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1.
The solubility of pentatungstate of sodium (PTS) Na2W5O16 · H2O and sodium tungsten bronzes (STB) Na0.16WO3 in acid chloride solutions containing 0.026, 0.26, and 3.02m NaCl have been studied at 500°C, 1000 bar, given fO2 (Co-CoO, Ni-NiO, PTS-STB buffers), and constant NaCl/HCl ratio (Ta2O5-Na2Ta4O11 buffer). Depending on experimental conditions, the tungsten content in the solutions after experiments varied from 10−3 to 2 × 10−2 mol/kg H2O. Obtained data were used to calculate the formation constants of predominant tungsten complexes (VI, V): H3W3VIO123−, W3VO93−, [WVW4VIO16]3−, for reactions
$
\begin{gathered}
3H_2 WO_4^0 \leftrightarrow H_3 W_3 O_{12}^{3 - } + 3H^ + \log K_p = - 7.5 \pm 0.1, \hfill \\
3H_2 WO_4^0 \leftrightarrow W_3 O_9^{3 - } + 1.5H_2 O + 3H^ + + 0.75O_2 \log K_p = - 25.7 \pm 0.2, \hfill \\
5H_2 WO_4^0 \leftrightarrow \left[ {W^V W_4^{VI} O_{16} } \right]^{3 - } + 3H^ + + 3.5H_2 O + 0.25O_2 \log K_p = - 4.6 \pm 0.1 \hfill \\
\end{gathered}
$
\begin{gathered}
3H_2 WO_4^0 \leftrightarrow H_3 W_3 O_{12}^{3 - } + 3H^ + \log K_p = - 7.5 \pm 0.1, \hfill \\
3H_2 WO_4^0 \leftrightarrow W_3 O_9^{3 - } + 1.5H_2 O + 3H^ + + 0.75O_2 \log K_p = - 25.7 \pm 0.2, \hfill \\
5H_2 WO_4^0 \leftrightarrow \left[ {W^V W_4^{VI} O_{16} } \right]^{3 - } + 3H^ + + 3.5H_2 O + 0.25O_2 \log K_p = - 4.6 \pm 0.1 \hfill \\
\end{gathered}
相似文献
2.
Solubility curves of water-hydrogen fluid were studied using a high-pressure gas apparatus at a pressure of 200 MPa under
variable fluid composition in haplogranite (Ab
39
Or
32
Qtz
29, 950°C), Na-disilicate (Na2Si2O5, 950°C), and albite melts (1200°C). The mole fraction of hydrogen in experiments was controlled directly by Ar-H2 mixtures using a specially designed cell with a Shaw membrane. $
X_{H_2 }^{Ar - H_2 }
$
X_{H_2 }^{Ar - H_2 }
ranged from 0 to 1. In some experiments with haplogranite and Na-disilicate melts under oxidizing conditions, in order to
increase the accuracy of experimental parameters, the fugacities of oxygen and hydrogen were controlled using the double-capsule
technique and the solid-phase buffer mixtures Ni-NiO (NNO) and Co-CoO (CCO). The addition of H2 to the H2O-saturated systems ($
X_{H_2 }^{H_2 O - H_2 }
$
X_{H_2 }^{H_2 O - H_2 }
≥ 0.012) results in the appearance of a distinct maximum on the solubility curves at $
X_{H_2 }^{H_2 O - H_2 }
$
X_{H_2 }^{H_2 O - H_2 }
= 0.05–0.07 (H2 mole fractions were calculated for real H2O-H2 mixtures of real gases), and the maximum content of H2O-H2 fluid increases relative to the H2O-saturated melts by 1.51 wt % for haplogranite melt at $
X_{H_2 }
$
X_{H_2 }
= 0.063, 2.68 wt % for albite melt at $
X_{H_2 }
$
X_{H_2 }
= 0.066, and 3.54 wt % for Na-disilicate melt at $
X_{H_2 }
$
X_{H_2 }
= 0.067. A further increase in H2 content in the gas mixture decreases the solubility of H2O-H2 fluid in the melts, and under pure H2 pressure, the contents of fluid components are 0.08 wt % in haplogranite melt and 0.06 wt % in albite melt. The 1H NMR study of aluminosilicate and Na-silicate glasses obtained under the pressure of H2O and H2O-H2 fluids suggests different mechanisms of the dissolution of H2O and H2O-H2 fluids in magmatic melts. In addition to the spectra of dissolved water fluid, the spectra of quenched glasses synthesized
under H2O-H2 fluid pressure exhibited a narrow line of molecular hydrogen with a width at half height of 1.8–2.0 kHz at $
X_{H_2 }
$
X_{H_2 }
≥ 0.653 for albite and $
X_{H_2 }
$
X_{H_2 }
≥ 0.063 for Na-disilicate and two lines at $
X_{H_2 }
$
X_{H_2 }
≥ 0.063 for the haplogranite composition. 相似文献
3.
The paper considers some petrological and geochemical aspects of the formation of oceanic plagiogranites (OPG)—felsic intrusive
rocks, which were found in the plutonic complexes of modern mid-ocean ridges (MOR) and ophiolites of paleo-collisional zones.
Based on the multi-equilibrium clinopyroxene-orthopyroxene-amphibole-plagioclase geothermobarometry, typical OPG found in
gabbros and peridotites were formed at temperatures of 820–850°C and pressure of 2–2.5 kbar. Close temperature estimates (825
± 50°C) were obtained from literature data on Ti content in zircon, with allowance for lowered TiO2 activity in the rock. Under these P-T parameters, OPG can be generated only in the presence of fluid of water activity $
\left( {a_{H_2 O} } \right)
$
\left( {a_{H_2 O} } \right)
close to 0.9. OPG and associated recrystallized gabbroids contain high-temperature hornblende with significant Cl content
(0.5–2 wt %). In addition, the plagiogranites are characterized by particular geochemical features such as extremely high
Na2O/K2O (up to 135), sharp LREE enrichment ((Ce/Yb)cn and (La/Sm)cn up to 10 and 4, respectively), and elevated 87Sr/86Sr ratio relative to DMM. All these facts point to the key role of hydrothermal fluid, the seawater derivative, in the OPG
formation. The fluid with $
a_{H_2 O} = 0.9
$
a_{H_2 O} = 0.9
(approximately 28 wt % NaCl) could be produced from seawater due to hydration reactions at the higher lower temperature horizons
of oceanic crust in the course of its percolation to the OPG generation areas. The formation of plagiogranites in the MOR
oceanic core complexes possibly reflects the fundamental feature of oceanic accretion: practically simultaneous (at the geological
time scale) proceeding of exogenic (neptunic) and endogenous (plutonic) processes. 相似文献
4.
The redox state of the continental lithospheric mantle of the Baikal-Mongolia region 总被引:1,自引:0,他引:1
L. P. Nikitina A. G. Goncharov A. K. Saltykova M. S. Babushkina 《Geochemistry International》2010,48(1):15-40
The thermal and redox state of the upper mantle beneath the Baikal-Mongolia region was estimated on the basis of the investigation
of the chemical composition (including iron oxidation state) of major minerals (olivine, orthopyroxene, clinopyroxene, and
spinel) in spinel and garnet-spinel peridotite xenoliths from the Cenozoic alkali basalts of the volcanic fields of the Dariganga
Plateau, Tariat Depression, and Vitim Plateau. At temperatures of 1030–1500°C and pressures of 29–47 kbar, the Δlog$
f_{O_2 }
$
f_{O_2 }
values relative to the FMQ buffer (calculated using the olivine-spinel oxygen barometer) range from −0.9 to −1.7 for the
xenoliths of the Dariganga Plateau, from −0.9 to −1.8 for the Tariat Depression, and from −0.8 to −0.1 for the Vitim Plateau.
The oxygen fugacity of peridotites from all of the areas is, in general, lower than that of the WM buffer. Oxygen fugacity
is usually below the CCO and EMOD/G buffers in the peridotites of the Dariganga Plateau and the Tariat Depression and higher
than these buffers in the peridotites of the Vitim Plateau. The T-PΔlog$
f_{O_2 }
$
f_{O_2 }
relationships in the xenoliths suggest the existence of spatial heterogeneity in the thermal and redox state of the upper
mantle of the Baikal-Mongolia region. This heterogeneity is probably related to the influence of the plume that was responsible
for the Late Mesozoic-Cenozoic intraplate magmatism of this region and reflects the different distance of the respective mantle
domains from the plume head. The C-O-H fluids in equilibrium with the upper mantle peridotites are composed mainly of water
and carbon dioxide. The mantle of the Dariganga Plateau and the Tariat Depression (Δlog$
f_{O_2 }
$
f_{O_2 }
< −0.9) is characterized by the dominance of H2O, whereas CO2-rich fluids are characteristic of the more oxidized mantle of the Vitim Plateau (Δlog$
f_{O_2 }
$
f_{O_2 }
is mostly higher than −0.8). 相似文献
5.
L. M. Chechin 《Astronomy Reports》2010,54(8):719-723
The rotational effect of the cosmic vacuum is investigated. The induced rotation of elliptical galaxies due to the anti-gravity
of the vacuum is found to be 10−21 s−1 for real elliptical galaxies. The effect of the vacuum rotation of the entire Universe is discussed, and can be described
by the invariant ω
ν
= ω
0 ∼ $
\sqrt {G\rho v}
$
\sqrt {G\rho v}
. The corresponding numerical angular velocity of the Universe is 10−19 s−1, in good agreement with modern data on the temperature fluctuations of the cosmic background radiation. 相似文献
6.
Ligang Zhang 《中国地球化学学报》1988,7(2):109-119
Based on the oxygen isotopic compositions of 133 wolframite samples and 110 quartz samples collected from 30 tungsten ore
deposits in south China, in conjunction withδD values and other data, these deposits can be divided into four types.
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