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61.
M. V. Portnyagin V. B. Naumov N. L. Mironov I. A. Belousov N. N. Kononkova 《Geochemistry International》2011,49(11):1085-1110
The powerful eruption in the Akademii Nauk caldera on January 2, 1996, marked a new activity phase of Karymsky volcano and
became a noticeable event in the history of modern volcanism in Kamchatka. The paper reports data obtained by studying more
than 200 glassy melt inclusions in phenocrysts of olivine (Fo
82-72), plagioclase (An
92-73), and clinopyroxene (Mg#83-70) in basalts of the 1996 eruption. The data were utilized to estimate the composition of the parental melt and the physicochemical
parameters of the magma evolution. According to our data, the parental melt corresponded to low magnesian, highly aluminous
basalt (SiO2 = 50.2 wt %, MgO = 5.6 wt %, Al2O3 = 17 wt %) of the mildly potassic type (K2O = 0.56 wt %) and contained much dissolved volatile components (H2O = 2.8 wt %, S = 0.17 wt %, and Cl = 0.11 wt %). Melt inclusions in the minerals are similar in chemical composition, a fact
testifying that the minerals crystallized simultaneously with one another. Their crystallization started at a pressure of
approximately 1.5 kbar, proceeded within a narrow temperature range of 1040 ± 20°C, and continued until a near-surface pressure
of approximately 100 bar was reached. The degree of crystallization of the parental melt during its eruption was close to
55%. Massive crystallization was triggered by H2O degassing under a pressure of less than 1 kbar. Magma degassing in an open system resulted in the escape of 82% H2O, 93% S, and 24% Cl (of their initial contents in the parental melt) to the fluid phase. The release of volatile compounds
to the atmosphere during the eruption that lasted for 18 h was estimated at 1.7 × 106 t H2O, 1.4 × 105 t S, and 1.5 × 104 t Cl. The concentrations of most incompatible trace elements in the melt inclusions are close to those in the rocks and to
the expected fractional differentiation trend. Melt inclusions in the plagioclase were found to be selectively enriched in
Li. The Li-enriched plagioclase with melt inclusions thought to originate from cumulate layers in the feeding system beneath
Karymsky volcano, in which plagioclase interacted with Li-rich melts/brines and was subsequently entrapped and entrained by
the magma during the 1996 eruption. 相似文献
62.
The Pogranichnoe ore occurrence of gold-bismuth type is closely related to Ordovician granitic rocks pertaining to the Sarkhoi granodiorite-granite complex of calc-alkaline series. This type of mineralization in the Eastern Sayan is described for the first time. The orebodies are represented by quartz veins and veinlets with greisenized granite as selvages. Three mineral assemblages consecutively follow one another: (1) pyrite-arsenopyrite, (2) base-metal with fahlore and Sb sulfosalts, and (3) gold-bismuth. The geological position of orebodies and character of microinclusions in accessory minerals of granites suggest that goldbismuth mineralization is related to granitoids. 相似文献
63.
M.I. Epov V.L. Mironov K.V. Muzalevskiy I.N. Eltsov U.P. Salomatov 《Russian Geology and Geophysics》2013,54(9):1103-1107
A theoretical study has been performed to check the possibility of using ultrabroadband nanosecond electromagnetic pulses as a geosteering tool for horizontal drilling to estimate the distance to the oil-water contact (OWC) in a floating oil accumulation. The voltage of a microwave-bandwidth pulse at the dipole receiver of a downhole radar was modeled for the case of a horizontal borehole near OWC in a formation saturated with oil and water. Numerical solutions to the boundary problem formulated on the basis of the Maxwell equations were obtained with the Microwave Studio software (www.cst.com). The frequency-dependent dielectric constants of the layered saturated formation and the drilling fluid were assumed according to experimentally tested models. The modeling has demonstrated that nanosecond electromagnetic pulses arriving from a layered oil-water contact can in principle be acquired and the distance from the wellbore to the OWC median can be inferred from the respective time delays recorded by a downhole radar. Additionally, the possible dynamic range and accuracy of sensing have been estimated. 相似文献
64.
Previous theoretical research on the characteristics of map readability [see MSRS, 1988, No. 4, pp. 276-283] is tested using several groups of subjects (already familiar with map use) in order to ascertain the most important elements facilitating map readability or detracting from it. The results are modeled through a series of regression equations in an effort to determine the relationships between specific characteristics (number of symbol size classes, frequency of symbols within classes, background complexity) and map readability (speed and accuracy of symbol identification). Translated by Edward Torrey, Alexandria, VA 22308 from: Vestnik Leningradskogo Universiteta, serlya 7 (geologiya, geografiya), 1988, No. 2, pp. 40-46. 相似文献
65.
The authors address a range of issues connected with the visual representation and interpretation of statistical data on maps. Attention is focused on common behaviors of map users in determinations of various characteristics of map symbols. Results are reported from experiments testing the relationship between the accuracy of obtaining quantitative information on a map with the total number of symbols and number of scale levels [size classes] employed, the use (or non-use) of color in the symbolization scheme, etc. Translated by Larry Richardson, Los Angeles, CA 90039 from: Izvestiya Vsesoyuznogo Geograficheskogo Obshchestva, 1989, No. 4, pp. 345–351. 相似文献
66.
This paper describes an application of the geographic information system (GIS) technology to a ground stability assessment
in the karst area of Dzerzhinsk, Russia. In the stability analysis, the groundwater level changes in the karst aquifer could
cause suffosion sinkholes when the gravitational force was greater than the soil strength. The GIS technology was used to
combine various data and to delineate the zones of potential gravitational collapse and suffosion collapse in the area.
相似文献
V. V. TolmachevEmail: |
67.
On the basis of detailed fieldwork and analytical procedures (microprobe, X-ray diffraction, chemical analysis, etc.), ores
and altered wall-rock rocks of the Khadatkanda and Etyrko deposits in the Kodar-Udokan mineragenic zone were studied. Economic
concentrations of gold and some other accompanying metals have been established in ore of the Khadatkanda uranium deposit
in the Syul’ban uranium district. REE-U lodes with brannerite-uraninite have been found at the Etyrko Fe-Ti-V deposit related
to the Chinei layered pluton in the Udokan mining district. The outlook for the discovery of new types of economic uranium
deposits is substantiated with respect to the known hydrothermal uranium ore objects and nontraditional setting related to
the layered mafic-ultramafic intrusions. 相似文献
68.
Nazarova D. P. Portnyagin M. V. Krasheninnikov S. P. Mironov N. L. Sobolev A. V. 《Doklady Earth Sciences》2017,472(1):100-103
Doklady Earth Sciences - The formation conditions of the parental magmas of Gorely volcano, which is located behind a volcanic front in Southern Kamchatka, have been evaluated using the modern... 相似文献