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441.
新疆希勒库都克铜钼矿区岩浆混合作用: 来自锆石U-Pb年代学的证据 总被引:7,自引:6,他引:1
新疆北部富蕴县内希勒库都克铜钼矿区的花岗闪长岩及其包体岩相学、矿物化学和岩石地球化学特征及野外地质特征显示其为岩浆混合作用的结果。本文获得花岗闪长岩及其中暗色微粒包体玄武安山玢岩、细粒辉长闪长岩锆石U-Pb年龄为326.8±2.1Ma、327.6±2.4Ma、329.3±2.3Ma,年龄值基本一致,这一结果从年代学角度为花岗闪长岩及其中暗色微粒包体的岩浆混合作用成因提供证据。偏酸性的花岗闪长质与偏基性玄武安山质岩浆混合作用形成了331.9±2.1Ma的安山玢岩脉。 相似文献
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Z. M. Malkin 《Astronomy Reports》2010,54(11):1053-1061
VLBI observations carried out by global networks provide the most accurate values of the precession-nutation angles determining
the position of the celestial pole; as a rule, these results become available two to four weeks after the observations. Therefore,
numerous applications, such as satellite navigation systems, operational determination of Universal Time, and space navigation,
use predictions of the coordinates of the celestial pole. In connection with this, the accuracy of predictions of the precession—nutation
angles based on observational data obtained over the last three years is analyzed for the first time, using three empiric
nutation models-namely, those developed at the US Naval Observatory, the Paris Observatory, and the Pulkovo Observatory. This
analysis shows that the last model has the best of accuracy in predicting the coordinates of the celestial pole. The rms error
for a one-month prediction proposed by this model is below 100 microarcsecond. 相似文献
447.
I.S. Peretyazhko S.Z. Smirnov A.R. Kotel’nikov Z.A. Kotel’nikova 《Russian Geology and Geophysics》2010,51(4):349-368
The phase state of fluid in the system H3BO3–NaF–SiO2–H2O was studied at 350–800 °C and 1–2 kbar by the method of synthetic fluid inclusions. The increase in the solubility of quartz and the high reciprocal solubility of H3BO3 and NaF in water fluid at high temperatures are due to the formation of complexes containing B, F, Si, and Na. At 800 °C and 2 kbar, both liquid and gas immiscible phases (viscous silicate-water-salt liquid and three water fluids with different contents of B and F) are dispersed within each other. The Raman spectra of aqueous solutions and viscous liquid show not only a peak of [B(OH)3]0 but also peaks of complexes [B(OH)4]–, polyborates [B4O5(OH)4]2–, [B3O3(OH)4]–, and [B5O6(OH)4]–, and/or fluoroborates [B3F6O3]3–, [BF2(OH)2]–, [BF3(OH)]–, and [BF4]–. The high viscosity of nonfreezing fluid is due to the polymerization of complexes of polyborates and fluorine-substituted polyborates containing Si and Na. Solutions in fluid inclusions belong to P–Q type complicated by a metastable or stable immiscibility region. Metastable fluid equilibria transform into stable ones owing to the formation of new complexes at 800 ºC and 2 kbar as a result of the interaction of quartz with B-F-containing fluid. At high concentrations of F and B in natural fluids, complexes containing B, F, Si, and alkaline metals and silicate-water-salt dispersed phases might be produced and concentrate many elements, including ore-forming ones. Their transformation into vitreous masses or viscous liquids (gels, jellies) during cooling and the subsequent crystallization of these products at low temperatures (300–400 °C) should lead to the release of fluid enriched in the above elements. 相似文献
448.
V. N. Golubev I. V. Chernyshev A. B. Kotov E. B. Sal’nikova Yu. V. Golzman E. D. Bairova S. Z. Yakovleva 《Geology of Ore Deposits》2010,52(6):496-513
An isotopic geochronological study of Russia’s largest Strel’tsovka uranium district has been carried out. Polychronous granite
generation, which determined the structure of the pre-Mesozoic basement, had important implications for the formation of volcanotectonic
structural elements bearing economic uranium mineralization. The study of U-Pb, Rb-Sr, and Sm-Nd isotopic systems of whole-rock
samples and minerals of granitic rocks allowed us to estimate the deportment of these systems in spatially conjugated granite-forming
and hydrothermal processes differing in age and gave grounds for revising the age of granites pertaining to the Urulyungui
Complex and refining the age of the Unda Complex. 相似文献
449.
H. Dresmann N. Keulen Z. Timar-Geng B. Fügenschuh A. Wetzel H. Stünitz 《International Journal of Earth Sciences》2010,99(2):285-297
The thermal history of the south-westernmost Black Forest (Germany) and the adjacent Upper Rhine Graben were constrained by
a combination of apatite and zircon fission-track (FT) and microstructural analyses. After intrusion of Palaeozoic granitic
plutons in the Black Forest, the thermal regime of the studied area re-equilibrated during the Late Permian and the Mesozoic,
interrupted by enhanced hydrothermal activity during the Jurassic. At the eastern flank of the Upper Rhine Graben along the
Main Border Fault the analysed samples show microstructural characteristics related to repeated tectonic and hydrothermal
activities. The integration of microstructural observations of the cataclastic fault gouge with the FT data identifies the
existence of repeated tectonic-related fluid flow events characterised by different thermal conditions. The older took place
during the Variscan and/or Mesozoic time at temperatures lower than 280°C, whereas the younger was probably contemporary with
the Cenozoic rifting of the Upper Rhine Graben at temperatures not higher than 150°C. 相似文献
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