10 dual-frequency radio occultation experiments     

G.S. Ivanov-Kholodny  M.A. Kolosov  N.A. Savich  Yu.N. Alexandrov  M.B. Vasilyev  A.S. Vyshlov  V.M. Dubrovin  A.L. Zaitsev  A.V. Michailov  G.M. Petrov  V.A. Samovol  L.N. Samoznaev  A.I. Sidorenko  A.F. Hasyanov 《Icarus》1979,39(2):209-213

We present results of the dual-frequency radio sounding of the Venusian ionosphere carried out by the Venera 9 and 10 satellites in 1975. Thirteen height profiles of electron density for different solar zenith angles varying from 10 to 87° have been obtained by analyzing the refraction bending of radiorays in the sounded ionssphere. The main maximum of electron density at a height of 140–150 km depends on the solar zenith angle and is 1.4 to 5 × 10⁵ cm^?3. The lower maximum is determined definitely to be at ～130 km high. In the main and lower maxima the electron density variations with solar zenith angle are in good agreement with the Chapman layer theory. For the first time it is found that the height of the upper boundary for the daytime ionosphere (h_i) depends regularly on the solar zenith angle. At Z_⊙ < 60°, h_i does not exceed 300 km while at Z_⊙ > 60°, it increases with Z_⊙ and comes up to ～ 600 km at Z_⊙ ～ 80°.  相似文献