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131.
New data on composition and age of Precambrian granites and volcanic rocks in the southern part of the Lyapin structure (Northern Urals) are considered. The geochemical features of the igneous rocks are similar to those of the rocks formed in both divergent and convergent environments. In the Late Precambrian (583–553 Ma), the investigated area is assumed to have been a part of the active margin above the mantle plume. 相似文献
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In the framework of the program for setting the Callisto spectrometer network into operation, the spectral measurements were
carried out at the sites of spectrometer locations in India and Russia in winter 2006. The results achieved at Badary, the
site where the Siberian Solar Radio Telescope (SSRT) is located, are presented. The measurements were performed using a broadband
log-periodic antenna connected to the Callisto spectrometer developed at the Institute of Astronomy (Zurich). The results
of these measurements should explain whether spectral studies at frequencies below 1 GHz can be performed using such antennas
or new antennas should be developed. The presented results are compared with the similar results obtained in Switzerland in
the frequency intervals of interest for radio astronomy. Concerning electromagnetic noise, Badary is a better site for observing
the Sun in the 50–800 MHz frequency range as compared to observatories in Switzerland. 相似文献
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Doklady Earth Sciences - Comparison of the distribution of trace elements in the products of mud volcanoes of the Northwest Caucasus, Dzhungar Basin, and Andaman Islands shows that these products... 相似文献
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Maslov A. V. Kuznetsov A. B. Politova N. V. Kozina N. V. Novigatsky A. N. Shevchenko V. P. 《Doklady Earth Sciences》2019,485(1):268-272
Doklady Earth Sciences - The isotopic characteristics (εNd, 207Pb/206Pb, and 87Sr/86Sr) of the modern bottom sediments sampled in the Barents Sea during the 67th voyage of the R/V Akademik... 相似文献
136.
Proterozoic magmatic and tectonometamorphic evolution of the Taratash complex, Central Urals, Russia
S. Sindern R. Hetzel B. A. Schulte U. Kramm Yu. L. Ronkin A. V. Maslov O. P. Lepikhina 《International Journal of Earth Sciences》2005,94(3):319-335
The Taratash Complex (TC) in the northernmost Bashkirian Anticlinorium (Middle Urals) is unique among the pre-Uralian polymetamorphic complexes along the eastern margin of the East European Craton because it experienced granulite facies peak metamorphic conditions (850–900°C/10 kbar). Herein, we constrain the post-granulite facies polystage evolution of the complex, which records various increments of the geodynamic history of the East European continental margin. Formation of granite and migmatite associated with amphibolite facies events are dated at 2,344±29 and 2,044±8 Ma (U–Pb, zircon) in different structural units. At 1,810±41 Ma, the TC was affected by a greenschist facies retrogressive metamorphism which was probably related to a stage of granite formation in the eastern part of the East European Craton. This is confirmed by a U–Pb–zircon age of 1,848±8 Ma obtained from a sheared granite in the adjacent Alexandrovskiy Complex (AC). Greenschist facies shear zones which separate different structural units of the TC formed before 1,350 Ma. Partial re-equilibration of Rb–Sr- and K–Ar-isotope systems between 1,350 Ma and 1,200 Ma is attributed to fluid flow probably induced by anorogenic magmatism in the Bashkirian Anticlinorium. Meso- to Neoproterozoic basaltic dykes indicate that the TC had been exhumed to upper crustal levels at that time. Evidence for a Grenvillian event or for the Timanian orogeny which affected other pre-Uralian complexes in the Urals is lacking. Uralian orogenic shortening and thrusting on Devonian limestones is recorded by shear zones in the AC to the east of the TC and has been dated at 300 Ma (Rb–Sr, 40Ar/39Ar). 相似文献
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A. V. Maslov A. D. Nozhkin V. N. Podkovyrov O. M. Turkina E. F. Letnikova M. T. Krupenin Yu. L. Ronkin N. V. Dmitrieva E. Z. Gareev O. P. Lepekhina 《Geochemistry International》2009,47(7):692-712
The geochemical features of basal fine-grained terrigenous rocks from the Riphean sedimentary megasequences of the Southern Urals, Uchur-Maya region, and Yenisei Range were compared in order to estimate the maturity of the continental crust that was formed by the beginning of the Riphean. It was shown that initial shales from the base of the Riphean sequence of the Yenisei Range and fine-grained aluminosiliciclastic rocks from the base of the Riphean sections of the Southern Urals were formed by the erosion of a rather mature continental crust. In contrast, fine-grained terrigenous rocks from the base of the Riphean of the Uchur-Maya region were derived from immature Late Archean protoliths or their Early Proterozoic analogs. The fine-grained terrigenous rocks of the three sedimentary megasequences show different variations in the (La/Yb)N ratio. In the Southern Urals, this ratio is high (12–15) in the Burzyan Group and decreases upsection to 6–10. In the shales of the Uchur-Maya region, the (La/Yb)N ratio decreases upsection, and the La/Sc ratio shows a sympathetic behavior. This is due to a decrease in the proportion of “primitive” tonalite-trondhjemite associations of the Archean granite-greenstone terranes in the provenance area with time and the appearance of intra-plate (riftogenic?) granitoids and significant amounts of basic and ultrabasic rocks. The latter marks the onset of large rift-forming events in the Uchur-Maya region at the beginning of the Late Riphean. The (La/Yb)N of the studied rocks from the Yenisei Range are mostly similar to the PAAS ratio, but higher values were found in the Upper Vorogovka and Chingasan groups, which was related to the contribution of strongly LREE-enriched granitoids and rift felsic and alkali basaltic volcanic associations to the formation of the terrigenous material. A comparison of Rb, Sr, Y, Zr, Ba, Hf, Th, U, Cr, and Ni contents and Zr/Y, (La/Yb)N, Ni/Co, Cr/Th, Cr/Sc, and La/Th ratios in the fine-grained terrigenous rocks of the Riphean megasequences of the Southern Urals, Uchur-Maya region, and the Yenisei Range with those in the model geochemical objects (PAAS, UCPR1, UCAR2, and others) showed that, in terms of most of the parameters, the Riphean fine-grained terrigenous rocks from the three regions are similar to each other, PAAS, and Proterozoic cratonic shales. This indicates a fairly high general maturity of the protoliths that were eroded during the Riphean in the eastern East European craton and in the southeastern and southwestern parts of the Siberian craton. 相似文献
139.
A. V. Maslov D. V. Grazhdankin V. N. Podkovyrov M. V. Isherskaya M. T. Krupenin G. A. Petrov Yu. L. Ronkin E. Z. Gareev O. P. Lepikhina 《Geochemistry International》2009,47(12):1212-1233
The provenance composition and geological evolution of different segments in the distal zone of the Late Vendian foreland
basin of the Timan orogen were deciphered on the basis of sequence stratigraphic reconstructions and precision geochemical
data on the Upper Vendian fine-grained terrigenous rocks from the Southeast White Sea region, Vychegda, Verkhnekama, and Shkapovo-Shikhan
basins, and the Kvarkush-Kamennogorsk and Bashkirian meganticlinoriums. The Upper Vendian of the Southeast White Sea region
is subdivided into four sequences: Agma, Solza, Zimnie Gory, and Erga. The tracing of sequence boundaries and lateral facies
associations from the Southeast White Sea Region to the South Urals made it possible to identify the main stages of the evolution
of sedimentary filling of the foreland basin: (I) shallow water epiplatformal basin, (II) isolated basin, (III) lowstand system
tract, and (IV) progradation of delta platforms. Position of data points of the Upper Vendian shales, silty mudstones, and
mudstones plotted in the diagrams Th-La, Ni-Cr, GdN/YbN-Eu/Eu*, Sc-Th/Sc, La/Sm-Sc/Th, and Co/Hf-Ce/Cr, together with their REE systematics and data on Nd model ages indicates that
the Proterozoic, including Neoproterozoic rocks of the Timan thrust-folded belt served as the main source for fine aluminosiliciclastic
material in the distal zones of the Timan foreland basin. Obtained results are consistent with the concept that the Vendian
stage of the evolution of the Eastern European platform is related to the intense input of allochthonous material in its peripheral
area owing to the activation of orogenic processes in the adjacent mobile belts and allow us to significantly specify the
paleogeographical reconstructions. 相似文献
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