The lithosphere beneath the Sangilen Plateau, Siberia: evidence from peridotite, pyroxenite and gabbro xenoliths from alkaline basalts     

V. V. Egorova  N. I. Volkova  R. A. Shelepaev  A. E. Izokh 《Mineralogy and Petrology》2006,88(3-4):419-441

Summary Ultramafic and mafic xenoliths in Ordovician Agardag alkaline basalt dikes from the Sangilen Plateau, southeastern Siberia, provide samples from the upper mantle and crust beneath central Asia. Three major groups were distinguished among the xenoliths: Group I xenoliths are spinel lherzolites, Group II xenoliths are spinel-garnet clinopyroxenites, and Group III comprises gabbroic xenoliths with two subgroups: Group IIIa comprises garnet bearing gabbroids and Group IIIb is represented by garnet-free gabbroids. The spinel lherzolite xenoliths represent the uppermost lithospheric mantle beneath the Sangilen Plateau and have geochemical characteristics similar to those of primitive mantle. Spinel-garnet clinopyroxenite and gabbroic xenoliths are of igneous origin and represent fragments of intrusive bodies crystallized at depths close to the mantle-crust boundary, as well as in the lower and the upper crust. The gabbroic xenoliths are evidently the crystallization products of melts similar in major and trace element composition to parental magma of the Bashkymugur gabbronorite-monzodiorite intrusion. Gabbroic xenoliths from the Ordovician Agardag alkaline basalt dikes demonstrate the presence of intermediate magmatic chambers within the crust beneath the Sangilen Plateau during the Early Palaeozoic. The relatively high equilibration temperatures of the mantle and lower crust xenoliths in the Agardag alkaline basalt dikes are largely attributable to a plume occurring beneath the Sangilen Plateau during the Ordovician.  相似文献   

Gated communities of the Moscow green belt: newly segregated landscapes and the suburban Russian environment   总被引：3，自引：0，他引：3  

Mikhail Blinnikov  Andrey Shanin  Nikolay Sobolev  Lyudmila Volkova 《GeoJournal》2006,66(1-2):65-81

The transition from the Soviet to the post-Soviet period in and near Moscow manifested itself in increasing production of segregated space both in the urban core and suburban areas outside of the beltway to accommodate the preferences of the new Russian business and governmental elite. This paper focuses on the residential single-family housing inside old and new settlements, which are frequently gated. Approximately 260 of such suburban communities have been developed within 30 km of the beltway during the past few years, of which a majority have some form of exclusion mechanism in place, typically tall solid fences, gates, closed-circuit video surveillance and guarded entry checkpoints. The difference in exclusivity varies from the most exclusive older communities inside Moscow Serebryany Bor enclave and Rublevskoe highway mansions to less exclusive new developments along Novorizkhskoe and Dmitrovskoe highways. Despite high rates of construction, based on sociological surveys in 2003, only about 11% of Russia’s upper class claimed to live in such new “cottages,” with the rest owning condos and luxury apartments in the inner city or older detached homes in villages and small towns. Therefore, not all the needs have been accommodated and more development is certain to take place. The environmental impact of such developments is profound. Based on preliminary LANDSAT image analysis, almost 22% of suburban “green belt” forested land within 30 km zone has been converted to new construction from 1991 to 2001. New construction is now focusing on the remaining fragments of natural vegetation, which will likely lower air quality and water quality available for the city. Ironically, the new developments advertise themselves as “clean and green” with massive investments in unnatural landscaping (seeded lawns, exotic shrubs, river and lake shore “improvements”). This investment highlights the well-known paradox of development in which people move out of town to live near nature, while destroying the wild nature they come to enjoy. “We left city for the weekend It was raining, saw no stars There were fences everywhere Our chiefs behind the bars.” Gennady Shpalikov  相似文献   

Water Quality of Small Rivers in the Zone of Influence of Gold-Mining Facilities in Krasnoyarsk Region     

Shchur  L. A.  Bazhina  L. V.  Volkova  N. I.  Trofimova  M. A. 《Water Resources》2003,30(1):72-80

Environmental and sanitary estimation of small-river water quality is made in the zone of influence of gold-mining facilities in Krasnoyarsk Region. The estimates are based on data on the hydrochemical regime and the characteristics of phytoplankton, microphyto-periphyton, macrozoobenthos, and ichthyofauna collected during the vegetation period of 2000.  相似文献   

Methane in the Sevastopol coastal area, Black Sea     

Lyudmila V. Malakhova  Viktor N. Egorov  Tatiana V. Malakhova  Sergey B. Gulin  Yury G. Artemov 《Geo-Marine Letters》2010,30(3-4):391-398

Concentrations of dissolved methane in seawater and bottom sediments, as well as of methane emanating from gas seeps were measured at 18 stations including several small bays in the Sevastopol coastal area (Black Sea) during 2007–2008. Methane concentrations in surface waters ranged from 10 to 2,970 nmol l^?1, and correlated well with values recorded for sediments. Methane concentrations in the water column were influenced by water depth, as well as by air and water temperatures. In the spring and summer of 2008, in situ CH₄ saturation relative to air was in the range of 970–71,900%. Maximum saturation was in summer. CH₄ fluxes to the atmosphere from the Sevastopol coastal area were estimated to vary from 190 to 1,550 μmol m^?2 day^?1. Gas bubbles escaping from the seepages contained about 57 vol% methane. Radiocarbon dating of the methane revealed an age not exceeding 150 years, implying a biogenic origin.  相似文献   

The Sixth All-Russia Conference on the Study of the Quaternary “Fundamental Problems of the Quaternary: Results and Trends of Further Research”     

Yu. A. Lavrushin  V. S. Volkova  I. V. Khazina 《Stratigraphy and Geological Correlation》2010,18(4):464-466

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New Find of Cuticular Coal in the Franz Josef Land     

I. B. Volkova  D. E. Bekh-Ivanov  I. N. Sidorova 《Lithology and Mineral Resources》2001,36(2):187-190

Coal pebbles found in 1994 in the Greham Bell Island (Franz Josef Land Archipelago) are made up of the Barzas-type cuticular liptobiolith. The coal belongs to the initial stage of catagenesis and is characterized by high content of cutinite (up to 70%) with very low reflectance (R_o= 0.1%). Maceration products show some tegillate elements of Arthropodaand individual Devonian spores. It is supposed that plant cuticle and Arthropoda exocuticle are present in this coal. The obtained data suggest the presence of Paleozoic rocks in the sedimentary sequence, although they are not yet recovered. These data complement the available information on the distribution of specific Devonian coals and allow us to have a new insight into the zoogenic material involved in the coal formation.  相似文献   

Composition of Li-F granite melt and its evolution during the formation of the ore-bearing Orlovka massif in Eastern Transbaikalia     

E. V. Badanina  L. F. Syritso  E. V. Volkova  R. Thomas  R. B. Trumbull 《Petrology》2010,18(2):131-157

By the example of the Orlovka massif of Li-F granites in Eastern Transbaikalia, the major- and trace-element (Li, Be, B, Ta, Nb, W, REE, Y, Zr, and Hf) compositions of the parental melt and the character of its variations during the formation of the differentiated rock series were quantitatively estimated for the first time on the basis of electron and ion microprobe analysis and Raman spectroscopy of rehomogenized glasses of melt inclusions in quartz. It was shown that the composition of the Orlovka melt corresponded to a strongly evolved alumina-saturated granitoid magma (A/CNK = 1.12–1.55) rich in normative albite, poor in normative quartz, and similar to ongonite melts. This magma was strongly enriched in water (up to 9.9 ± 1.1 wt %) and fluorine (up to 2.8 wt %). Most importantly, this massif provided the first evidence for high B₂O₃ contents in melts (up to 2.09 wt %). The highest contents of trace elements were observed in the melt from pegmatoid bodies in the amazonite granites of the border zone: up to 5077 ppm Li, 6397 ppm Rb, 313 ppm Cs, 62 ppm Ta, 116 ppm Nb, and 62 ppm W. Compared with the daughter rock, the Orlovka melt was depleted at all stages of formation in SiO₂ (by up to 6 wt %), Na₂O (by up to 2.5 wt %), and, to a smaller extent, in Ti, Fe, Mg, Sr, and Ba, but was enriched in Mn, Rb, F, B, and H₂O.  相似文献   

U-Pb isotopic dating of zircons (SHRIMP-II) from granulites of the Ol’khon region of Western Baikal area     

Volkova  N. I.  Vladimirov  A. G.  Travin  A. V.  Mekhonoshin  A. S.  Khromykh  S. V.  Yudin  D. S.  Rudnev  S. N. 《Doklady Earth Sciences》2010,432(2):821-824

Doklady Earth Sciences -  相似文献   

Continental crust in Gorny Altai: nature and composition of protoliths     

N.N. Kruk  A.G. Vladimirov  G.A. Babin  S.P. Shokalsky  N.V. Sennikov  S.N. Rudnev  N.I. Volkova  V.P. Kovach  P.A. Serov 《Russian Geology and Geophysics》2010,51(5):431-446

The history of the Vendian–Early Paleozoic formation of protoliths of continental crust in the Gorny Altai segment of the Central Asian fold belt is considered, and their composition, isotopic characteristics, and formation mechanisms are estimated. We have established two stages of crust-forming processes in Gorny Altai: Early and Late Caledonian, with the different structures of formed geoblocks and nature and compositions of crustal protoliths. At the Early Caledonian stage, fragments of oceanic lithosphere of basic composition (MORB, OIT, OIB) (T_Nd(DM-2st) = 0.65–1.1 Ga) formed, as well as island arcs with andesite-basaltic and andesitic protoliths with low contents of incompatible elements (T_Nd(DM-2st) = 0.7–0.9 Ga). At the Late Caledonian stage, the redistribution of the substance of these blocks and the external supply of material led to the formation of heterogeneous crust of turbidite basins with an oceanic basement and andesite-dacitic upper-crustal protoliths (T_Nd(DM-2st) varies from 0.8–0.9 Ga in the framing of the volcanic arc of Altaids to 1.4–1.6 Ga at the boundary of the Altai–Mongolian microcontinent).  相似文献   

Thermochronology of granulites from the Svyatoi Nose Peninsula (Transbaikalia)     

E. I. Mikheev  A. G. Vladimirov  N. I. Volkova  T. B. Bayanova  A. V. Travin  D. S. Yudin  A. S. Mekhonoshin  D. A. Orsoev 《Doklady Earth Sciences》2014,455(1):336-340

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