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1.
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
2.
The massif of Fedorov Tundra was formed as part of the Paleoproterozoic (2.5 Ga) Fedorov-Pana platinum-bearing layered complex
as a result of consecutive emplacement of two intrusive phases. The emplacement of the first phase resulted in the formation
of a large layered intrusive body composed of amphibole gabbro, gabbronorite, norite, pyroxenite, olivine pyroxenite, and
harzburgite. The second phase gave birth to a gabbronorite intrusion smaller in volume and enriched in sulfides and PGM. Magmatic
breccia has been observed in the contact zone between two phases. The rocks of the massif are referred to the series of normal
alkalinity and to the quartz- and olivine-normative groups differing in saturation with silica. Using isoplethic and isobaric
joins of the q-fo-fa-di-hd-ab-an-aq phase diagram, the stages of rock formation are considered. The thermodynamic conditions of rock crystallization were determined
as T = 1000−800°C and $
P_{H_2 O}
$
P_{H_2 O}
= 1000−2500 bar for the first intrusive phase and T = 1000–900°C and $
P_{H_2 O}
$
P_{H_2 O}
= 800−1000 bar for the second intrusive phase. 相似文献
3.
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
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.
The data of the bottom “summit” surface were used for compiling the schematic structural-neotectonic map and map of the main
neotectonic structural elements. Their comparison with the schematic paleogeographic maps of the lithophysical complexes for
four periods (K2-$
_{1 - 2}
$
_{1 - 2}
, $
\rlap{--} P_3
$
\rlap{--} P_3
-N11, N11–2, and N13-N2) reveals that the largest part of the considered area was characterized by either a continental or relatively shallow-sea
environment, except for the western areas occupied at that time by the relatively deep trough with its axis located substantially
westward of the neotectonic Deryugin Basin and the Staritskii Trough. In the Late Pliocene, the deep paleotrough ($
\rlap{--} P_3
$
\rlap{--} P_3
-N22) and Deryugin Basin were likely occupied by shelf settings with continuing sedimentation. The paleogeographic environments
of the area for the period from the terminal Pliocene to the late Riss (Taz) Glaciation (Q26; MIS6) are unknown so far. The most complete Quaternary section recovered by Core LV 28-34-2 consists of six units; the odd
(1, 3, and 5) and even (2, 4, and 6) among them correspond to the warm and cold marine isotopic stages, respectively. Judging
from the benthic foraminiferal assemblages, the water depths during cold periods were shallower as compared with the warm
stages, which is explained by the respective ascending and descending bottom movements and, partially, by the eustatic sea
level fluctuations. In the Late Pleistocene-Holocene (∼17 ka), the bottom of the Deryugin Basin and the summit part of the
Institut Okeanologii Rise subsided with average rates of 8 and 3 cm/year, respectively. 相似文献
6.
A new version of the STRUCTON (2009) computer model is proposed for the simulation of the molecular mass distributions (MMD)
characterizing the diversity of anions in silicate melts depending on their polymerization and temperature. In contrast to
earlier versions, the new version of the model accounts for disproportionation reactions of Q
n
species and makes use of their proportions in the statistical simulations of the origin of real Si-O complexes. The new potentialities
of the STRUCTON program package are illustrated by its application to studying the structural-chemical characteristics of
melts in the Na2O-SiO2 system along its liquidus line, including the points of eutectics and phase transitions at 0.333 ≤ $
N_{SiO_2 }
$
N_{SiO_2 }
< 0.500. This problem is solved with the use of a temperature-composition dependence of polymerization constants K
p
Na in the Toop-Samis approximation. The variations in K
p
Na were proved to be as large as three orders of magnitude due to both the temperature effect at a constant composition and
the composition effect at a constant temperature. The results of the MMD simulations on the liquidus show that the concentration
of the SiO44− ion strongly decreases, and the proportion of chain species increases compared to those at a stochastic distribution. The
concentration of the Si2O76− anion reaches its maximum (∼42%) at 40 mol % in the liquid, i.e., the composition of Na6Si2O7. At $
N_{SiO_2 }
$
N_{SiO_2 }
> 0.40, this ion dominates over the SiO44− monomer. More silicic melts with $
N_{SiO_2 }
$
N_{SiO_2 }
≥ 0.45, are dominated by (Si
n
O3n
)3n− ring species, and the concentrations of these species are related as (Si3O9)6− > (Si4O12)8− > (Si5O15)10−. The maximum concentration of these flat rings also occurs near the composition of stoichiometric metasilicate with Si/O
= 0.333. The comparison of the dependence of the average size of anions i
av and the average number of their species on depolymerization indicates that a change in the proportion of Q
n
species in melt at decreasing temperature results in structural restyling and an increase in the average size of Si-O complexes.
The average number of anion species thereby decreases compared to that in a stochastic MMD. The results presented in this
publication direct the progress in the thermodynamic theory of silicate melts to a new avenue that makes use of the capabilities
and advantages of the ion-polymer model, the theory of associated solutions, spectroscopic data, and the experimental study
of variations in oxide activities depending on composition and temperature. 相似文献
7.
Most altered clay minerals in uranium ore deposits in granites in the selected provinces of South China haveδ
18O
m
values ranging from 6.22 to 7.24,δDm from −60 to −70,δ
18O
from +3.05 to −3.07, and
from −20.2 to −37.5‰. Relative enrichment of32S in the uranium ore deposits and greater variations in Pb isotopic composition of galenas from them show that uranium ores
in the granites were formed in such a way that uranium in shallow-source granites had been mobilized by heated meteoric waters
and then migrated to local favourable locations along great faults to form uranium ore deposits.
Zhang Shaoli, Yang Wenjin, Tang Chunjing and Xu Wenxin did part of this work. 相似文献
8.
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
9.
Charnockitization of mafic Opx-Cpx-Grt-Hbl-Bt-Pl ± Qtz granulites and Hbl-Opx-Bt hornblendites was studied in the southeastern part of the Lapland Granulite Belt. The evolutionary trends of the whole-rock
compositions and mineral assemblages indicate that the rocks were affected by Na-K-Si-H2O-CO2-Cl brines, which came from outside, alkalinized and debasified the granulites, introduced Na, K, and Si into them, and depleted
them in Mg, Fe, and Ca prior to the onset of charnockite melting; the latter began in the granulites only in their most extensively
debasified domains. In the course of alkaline metasomatism, pyroxene were replaced by secondary hornblende and biotite with
high Ti concentrations, analogous to those in the unaltered granulites. This suggests that the pre-charnockite amphibolization
and biotitization were induced not by a temperature decrease but by the effect of Na- and K-bearing fluid during the metamorphic
culmination. The metasomatically altered granulites, which were transformed into leucocratic disintegrated amphibolite skialiths,
were gradually resorbed and dissolved in the charnockite melt, whose bulk composition corresponded to low-alkaline granites
and tonalites. Hence, no contamination took place, and the excess Mg, Fe, and Ca amounts with respect to the eutectic composition
were removed from the reaction zone. Variation diagrams indicate that the whole-rock composition of the granulites is gradually
shifted toward the composition of charnockitoids. In certain instances, however, melanocratic Hbl-Grt-Opx-Cpx-Pl rims were formed along the granulite-charnockite interface, with the bulk composition of these fringes richer in Mg, Fe,
and Ca than that of the ambient granulites. The reason for this was the sporadic redeposition of Mg, Fe, and Ca, which were
mobilized from during charnbockitization and redeposited immediately in the reaction zone. In addition, rocks around the charnockite
veins bear autonomous melanocratic Grt-Opx-Cpx-Hbl ± Mag ± Ilm ± Scp ± Pl ± Qtz veins whose mineral assemblages and bulk composition are close to those of the melanocratic rims around charnockitoids. The
veins were formed via the transportation of Mg, Fe, and Ca for long distances outside the charnockitization zones. TWQ thermobarometric
calculations indicate that the pre-charnockite alkaline metasomatism and debasification (amphibolization, biotitization, and
feldspathization), anatectic formation of charnockite migma or magma, and the development of the melanocratic veins took place
at the peak of the high-pressure granulite metamorphism at the same P-T parameters: approximately 800°C and 9–9.5 kbar. The calculated composition of the charnockitizing fluids suggests that they
were homogeneous brines with $
X_{H_2 O} = 0.45
$
X_{H_2 O} = 0.45
, $
X_{CO_2 } = 0.10
$
X_{CO_2 } = 0.10
, X
NaCl = 0.30, and X
KCl = 0.15. 相似文献
10.
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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