A new method of estimation of the bulk coefficients of minor component distribution was worked out on the basis of analysis of covariations of minor element concentrations in intrusive bodies. The ...partition coefficients for some minor elements were calculated using the geochemical data for the Elet-Ozero intrusive complex (North Karelia). The analysis performed shows that the whole rock series of the Elet-Ozero massif from the early basic rocks to leucocratic nepheline syenite was formed during a single process of crystallization differentiation controlled by the same partitioning coefficients as those in common basaltic magmas. The signs of sulfide liquid separation during the evolution of the magmatic system provide evidence for the probable association of sulfide ore deposits with plutons of the Elet-Ozero type.
The work is devoted to the problem of flexible small-scale production of galvanized steel of various sizes on a continuous hot-dip galvanizing unit with varying productivity. The main focus is on the ...heat treatment of steel strip, the requirements for which limit productivity. In conditions of disturbances, it is necessary to proactively control the heat treatment using models, or to reduce the speed of the strip to ensure that the requirements are met. Unlike most of the works that focus on heat control, this work focuses on strip cooling. Based on the analysis of production data of the Magnitogorsk Iron and Steel Works, it is shown that violation of the cooling requirements leads to the appearance of defects in the zinc coating. Dependence of the probability of defect occurrence on the strip temperature is given. Problems of cooling predictive control are formulated using models in the absence of temperature control of the cooling section cavity. For each of the tasks, the model structure and the method of its tuning are determined according to the data accumulated over a significant period of the unit operation under conditions of uncontrolled systematic disturbances. The structure of the cooling control system is proposed by estimation of the cooling section cavity temperature as a controlled variable. The temperature estimate is determined from the model. The lack of measurement of the cooling section cavity temperature is not a problem when varying productivity. The results of the model tuning are presented according to the data of the Magnitogorsk Iron and Steel Works continuous hot-dip galvanizing unit. The proposed structures of the models and methods for their adjustment can be applied in the development of models for metal heating in furnaces.
The demand for titanium has increased steadily over recent decades and is expected to remain strong in the future. This has stimulated increased interest in layered mafic intrusions with layers ...enriched in ilmenite and titanomagnetite. Among these intrusions is the Eletozero Massif located in north Karelia.
The study of melt microinclusions in olivine megacrysts from meimechites and alkali picrites of the Maimecha–Kotui alkali ultramafic and carbonatite province (Polar Siberia) revealed that the melt ...compositions corrected for loss of olivine due to post-entrapment crystallization of olivine on inclusion walls (differentiates of primary meimechite magma) match well to the composition of nephelinites and olivine melilitites belonging to carbonatite magmatic series. Modeling of fractional crystallization of meimechite magmas results in the high-alkali melt compositions corresponding to the silicate–carbonate liquid immiscibility field. The appearance of volatile-rich melts at the base of magma-generating plume systems at early stages of partial melting can be explained by extraction of incompatible elements including volatiles, by near-solidus melts at low degrees of partial melting, and meimechites are an example of such magmas. Subsequent accumulation of CO
2
in the residual melt results in generation of carbonate magma.
We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. We ...determine the dependence of the average of the measured μ+ and μ− cross sections for deeply virtual Compton scattering on the squared four-momentum transfer t from the initial to the final proton. The slope B of the t-dependence is fitted with a single exponential function, which yields B=(4.3±0.6stat|sys−0.3+0.1)(GeV/c)−2. This result can be converted into a transverse extension of partons in the proton, 〈r⊥2〉=(0.58±0.04stat|sys−0.02+0.01±0.04model)fm. For this measurement, the average virtuality of the photon mediating the interaction is 〈Q2〉=1.8(GeV/c)2 and the average value of the Bjorken variable is 〈xBj〉=0.056.
The composition of the lower mantle zones may be studied from the composition of minerals included in sub lithospheric diamonds. Multiphase mineral inclusions are rarely observed in such diamonds, ...and therefore, we may judge on the rock types hosting these diamonds on the basis of the chemistry of individual minerals.
A study investigated the oxygen potential of high-magnesium magmas. The development of methods for estimation of FeO activity in magmatic melts opens new perspectives for revealing the oxygen regime ...in the deep zones of the Earth and allows us to approach measurement of activities of SiO2 and other components of natural magmas.
The rocks of the Elet’ozero intrusion are characterized by high relative abundances of incompatible elements, with (La/Lu)
N
varying from 2.1 to 36.6, and a distinct positive Ba anomaly, which may ...record crystallization of Ba minerals during the formation of mafic rocks. The anomalous Ba enrichment is probably associated with a large-scale fluid-mediated mass transfer during subduction of a lithospheric slab within the Karelian craton which was synchronous with the generation of magmas parental to the Elet’ozero pluton. The presence of Al-rich spinel in gabbroic rocks as early-formed magmatic phases suggests crystallization at relatively high pressures (~0.5 GPa or ~15 km depth). The oxygen fugacity changed with time during the evolution of the magmatic system, approaching its maximum values (approximately 1.5 log units above the quartz–fayalite–magnetite buffer) during extensive crystallization of Fe–Тi oxides. High oxygen fugacities, Ti enrichment of mafic rocks, and lack of any positive correlation between Mg-numbers and Ni content in olivine can be useful indicators of potentially mineralized mafic intrusions.
Thermodynamic analysis of equilibria involving minerals of the lower mantle of pyrolite composition and crystalline carbon-bearing compounds indicates that the range of oxygen fugacity values at ...which diamond can be formed is separated from the region in which Fe-rich metallic alloy is generated by a field in which Fe carbides are stable. This implies that diamond can be formed in the lower mantle under more oxidizing conditions than those thought to be dominant in this geosphere. The absence of a metallic phase from the lower-mantle diamond-bearing mineral assemblage is consistent with the high (approximately 1%) Ni concentration in the ferropericlase found as inclusions in diamonds (Fe-rich metallic alloy is able to intensely extract Ni). An elevated redox potential also follows from the occurrence of carbonate phases found among mineral inclusions in lower-mantle diamonds. The main reason for a local increase in oxygen fugacity in the lower mantle may be shifts of redox equilibria toward a decrease in the amount, and then the disappearance of the Fe-Ni alloy with increasing temperature. An important role in the formation of diamond may be played by the generation of carbonate-phosphate and silicate melts in high-temperature zones and the migration of these melts and their interaction with wall rocks.
A natural orange diamond crystal from Siberian kimberlite has been studied using complementary spectroscopic techniques. The IR-spectra of the crystal revealed presence of low concentration of ...nitrogen A, B and C centers. In addition to these common defects a Y-center and 1240 cm
−1
band were clearly detected. Absorption UV–Vis spectra exhibited the 490 nm band and an unknown very broad band with diffuse maximum at 320–380 nm, with low energy edge extending far into the visible region. Photoluminescence spectra showed presence of N3, 440 nm, 455 nm, S1, 575.8 nm vibronic systems as well as zero-phonon lines at 418.2, 525.1, 560.8, 645.7 and 799.7 nm. Luminescence of the 575.8 nm system with broad vibronic band peaked at 690 nm noticeably contributes to the color of the diamond, i.e. its orange color is not only due to absorption but also to emission of light. Electron Paramagnetic Resonance revealed several structural defects: nitrogen-related P1, M5, M6 centers, oxygen-related OK1 and N3 centers, previously unreported nickel M7 center and tentatively phosphorus-related W24 center. The M5 and M6 centers involving two nitrogen atoms separated by ca. 8–10 interatomic distances represent an unusual long-range bonding. It is suggested that M6 and M7 might be related to the IR Y-center and to the broad band with maxima at 320–380 nm in the optical spectra of the diamond.
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