排序方式: 共有38条查询结果,搜索用时 15 毫秒
21.
A simple method for obtaining a space-time model of the main magnetic field from the high-precision satellite survey data is described. At the first stage, the CHAMP satellite data for one-day interval are expanded into the spherical harmonics with constant coefficients. This yields a set of daily mean spherical harmonic models (DMSHM) over the survey interval of a few years. At the second stage, the coefficients of this set are used as source data for expansion into the natural orthogonal components (NOC). It is shown that the terms of the NOC series decrease rapidly, and the accuracy of the space-time model of the main geomagnetic field over the time interval under discussion is not worse than the accuracy of the models obtained by traditional methods. 相似文献
22.
A. I. Chernova D. V. Metelkin V. A. Vernikovsky N. Yu. Matushkin 《Doklady Earth Sciences》2018,481(1):847-851
This study demonstrates rock-magnetic and paleomagnetic investigations of Devonian and Mesozoic deposits of Kotelny, Stolbovoy, and Great Lyakhovsky islands. The results indicate that local remagnetization took place on the southwestern periphery on the archipelago of the New Siberian Islands. A comparison of new data with the apparent polar wander path for Siberia shows that the remagnetization happened during collisional events between 140 and 80 Ma and affected only the marginal part of the terrane of the New Siberian Islands that was directly facing the deformation front. The consistent younging of the remagnetization age from the south to the north indicates dextral rotation of the terrane of the New Siberian Islands during its collision with Siberia. 相似文献
23.
24.
Taphonomic phenomenon of ancient hair from Glacial Beringia: perspectives for palaeoecological reconstructions
下载免费PDF全文
![点击此处可从《Boreas: An International Journal of Quaternary Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Irina V. Kirillova Johannes van der Plicht Stanislav V. Gubin Oksana G. Zanina Olga F. Chernova Elena G. Lapteva Svetlana S. Trofimova Eugeny V. Zinovyev Anton A. Zharov Elena O. Fadeeva Thijs Van Kolfschoten Fedor K. Shidlovskiy Alexey A. Kotov 《Boreas: An International Journal of Quaternary Research》2016,45(3):455-469
An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post‐mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750±50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115±40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3‐1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrost‐preserved hair is a unique repository of Ice Age organisms. 相似文献
25.
The dependence of brightness and polarization of cometary on the phase angle is studied. The similarity between the phase curves of comets, minor planets, and the zodiacal cloud is pointed out. The dependence found correspond to dielectric particles with dimensions greater than 1 μm. 相似文献
26.
Kotlyakov V. M. Chernova L. P. Khromova T. E. Muraviev A. Ya. Kachalin A. B. Tiuflin A. S. 《Doklady Earth Sciences》2018,483(2):1547-1552
Doklady Earth Sciences - The results of 20 years of field data (1963–1982) and 50 years of remote observations (1963–2012) on Medvezhy Glacier in the Pamirs by the Institute of... 相似文献
27.
28.
A. I. Chernova D. V. Metelkin N. Yu. Matushkin V. A. Vernikovsky A. V. Travin 《Doklady Earth Sciences》2017,475(2):849-853
The paper presents results of geochronological and paleomagnetic studies of the volcanogenicsedimentary sequence of Henrietta Island in the East Siberian Sea. Our 40Ar/39Ar investigations confirm existing ideas that the bottom part of the section formed in the Ediacaran (~565 Ma) and that the basalts in the top of the section formed before the middle Cambrian (~520 Ma). Calculated paleomagnetic data confirm that during the rocks formation the territory of present-day Henrietta Island was located close to the 20° latitude, which lets us adjust some information published earlier on the age and natural remanent magnetization of the dolerite dikes of the nearby Jeannette Island. The new data also let us propose that a regional tectonothermal event, probably caused by accretion-related processes, took place at the beginning of the Ordovician. 相似文献
29.
D. V. Metelkin A. I. Chernova V. A. Vernikovsky N. Yu. Matushkin 《Doklady Earth Sciences》2017,477(1):1277-1281
The New Siberian Islands archipelago is one of the few research objects accessible for direct study on the eastern Arctic shelf. There are several models that have different interpretations of the Paleozoic tectonic history and the structural affinity of the New Siberian Islands terrane. Some infer a direct relationship with the passive continental margin of the Siberian paleocontinent. Others connect it with the marginal basins of Baltica and Laurentia, or the Chukotka-Alaska microplate. Our paleomagnetic investigation led us to create an apparent polar wander path for the early Paleozoic interval of geological history. Based on it we can conclude that the New Siberian Islands terrane could not have been a part of these continental plates. This study considers the possible tectonic scenarios of the Paleozoic history of the Earth, presents and discusses the corresponding global reconstructions describing the paleogeography and probable mutual kinematics of the terranes of the Eastern Arctic. 相似文献
30.
Astronomy Letters - Small perturbations of a protostellar disk with vertical and azimuthal magnetic field components are considered in terms of Hall magnetohydrodynamics. The dispersion equation... 相似文献