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111.
112.
The viscosity of basalts (quartz and olivine tholeiite) was studied under pressure in dry conditions and in the presence of water. In dry conditions at 1400°C when pressure increases to 20 kbars the viscosity reduces by a factor of 2. In conditions of water saturation of basalt melts at 5 kbar the viscosity is smaller by a factor of ~ 50 than that in dry conditions. In the water undersaturated conditions when water content is fixed (3.3% H2O) in melt the viscosity considerably decreases with pressure and takes intermediate value between those in dry and water saturated conditions. Experimental data recently obtained permit us to consider the peculiarities of physical properties of magma in the presence of water on a new base. Ascending magma can reach critical velocities of transition to the turbulent regime under negligible pressure drop, as a result of low viscosity. It is known at present that water influences on the viscosity of acidic melt under pressure of 1–8 kbars and at temperatures between 800–1200°C. Various authors gave physico-chemical evaluation of the dynamics of granite melts on the basis of these data. The viscosity of basalt melts and their dynamics under normal pressure is also well-known. The known new experimental data of basaltic melt viscosity under pressure in dry conditions (Kushiro et al., 1976;Khitarov et al., 1978) and in the presence of water (Khitarov et al., 1976) embrace broader intervals of physico-chemical conditions as on the pressure (up to 20–30 kbar) as well on the content of water (from 3% up to 12 %). These data permitted to evaluate on a new base the dynamics of magmatic melts under pressure. 相似文献
113.
Lebedev I. E. Tikhomirov P. L. Pasenko A. M. Eid B. Lhuillier F. Pavlov V. E. 《Izvestiya Physics of the Solid Earth》2021,57(2):232-246
Izvestiya, Physics of the Solid Earth - Abstract—Paleomagnetic studies of several Late Cretaceous volcanic sections of the Okhotsk–Chukotka volcanic belt have been carried out in the... 相似文献
114.
Akulichev V. A. Burenin A. V. Voytenko E. A. Lebedev M. S. Morgunov Yu. N. Tagiltsev A. A. 《Doklady Earth Sciences》2021,498(2):498-501
Doklady Earth Sciences - The results of experimental studies on the features of propagation and reception of broadband pulsed signals in an underwater sound channel (USC) at a distance of 300 km... 相似文献
115.
M. Keskin A. V. Chugaev V. A. Lebedev E. V. Sharkov V. Oyan O. Kavak 《Journal of Volcanology and Seismology》2012,6(6):361-382
A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacada? neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacada? neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17–18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity. 相似文献
116.
Yu. I. Troitskaya G. V. Rybushkina I. A. Soustova G. N. Balandina S. A. Lebedev A. G. Kostyanoi A. A. Panyutin L. V. Filina 《Water Resources》2012,39(2):184-199
An algorithm is proposed for determining water level in inland water bodies and coastal zones of seas and oceans. The algorithm
was tested for the water area of the Gorki Reservoir, for which radioaltimeter databases show considerable data losses. A
model was constructed, describing the shape of a mean impulse reflected from a statistically heterogeneous piecewise-constant
underlying surface (topographic model). The model was used to substantiate criteria for data choice for the Gorki Reservoir
and to construct a regional algorithm for estimating water level using data from Jason-1 satellite and based on the analysis
of the shape of telemetric impulses (retracking). Water level was calculated with the use of an algorithm of regional adaptive
retracking Sensor Geophysical Data Record databases for the Gorki and Rybinsk reservoirs. Algorithm application has been shown
to considerably increase the amount of actual data and significantly improve the accuracy of water level evaluation. The general
principles of retracking of a complex domain (a coastal zone, an inland water body, etc.) are discussed. The principles are
based on the calculation of signal with allowance made for the roughness of the reflecting surface and they can be applied
to different geographic regions. 相似文献
117.
The mathematical basis for analyzing the dimensional stability of cartographic drafting surfaces, and more specifically paper, is presented in the form of a simple mechanical model. Deduction from a universal equation incorporating such factors as elasticity, viscosity, and relaxation time yields less general but more applicable equations once assumptions are made about which factors are dominant and, on the other hand, insignificant. Translated from: Izvestiya vysshykh uchebnykh zavedeniy, Geodeziya i aerofotos” yemka, 1986, No. 4, pp. 106-111. 相似文献
118.
119.
Tourmaline solid solutions containing Fe, Fe+ Ti, Cr, Ni, Cu, Co, Mn chromophoric centers have been grown hydrothermally at 650° C and 1,5 kbar on natural seeding plates close to the elbaite composition. The newly grown tourmalines were characterized by chemical analyses and optical absorption spectroscopy in the range 26316-5000 cm-1 at 297 K and in the range 26316-9090 cm-1 at 77 K. Most characteristic of Fe2+, Fe3+-bearing specimens is the presence of intensive σpolarized absorption bands caused by exchange-coupled Fe2+-Fe3+ pairs in Y- and Z-sites of the tourmaline structure. An additional intensive absorption band 12500 cm-1 (σ-polarisation) appears in some specimens but is not yet found in spectra of natural tourmalines. The colour and spectroscopic properties of the Fe3+, Mn3+ and Cu2+ containing tourmalines are significantly affected by the presence of even the smallest Li-contents. The results suggest that Fe2+, Cu2+, Co2+, Ni2+-ions occupy, predominantly, Y-sites of the tourmaline structure, whereas the Cr3+-ions seem to enter the smaller Z-octachedra. 相似文献
120.
V. A. Baskina V. Yu. Prokof’ev V. A. Lebedev S. E. Borisovsky M. G. Dobrovol’skaya A. I. Yakushev S. A. Gorbacheva 《Geology of Ore Deposits》2009,51(3):179-196
The Dal’negorsk borosilicate skarn deposit (44° 34′ N and 135° 37′ E), located in the center of the ore field bearing the same name, is referred to the category of giant deposits. The currently predominant genetic concept assumes that ore mineralization at this deposit is related to a mantle source and that boron and ore-bearing alkaline fluids are derivatives of a juvenile source as well. The alternative model considered in this paper suggests that sedimentary sequences, probably, evaporites of a local basin, were immediate boron sources and hot subsurface water served as an agent of ore deposition. The authors’ conclusions are based on (1) mineralogical and geochemical features of alteration of premineral dikes as evidence for the composition of percolating ore-bearing fluids, (2) results of fluid inclusion study, and (3) boron and oxygen isotopic compositions of datolite.The latite bodies immediately predating deposition of economic datolite ore do not show mineralogical or geochemical attributes of their belonging to alkaline rock series. According to our data, these bodies are composed of Paleogene premineral basalts that intruded into the future borosilicate deposit close to the central channel of ore-bearing fluid, served as fluid conduits, and were altered to ultrapotassic rocks under the effect of such fluid. It is suggested that hot aqueous ore-bearing fluid was enriched in highly soluble compounds of Ba, K, and B and extremely depleted in poorly soluble compounds of Zr, Nb, Ta, La, and Ce. This suggestion does not contradict the properties and composition of primary and pseudosecondary two-phase fluid inclusions in danburite, datolite, quartz, and fluorite from orebodies. Judging from the boron isotopic composition of datolite (δ11B = ?9 to ?31 ‰), the main amount of boron was extracted from metasedimentary rocks of the Mesozoic basement. The oxygen isotopic composition of datolite from the Dal’negorsk deposit (δ18OSMOW = ?1.64 to ?2.97 and less frequently up to ?5‰) indicates a significant contribution of subsurface water to the transport of boron. A model of multistage accumulation of boron in ore of the Dal’negorsk borosilicate skarn deposit is proposed. 相似文献