排序方式： 共有19条查询结果，搜索用时 15 毫秒
1.
2.
V.L. Tauson T.M. Pastushkova D.N. Babkin T.S. Krasnoshchekova E.E. Lustenberg 《Russian Geology and Geophysics》2010,51(7):764-773
The dependence of trace-element concentration on the size of crystal in sample is experimentally studied by the example of gold distribution among single crystals of different sizes of hydrothermally grown pyrite, As-pyrite, and magnetite. The effect is modeled on the assumption that the Au uptake is due to a nonautonomous phase (NAP) at crystal surface. The structurally bound gold admixture is estimated from the dependence of the average content of evenly distributed gold on the specific surface of average crystal (1.5, 0.5, and 0.7 ppm for pyrite, As-pyrite with 0.02–0.08 wt.% As, and magnetite, respectively). The gold concentrations in hypothetical “pure” NAPs have been estimated by the extrapolation of the concentration dependence to the characteristic size of an NAP. The coefficients of fractionation of Au into an NAP relative to the bulk phase are 1.1 × 103, 3.5 × 103, and 2.4 × 103 for pyrite, As-pyrite, and magnetite, respectively. Thus, the above effect is comparable in magnitude with the known effect of trace-element trapping by defects of crystal structure. Arsenic admixture favors the fractionation of gold into an NAP. We also considered other manifestations of this effect and its significance for solving problems of experimental geochemistry and analytical chemistry of trace elements and mineral processing. The data obtained substantiate the new mechanism of uptake of incompatible elements (including noble metals) during endogenic ore formation as more common and more effective than classical adsorption, including reducing adsorption of mercury and noble metals on mineral phases. 相似文献
3.
The results of recent studies carried out in the State Hydrological Institute were generalized to present new data on the
estimation of long-term dynamics of water resources and water use for all administrative regions of RF, as well as current
and anticipated variations in water resources in the nearest future. Estimates were constructed for changes in water use,
load on water resources, and water availability, especially in the recent two decades, during which Russia experienced most
significant changes in the major factors determining the state of water resources, i.e., climate change and socio-economic
transformations. Estimates are given for constituent entities of RF and for hydroclimatic regions of the country as a whole. 相似文献
4.
V.L. Tauson D.N. Babkin V.V. Akimov S.V. Lipko N.V. Smagunov I.Yu. Parkhomenko 《Russian Geology and Geophysics》2013,54(5):526-543
The three-mode distribution of trace-element (TE) concentrations is observed in accordance with three main forms of TE occurrence in mineral: structural, surficial, and phase (native TE phases). Minerals of hydrothermally synthesized pyrite–pyrrhotite–magnetite–greenockite assemblage in the presence of Au and Mn are studied. Discrimination of modes is made, using the method of statistical sample of analytical data for single crystals (SSADSC), which is based on the postulate that individual crystals can contain predominantly one of possible forms. This is supported by study of Cd modes of occurrence by element thermorelease atomic-absorption spectrometry. X-ray photoelectron spectroscopy and atomic-force microscopy were used to examine the surficial TE forms. It has been confirmed that the dependence of the TE content on the crystal size in the sample is mainly due to surficial nonautonomous phases absorbing TEs. The effect of correspondence of chemical-component forms on the surfaces of coexisting minerals is also corroborated. This phenomenon is not related to the mutual contamination of phases but is due to the induction of the corresponding states of chemical forms in coexisting nonautonomous phases. It is possible to obtain true coefficients of interface distribution, characterizing structural TE impurities. These coefficients differ strongly from apparent distribution coefficients calculated from the bulk contents of impurities, except for Mn in pyrrhotite and magnetite, where its structural mode is predominant. The results obtained show that TEs can be used as quantitative geochemical indicators, which help to obtain correct information about the parameters of mineral formation and TE contents in the fluid phase. 相似文献
5.
R. H. Meade N. N. Bobrovitskaya V. I. Babkin 《International Journal of Earth Sciences》2000,89(3):461-469
Of the world's great rivers, the Ob and Yenisey rank among the largest suppliers of fresh water and among the smallest suppliers of suspended sediment to the coastal ocean. Sediment in the middle reaches of the rivers is mobilized from bordering terraces and exchanged between channels and flood plains. Sediment in the lower reaches of these great rivers is deposited and stored (permanently, on a millennial time scale) in flood plains. Sediment discharges, already small under natural conditions, are diminished further by large manmade reservoirs that trap significant proportions of the moving solids. The long winter freeze and sudden spring breakup impose a peakedness in seasonal water runoff and sediment discharge that contrasts markedly with that in rivers of the tropics and more temperate climates. Very little sediment from the Ob and Yenisey rivers is being transported to the open waters of the Arctic Ocean under present conditions. 相似文献
6.
V. L. Tauson D. N. Babkin T. M. Pastushkova N. V. Smagunov S. V. Lipko I. Yu. Voronova V. I. Men’shikov N. V. Bryanskii K. Yu. Arsent’ev 《Geochemistry International》2016,54(2):149-166
Distribution coefficients D of Au and Pd between magnetite (manganmagnetite) and ammonium chloride hydrothermal solution and the structural Dstr and surface-related Dsur terms of these coefficients were determined at 450 and 500°С and a pressure of 1 kbar using internal sampling techniques. Quantitative data on the speciation of precious metals are obtained using the technique of statistical selections of analytical data on single crystals SSADSC and compared with LA-ICP-MS data. Both Pd and Au are elements compatible with magnetite and its manganoan variety: Dstr is ≈3 for Pd and ≈1 for Au, although Au seems to weakly enrich fluid at 500°C: Dstr ≈ 0.5–0.8. The trends of postmagmatic Pd and Au fractionation can thus strongly depend on the presence of spinel-group minerals, first of all, magnetite and its solid solutions. The dualistic nature of the distribution coefficients provides sound grounds to believe that both elements are highly compatible, with regard not only for the structural but also for the surface-related modes of their occurrence (Dsur ≈ 17 and ≈50–70 for Au and Pd, respectively). The maximum concentrations of structural modes of the elements are 5.3 ppm for Au and 5.1 ppm for Pd and were found in the solid solution whose jacobsite mole fractions were 0.82 and 0.49, respectively. The principal distribution patterns of the elements in crystals are confirmed by LA-ICP-MS data. Data on this system testify that the distribution coefficients of minor and trace elements are geochemically dualistic because of the abnormal absorption properties of nanometer-sized nonautonomous phases on the surface of ore minerals, and this dualism plays an important geochemical role. 相似文献
7.
The Kalguty complex deposit, the Gorny Altai: Mineralogical and geochemical characteristics and fluid regime of ore formation 总被引：1，自引：0，他引：1
The results of detailed mineralogical, geochemical, and thermobarogeochemical studies of the Kalguty complex greisen deposit are presented. The chemical compositions of ore veins, greisens, and other geological bodies have been determined. A wide range of chemical elements from Li to U (48 elements, including noble metals and REE) has been determined in ore minerals. Graphite in association with quartz and sulfides was identified in ore veins for the first time. Graphite is enriched in a light carbon isotope. The δ13C value varies from ?26.3 ± 0.4 to ?26.6 ± 0.3‰. High Au, Ag, Hg, Te, Sb, Bi, Cu, Pb, Zn, Fe, and S contents were detected in graphite grains with a microprobe. The graphite content increases regularly with depth; the spatial correlation of graphite with W, Mo, Cu, Au, Pt, Pd, and other metals is established. The highest Au, Ag, Pt, Pd, and Os contents are characteristic of minor intrusions of albitized granite porphyry (γπ2J1vk), intramineral dikes of hydrothermally altered kalgutite (γπ3J1vk), ore veins, their greisen selvages, and autonomous ore-bearing greisen bodies of the Mo stock type. Gold occurs in native form, while silver is contained largely in sulfides and sulfosalts. High PGE contents are characteristic of pyrite, wolframite, and molybdenite. The major components of fluid inclusions in quartz (H2O, CO2, CO, and H2) have been studied, as well as hydrocarbons (CH4, C2H6, C3H8, C4H10, C5H12, C6H14, C2H2, and C2H4) contained therein. Two-phase fluid inclusions are predominant, while single-and three-phase inclusions are less abundant. The homogenization temperatures of primary and secondary inclusions are 290–340 and 140–160°C, respectively. The concentration of dissolved salts (NaCl and KCl) in two-phase inclusions amounts to 11.6–14.0%. The H2O and CO2 contents decrease with depth, whereas the CO, H2, and HC concentrations increase in the same direction. Graphite is regarded as a product of reactions with participation of fluid (gas) components. The ore mineralization was formed under contrasting conditions related to the oxidation of a primary reduced deep metalliferous fluid. 相似文献
8.
Water resources of the Russian Federation in 1930–2000 are assessed. It is shown that, as a result of intensification of general atmospheric circulation, water resources increased since 1981 to 2000 by about 6% as compared with those for 1930–1980. 相似文献
9.
Koroleva E. S. Khairullin R. R. Babkina E. A. Slagoda E. A. Khomutov A. V. Melnikov V. P. Babkin E. M. Tikhonravova Ya. V. 《Doklady Earth Sciences》2020,491(1):179-182
Doklady Earth Sciences - Remote sensing methods make it possible to evaluate the reaction of the cryolithozone and tundra landscapes in hard-to-reach Arctic areas based on the indicators of modern... 相似文献
10.
Water and heat regimes of an arid area are simulated with the use of differential equations of the water and heat balances. The equations are developed, analyzed, and used to calculate the dynamics of the main hydrological and climatic characteristics, given the linear increase or variations in the amount of precipitation. Calculations are made for the area of the Caspian Depression and West Khazakhstan. 相似文献