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281.
Sh. K. Baltybaev O. A. Levchenkov V. M. Savatenkov 《Stratigraphy and Geological Correlation》2010,18(3):234-251
The petrologic and isotopic-geochronologic study of basement rocks that were penetrated by a deep borehole in the marginal
part of the East European Platform revealed that its section overlain by the Vendian-Paleozoic sedimentary cover is Early
Proterozoic in age and largely consists of aluminous migmatized biotite, biotite-cordierite, and biotite-cordierite-sillimanite
gneisses, which are intruded by granites, plagiogranites, and metatonalites. The lower part of the section is dominated by
amphibole schists and amphibolites with subordinate nonmetamorphosed dolerite dikes and pegmatite veins. By metamorphism parameters
(T = 630–680°C, P = 2–4 kbar), the metamorphic complex may be considered as the shallowest one, compared with other Early Proterozoic complexes,
developed at least in the southwestern part of Fennoscandia. The progressive decrease in the mineral-formation pressure observed
in the Lower Proterozoic metamorphic rocks southward, away from the Karelian Craton is likely explained by the tectonic transport
(thrusting) of the Svecofennides over the margin of the Karelian Craton and their subsequent deeper erosion near the craton.
The magmatic crystallization of metamorphic palgiogranites, penetrated at depths of 925–928 and 1004 m, is estimated by the
U-Pb ID-TIMS method on zircons to occur 1860 ± 9 Ma ago. It is shown that by their age, the REE composition, and isotopic-geochemical
characteristics, these rocks are close to the plagiogranites formed in the southeastern extremity of the Svecofennnian belt
in the present-day northern Ladoga region and the Karelian Isthmus. No rocks, which could be correlated by their lithology
with the Archean rocks of the Karelian Craton, are found. 相似文献
282.
V. B. Petkov E. V. Bugaev P. A. Klimai M. V. Andreev V. I. Volchenko G. V. Volchenko A. N. Gaponenko Zh. Sh. Guliev I. M. Dzaparova D. V. Smirnov A. V. Sergeev A. B. Chernyaev A. F. Yanin 《Astronomy Letters》2008,34(8):509-514
Temporal and energy characteristics of the very-high-energy gamma-ray bursts from evaporating primordial black holes have been calculated by assuming that the photospheric and chromospheric effects are negligible. The technique of searching for such bursts on shower arrays is described. We show that the burst time profile and the array dead time should be taken into account to interpret experimental data. Based on data from the Andyrchy array of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences), we have obtained an upper limit on the number density of evaporating primordial black holes in a local region of space with a scale size of ~10?3 pc. Comparison with the results of previous experiments is made. 相似文献
283.
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286.
为改善储层目标区域的成像质量,结合地面地震、VSP和井间地震的各自优势,采用归一化后的自适应叠加方法,实现3种资料偏移结果的联合成像,以达到各种资料优势互补、提高成像精度的目的。为了给联合成像提供精度较高的单种资料成像剖面,采用傅里叶有限差分叠前深度偏移算法实现地面地震资料成像;在VSP和井间地震资料的叠前成像中采用了基于起伏地表直接下延法成像思想,基于傅里叶有限差分延拓算子得到VSP和井间地震偏移结果。模型试算和实际资料的处理验证了多尺度地震资料联合成像法的正确性和有效性。 相似文献
287.
E. Sh. Elizbarashvili O. Sh. Varazanashvili N. S. Tsereteli M. E. Elizbarashvili 《Russian Meteorology and Hydrology》2013,38(3):168-170
The statistical structure of hurricane winds is studied using the data of observation at 50 meteorological stations in Georgia for the period of 1961–2008. Determined are the number of days and the duration of hurricane winds in different regions of the country. Studied are the empirical functions of their distribution and the areal limits. 相似文献
288.
Determination of importance for comprehensive topographic factors on landslide hazard mapping using artificial neural network 总被引:1,自引:0,他引:1
Mutasem Sh. Alkhasawneh Umi Kalthum Ngah Lea Tien Tay Nor Ashidi Mat Isa 《Environmental Earth Sciences》2014,72(3):787-799
A landslide is one of the natural disasters that occur in Malaysia. In addition to the geological factor and the rain as triggering factor, topographic factors such as elevation, slope angle, slope aspect, and curvature are considered as the main causes of landslides. The study in this paper was conducted in three stages. The first stage involved the extraction of extra topographic factors. Previous landslide studies had identified only four of the topographic factors. However, eight new additional factors have also been identified in this study. They are general curvature, longitudinal curvature, tangential curvature, cross-section curvature, surface area, diagonal line length, surface roughness, and rugosity. At this stage, 13 factors were extracted from the digital elevation model. The second stage involved specifying the importance of each factor. The multilayer perceptron network and backpropagation algorithm were used to specify the weight of each factor. Results were verified using the receiver operating characteristics based on the area under the curve method in the third stage. The results indicated 76.07 % accuracy in predicting of landslides, with slope angle as the most important factor while the tangential curvature has the least importance. 相似文献
289.
A relativistic, first-order differential equation is derived for the accumulated moment of inertia of a spherically symmetric
celestial body. An approximate equation is proposed to describe the contribution of relativistic effects to the moment of
inertia of a superdense star. For configurations of an incompressible fluid, this approximation describes the results of the
numerical calculations of Chandrasekhar and Miller to within 5% in the entire range of central pressures from 0 to ∞.
Translated from Astrofizika, Vol. 40, No. 1, pp. 87–96, January–March, 1997. 相似文献
290.
Based on the HLH and TON ground-based helioseismological projects and the SOHO/MDI spaceborne project, we obtained acoustic power maps of active regions averaged over 1 mHz intervals. These maps allowed the spatial and frequency distributions of acoustic power in an active region and its surroundings to be studied. The time step of the HLH data is 42 s, which makes it possible to investigate the acoustic power up to 11.9 mHz. Data in the Ca II K and Ni I lines, which originate in the middle chromosphere and the photosphere, respectively, give an idea of the height distribution of acoustic oscillation energy in the solar atmosphere. The acoustic halo produced by excess acoustic power around sunspots clearly shows up on acoustic maps in the Ca II K line and, to a lesser degree, in the Doppler Ni I line shifts. Ground-based observations also reveal a large enhancement of acoustic power inside sunspots. Our tests show that this effect results from the combination of a high intensity gradient in the data and atmospheric seeing. The latter was reduced by referencing each image to the sunspot. The spatial distribution of power inside the sunspot due to atmospheric seeing was found to depend on the exposure time of the data used. Excluding the nonsolar effects, a common property of all acoustic maps is the suppression of the solar-oscillation acoustic power in active regions. 相似文献