Neoproterozoic rift and within-plate magmatism in the Yenisei Ridge: implications for the breakup of Rodinia
A.D. Nozhkina, O.M. Turkinaa, T.B. Bayanova b , N.G. Berezhnaya c , A.N. Larionov c , A.A. Postnikov d , A.V. Travina, R.E. Ernst e
a Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
b Geological Institute, Kola Science Center of the RAS, 14 ul. Fersmana, Apatity, 184209, Russia
c Center for Isotope Research, All-Russian Geological Institute, 74 Srednii prosp., St. Petersburg, 199026, Russia
d Institute of Petroleum Geology and Geophysics, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
e Ernst Geosciences, 43 Margrave Avenue, Ottawa, Canada KIT 3Y2; Department of Earth Sciences, Carleton U., Ottawa, Canada KIS 5B6
Keywords: Neoproterozoic; rifting; within-plate magmatism; Rodinia breakup; Yenisei Ridge
Pages: 503-519
Abstract
Geological, petrological, geochemical, and isotope data from the Yenisei Ridge indicate three stages of rifting and attendant within-plate magmatism at 750, 700, and 670 Ma. The igneous rocks of the three stages are, respectively, metarhyolite-basalt, trachybasalt-trachyte, and alkali ultramafic (alkali picrite) associations. Magmatism was concurrent with terrigenous deposition of the Neoproterozoic Upper Vorogovka, Chingasan, and Chapa Groups. The volcanosedimentary complexes were deposited in narrow rift-like graben along faults. The earlier consolidated flanking uplifts of the graben experienced granitoid magmatism synchronously with rifting and within-plate volcanism. The respective plutonic events produced granitoid intrusions of the Ayakhta (760-750 Ma), Kutukas (690-700 Ma), and Middle Tatarka (~700 Ma) alkaline complexes, and the later (about 650-670 Ma) alkali ultramafic Chapa complex of carbonatites and metasomatites. Basalts and alkaline rocks are chemically similar to ocean-island and continental-rift basalts which have been reliably attributed to mantle plumes. Neoproterozoic rifting and within-plate magmatism were possibly related to the plume activity responsible for the breakup of Rodinia. These events in the Yenisei Ridge appear to be coeval with rifting and within-plate magmatic processes in other continental blocks which may have been parts of the Rodinia supercontinent.
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