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Oceanology - The volcanic structure of the Seymour Sewell seamount appears to have formed over a relatively long time in at least two stages. Its main massif was formed as a result of volcanic... 相似文献
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We have studied an electron-photon cascade in an isotropic photon field as one of the possible gamma-ray generation mechanisms in compact sources.A cascade in a monoenergetic photon field and in a field of the power-law spectrum is considered. Two types of interaction of cascade particles with the photon field are taken into account: the inverse Compton scattering of electrons and the photoproduction of electron-positron pairs by gamma-quanta. The cascade characteristics have been obtained by numerical solution of the kinetic equations. A quantitative and qualitative analysis is made of the main regularities of the cascade. We have established simple relations between the spectra of cascade particles and the parameters of the photon field and primary radiation. The magnetic field effect on the cascade characteristics is estimated. The results obtained are compared with the results of calculation of other investigators.In the first part of the paper we outline the method of solution and the results relating to the monoenergetic photon field. The theory of cascades in a photon field of the power-law spectrum and its application to the problem of gamma-rays in compact sources are discussed in the second part of the present paper. 相似文献
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A. M. Gorodnitskii Yu. V. Brusilovskii A. N. Ivanenko K. V. Popov N. A. Shishkina 《Izvestiya Physics of the Solid Earth》2017,53(5):795-802
The analysis of the magnetic survey data suggests the presence of a frontal zone of intense magnetic anomalies in a number of the Pacific island-arc systems. These zones with amplitudes of 100–300 nT are observed within the Kuril–Kamchatka and Aleutian island arc systems, in Southern and Central America, and Alaska. As demonstrated by the solution of the inverse problem and petromagnetic investigation of the rocks, these zones are presumably related to the serpentinite bodies which form as a result of the hydration of the upper mantle peridotites by the oceanic water penetrating through a system of cracks and fractures into the subducting slab at its bend. The rock magnetic studies show that magnetite is the main carrier of magnetization in these serpentinite bodies. Hydration of the subducting slab also causes hydration of the mantle rocks of the overriding plate with the formation of the magnetized serpentinite wedge. The decompaction of ultrabasic rocks under hydration is marked by a decrease in the gravity field and velocities of elastic waves. As the subducting plate loses water, it becomes embrittled and becomes the localization region for the epicenters of the strongest earthquakes. Magnetic survey can be used for revealing the potential sources of catastrophic earthquakes. 相似文献
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对1986—2001年间巴伦支海南部海洋磁力测量的数据处理结果进行了研究。南巴伦支海底的地磁测量揭示出其复杂多期的地质构造结构,其中以两期分离型的构造为主导:(1)具NW走向的里菲-文德期继承性裂谷构造;(2)NE向转换叠加断层正交系统。晚泥盆世碱性侵入体及其相关的金属矿化作用恰位于这些构造系统的交点上。 相似文献
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Skolotnev S. G. Peyve A. A. Sanfilippo A. Ivanenko A. N. Ligi M. Veklich I. A. Petracchini L. Basch V. Kuleshov D. A. Ferrando C. Dobrolyubov V. N. Sani C. Shkittin N. A. Bickert M. Dokashenko S. A. Muccini F. Yakovenko E. S. Palmiotto C. Cuffaro M. 《Doklady Earth Sciences》2022,504(1):233-239
Doklady Earth Sciences - Geological and geophysical data collected during the 53rd cruise of the R/V Akademik Sergey Vavilov are presented. It is shown that the lateral distribution of the... 相似文献
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New data about the structure of the anomalous magnetic field in the central part of the Kuril-Kamchatka island arc were obtained during cruise 37 of R/V Akademik Lavrent’ev in 2005. In order to study the deep geological and tectonic structure of this seismically hazardous area, calculations of the depths of the sources of magnetic anomalies with the use of the method of space-frequency analysis of the field were carried out. Transformations of the magnetic field were executed and a part of the samples dredged were petromagnetically examined. An analysis of the data obtained suggests the mainly block-wise structure of the research area. The fracture zones that border the blocks were recognized; the width of the tectonic blocks varies from 10 to 100 km. The most typical extension of the blocks is 25–30 km. In the central part of the region, an extensive V-shaped zone of a negative anomalous field is distinguished together with conjugated intensive positive magnetic anomalies that represent the boundaries of a tentative zone of extension. At the flanks of this zone and on its central rise, areas of manifestations of volcanic activity are outlined. 相似文献
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The changes in the high-energy gamma-ray spectra due to electron-photon cascading in the photon field (e.g., microwave background radiation) are investigated.The propagation of gamma-rays with an initial power-law spectrum through an isotropic monoenergetic photon field is considered. Two processes of the cascade particle-photon field interaction are taken into account, namely, the photoproduction of electron-positron pairs and the inverse Compton effect. The effect of the synchrotron energy loss by cascade electrons in a magnetic field on the cascade gamma-quantum spectrum is studied. The results may be used to estimate the absorption and the variations in the shape of the spectrum of radiation from compact gamma-ray sources in the metagalaxy.The cascade characteristics have been obtained by numerically solving the cascade equations by the moment method. 相似文献
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Consideration is given to the motion of electrons in a photon field of the monoenergetic or power-law spectrum under the conditions when the main mechanism of energy loss is the inverse Compton scattering by field photons. This process changes the primary spectrum of electrons and converts low-energy field photons to high-energy gamma-quanta for which the electron confinement region is assumed to be optically thin. The electron and gamma-ray spectra have been obtained in a wide energy interval including the Klein-Nishina and Thomson regions. A simple qualitative dependence of the solutions found on the field parameters and the primary spectrum of electrons has been established.The electron and gamma-ray spectra have been obtained by numerically solving the kinetic equation dependent on two variables: the energy of electrons and their path (or the time of motion) in a photon field. The results dramatically differ from the solution of the steady-state kinetic equation which depends only on the electron energy and is frequently used in the given problem. 相似文献
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Yu. V. Brusilovsky A. G. Gorshkov A. M. Gorodnitskii A. N. Ivanenko S. V. Lukyanov A. M. Filin Yu. V. Khan 《Oceanology》2007,47(3):406-414
The objective of our research is the interpretation of the results of the geomagnetic survey of the geologic structure in the Gorlo Strait of the White Sea. We used the maps of the anomalous magnetic field (AMF) available and processed them with original interpretation software. As a result of this processing, we compiled a structural-tectonic chart of this region. We distinguished the boundaries of the major first-order tectonic structures such as the underwater extension of the Leshukon graben and a number of minor structures related to the Proterozoic and Paleozoic stages of the magmatic activity in the region. Modeling was performed for the most important objects, which allowed us to refine the geological structure of these objects and their genesis. 相似文献