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Sokolov S. Yu. Moroz E. A. Agranov G. D. Sukhikh E. A. Ananyev R. A. Razumovkiy A. A. Levchenko O. V. 《Doklady Earth Sciences》2021,499(2):605-610
Doklady Earth Sciences - The spatial distribution of subsurface seismoacoustic anomalies of the “bright spot” type in the Pechora Sea, which are indicators of free gas accumulation, is... 相似文献
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F. E. Maksimov S. A. Laukhin Kh. A. Arslanov V. Yu. Kuznetsov G. N. Shilova S. B. Chernov I. E. Zherebtsov S. B. Levchenko 《Doklady Earth Sciences》2010,433(1):915-919
For a sample from the roof of peat (0–2 cm) located in a reference section for the Middle Neopleistocene in West Siberia near
the village of Krivosheino, we obtained an exorbitant value of 14C date ≥53.9 ka B.P. (LU-6024). In the peat proper, the 230Th/U dates obtained by the isochronous method are 195.2 ± 10.8/9.1 ka B.P. for the L/L model and 204.1 ± 17/13 ka B.P. for
the TSD model. The palynospectra of the peat characterize, from the bottom up, birch forests with fir and spruce participation;
then spruce forests with fir; next spruce-cedar forests, similar to the middle taiga subzone. In the clay, the following palynospectra
have been examined: forb-gramineous grasslands and light forests with spruce and Betula fruticosa. In the upper part of clays, the palynospectra reflect the evolution of swampy, birch, light forests with spruce participation.
The conclusion is made that the studied part of the section formed at the end of the Samarovo Ice Age and in the last third
of the Taz Ice Age. The break in sedimentation related to the erosion contact covers a part of the Samarovo Ice Age and the
first two-thirds of the Taz Ice Age. 相似文献
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D. G. Borisov I. O. Murdmaa E. V. Ivanova O. V. Levchenko V. V. Yutsis T. N. Frantseva 《Oceanology》2013,53(4):460-471
Seismoacoustic investigations with a high-resolution parametric echo-sounder “SES 2000 deep” carried out on cruises 33, 35, and 37 of the R/V Akademik Ioffe revealed several erosional-depositional contourite systems on the São Paulo Plateau escarpment and its toe in the South Atlantic. Two contourite terraces related to interfaces between different water masses are observable on the escarpment. These terraces presumably reflect the activity of internal waves and turbulent eddies. The São Paulo contourite channel and genetically related drift are traceable along the escarpment toe. Changes in planktonic foraminiferal assemblages in Core AI-2563 retrieved from the summit of the São Paulo contourite drift suggest a shallowing of the Weddell Sea Deep Water mass during glacial times. It is established that the contour current of the Weddell Sea Deep Water and Lower Circumpolar Water considerably affect the formation of contourite depositional systems on the escarpment and its toe. 相似文献
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D. G. Levchenko 《Oceanology》2006,46(5):739-750
Recording seismic signals on the bottom is accompanied by specific distortions caused by resonance phenomena. In the literature, such distortions are explained by the natural vibration of the heavy housing of a seismometer on a soft elastic sediment layer. Meanwhile, there are experimental results that contradict this model. In the present paper, we consider the rheological properties of the bottom sediments, which in fact were not taken into account previously. The model of a viscoplastic medium was used (the Bingham model), and the parameters of the model were experimentally determined. The estimates show that, in the frequency range from 0.003 to 30 Hz used in broadband bottom seismology, the effect of the mass of the seismometer on the results of recording on a soft bottom is negligible. Large errors can be introduced only when a seismometer is placed on rubberlike media such as peat soil, algae aggregations, etc. Resonance phenomena in recording signals on the bottom can occur when seismic waves propagate through a layer of water-saturated sediments. These phenomena are more pronounced for shear waves, whereas the distortions of the longitudinal waves propagating through the water-saturated layer are relatively weak. 相似文献
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The results of registration of the catastrophic earthquake of March 11, 2011, that occurred near Honshu Island (Japan) with
the broadband bottom seismograph of the Oceanology Institute, Russian Academy of Sciences on a test bed of the Experimental
Design Bureau of Oceanologic Equipment (EDBOE), Russian Academy of Sciences (Moscow) are considered. The specification of
the equipment and conditions of the experiment are presented. The records of the earthquake made in EDBOE and those made with
a seismograph at the University of Portland (Oregon, United States) are compared, since these registration points are located
at identical distances from the epicenter, but the distributions of seismic waves are essentially different. The possible
directions of the development of methods and equipment for forecasting strong sea earthquakes and tsunami are examined. 相似文献
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