I. G. Barash
Russian Academy of Sciences
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Featured researches published by I. G. Barash.
Stratigraphy and Geological Correlation | 2007
E. B. Sal’nikova; A. B. Kotov; V. I. Levitskii; L. Z. Reznitskii; A. I. Mel’nikov; I. K. Kozakov; V. P. Kovach; I. G. Barash; S. Z. Yakovleva
Geochronological data obtained in this work and previously known results of U-Pb geochronology suggest that principal metamorphic events, which took place in eastern part of the Irkut block (the Sharyzhalgai marginal ledge of the Siberian platform basement), correspond in age to (1) about 2.8 Ga, (2) 2649 ± 6 to 2562 ± 20 Ma, and (3) 1865 ± 4 to 1855 ± 5 Ma. Structural and metamorphic reworking of the earliest event originated under conditions of the granulite facies, whereas conditions of granulite and amphibolite facies were characteristic of the second and third events. Metasomatites after carbonate rocks originated in eastern part of the Sharyzhalgai ledge during the Early Proterozoic metamorphic event that lasted approximately 20 m.y. Being combined with age data, which are known at present for the reference syn-and post-collision granitoids in the Siberian platform basement and flanking foldbelts, new geochronological results show that accretion of basement blocks to the Siberian craton progressed from the east to the west between 1900 and 1840 Ma. To a first approximation, this geochronological interval characterizes time span of the Paleoproterozoic ocean closure and ultimate time, when the craton and supercontinent Columbia became amalgamated.
Geochemistry International | 2011
S. I. Shkol’nik; L. Z. Reznitsky; I. G. Barash
The Slyudyanka crystalline complex is located within the composite Khamar-Daban metamorphic terrane, the part of the Central Asian fold belt. Geochemical composition of the basic crystalline schists of the Slyudyanka Group (subterrane) metamorphosed under the high-temperature subfacies of the granulite facies suggests that their protoliths were tholeiitic basalts. Their geochemical signatures are intermediate between mid-ocean ridges and island arc basalts, best approximating back-arc basin basalts. The types of the metamorphic rocks of the Slyudyanka Group and their combination in sequences also most correspond to accumulation in back-arc basins. It was concluded that the high-grade metavolcanic rocks retain main geochemical signatures of protoliths, which allows the reconstruction of their paleogeodynamic settings, including back-arc basins.
Doklady Earth Sciences | 2015
L. Z. Reznitsky; Elena I. Demonterova; I. G. Barash; Hunh Chien-Hui; Chung Sun-Lin
356 Tunka Bald Mountains or the Tunka Alps is the southeastern part of the East Sayan Ridge in the inter fluve of the Irkut and Kitoy rivers. This area has always been attractive to geologists because of its marginal position. Depending on the prevailing ideas on the geology of this area, the Tunka Bald Mountains were regarded as a basement high of the Siberian Platform (SP), bordering the fold belt, or as a part of this fold belt, separating different structural and formational zones [1, 2].
Doklady Earth Sciences | 2011
S. I. Shkol’nik; V. G. Belichenko; L. Z. Reznitskii; I. G. Barash
High magnesium metavolcanites, which are found for the first time in the Tunka terrane (the Baikal-Khubsogul region), are described. By the content of MgO (12–16%), SiO2 (up to 52%), and alkali oxides, they are classified as metamorphosed picrites. There are two groups of them, divided by the TiO2 content and by the TiO2/Al2O3 ratio. When making a distinction between geochemical peculiarities of two groups, their rare-element composition is intermediate between picrites and boninites. The comparison between metavulcanites and their nonmetamorphosed analogues is made, some aspects of their genesis are considered, and the conclusion is made that these metavulcanites mark paleospreading of the back-arc basin.
Doklady Earth Sciences | 2018
L. Z. Reznitsky; E. V. Sklyarov; Z. F. Ushchapovskaya; I. G. Barash
Mannardite was found in a type of Cr–V–bearing metamorphic rock of the Slyudyanka complex (South Baikal region). The X-ray data of the mineral are recalculated for three scenarios taking into account possible variations of the mannardite structure. The mean chemical composition is as follows (14 analyses, wt %): 0.11 SiO2, 52.08 TiO2, 6.19 VO2, 13.51 V2O3, 5.50 Cr2O3, 0.24 Al2O3, 0.16 Fe2O3, 0.05 MgO, 20.09 BaO, 2.09 H2O (the H2O, VO2, and V2O3 contents are recalculated). The formula of the mean composition is (Ba1.06H2O0.94)(Ti5.27Si0.21V0.614+V1.453+Cr0.59Fe0.02Mg0.01)O16. Mannardite is characterized by the presence of different valent V. The mineral can be hydrous with molecular H2O or hydroxylion in tunnels or anhydrous. Mannardite can be considered an indicator of the hydroxyl or oxygen regime of petrogenetic processes.
Doklady Earth Sciences | 2017
S. I. Shkolnik; E. F. Letnikova; A. V. Maslov; M. D. Buyantuev; L. Z. Reznitskii; I. G. Barash
The results of geochemical, mineralogical, and isotope (U–Pb and Sm–Nd) studies of metasedimentary manganese-bearing rocks from the Itantsa Formation of the Ikat terrane are presented. It is found that the carbonate-effusive-shale complex of the Itantsa Fm. formed under the continental margin environment, with volcanic activity accompanying sedimentation, in the interval of 650–540 Ma ago.
Doklady Earth Sciences | 2011
S. I. Shkol’nik; I. G. Barash; V. G. Belichenko; E. F. Letnikova
This paper presents comprehensive geochemical characteristics of highly aluminiferous schists discovered in the Tunka Bald Mountains and associated with the Vendian-Cambrian cover of the Tuva-Mongolian Microcontinent. The Al2O3 content varies within a wide range, the maximum being up to 36.11 wt. %. A specific feature of the geochemical composition of these rocks is the simultaneously high contents of Cr (up to 1400 ppm), V (up to 2700 ppm), and Zr (up to 800 ppm). The origin has been interpreted, and the conditions in which the highly aluminiferous rocks formed have been considered. Based on geochemical data, it is assumed that the main origin could be weathering crusts formed after ultramafic and mafic rocks, with a felsic source playing a secondary role.
Doklady Earth Sciences | 2007
L. Z. Reznitsky; E. B. Sal’nikova; I. G. Barash; V. G. Belichenko; V. A. Glebovitsky; A. B. Kotov; V. P. Kovach; S. Z. Yakovleva; A. M. Fedoseenko
Doklady Earth Sciences | 2006
I. G. Barash; E. B. Sal’nikova; L. Z. Reznitsky; A. B. Kotov; V. P. Kovach; S. Z. Yakovleva; A. M. Fedoseenko
Russian Geology and Geophysics | 2009
S.I. Shkol'nik; L.Z. Reznitskii; V. G. Belichenko; I. G. Barash