Late paleozoic gabbroids of the Lesser Khingan terrane of the eastern Central-Asian fold belt: Age, geochemistry, and tectonic setting |
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| Authors: | I V Buchko A A Sorokin N M Kudryashov |
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| Institution: | 1. Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, per. Relochnyi 1, Blagoveshchensk, Amur Region, 675000, Russia
2. Institute of Geology, Kola Science Center, Russian Academy of Sciences, ul. Fersmana 15, Apatity, Murmansk Region, 184200, Russia
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| Abstract: | This paper considers the results of mineralogical, geochemical, and geochronological studies of leucogabbroids of the Karagai Massif located within the Lesser Khingan superterrane of the Central Asian fold belt. The main features of the rock-forming minerals of the gabbroids are the high calcium content of the clinopyroxene corresponding in composition to diopside-salite (Wo48–51En33–39Fs11–16) or augite (Wo22–35En46–47Fs18–33), the high basicity of the plagioclase (An90–92), and the presence of primary magmatic magnesian hornblende. The age of the massif was determined by U-Pb zircon dating as 257 ± 1 Ma. The compositional peculiarities of the gabbroids indicate that they were most probably formed in island-arc or active continental margin settings. With allowance for the existing geodynamic reconstructions and the data obtained in the present study, the formation of the Late Paleozoic gabbroids of the Karagai Massif was presumably related to the final stages of the subduction processes that preceded the collapse of the terranes of the eastern Central Asian fold belt. |
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