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Russian Geology and Geophysics

2012 year, number 11

NEOPROTEROZOIC ALKALINE MAGMATISM AND ASSOCIATED IGNEOUS ROCKS IN THE WESTERN FRAMING OF THE SIBERIAN CRATON: PETROGRAPHY, GEOCHEMISTRY, AND GEOCHRONOLOGY

I.V. Romanovaa, A.E. Vernikovskayaa, V.A. Vernikovskya,b, N.Yu. Matushkina,b, and A.N. Larionovc
aA.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
bNovosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
cA.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Alkaline magmatism, mineralogy, petrography, geochemistry, geochronology, Neoproterozoic, active continental margin, southwestern framing of the Siberian craton
Pages: 1176-1196

Abstract

The formation and evolution conditions for alkaline magmatism and associated igneous rocks in the western framing of the Siberian craton are shown by the example of alkaline and subalkaline intrusive bodies of the Yenisei Ridge. We present petrographic, mineralogical, geochemical, and geochronological data for the rocks of the Srednetatarka and Yagodka plutons, located within the Tatarka-Ishimba suture zone. Ferroan and metaluminous varieties enriched with rare elements (Nb, Ta, Zr, Hf, REE) are making up most of the studied rocks. They formed at the stages of fractional crystallization of alkaline magma in a setting of active continental margin in the west of the Siberian craton in the Late Neoproterozoic (710-690 Ma). As differentiates of mantle magmas, these rocks associate with Nb-enriched rocks - A -type leucogranites and carbonatites. Sm/Nd and Rb/Sr isotopic data imply a predominance of the mantle component in the magmatic sources of the mafic and intermediate rocks as well as contamination of various volumes of continental crustal material by this magma.