共查询到20条相似文献,搜索用时 93 毫秒
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V. V. Shcherbakova G. V. Zhidkov V. P. Shcherbakov 《Izvestiya Physics of the Solid Earth》2008,44(10):816-821
A large volume of data on the paleointensity H an obtained by A.S. Bol’shakov and G.M. Solodovnikov is ignored in modern reconstructions because the authors did not indicate whether they used the check-point procedure for the detection of chemical alterations in rocks associated with determination of H an. The paper presents new values of H an determined by the Thellier-Coe method with the use of the checkpoint procedure from samples of the Armenian collection of Cretaceous rocks used in published studies of Bol’shakov and Solodovnikov. The new results are close to the published ones and point to a small value of the geomagnetic field in the Cretaceous, thereby corroborating Bol’shakov-Solodovnikov’s hypothesis on a low paleofield in the Mesozoic. Our study of samples of the collection studied confirms the reliability of Bol’shakov-Solodovnikov’s determinations of H an. 相似文献
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《Marine pollution bulletin》1987,18(4):195-196
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The results of a periodogramanalysis of the variations in the ionospheric parameters, measured using the vertical radio sounding
method at midlatitude Irkutsk observatory (Eastern Siberia), are presented. The 1984–1986 period of observations was used.
It has been indicated that the statistically significant oscillations with periods typical of planetary waves are present
in the variations in f
0Es, f
bEs, h′Es, f
min, f
0F2, and h′F. 相似文献
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Izvestiya, Physics of the Solid Earth - 相似文献
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All existing data (6 years) on gravity wave activity, inferred from the nighttime A3 (oblique incidence on the ionosphere) radio wave absorption measurements in the lower ionosphere on 270 kHz at Prhonice in Central Europe, have been exploited to get information on the effects of QBO phases and the Mt. Pinatubo volcanic eruption on the gravity wave activity in the winter half of the year. There appears to be an enhancement of gravity wave activity in the two winters just after the strong volcanic eruption of Mt. Pinatubo. This enhancement is remarkable for long-period waves (T=2–3 hours). No clear effect of the phase of QBO on the level of gravity wave activity has been found; a possible effect of QBO on the correlations between gravity wave activities in individual period bands is indicated. The results are limited by a relatively short data series; however, no more data will he available. 相似文献
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V. F. Belyi 《Journal of Volcanology and Seismology》2010,4(3):149-163
A detailed petrographic study of the impactites found in the El’gygytgyn depression suggested a division of those into the
dacite-rhyolite (dominant) and the andesite-basalt (about 1% of the total impactite volume) groups. The protolith for the
dacite-rhyolite group was the Cretaceous ignimbrite rock association of the Okhotsk-Chukchi volcanic belt (OChVB), from which
the depth of their origin is estimated as 1–1.5 km. The impactites of the andesite-basalt group, which are generally older,
formed from protoliths of apparently metamorphic and magmatic complexes in the OChVB basement occurring at depths of 6.5–8.5
km. The hypothesis that the depths of origin for these groups are different is supported by certain features of clinopyroxene
composition. Geochemical relationships are found to exist between deep and shallow impactites, as shown in the distribution
of Ni, Cr, and Co. The succession of development for the shallow impactite generation forms the following series: impact ignimbrite
→ pumice → cinder → massive glass. The glasses have the most homogeneous overall chemical composition, but these too are characterized
by a high inhomogeneity in the composition of the vitric phases, indicating a rapid and discrete impactite generation that
impeded melt homogenization. The glasses are the final product of impactite generation; they show a dramatic drop in fluid
content and the associated reducing components. 相似文献
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Zhang Shiqi 《国际泥沙研究》2000,(3)
Mr. Singh and Mr. Ghosh have carefully reviewed and made valuable suggestions and comments. Theauthor would like to express his gratitude to them. The explanations to the comments and some detailsof the model development are as follows.1 MATHEMATICAL MODEL ON SUSPENDED SEDIMENT TRANSPORTATIONThere are three types of models on sediment transportation, i.e. for simulating (1) bedload; (2)suspended sediment; and (3) all sediment including bedload and suspended sediment. In t… 相似文献
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It is well known that the results of determining earthquake parameters depend to a large extent on data processing algorithms and velocity models of the seismic wave propagation medium used in solving hypocenter problems. In 1992, V.Yu. Burmin developed a hypocentric algorithm that minimizes the functional of distances between the points corresponding to the theoretical and observed travel times of seismic waves from an earthquake source to recording stations. The determination of the coordinates of earthquake hypocenters in this case is much more stable than for the commonly used minimization of the functional of discrepancies in the seismic wave arrival times at a station. Using this algorithm and the refined velocity model of the medium, V.Yu. Burmin and L.A. Shumlyanskaya reinterpreted the earthquake parameters for the Crimea–Black Sea region. The most important result of this reinterpretation was the conclusion about the occurrence of deep earthquakes with a source depth of more than 60 km in the region. This result contradicts the conventional beliefs about the seismicity of the region and therefore aroused strong criticism from experts directly involved in compiling the existing catalogs of regional earthquakes. These comments and criticisms are presented by V.E. Kulchitsky with coauthors in a work published in this issue of the journal. In the present paper, we analyze the comments in detail and respond. In particular, we show that the previously used methods of seismic data processing made it highly unlikely by default that deep earthquakes would appear in the results. As an example, we refer to the use of travel-time curves for depths down to 35 km. It is clear that deep earthquakes could not have been found with this approach. 相似文献
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V. G. Eselevich V. M. Bogod I. V. Chashey M. V. Eselevich Yu. I. Yermolaev 《Geomagnetism and Aeronomy》2009,49(1):133-135
The solar sources of the magnetic storms of November 8 and 10, 2004, are analyzed. The preliminary results of such an analysis [Yermolaev et al., 2005] are critically compared with the results of the paper [Tsurutani et al., 2008], where solar flares were put in correspondence with these magnetic storms. The method for determining solar sources that cause powerful magnetospheric storms is analyzed. It has been indicated that an optimal approach consists in considering coronal mass ejections (CMEs) as storm sources and accompanying flares as additional information about the location of CME origination. 相似文献
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Izvestiya, Physics of the Solid Earth - Abstract—In my comment on the paper by A.A. Lyubushin, G.N. Kopylova, and Yu.K. Serafimova, I focus on the problem of legitimacy of seismological data... 相似文献
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《Continental Shelf Research》1990,10(5):397-428
Bottom stress is calculated for several long-term time-series observations, made on the U.S. east coast continental shelf during winter, using the wave-current interaction and moveable bed models of Grant and Madsen (1979, Journal of Geophysical Research, 84, 1797–1808; 1982, Journal of Geophysical Research, 87, 469–482). The wave and current measurements were obtained by means of a bottom tripod system which measured current using a Savonius rotor and vane and waves by means of a pressure sensor. The variables were burst sampled about 10% of the time. Wave energy was reasonably resolved, although aliased by wave groupiness, and wave period was accurate to 1–2 s during large storms. Errors in current speed and direction depend on the speed of the mean current relative to the wave current. In general, errors in bottom stress caused by uncertainties in measured current speed and wave characteristics were 10–20%.During storms, the bottom stress calculated using the Grant-Madsen models exceeded stress computed from conventional drag laws by a factor of about 1.5 on average and 3 or more during storm peaks. Thus, even in water as deep as 80 m, oscillatory near-bottom currents associated with surface gravity waves of period 12 s or longer will contribute substantially to bottom stress. Given that the Grant-Madsen model is correct, parameterizations of bottom stress that do not incorporate wave effects will substantially underestimate stress and sediment transport in this region of the continental shelf. 相似文献
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Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the Chinese Loess Plateau since 8.0 Ma B.P. 总被引:4,自引:1,他引:4
1 Introduction and methods Many geoscientists have agreed[1-29] that the wind blown dusty sediments appeared in China since about 8.0 Ma B.P. The eolian earthy deposits are the red clays of the middle-late of the Late Miocene and those of Pliocene as well as the loess-paleosol sequence of the Pleistocene and Holocene. These eolian earthydeposits are distributed chiefly in northwestern China, mostly corresponding in area to the modern Loess Plateau. The Neogene red clay was deposited unco… 相似文献
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Studia Geophysica et Geodaetica - 相似文献
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Studia Geophysica et Geodaetica - 相似文献