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21.
The paper presents the results of statistical analysis and estimation of long-term changes in surface air temperature, the
gas composition of the atmosphere, the depth of seasonal thawing, and the temperature and area of permafrost occurrence in
the circumpolar zone of the Northern Hemisphere. Preliminary estimates were obtained for the possible influence of the current
changes in the thermophysical parameters of permafrost rocks on the albedo of the underlying surface, air moisture content,
and the concentrations of carbon dioxide and methane in the atmosphere. The density of anthropogenic and natural methane fluxes
from the underlying surface to the atmosphere is evaluated. The possible formation mechanisms of global maximums in carbon
dioxide and methane concentration in the atmosphere of circumpolar areas in the context of interaction between methane cycle
and the processes of permafrost thawing are described. 相似文献
22.
O. S. Urman O. S. Dzyuba G. L. Kirillova B. N. Shurygin 《Russian Journal of Pacific Geology》2014,8(5):346-359
Abundant Buchiidae (Bivalvia) from the Upper Volgian-Lower Valanginian sediments of the Northern Sikhote-Alin (Russian Far East) were studied in the key section at right bank of the Amur River opposite to Komsomolsk-on Amur. The analysis of the Buchiidae stratigraphic distribution in the section allowed us to reveal the sequence of Buchia-bearing beds: this is well correlated with the Buchia zonal scales of many Arctic regions. Here, from the base upward, there have been recognized the following: beds with Buchia terebratuloides, beds with B. unschensis and B. terebratuloides, beds with B. volgensis, and beds with B. inflata and B. keyserlingi. The beds with B. unschensis and B. terebratuloides also yielded the Berriasian ammonite Pseudosubplanites? sp. of Tethyan affinity. The obtained paleontological data confirm the occurrence of a large syncline in the studied section. The data also permit one to refine the age spans of the local stratigraphic units. 相似文献
23.
B.L. Nikitenko B.N. Shurygin V.G. Knyazev S.V. Meledina O.S. Dzyuba N.K. Lebedeva E.B. Peshchevitskaya L.A. Glinskikh A.A. Goryacheva S.N. Khafaeva 《Russian Geology and Geophysics》2013,54(8):808-837
Recent integrated studies of Mesozoic reference sections of the Anabar area (northern Middle Siberia, Laptev Sea coast) and the reinterpretation of all the previous data on a modern stratigraphic basis permit considerable improvement of the bio- and lithostratigraphic division and facies zoning of Jurassic and Cretaceous sediments in the region. Analysis of abundant paleontological data allows the development or considerable improvement of zonal scales for ammonites, belemnites, bivalves, foraminifers, ostracods, dinocysts, and terrestrial palynomorphs from several Jurassic and Cretaceous intervals. All the zonal scales have been calibrated against one another and against regional ammonite scale. Reference levels of different scales useful for interregional correlation have been defined and substantiated based on the analysis of lateral distribution of fossils in different regions of the Northern Hemisphere. It provides the possibilities to propose and consider parallel zonal scales within the Boreal zonal standard for the Jurassic and Cretaceous periods. A combination of these scales forms an integrated biostratigraphic basis for a detailed division of Boreal-type sediments regardless of the place of their formation and for the comparison with the international stratigraphic standard as far as a possible use of a set of reference levels for correlation. 相似文献
24.
The reality of the global‐scale sedimentation breaks remains controversial. A compilation of data on the Jurassic–Cretaceous unconformities in a number of regions with different tectonic settings and character of sedimentation, where new or updated stratigraphic frameworks are established, permits their correlation. Unconformities from three large reference regions, including North America, the Gulf of Mexico, and Western Europe, were also considered. The unconformities, which encompass the Jurassic‐Cretaceous, the Lower–Upper Cretaceous and the Cretaceous–Palaeogene transitions are of global extent. Other remarkable unconformities traced within many regions at the base of the Jurassic and at the Santonian–Campanian transition are not known from reference regions. A correlation of the Jurassic–Cretaceous global‐scale sedimentation breaks and eustatic curves is quite uncertain. Therefore, definition of global sequences will not be possible until eustatic changes are clarified. Activity of mantle plumes is among the likely causes of the documented unconformities. 相似文献
25.
O. S. Dzyuba 《Stratigraphy and Geological Correlation》2012,20(1):53-72
The study of new collections from the Urdyuk-Khaya Cape (Nordvik Peninsula) made it possible to specify the taxonomic composition
of belemnites from the Volgian and basal Ryazanian in northern East Siberia. Cylindroteuthis knoxvillensis Anderson, 1945, C. cf. newvillensis Anderson, 1945, and Arctoteuthis tehamaensis (Stanton, 1895) known from northern California, as well as the new species C. venusta sp. nov. and A. britanna sp. nov. are first described from the Arctic region. Belemnite stratigraphy of Jurassic-Cretaceous boundary layers is fundamentally
revised, allowing a new refined version of their scale to be proposed as a Boreal standard. Two independent successions of
biostratigraphic units are defined in the section interval spanning the uppermost Middle Volgian Substage to the basal Ryazanian
Stage: (1) Liobelus russiensis Zone, Lagonibelus gustomesovi and Arctoteuthis porrectiformis beds; (2) Lagonibelus napaensis, Arctoteuthis tehamaensis, and Cylindroteuthis knoxvillensis zones. 相似文献
26.
A. B. Kuznetsov O. P. Izokh O. S. Dzyuba B. N. Shurygin 《Doklady Earth Sciences》2017,477(2):1408-1413
The belemnite Sr isotope characteristics obtained over an interval from the Upper Volgian Regional Substage to the lower part of the Ryazanian Regional Stage in the section on the Maurynya River (Western Siberia) fills a gap in the 87Sr/86Sr ocean water variation curve over the Jurassic–Cretaceous boundary. The increase in the 87Sr/86Sr values from 0.707172 to 0.707242 revealed in the section coincides with a general rise in this ratio in the Late Jurassic–Early Cretaceous ocean. 相似文献
27.
28.
Accumulation of salts in lakes with small catchment areas and substrate composed of magmatogene, metamorphized, and sedimentary rocks have been studied. Direct dependence of the chemical composition of salt-lake waters on that of deep-seated endogenous waters is demonstrated. Groups of salt lakes have been found to form linear rows or ellipses.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 13–17.Original Russian Text Copyright © 2005 by Dzyuba, Kulagina. 相似文献
29.
O. S. Dzyuba 《Stratigraphy and Geological Correlation》2013,21(2):189-214
The stratigraphic distribution and taxonomic diversity of belemnites from the Volgian and Ryazanian deposits exposed in the eastern foothills of the North and Subpolar Urals, are studied and analysed. Studies of new collections from the Mauryn’ya and Yatriya rivers have revealed within the Laugeites groenlandicus-basal Surites analogus ammonite zones, the East Siberian Lagonibelus napaensis, Cylindroteuthis knoxvillensis, and Liobelus russiensis belemnite zones (the latter in the beds’ rank), the Lagonibelus gustomesovi and Arctoteuthis porrectiformis Beds, and local beds with Boreioteuthis explorata and Simobelus compactus. Since in the boundary beds of the Volgian and Ryazanian stages a great number of belemnite species known from the Tordenskjoldberget Member, Kong Karls Land, Svalbard, were found, it is inferred that the accumulation of the member started not in the Valanginian as many researchers believe but immediately at the beginning of the Cretaceous. The dynamics of belemnite species diversity in the northwestern margin of the West Siberian marine basin correlates well with climatic events. An increase of species number in the terminal Volgian-beginning of the Ryazanian corresponds to a temperature elevation in the Siberian paleoseas, and the subsequent reduction of species diversity in the second half of the Ryazanian is correlated with a gradual cooling. The peak of belemnite taxonomic diversity falls at the beginning of the Cretaceous when up to 15 species belonging to eight Cylindroteuthididae genera occurred concurrently. The new species Cylindroteuthis ornata sp. nov., Acroteuthis pseudoconoides sp. nov., Pachyteuthis eximia sp. nov., and Simobelus compactus sp. nov. are described. 相似文献
30.
The regularities in present-day variations in the wind speed vector are examined at 18 stations along the section from Kola Peninsula to the Caspian Sea. Data on long-term variations in the major climate-forming factors and climatic parameters are generalized. The statistically significant tendency toward a considerable decline in the wind speed with a maximum module and the most frequent wind speeds of zonal, mostly western, directions (this tendency has been revealed earlier for the eastern coast of the middle and southern Caspian Sea) was found to hold for the greater part of the European Russia. Possible causes of present-day climate changes and their manifestations at the regional level are analyzed. A possible mechanism of present-day climate changes is proposed 相似文献