Rare-metal granitoids of the Ulug-Tanzek deposit (Eastern Tyva): Age and tectonic setting     

Yarmolyuk  V. V.  Nikiforov  A. V.  Sal’nikova  E. B.  Travin  A. V.  Kozlovskiy  A. M.  Kotov  A. B.  Shuriga  T. N.  Lykhin  D. A.  Lebedev  V. I.  Anisimova  I. V.  Plotkina  Yu. V.  Yakovleva  S. Z. 《Doklady Earth Sciences》2010,430(1):95-100

Doklady Earth Sciences -  相似文献   

The Triassic stage of mafic magmatism in the Dzhugdzhur–Stanovoi superterrane (southern framing of the North Asian craton)     

I.V. Buchko  A.A. Sorokin  E.B. Sal'nikova  A.B. Kotov  S.D. Velikoslavinskii  A.M. Larin  A.E. Izokh  S.Z. Yakovleva 《Russian Geology and Geophysics》2010,51(11):1157-1166

With U-Pb zircon dating, the ages of the Ul'degit (228 ± 1 Ma) and Chek-Chikan (203 ± 1 Ma) mafic massifs were determined. These massifs were earlier considered to form at the Early Precambrian stage of the geologic evolution of the Dzhugdzhur–Stanovoi superterrane. In geochemical features the igneous rocks of the massifs show relation with a within-plate source, on the one hand, and are similar to igneous rocks of subduction zones, on the other. They might have formed after subduction, which caused the intrusion of gabbroids of the Lucha massif (248 ± 1 Ma) and diorites of the Tok-Algoma complex (238 ± 2 Ma), followed by the fracturing of the subducted plate.  相似文献   

A GIS-Based Ground Water Contamination Risk Assessment Tool for Pesticides   总被引：4，自引：0，他引：4  

Michael G. Sinkevich Jr  .  M. Todd Walter  Arthur J. Lembo Jr  .  Brian K. Richards  Natalia Peranginangin  Sunnie A. Aburime  Tammo S. Steenhuis 《Ground Water Monitoring & Remediation》2005,25(4):82-91

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Mineralogy,Mossbauer Characteristics,and K-Ar Isotopic Age of Glauconite from the Lower Cambrian Sediments,Western Lithuania     

T. S. Zaitseva  I. M. Gorokhov  T. A. Ivanovskaya  B. B. Zvyagina  N. N. Mel’nikov  O. V. Yakovleva 《Lithology and Mineral Resources》2005,40(4):353-363

The paper presents results of lithological-mineralogical, Mossbauer, and isotope-geochronological study of globular phyllosilicates (glauconite and illite) from the Lower Cambrian Virbalis Formation in western Lithuania. K-Ar dates of these minerals (382 and 374 Ma) do not correspond to stratigraphic positions of the studied samples and indicate the loss of radiogenic ⁴⁰Ar, probably, in Middle Devonian. Simulation of cation distribution in the mineral structure and comparison of the obtained data with Mossbauer spectral characteristics suggest that loss of ⁴⁰Ar was caused by the structural rearrangement of globular phyllosilicates during the postdiagenetic substitution of Fe²⁺, Mg²⁺, and Fe³⁺ by Al³⁺, with the subsequent ordering of cation distribution in octahedral layers. These processes were presumably related to the same Caledonian tectonic events that were responsible for metasomatic dolomitization of Lower Paleozoic rocks in adjacent areas of the Baltic region at the terminal Silurian-Devonian. Diffraction analysis showed that globules consist of two micaceous phases with different Fe contents (illite and glauconite). Two alternative models are considered to explain the formation of two-phase globules: (1) disequilibrium conditions of diagenetic mineral formation; (2) transformation of glauconite into illite. Although the available data are insufficient to make an unambiguous choice between these models, the second mechanism seems to be more preferable.__________Translated from Litologiya i Poleznye Iskopaemye, No. 4, 2005, pp. 403–415.Original Russian Text Copyright © 2005 by Zaitseva, Gorokhov, Ivanovskaya, Zvyagina, Mel’nikov, Yakovleva.  相似文献   

A spectroscopic and photometric study of NGC 2685, the prototype polar-ring galaxy     

V. A. Hagen-Thorn  L. V. Shalyapina  G. M. Karataeva  V. A. Yakovleva  A. V. Moiseev  A. N. Burenkov 《Astronomy Reports》2005,49(12):958-966

We present and analyze spectroscopic and photometric observations for NGC 2685, the prototype polar-ring galaxy. The spectroscopic data were acquired using the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the UAGS spectrograph and a scanning Fabry-Perot interferometer, while the photometric analysis was based on images from the Hubble Space Telescope archive. We demonstrate that the subsystem usually called the “inner polar ring” is a highly inhomogeneous gas and dust disk rotating approximately in the polar plane relative to the galaxy’s main body. When the self-absorption in the disk is taken into account, a comparison of its color indices with those from model computations of the color evolution of galaxies results in an age for the disk of about 1.4 × 10⁹ years, much lower than the previously accepted estimate.  相似文献   

Paleozoic rocks in infrastructure of the metamorphic core, the Greater Caucasus Main Range zone     

M. L. Somin  A. B. Kotov  E. B. Sal’nikova  O. A. Levchenkov  A. N. Pis’mennyi  S. Z. Yakovleva 《Stratigraphy and Geological Correlation》2006,14(5):475-485

Granitoid orthogneisses and migmatites are widespread in the lower, deeply metamorphosed gneiss-migmatite complex of the pre-Alpine basement (infrastructure) exposed within northern part of the Greater Caucasus Main Range zone. Like the other rocks of the complex, they have been traditionally attributed to the Proterozoic, but the U-Pb dating revealed the Late Paleozoic age of migmatites and Devonian age of orthogneiss protolith. Bodies of blastomylonitic apogranite gneisses, which are confined to boundary between gneiss-migmatite complex and overlying Makera Complex of supracrustal rocks, turned out to be of the Late Paleozoic age as well. The dating results suggest synchronism and, apparently, genetic interrelations between the high-T/low-P metamorphism and granite formation in the Main Range zone of the Greater Caucasus.  相似文献   

Early Cretaceous age of regional metamorphism of the Stanovoi group in the Dzhugdzhur-Stanovoi foldbelt: Geodynamic implications     

A. M. Larin  E. B. Sal&#;nikova  A. B. Kotov  V. A. Glebovitsky  S. D. Velikoslavinsky  A. A. Sorokin  S. Z. Yakovleva  A. M. Fedoseenko  I. V. Anisimova 《Doklady Earth Sciences》2006,409(5):727-731

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Protoliths of the metamorphic rocks of the Fedorov Complex, Aldan shield: Character, age, and geodynamic environments of origin     

S. D. Velikoslavinsky  A. B. Kotov  E. B. Sal’nikova  V. P. Kovach  V. A. Glebovitsky  N. Yu. Zagornaya  S. Z. Yakovleva  E. V. Tolmacheva  I. V. Anisimova  A. M. Fedoseenko 《Petrology》2006,14(1):21-38

Geochemical data indicate that the protoliths of the overwhelming majority of the metamorphic rocks composing the Fedorov Complex in the Aldan granulite megacomplex were volcanic rocks of three groups, which occur in different proportions in the complex: (i) volumetrically predominant (no less than 90%) continuous differentiated island-arc basalt-andesite-dacite-rhyolite series, (ii) within-plate basalts, whose composition was similar to that of low-Ti traps, and (iii) basalts of composition similar to that of continentalrift basalts. The U-Pb zircon crystallization age of the metamorphosed basaltic andesites of the Fedorov Complex was estimated at 2006 ± 3 Ma, which testifies, when considered together with preexisting geochronological data, that the complex was produced during a time span of no longer than 25 m.y. A model is proposed according to which the complex was produced within the geodynamic system of the active continental margin of the Olekma-Aldan continental microplate and the Fedorov island arc.  相似文献   

Interactive maps for visual exploration of grid and vector geodata     

Gennady Andrienko  Natalia Andrienko  Valeri Gitis 《ISPRS Journal of Photogrammetry and Remote Sensing》2003,57(5-6):380

This article considers two types of tools used for the analysis of spatial data: computational tools for grid data and visualization-based interactive exploratory techniques. The main purpose is to demonstrate that computational and visual techniques are complementary, and their combined use in data analysis may produce a synergistic effect. To this end, we describe two example scenarios of data analysis in the evaluation of potential damage from earthquakes and in analysis of forest resources. The analyses were performed with the use of CommonGIS, featuring the availability of powerful geocomputational tools and interactive visualization-related facilities that can be efficiently used in combination in a desktop environment or via the World Wide Web.  相似文献   

Permian palaeomagnetism of East Kazakhstan and the amalgamation of Eurasia     

Natalia M. Levashova  Kirill E. Degtyarev  Mikhail L. Bazhenov  Adam Q. Collins  Rob Van der Voo 《Geophysical Journal International》2003,152(3):677-687

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