GABBRO-PERIDOTITE SILLS OF THE LATE RIPHEAN DOVYREN PLUTONIC COMPLEX (northern Baikal area, Russia)
D.A. Orsoev1, A.S. Mekhonoshin2, S.V. Kanakin1, R.A. Badmatsyrenova1, E.A. Khromova1
1Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakhyanovoi 6a, Ulan-Ude, 670047, Russia
2A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Габбро-перидотитовые силлы, дифференциация, внутриплитные рифты, мантийный плюм, Gabbro-peridotite sills, magma differentiation, within-plate rifting, mantle plume
Abstract
We report data on the geology, mineralogy, petrography, and chemistry of 733 Ma gabbro-peridotite sills from the Late Riphean Dovyren plutonic complex. Thick sills were differentiated into plagiolherzolite to olivine gabbronorite compositions by fractional crystallization of the K-Na series high-Mg low-alkali low-Ti picritic parental magma. The magma already contained up to 5% of intratelluric olivine crystals when entering the reservoir. The sills emplaced before the whole complex, judging by the presence of their fragments as plagiolherzolite xenoliths in the gabbro zone of the Yoko-Dovyren layered pluton. The gabbro-peridotite sills are products of high-temperature within-plate magmatism. High heat flow during the generation of the magma, evident from its high-Mg composition, was, likely maintained by the activity of a mantle plume associated with the Neoproterozoic Franklin large igneous province.
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