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A. B. Kuznetsov E. F. Letnikova I. A. Vishnevskaya G. V. Konstantinova E. P. Kutyavin N. K. Geletii 《Doklady Earth Sciences》2010,432(1):577-582
This study uses Sr isotope chemostratigraphy to place constraints on the depositional age of carbonate rocks from the Tuva-Mongolian
microcontinent. The age of carbonate rocks of the Irkut Formation (87Sr/86Sr initial ratio equal to 0.70480–0.70485) is determined to be older than 1250 Ma, whereas carbonates of the Zabit (0.70706–0.70727
and 0.70828–0.70848) and Agarin Gol (0.70725–0.70743) formations were deposited in the interval 630–560 Ma. 相似文献
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Doklady Earth Sciences - Niobium metallogeny over the course of geological history has been considered on the basis of data from 45 largest deposits in the world belonging to any of three... 相似文献
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V. N. Benyamovskiy A. S. Alekseev M. N. Ovechkina V. S. Vishnevskaya A. V. Podgaetskii V. G. Pronin 《Stratigraphy and Geological Correlation》2012,20(4):346-379
Four upper Campanian-lower Maastrichtian reference sections are described in the Glubokaya and Kalitva river basins and in the Znamenka 1-A Borehole located in the northwestern Rostov region. The sections are composed of the upper Campanian Kagal??nik, Belgorod, Pavlovka, Sukhodol and lower Maastrichtian Efremovo-Stepanovka formations. They are characterized by successive stratigraphically significant macro- and microfossil assemblages: belemnites, calcareous nannoplankton, benthic foraminifers, and radiolarians. The Pavlovka and, particularly, Sukhodol formations contain a specific assemblage of coarsely-agglutinated benthic foraminifers. The first data obtained on radiolarians in upper Campanian-lower Maastrichtian sections of the northwestern Rostov region revealed four assemblages, two of which were previously unknown from Upper Cretaceous sediments of the East European Platform. Most sections enclose a hiatus at the base of the Sukhodol Formation, which comprises two upper Campanian benthic foraminiferal zones. The problem of recognition of the lower Maastrichtian boundary on the East European Platform is considered in accordance with international GSSP requirements. 相似文献
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Water Resources - The notion of diffuse pollution process in water bodies of different dimensions is formulated. An algorithm is given for calculating the average annual volume of the export of... 相似文献
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E. F. Letnikova F. A. Letnikov S. I. Shkol’nik T. Yu. Cherkashina L. Z. Reznitskii I. A. Vishnevskaya 《Doklady Earth Sciences》2016,466(1):42-46
Isotope–geochemical studies of Mn, P, and Ba ores were performed in order to establish the influence of submarine hydrotherms on the formation of Early Cambrian sedimentary rocks of the southern environs of the Siberian Platform. Based on study of the geochemical and isotope (εNd) characteristics of the shallow-water Mn and Ba ores and phosphorites of southern environs of the Siberian Platform with similar ages, two types of sedimentary basins of the different geodynamic origins were distinguished: intraplate oceanic and those of the active continental margin, for which the sources of ore materials differ by the proportions of the mantle and contaminated crustal matter. 相似文献
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The distribution of integrated resources of large and superlarge mineral deposits (LSLDs) of silver, where the main part of industrially recoverable silver reserves is concentrated, is compared with the existing model of supercontinent cyclicity over the geological history of the Earth. It is found that each supercontinent cycle (Kenoran, Columbian, Rodinian, Pangean, and Amasian) is particularly expressed in the silver metallogeny. The significant intercycle variations in the numbers of LSLDs, diversity of types of these deposits, accumulated resources, mean tenors of silver in ores, and some other numerically expressible characteristics are revealed. These variations correlate with a number of geohistorical changes in the conditions under which endogenous and exogenous geological processes run. 相似文献
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V. S. Vishnevskaya 《Russian Journal of Pacific Geology》2010,4(2):131-144
Radiolarians, which represent the most widespread fossil faunal group in jaspers and cherts, are the best tool for determining
the geological age of Jurassic-Cretaceous volcanogenic-siliceous sequences in the Pacific margin of Russia, because they meet
all the conditions required for orthostratigraphic groups, i.e., demonstrate rapid evolutionary changes of their assemblages,
completeness of their record through the geological section, and a wide lateral distribution. The selection of biostratigraphic
scales for determining the age of radiolarian assemblages is of principal significance. The significant difficulty in correlating
Tethyan and Pacific assemblages is similar to that appearing in the case of the correlation between the Tethyan and Boreal
ammonite standards. The existing discrepancies are explained by the different life spans of some guide species that determine
the stratigraphic range of particular zones in their geographic type areas and may be different in other paleobiogeographic
regions and provinces. The program of scientific studies should include the search for and thorough analysis of Jurassic-Cretaceous
sections in Russia that contain simultaneously radiolarians, buchians, and ammonites. Such sections might provide the possibility
for developing a single scale for the transitional sections and outlining ways for correlating the Tethyan and Pacific assemblages. 相似文献