| Инд. авторы: | Krupchatnikov V.I., Vrublevskii V.V., Kruk N.N. |
| Заглавие: | Early Devonian volcanics of southeastern Gorny Altai: geochemistry, isotope (Sr, Nd, and O) composition, and petrogenesis (Aksai complex) |
| Библ. ссылка: | Krupchatnikov V.I., Vrublevskii V.V., Kruk N.N. Early Devonian volcanics of southeastern Gorny Altai: geochemistry, isotope (Sr, Nd, and O) composition, and petrogenesis (Aksai complex) // Russian Geology and Geophysics. - 2018. - Vol.59. - Iss. 8. - P.905-924. - ISSN 1068-7971. - EISSN 1878-030X. |
| Внешние системы: | DOI: 10.1016/j.rgg.2018.07.012; SCOPUS: 2-s2.0-85051115010; WoS: 000441022800001; |
| Реферат: | eng: Geological, geochemical, and isotope (Sr, Nd, and O) parameters of Early Devonian (405 Ma) volcanics of southeastern Gorny Altai (Aksai and Kalguty volcanotectonic structures) are discussed. The studied igneous rock association comprises magnesian andesitoids, Nb-enriched andesite basalts, and A-type peraluminous silicic rocks (dacites, rhyolites, granites, and leucogranites). Magnesian andesitoids (mg# > 50) are characterized by a predominance of Na among alkalies (K2O/Na2O approximate to 0.1-0.7), medium contents of TiO2 (similar to 0.8-1.3 wt.%) and Al2O3 (similar to 12-15 wt.%), enrichment in Cr (up to 216 ppm), and low Sr/Y ratios (4-15). The Nb-enriched (Nb = 10-17 ppm) andesite basalts have high contents of TiO2 (1.7-2.7 wt.%) and P2O5 (0.4-1.4 wt.%). The A-type granitoids are characterized by high contents of K(K2O/Na2O <= 60) and alumina (ASI <= 2.9) and depletion in Ba, Sr, P, and Ti. The magnesian andesitoids and Nb-enriched andesite basalts are products of melts generated in the metasomatized lithospheric mantle; silicic magmas were formed through the melting of Cambrian-Ordovician metaturbidites of the Gorny Altai Group and, partly, Early-Middle Cambrian island-arc metabasites. The above rock association might have resulted from a plume impact on the lithospheric substrates of the continental paleomargin during the evolution of the Altai-Sayan rift system. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.
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| Ключевые слова: | DISCRIMINATION; ROCKS; MANTLE SOURCES; KUZNETSK ALATAU; MAGNESIAN ANDESITES; PERALUMINOUS GRANITES; TECTONIC IMPLICATIONS; EVOLUTION; Central Asian Orogenic Belt; Gorny Altai; geochemistry; A-type granitoids; Nb-enriched andesite basalts; magnesian andesitoids; Early Devonian magmatism; A-TYPE GRANITES; MAGMATISM; |
| Издано: | 2018 |
| Физ. характеристика: | с.905-924 |