排序方式： 共有11条查询结果，搜索用时 42 毫秒
1.
The paper presents data on lechatelierite form suevites of the Daldyn Formation in the Popigai astrobleme. Some of the lechatelierite
samples show a complicated structure and contain block of diaplectic quartz glass and dynamic “intrusions” of glasses of types
I, II, and III. The glasses of types I and II abound in fluid inclusions and display evidence of partial homogenization with
lechatelierite. The glasses of type III are clearly separated from all other glasses but show evidence of dynamic interaction
with them in the molten state. Fluid inclusions in the glasses of types I and II are syngenetic but have notably different
densities from those of completely liquid or gaseous inclusions at 20°C. As is indicated by cryometric data, the liquid phase
of the inclusions is aqueous solution of low salinity (5–8 wt % NaClequiv). The bulk petrochemistry of the glasses of type I characterizes them as highly silicic (96.04 wt % SiO2 on average), with elevated K and Na concentrations (Na2O + K2O = 0.72 wt % on average), with 0.73 wt % Al2O3 (on average) and analytical totals 1.97 wt % less than 100%. The glasses of type II are also rich in SiO2 (91.51 wt % SiO2 on average) but contain a broader spectrum of concentrations of major oxides (totaling 5.53 wt % on average) and deficient
analytical totals (by 2.96 wt % on average). The glasses of type III are completely equal to impactites produced by melting
gneisses of the Popigai astrobleme. The glasses of type I are interpreted to be the intrusion products of the “early” highly
mobile and H2O-rich fluid+melt mixtures, whose protolithic material was K-Na feldspars of the target rocks. The derivation of these melts
was associated with the capturing of much silica and water at a highly mobile behavior of K and Na and an inert behavior of
Al. The glasses of type II were produced by the extensive mixing of silica and water at the limited involvement of apogneiss
melts, and these glasses are sometimes deficient in Al. The glasses of type III are usual mixed apogneiss melts. Excess silica
in the glasses of types I and II and their richness in water and deficiency in Al suggest impact anatexis and the selective
separation of components during their derivation; the parental fluid-melt mixtures of these glasses were derived from such
“hydrous” varieties of the target gneisses as diaphthorized and fractured rocks. The evolution and partial vitrification of
lechatelierite and the glasses of types I and II proceeded under residual shock pressures, as follows from data on the dense
(from ∼0.5 to 1 g/cm3) aqueous inclusions in these glasses, which suggest that the inclusions were captured in the glasses under pressures from
∼0.8 to 3.3 GPa. It follows that our lechatelierite samples have a complex multistage genesis, and their quenching facilitated
the preservation of “intrusions” of various stages of shock melting, including the products of the “early” impact anatexis
of the gneisses with the selective separation of components at the active participation of water. 相似文献
2.
Vishnevsky D. M. Kolyukhin D. R. Lisitsa V. V. Protasov M. I. Reshetova G. V. Tcheverda V. A. Qu D. Tveranger J. 《Doklady Earth Sciences》2017,473(2):477-481
Doklady Earth Sciences - This paper addresses seismic imaging of fault zones and analysis of the seismic data with the use of the fault facies model developed at Uni Research CIPR. Simulated and... 相似文献
3.
4.
T. Oyunchimeg A.E. Izokh A.V. Vishnevsky V.M. Kalugin 《Russian Geology and Geophysics》2009,50(10):863-872
Platinum group element (PGE) mineral assemblage has been discovered in the gold placers along the Burgastain Gol and Iljgen Gol (Western Mongolia). It includes isoferroplatinum (Pt3Fe) grains with inclusions of cooperite (PtS), laurite-erlichmanite (RuS2-OsS2), cuprorhodsite-malanite (CuRh2S4-CuPt2S4), irarsite-hollingworthite (IrAsS-RhAsS), and bowieite (Rh2S3).It has been established that the isoferroplatinum assemblage was generated from a volcanoplutonic picrite complex in the Ureg Nuur area, which is widespread in the central part of the Harhiraa accretionary terrane. According to composition, the PGE mineral–Cr-spinel assemblage was referred to as the Ural-Alaskan type. 相似文献
5.
V. M. Khomenko K. Langer M. Andrut M. Koch-Müller A. A. Vishnevsky 《Physics and Chemistry of Minerals》1994,21(7):434-440
Synthetic pyrope crystals up to 0.5 mm in diameter, substituted by titanium or by titanium plus iron, were grown under defined conditions of P, T, $f_{O_2 }$ in the presence of water using a piston-cylinder device. The crystals were characterized by X-ray and microprobe techniques. Their single-crystal optical absorption spectra were measured by means of a microscope-spectrometer. Two absorption bands at 16100 and 22300 cm{cm-1} in the spectra of pale-blue Fe-free Ti-bearing pyropes, grown under reduced conditions, were identified as originating from spin-allowed transitions, derived from 2 T 2g → 2 E g of octahedral Ti3+ ions. The splitting value of the excited 2E g state, 6200 cm-1, and the crystal field parameter of Ti3+ in pyrope Δ 0 = 19 200 cm-1 are both in agreement with literature data. In spectra of brown Fe, Ti-bearing garnets, a broad band at 23000 cm-1 was interpreted as a Fe2+[8] → Ti4+[6] charge-transfer band. The spectral position and width of this band agree with those observed for a FeTi charge transfer band in natural garnets. Fe, Ti-containing garnets synthesized at relatively high oxygen fugacity (10-11,0 atm), which permits a fraction of Fe3+ to enter the garnet, show an additional Fe2+[8] → Fe3+[6] charge transfer band at 19800 cm-1. 相似文献
6.
M. V. Charykova A. V. Vishnevsky V. G. Krivovichev E. L. Fokina N. M. Ivanova N. V. Platonova V. V. Semenova 《Geology of Ore Deposits》2016,58(8):636-645
Understanding the mechanisms of cadmium and selenium behavior under near-surface conditions is very important for solving certain environmental problems. The principal aim of this study is physicochemical analysis of the formation conditions of synthetic cadmium selenite CdSeO3 · H2O and experimental investigation of its thermal stability and dehydration and dissociation mechanisms. The synthesis was performed by boiling-dry aqueous solutions of cadmium nitrate and sodium selenite. The obtained samples were identified with electron microprobe and powder X-ray diffraction. Complex thermal analysis (thermogravimetry and differential scanning calorimetry) have shown that CdSeO3 · H2O is dehydrated at 177–241°C in two stages, apparently corresponding to the formation of CdSeO3 · 2/3H2O. The Eh–pH diagrams were calculated using the Geochemist’s Workbench (GWB 9.0) software package. The Eh–pH diagrams have been calculated for the Cd–Se–Н2О and Cd–Se–CO2–H2O systems for the average content of these elements in underground waters. The formation of cadmium selenite, CdSeO3 · H2O in the oxidation medium is quite possible. The existence of CdSeO3 is possible at high temperature. 相似文献
7.
Numerical simulation of seismic waves in models with anisotropic formations: coupling Virieux and Lebedev finite-difference schemes 总被引：2，自引：0，他引：2
Anisotropy is widespread in the Earth’s interior. However, there is a number of models where anisotropic formations comprise as few as 10–20?% of the volume, and this includes fractured reservoirs, thin-layered packs, etc. while the major part of the medium is isotropic. In this situation, the use of computationally intense anisotropy-oriented approaches throughout the computational domain is prodigal. So this paper presents an original advanced finite-difference algorithm based on the domain decomposition technique with individual scheme used inside subdomains. It means that the standard staggered grid scheme or the Virieux scheme is used in the main part of the model which is isotropic, while the anisotropy-oriented Lebedev scheme is utilized inside domains with anisotropic formations. Finite-difference consistency conditions at the artificial interface where the schemes are coupled are designed to make the artificial reflections as low as possible, namely, for the second-order scheme, the third order of convergence of the reflection coefficients is proved. 相似文献
8.
A. S. Mekhonoshin N. D. Tolstykh M. Yu. Podlipsky T. B. Kolotilina A. V. Vishnevsky Yu. P. Benedyuk 《Geology of Ore Deposits》2013,55(3):162-175
The Pt-Pd and Au-Ag mineralization hosted in both wehrlite without visible links to sulfide mineralization (dispersed assemblage of the Tartai massif) and disseminated Cu-Ni sulfide ore (ore assemblage of the Ognit massif) was found in dunite-wehrlite massifs localized in the fold framework of the Siberian Craton. The Pt minerals in both assemblages comprise sperrylite (PtAs2) and secondary Pt-Fe-Ni alloys in the Ognit massif and Pt-Fe-Cu and Pt-Cu alloys in the Tartai massif. The Pd minerals are widespread in the ore assemblages as compounds with Te, Sb, and Bi, whereas in the dispersed assemblage Pd is concentrated primarily in Pd-Cu-Sb compounds. Both assemblages are characterized by similar substitution of sperrylite with orcelite (Ni5 ? xAs2) and then with secondary Pt-Fe-Ni or Pt-Fe-Cu and Pt-Cu alloys; the occurrence of Au-Ag alloys with prevalence of Ag over Au; and replacement of them with auricupride (Cu3Au) at the late stage. Sperrylite in both assemblages contains Ir impurities, while the Pd minerals contain Cu and Ni admixtures, which are typical of mineral assemblages related to the ultramafic intrusions with nickel specialization. PGM were formed under a low sulfur fugacity and high As, Bi, and Sb activities. The postmagmatic fluids affected the primary mineral assemblages under reductive conditions, and this effect resulted in replacement of sperrylite with Ni arsenide (orcelite) and Pt-Fe-Ni and Pt-Fe-Cu alloys; Ni and Cu sulfides were replaced with awaruite and native copper. 相似文献
9.
Vishnevsky A. V. Belogub E. V. Charykova M. V. Krivovichev V. G. Blinov I. A. 《Geology of Ore Deposits》2018,60(7):559-567
Selenium is one of the most important minor elements in massive sulfide ores. This study focuses on selenium minerals present in the oxidation zone of the Yubeleinoe massive sulfide deposit, the South Urals, Russia: clausthalite (PbSe), tiemannite (HgSe), and naumannite (Ag2Se). These minerals are associated with goethite and siderite. Thermodynamic modeling was used to estimate the physicochemical parameters of selenide stability and the possible formation of Pb, Hg, and Ag selenites as a result of sulfide ore oxidation. The Eh–pH diagrams for the Fe–S–CO2–H2O and Fe–Se–CO2–H2O systems were calculated to estimate the physicochemical formation conditions of the Yubileinoe oxidation zone, as well as for the M–Se–Н2О and M–S–H2O (M = Hg, Pb, Ag) systems. The physicochemical parameters of clausthalite, naumannite, and tiemannite stability are consistent with these conditions. Only the formation of PbSeO3 is theoretically possible among Pb, Ag, and Hg selenites.
相似文献10.