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1.
The composition, structure, and geochemical properties of the thickest, relatively deep-water Lower Miocene sediments developed in western Ciscaucasia are considered. Of particular interest are materials from the Kuban superdeep borehole SG-12000 that recovered the uppermost layers of the Maikop Group at 3148–3961 m in the central Indol-Kuban Trough west of Krasnodar. However, the borehole did not penetrate the whole Lower Miocene section of the Maikop Group. Therefore, characteristics of the Maikop Group are supplemented with new materials from several other boreholes drilled in the eastern Kuban region. Thus, the typical (reference) Lower Miocene section of central and western Ciscaucasia has been sufficiently well described. 相似文献
2.
Elen Roaldset 《Lithos》1973,6(4):349-372
Rare earth elements (REE) in the clay fraction (< 2μ) of the Quaternary deposits in the Numedal area, southern Norway, have been determined by a spark source mass spectrometric method. The REE content was studied in relation to weathering and sedimentological factors.
The total REE content varies from 100 to 1300 ppm. An average of the similar fraction of 16 non-marine clays, mostly tillitic, gave 527 ppm REE. An average of 38 glacial and postglacial marine clays from the lower part of the Numedal valley gave 335 ppm REE (max. 781 ppm). After removal of adsorbed ions the average total REE content of morainian and marine clays decreased to 186 ppm.
The content and distribution of the REE in the Numedal clays are strongly influenced by environmental factors. Under neutral and alkaline conditions the REE are accumulated by adsorption on clay minerals, and by increasing the hydrogen ion concentration the adsorbed ions are readily removed. 相似文献
3.
Presented are the stages of the formation and development of the system of monitoring and studying the atmospheric pollution in the cities for the 50-year period (since 1963). In this time period, important information on the quality of the air has been collected by monitoring network and has been published in yearly Roshydromet editions. Using the observational data, the trend is assessed of variations of the air pollution level in the largest cities of Russia for the long-term period. Demonstrated is the need in taking account of climatic conditions of the spread of atmospheric pollutants coming to the atmosphere with anthropogenic emissions for the decision-making on the air protection. Stated are the results of recent studies of the atmospheric chemical activity and effects of the air temperature and total solar radiation on the formation of secondary pollutants. 相似文献
4.
Alberto G. Figueiredo Jr. Charles A. Nittrouer Elen de Alencar Costa 《Geo-Marine Letters》1996,16(1):31-35
Seismic profiling with 3.5-kHz and GeoPulse in the Amazon submarine delta indicates that gas-charged sediments cover an area greater than 31,000 km2. Gas appears on seismic profiles as gas-brightening reflectors near the river mouth, where mud and sand are well stratified. In fine sediments of the distal portion of the system, gas turbidity zones predominate. Biogenic gas is generated during degradation of terrestrial and marine organic matter by bacteria. The depth of gas in sediment below the seabed depends in part on anaerobic methane oxidation and the base of the sulfate reduction zone and on stratigraphic traps. 相似文献
5.
A. S. Ivleva V. N. Podkovyrov V. B. Ershova O. A. Anfinson A. K. Khudoley P. V. Fedorov A. V. Maslov D. Yu. Zdobin 《Doklady Earth Sciences》2016,468(2):593-597
Here we present the results of U–Pb LA–ICP–MS dating of detrital zircons from the Ediacaran–Early Cambrian deposits of the eastern part of the Baltic monoclise (Leningrad Region). The obtained age spectra of the detrital zircons suggest that, in the Ediacaran–Early Cambrian, the main clastic material source to the northwest of the Russian Platform was the Baltic Shield. Then in the Early Cambrian along with the Baltic Shield provenance, a clastic source from the Timanian margin of Baltica (northeast in modern coordinates) contributed to the deposits. The obtained data either somewhat set limits of the Timanian orogen formation as older than the previously suggested Middle Cambrian (about 510 Ma), based on the “absence of a Proto–Uralian–Timanian provenance signal” in the Sablino Formation rocks in the south Ladoga, or suggest another rearrangement of detritus transportation paths at the end of Stage 3 (Atdabanian). 相似文献
6.
A. S. Ivleva V. N. Podkovyrov V. B. Ershova V. B. Khubanov A. K. Khudoley S. N. Sychev N. I. Vdovina A. V. Maslov 《Doklady Earth Sciences》2018,480(2):695-699
The results of LA–ICP–MS U–Pb analyses of detrital zircons from the Precambrian deposits of Luga–Ladoga monocline are discussed. The age spectra of the zircons separated from the Riphean to Upper Vendian sandstones from the Shotkusa-1 well demonstrate dominance of the Paleo- and Mesoproterozoic grains while the Archaean zircons are subordinate. The Riphean debris sources were local swells of the Northern Ladoga basement. The sequence interval presumably corresponding to the Vasilieostrov Formation (Upper Vendian) has yielded not only Paleo- and Mesoproterozoic zircon ages, but Neoproterozoic as well, implying a Timanide provenance: these zircons (527 ± 9 and 516 ± 13 Ma) allow deposition of a significant part of the Shotkusa-1 sequence at the very beginning of the Cambrian. 相似文献
7.
M. V. Borisov D. A. Bychkov N. F. Pchelintseva E. A. Ivleva 《Moscow University Geology Bulletin》2018,73(5):451-456
The data on the distribution of elements in the Pb–Zn cross-section of the Gatsirovskaya vein (the Upper Zgid deposit, North Ossetia, Russia) have shown that the spectra of rare-earth elements (REEs) changed significantly in the ore samples during the vein formation. The sharp growth of the LaN/YbN, LaN/NdN, GdN/HoN, and GdN/YbN ratios is confined to the vein intervals, where the maximum amount of ore components is deposited. The comparison of the REE spectra of ores to the characteristics of the spectra of the rocks surrounding the vein and the host rocks suggests that the vein material deposited from the solutions in which the REE ratio changed with time. REE fractionation occurred due to the mobilization of components by hydrothermal solutions during their interaction with the Paleozoic host granites. 相似文献
8.
Upper Oligocene sediments of the Eastern Paratethys are distinguished in the Maikop Group owing to several characteristic features. They form a thick (1000–1200 m) sequence with specific composition and structure in different structural–facies zones of the basin. The development of fish facies is the most remarkable feature. It includes unique sediments composed of fish bone detritus (FBD) and iron sulfides with high contents of REE, U, Sc, Re, Ni, Co, Mo, and other elements. These elements form commercial uranium–base metal deposits so far unknown in other formations of the Earth. The structure of thick rock sequences in the deepest part of the Eastern Paratethys is also characterized by specific features. Deep-sea clayey fish-facies sediments intercalate with beds of fine-grained sandy and silty material. Their influx into the central part of the basin was responsible for the clinoform structure of the rock sequence revealed by seismostratigraphic studies. This communication presents new data on the distribution of bone detritus deposits, composition and structure of sediments, and summary characteristics of Upper Oligocene sediments that are essential for the further analysis of facies–paleogeographic sedimentation conditions in the central Eastern Paratethys. 相似文献
9.
Rare earth element distributions in some Precambrian rocks and their phyllosilicates,Numedal, Norway
Elen Roaldset 《Geochimica et cosmochimica acta》1975,39(4):455-469
Mass spectrometric analyses for rare earth elements (REE) have been carried out on some Precambrian mica schists, gneisses and granites from the Precambrian Numedal area, Norway and on their phyllosilicates. The rocks, which are metamorphosed in the upper greenschist to amphibolite facies, were originally partly sedimentary, partly magmatic.The total REE contents for rocks varies from 145 to 761 ppm. An average of 16 phyllosilicate samples gave 417 ppm REE (max. of 1809 ppm, min. of ca. 50 ppm). Coexisting light and dark phyllosilicates have similar abundances of REE. For the micas of high REE content most of the REE was extractable by rinsing with EDTA. The data thus support the possibility of an extensive adsorption of REE ions on micaceous minerals. The REE distribution patterns do not provide a clear distinction between the sedimentary and magmatic origin for the rocks examined. 相似文献
10.
The rare carth elements are determined in vivianite concretions and surrounding clay sediments. Approximately 3/4 of the rare earth elements in the clay is present in adsorbed state. The concentration of REE in the pore water is calculated from the composition of the vivianite, assuming a diffusion model for the formation of the concretions and lower solubility of the rare earth elements above the concretions than in the pore water at some distance from the concretions. The concentrations thus calculated are similar to published values for ocean water. 相似文献