YERUDA AND CHIRIMBA GRANITOIDS (Yenisei Range) AS INDICATORS OF LATE PROTEROZOIC COLLISIONS
A. E. Vernikovskaya, V. A. Vernikovskii, E. B. Sal'nikova, V. M. Datsenko, V. P. Kovach, A. B. Kotov, A. V. Travin, and S. Z. Yakovleva
Keywords: Late Proterozoic, petrology and geochemistry of granitoids, isotope data, Yenisei Range
Pages: 259-272
Abstract
Petrological, geochemical, and isotope (U-Pb, Sm-Nd, Sr-Sr, and Ar-Ar) studies of the Yeruda and Chirimba granitoids show that they belong to different magmatic complexes. The Yeruda low-Kcalc-alkalic granitoids (878  1.5 Ma, U-Pb dating from zircon) have a geochemistry corresponding to intermediate I-S-type granites. Their primary melts may have been derived from island-arc complexes, strongly contaminated with the material of old continental crust, which were molten as a result of a collision about 880 Ma ago. The Chirimba high-K and high-F subalkalic granitoids (761 8 Ma, U-Pb dating from zircon) apparently formed by melting of Early Proterozoic (Sm-Nd model age) crustal substrate, including the lower crustal material. In geochemistry and isotope composition they are similar to A-type granites that formed in postcollisional or within-plate environments. The Chirimba granitoids are 120 Ma younger than the Yeruda rocks and thus cannot have been caused by the same event. Therefore, the region of the Yenisei Range may have experienced repeated accretionary and collisional events in Late Proterozoic time. |
