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Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position |
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| Authors: | A A Sorokin A B Kotov E B Sal’nikova N M Kudryashov V P Kovach |
| Institution: | (1) Institute of Geology and Nature Management, Far East Division, Russian Academy of Sciences, Blagoveshchensk, Russia;(2) Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg, Russia;(3) Institute of Geology, Kola Scientific Center, Russian Academy of Sciences, Apatity, Russia |
| Abstract: | Magmatic rocks of the Pikan and Un’ya massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya massif. As is suggested, the Pikan and Un’ya massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development. |
| Keywords: | Mongolian-Okhotsk foldbelt geochronology U-Pb dating Early Paleozoic granitoids Amur River basin |
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