Late Paleozoic gabbroids of western Transbaikalia: U-Pb and Ar-Ar isotopic ages,composition, and petrogenesis |
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| Institution: | 1. Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakh’yanovoi 6a, Ulan-Ude, 670047, Russia;2. Buryat State University, ul. Smolina 24a, Ulan-Ude, 670000, Russia;3. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;4. Tomsk State University, pr. Lenina 36, Tomsk, 634050, Russia;5. A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia;6. Institute of Geology, Komi Science Center, Ural Branch of the Russian Academy of Sciences, ul. Pervomaiskaya 54, Syktyvkar, 167982, Russia;1. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;2. Institute of Archeology and Ethnography, Siberian Branch of the Russian Academy of Sciences, pr. Lavrentieva 17, Novosibirsk, 630090, Russia;3. A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;4. Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia;5. Gorno-Altaisk Expedition JSC, ul. Sovetskaya 15, Maloeniseiskoe Village, Altai Territory, 659370, Russia;6. A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia;7. St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034, Russia;1. A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia;2. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;3. Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia;4. Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences, Irkutsk Branch, ul. Lermontova 130a, Irkutsk, 664033, Russia;1. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;2. A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;1. A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;2. Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia;1. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Koptyuga 3, Novosibirsk, 630090, Russia;2. Institute of Precambrian Geology and Geochronology, nab. Makarova 2, St. Petersburg, 199034, Russia;3. Institute of the Earth Crust, ul. Lermontova 128, Irkutsk, 664033, Russia;4. Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong |
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| Abstract: | We provide new isotope-geochronological evidence for the synchronous occurrence of Late Paleozoic basic and granitoid magmatism in western Transbaikalia; this is a strong argument for the contribution of mantle magmas to granitoid petrogenesis. The Late Paleozoic basic rocks originated from the phlogopite-garnet-bearing lherzolitic mantle, which melted under “hydration conditions.” The specific features of Late Paleozoic magmatism in western Transbaikalia were determined by the combination of the activity of a low-energy mantle plume with the final stage of the Hercynian orogeny in space and time. At the early stage of magmatism, during the formation of the Barguzin granites,the plume had only a thermal influence on the crustal rocks heated as a result of Hercynian fold-thrust deformations. The mixing of mantle basic and crustal salic magmas at different levels marked the transition from crustal to mixed (mantle-crustal) granites, which include all post-Barguzin complexes (probably, except for alkali granites). In the geologic evolution of Transbaikalia, the Late Paleozoic magmatism was postorogenic, but it was initiated and influenced by the mantle plume. |
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