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The compositions of parental melts of Tolbachinsky Dol (Kamchatka) basalts were estimated from the compositions of olivine-hosted (Fo90.5-83.1) primitive melt inclusions in the rocks of the Northern breakthrough of the Great Tolbachik Fissure Eruption (1975 A.C.) and of the late-Holocene cone “1004”. The parental melts contain 100–150 ppm Cu and 0.16–0.30 wt % S. These concentrations are much higher than those determined for the initial magmas of mid-ocean ridge basalts (MORB), for example of the Juan de Fuca ridge (Cu = 55–105 ppm, S=0.09–0.12 wt %). Modeling of mantle melting under variable redox conditions demonstrated that the high Cu and S contents in the Tolbachinsky Dol melts can be obtained by 6–12% melting of DMM-like source under oxidized conditions (ΔQFM = +1.2 ± 0.1) and do not require a significant (>30–35% for S) subduction-related influx of these elements to the mantle source. The high contents of Cu and S in the Tolbachinsky Dol melts are largely explained by the increase of sulfide solubility in a silicate melt under oxidized conditions. In contrast, relatively reduced (ΔQFM ～ 0) conditions of MORB generation result in low contents of Cu and S in their initial magmas. The estimated ΔQFM values agree well with the data obtained using the Cr-spinel–olivine oxybarometer. The high oxygen potential of Tolbachinsky Dol primary magmas is inherited by more evolved magmas, thus favouring Cu enrichment up to 270 ppm during magma fractionation, approaching maximum copper contents in the global systematics of island-arc rocks. 相似文献
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Oleg?MalkovEmail author Aleksej?Mironov Sergej?Sichevskij 《Astrophysics and Space Science》2011,335(1):105-111
Detection of a composite flux in photometry can serve as an indication of a photometrically unresolved binarity and can contribute
to the parameterization of the components of binary systems. A main goal of the present study is to develop a method of automatic
photometric detection of binaries, based on multi-color photometry, theoretical stellar spectral energy distributions and
general understanding of binary evolution. In particular, we consider an ultraviolet photometry where, in combination with
optical and infrared photometry, interstellar reddening can be easier distinguished from temperature reddening. 相似文献
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N. V. Chertkova A. E. Tsai N. L. Mironov V. D. Shcherbakov 《Moscow University Geology Bulletin》2010,65(1):39-48
Theoretical models and experimental data on the thermodynamic and rheological properties of basalts from the Apakhonchich
lava flow (Klyuchevskoi Volcano, Kamchatka) were invoked for plotting projections of water-containing and dry liquidus and
solidus curves on the P
s
-T plane. The P-T-X
H
2O conditions for the formation of basaltic magma and the degree of its differentiation were determined from data on melt inclusions.
The calculated apparent viscosity of the melt containing 10% crystals at 1100°C, 1 GPa, and 3 wt % water is 1.1 × 103 Pa s, and the density is 2.5 g/cm3. 相似文献
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Maxim V. Portnyagin Kaj Hoernle Nikita L. Mironov 《International Journal of Earth Sciences》2014,103(7):1963-1982
Melt inclusions in olivine Fo83–72 from tephras of 1867, 1971 and 1992 eruptions of Cerro Negro volcano represent a series of basaltic to andesitic melts of narrow range of MgO (5.6–8 wt %) formed by ~46 wt % fractional crystallization of olivine (~6 wt %), plagioclase (~27 wt %), pyroxene (~13 wt %) and magnetite (<1 wt %) from primitive basaltic melt (average SiO2 = 49 wt %, MgO = 7.6 wt %, H2O = 6 wt %) as it ascended to the surface from the depth of about 14 km. The crystallization occurred at increasing liquidus temperature from 1,050 to 1,090 °C in the pressure range from 400 to 50 MPa and was induced by release of mixed H2O–CO2 fluid from the melt at decreasing pressure. Matrix glass compositions fall at the high-Si end of the melt inclusion trend and represent the final stage of melt crystallization during and after eruption. The bulk compositions of erupted Cerro Negro magmas (tephras and lavas) range from high- to low-MgO (3–10 wt %) basalts, which form a compositional array crossing the trend of melt inclusions so that virtually no rock from Cerro Negro has composition akin to true melt represented by the inclusions. The variations of the bulk magma (rocks) and melt (melt inclusions) compositions can be generated in a dyke connecting a deep primitive magma reservoir with the Cerro Negro edifice. While the melt inclusions represent the compositional trend of instantaneous melts along the magma pathway at decreasing pressure and H2O content, occurrence of low-Mg to high-Mg basalts reflects the process of phenocryst re-distribution in progressively evolving melt. The crystallization scenario is anticipated to operate everywhere in dykes feeding basaltic volcanoes and can explain the predominance of plagioclase-rich high-Al basalts in island arc as well as typical compositional variations of magmas during single eruptions. 相似文献
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The development and application of new methods for intelligent analysis and extraction of information from digital sky surveys carried out in various spectral domains have now become a popular field in astrophysical research and, in particular, in stellar studies. Modern large-scale photometric surveys provide data for 105–106 relatively faint objects, and the lack of spectroscopic data can be compensated by the cross identification of the objects followed by an analysis of all catalogued photometric data. In this paper we investigate the possibility of determining the effective temperature, surface gravity, total extinction, and the total-to-selective extinction ratio based on the photometry provided in the 2MASS, SDSS, and GALEX surveys, and estimate the accuracy of the inferred parameters. We use a library of theoretical spectra to compute the magnitudes of stars in the photometric bands of the above surveys for various sets of input parameters. We compare the differences between the computed magnitudes with the errors of the corresponding surveys. We find that stellar parameters can be computed over a sizable domain of the parameter space. We estimate the accuracy of the resulting parameters. We show that the presence of far-ultraviolet data in the available set of observed magnitudes increases the accuracy of the inferred parameters. 相似文献
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The publication of large photometric surveys and the tools for the cross-identification of their objects open up a possibility
for obtaining multicolor photometry of hundreds of millions of objects. This, in turn, makes it possible not only to classify
the objects and determine their parameters, but also to measure the interstellar extinction towards them and produce an extinction
map for the Milky Way. The aim of this study is to develop a tool for the cross identification of objects in the most well-known
surveys and test it in several sky areas. To this end, we implemented an algorithm of fast positional matching of large astronomical
catalogs in small (up to one degree) sized areas with filtering of false identification. As a result, we drew in seven 0.1-degree
radius areas samples of objects from the DENIS, 2MASS, SDSS, GALEX, and UKIDSS surveys, and performed the cross-identification
of these surveys. We compiled the corresponding subcatalogs in the VO Table format. The tool developed as a result of this
work can be used to cross-identify objects in arbitrary sky areas for the further classification and determination of stellar
parameters, including the measurement of the amount of interstellar extinction. 相似文献
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I. A. Pozdnyakova I. V. Galitskaya O. K. Mironov I. A. Kostikova A. L. Dorozhko G. I. Batrak L. A. Matveeva K. I. Fesel 《Water Resources》2016,43(7):1012-1022
An original procedure for mapping hydrogeological windows is based on studying the geological structure of the massif overlaying the Podol’sko-Myachkovskii aquifer, changes in the hydrodynamic and hydrogeochemical conditions in the zone of “windows”; as well as calculating the travel time of contaminants in the vertical flow from the Meso-Cenozoic to Podol’sko-Myachkovskii Carboniferous aquifer. Both the areal and vertical distributions of low-permeability deposits are taken into account along with the variations of their thickness and permeability. The results obtained can be used in the development of groundwater protection measures and economic activity regulations in areas with hydrogeological windows. 相似文献
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Melt inclusions and hosting them highly magnesian olivine from rocks of Kamchatka and the Western Aleutian island arc were analyzed for copper content by LA-ICP-MS to determine the copper partition coefficient in primitive island-arc magmas. Based on measurements of 45 olivine–melt pairs, this coefficient was determined to be 0.028 ± 0.009 (2σ), which is the lowest value among previously published data. Mass-balance calculations of copper in a typical mantle peridotite using obtained partition coefficient indicate that its content in peridotite and primary mantle magmas is mainly determined by mantle sulfide. The Cu partition coefficient was also used to calculate the copper content in parental magmas of volcanoes of the Central Kamchatka Depression. Estimates obtained using copper content in phenocrysts of primitive olivine (Fo > 88 mol %) from these rocks are, on average, 139 ± 58 ppm (2σ), which exceed copper contents in primitive basalts (MgO > 8.5 wt %) of mid-ocean ridges (MORB 93 ± 31 ppm). This suggests the primary enrichment of Central Kamchatka magmas in copper and correlates with their more oxidizing conditions of formation as compared to MORB. 相似文献
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