AGE AND MINERALOGICAL AND GEOCHEMICAL PARAMETERS OF ROCKS OF THE CHINA ALKALINE MASSIF (western Transbaikalia)
I.A. Izbrodin1, A.G. Doroshkevich1,2, M.O. Rampilov1, G.S. Ripp1, E.I. Lastochkin1, V.B. Khubanov1, V.F. Posokhov1, N.V. Vladykin3
1Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakh'yanovoi 6a, Ulan Ude, 670047, Russia
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Щелочные и нефелиновые сиениты, высококалиевые породы, позднепалеозойский магматизм, источники, Западное Забайкалье, Alkali and nepheline syenites, high-K rocks, Late Paleozoic magmatism, sources, western Transbaikalia
Abstract
Geochemical and U-Pb geochronological studies have shown that the alkali syenites of the China massif have an age of 311.4 ± 1.8 Ma and potassic specialization in contrast to most massifs of the Vitim alkaline-magmatism zone. The rocks are similar in geochemistry to the nepheline syenites of the Synnyr massif, dated at 289.5 ± 3.5 Ma. The alkali syenites of the China massif formed, most likely, from crustal protoliths.
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