Geochronological and isotope geochemical characteristics of mafic intrusions of the Norilsk region     

Petrov  O. V.  Sergeev  S. A.  Prasolov  E. M.  Khalenev  V. O.  Lokhov  K. I. 《Doklady Earth Sciences》2010,434(1):1272-1274

Doklady Earth Sciences -  相似文献   

Paleoarchaean tonalites in the Orekhovo-Pavlogradskaya palaeoproterozoic collsional zone (Ukrainian Shield)     

S. B. Lobach-Zhuchenko  E. V. Bibikova  V. V. Balagansky  S. A. Sergeev  G. V. Artemenko  N. A. Arestova  N. P. Shcherbak  S. L. Presnyakov 《Doklady Earth Sciences》2010,433(1):873-878

The novel detailed geological and geochronological data for the tonalitie rocks and products of its structural and metamorphic overprint in the Orekhovo-Pavlogradskaya collision zone (Ukrainian Shield) are discussed. Magmatic crystallization of tonalites (3500 ± 13 Ma) followed by amphibolite (2863 ± 22 Ma) and granulite (2105 ± 40 Ma) facies metamorphic events, resulting in biotite-garnet gneisses formation. The last date also indicating the time of collision event. The earliest age of 3.64 Ga was found in the zonal zircon fragment within 3.5-Ga old magmatic zircon from tonalite.  相似文献   

Polychronic sources and isotopic age of the volcanogenic complex (Arvarench Unit) of the Imandra-Varzuga structure,Kola Peninsula     

Vrevskii  A. B.  Bogomolov  E. S.  Zinger  T. F.  Sergeev  S. A. 《Doklady Earth Sciences》2010,431(1):386-389

Doklady Earth Sciences -  相似文献   

The Olkhon metamorphic terrane in the Baikal region: An Early Paleozoic collage of Neoproterozoic active margin fragments     

D.P. Gladkochub  T.V. Donskaya  V.S. Fedorovsky  A.M. Mazukabzov  A.N. Larionov  S.A. Sergeev 《Russian Geology and Geophysics》2010,51(5):447-460

We report data from the Khadarta, Khoboi, and Orso metamorphic complexes of the Olkhon terrane in the western Baikal region. High-grade rocks in the three complexes may have been derived from active continental margin rocks (island arc–backarc basin system). The backarc basin history possibly began at 840–800 Ma, according to SHRIMP-II U-Pb zircon ages of the Orso gneiss. Many tectonic units in the Olkhon terrane belonged to the active margin of the Barguzin microcontinent which rifted off the Aldan province of the Siberian craton in the early Neoproterozoic. The accretion of the microcontinent to the craton was accompanied by high-grade metamorphism recorded in the Khadarta and Khoboi granulites. The 507 ± 8 Ma and 498 ± 7 Ma SHRIMP-II U-Pb zircon ages of the latter complexes, respectively, may refer to the earliest evolution stage of the Olkhon metamorphic terrane. New data for the Olkhon terrane agree well with the ages of other high-grade complexes along the southern Siberian craton (Slyudyanka, Kitoikin, Derba) and correspond to the initiation of the Central Asian orogen. With these data, the Olkhon metamorphic terrane has been interpreted as an Early Paleozoic collisional collage of fragments of the microcontinent’s Neoproterozoic active margin.  相似文献   

Wide-field plate archives stored in the Ukrainian observatories     

K. P. Tsvetkova  M. K. Tsvetkov  T. P. Sergeeva  A. V. Sergeev 《Kinematics and Physics of Celestial Bodies》2009,25(5):269-276

The latest version of the Wide-Field Plate Database Catalogue of Wide-Field Plate Archives (April 2008) contains 43 archives stored at some Ukrainian observatories, namely, at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (Golosiiv, Kyiv), at the Crimean Astrophysical Observatory (Nauchnyi and Simeiz), at the Kyiv, L’viv, and Odesa University Observatories, and at the Mykolaiv Observatory. About 126000 plates were obtained from 1898 to 2005 in the framework of the following observing programmes: Solar System Bodies Observations, Observations of Variable Stars, Investigations of the Emission Nebulae and Connected Stars, Spectral Classification of the Stars and Determination of the Stellar Absorption in the Direction of the Emission Nebulae, Photographic Survey of the Northern Sky (FON), Investigation of the Kinematics and Structure of the Main Meridian Section of our Galaxy (MEGA), Observation of Selected Reference Stars, Artificial Satellites Observations and other. At the moment the basic information on 12609 plates from 13 plate archives of the Main Astronomical Observatory and Crimean Astrophysical Observatory is included into the Wide-Field Plate Database Catalogue of Wide-Field Plate Indexes (Sofia, Bulgaria). The plate digitization is just started with flatbed scanners. Some illustrations of the potential of the Ukrainian plate archives for future reusage are given and some compiled plate catalogues are presented on the basis of data from the Wide-Field Plate Database.  相似文献   

The 3.98–3.63 Ga zircons as indicators of major processes operating in the ancient continental crust of the east Antarctic shield (Enderby Land)     

B. V. Belyatsky  N. V. Rodionov  A. V. Antonov  S. A. Sergeev 《Doklady Earth Sciences》2011,438(2):770-774

This study presents new results on zircons from the enderbite-charnockite rocks of Enderby Land, East Antarctica. U-Pb age of 3981 ± 8 Ma (SIMS SHRIMP II), which was first obtained for a protolith of massive enderbites from Aker Peaks, eastern Napier Mts, suggests that the existence of sialic crust in the study area at 4 Ga. Although there was only one magmatic zircon (of 150 grains analyzed) in the study area known with the oldest age, its significance cannot be overestimated, since it may indirectly evidence the existence of an Early Archean crustal block with a minimum age of 4 Ga, which extends for over 300 km across Enderby Land from its western to eastern part. Based on the U-Pb systematics, REE and trace element distributions in zircons from charnockite and enderbite gneisses, high-aluminous gneisses, and basic granulites, we first revealed that an early high-temperature metamorphic event accompanied by the emplacement of granodiorite intrusions occurred in the vicinity of Aker Peaks at 3620–3630 Ma. Although the 2850–3050 metamorphic overprints are clearly observed in some other areas of Enderby Land and are widely considered to be of critical importance on a regional scale, their metamorphic signatures are apparently absent from the U-Pb systematics of the studied zircon, thus suggesting the presence of similar old zircons in the study area. At the same time, all samples in this study record a 2480–2550 Ma granulite-amphibolite facies overprint represented as new zircon growths or recrystallization of earlier phases.  相似文献   

Multi-frequency studies of the non-stationary radiation of the blazar 3C 454.3     

A. E. Vol’vach  L. N. Vol’vach  A. M. Kut’kin  M. G. Larionov  M. Villata  K. M. Panteri  A. Lahteenmaki  M. Tornikoski  P. Savolainen  G. Tammi  A. F. Aller  H. D. Aller  S. G. Sergeev  V. T. Doroshenko  Yu. S. Efimov  S. A. Klimanov  S. V. Nazarov  G. V. Borman  A. B. Pushkarev  V. I. Zhdanov  E. V. Fedorova  I. B. Vavilova  N. G. Chesnok 《Astronomy Reports》2011,55(7):608-615

Long-term monitoring data at five radio frequencies from 4.8 to 37 GHz obtained at the Crimean Astrophysical Observatory, Metsahovi Radio Observatory of Aalto University, and the University of Michigan Radio Astronomy Observatory are used to analyze variations of the flux of the Active Galactic Nucleus (AGN) 3C 454.3. The dynamical characteristics of the three latest powerful flares from 2004 to 2010 are analyzed in detail. Observations in the gamma-ray (0.1–300 GeV), X-ray (2–10 kev, 15–50 keV), and optical are also used. Delays in the development of flares at different frequencies are derived. An empirical frequency dependence for the delays of flares from the gamma-ray to the radio is determined, which can be fit using a logarithmic low and remains the same from flare to flare. The physical characteristics of the central region of the AGN 3C 454.3 are used to estimate the size of its Strömgren sphere, taking into account the relevant mechanisms for heating and cooling the medium, as well as the adopted laws for the variation of the density and temperature with distance from the source of ionization. A model for the location of the radiation regions in the jet at various frequency ranges during the development of flares is proposed.  相似文献   

On the genesis of some bottom and coastal features in the Eastern Gulf of Finland     

I. O. Leont’ev  D. V. Ryabchuk  A. Yu. Sergeev  L. L. Sukhacheva 《Oceanology》2011,51(4):688-698

An investigation undertaken recently by the Division of Regional Geoecology and Marine Geology of the Karpinsky All-Russian Research Geological Institute in the coastal zones of the Eastern Gulf of Finland allowed finding some specific relief forms of both near-shore bottom topography and shoreline shape. First of all, among the most interesting objects, the sand ridges on the surface of submarine terrace (between Repino locality and Cape Lautaranta) should be mentioned. These ridges are elongated at an angle to the shoreline and are located beyond the limits of wave action. The other interesting morphological type is represented by longshore sand waves up to some hundreds of meters long and some tens of meters wide near the Bol’shaya Izhora locality. Longshore sand waves move along the southern coast of the gulf, this causing alteration of erosion and accretion zones and leading to formation and degradation of the sand spits. Shore-face-connected ridges are believed to develop under the action of drift currents generated during the passage of deep west cyclones. It is shown that the ridge turned toward the current gives rise to a convergence of the cross-shore flows over the crest and provokes a shift of the maximum velocity toward the front side of the structure. Associated changes in sediment discharges result in accumulation and growth of the ridge. The origin of wavelike features in the shoreline contour (longshore sand waves) is due to a very oblique wave approach caused by predominance of the west winds blowing along the axis of the gulf. Under these conditions a small perturbation of the shoreline contour is shown to manifest a trend to increase with time.  相似文献   

Laboratory study of two-dimensional nonuniform surface currents over a sphere moving in a fluid column     

V. V. Bakhanov  N. A. Bogatov  S. N. Vlasov  V. I. Kazakov  E. V. Koposova  D. A. Sergeev 《Oceanology》2011,51(4):543-553

This paper presents the results of laboratory measurements of surface currents over a sphere moving in the fluid column based on the particle tracing velocimetry. A theoretical model of the fluid flowing around the sphere is presented. The experimental data are compared with the results of theoretical calculations. It is shown that, at low tow speeds of the sphere, the experimentally measured current velocities exceed the velocities calculated from the theoretical model. At greater tow velocities when generation of surface waves by the sphere was observed in the experiment, the experimental data agree well with the results of the theoretical calculations.  相似文献   

BVRI CCD-Photometry of Comparison Stars in the Neighborhoods of Galaxies with Active Nuclei. I     

V. T. Doroshenko  S. G. Sergeev  N. I. Merkulova  E. A. Sergeeva  Yu V. Golubinsky  V. I. Pronik  N. N. Okhmat 《Astrophysics》2005,48(2):156-178

Results are presented from CCD BVRI observations of comparison stars in the neighborhoods of 22 galaxies with active nuclei having right ascensions ranging from 0 to 12 hours, of which 19 are Seyfert galaxies. The observed stars have magnitudes ranging from V=11 to V=17. For stars brighter than V=14 the typical photometic error is 0.01^m. The B, V, Rc, and Ic magnitudes of most of these stars were not known previously. 14′×14′ finding charts are included. These results can be used for differential photometry of the AGNs in the B, V, Rc, and Ic bands.__________Translated from Astrofizika, Vol. 48, No. 2, pp. 191–211 (May 2005).  相似文献