Страницы: 873
Аннотация
Based on the preceding data (1-4) and new geological, geochemical and zircon U-Th-Pb results, we recognize NP1 collisional granitoids in several terranes, which were assembled during NP2 collision-accretional processes onto the western margin of the Siberian craton. The Neoproterozoic accretionary Transangara complex is situated in the north of the fold-and-thrust Yenisey Ridge belt extending along a south-western margin of the Siberian craton. There is Central Angara terrane with 880 - 865 Ma Teya granitoids which intruded mainly terrigenous and terrigenous-carbonate deposits that metamorphosed up to amphibolite facies. Teya rock have intermediate geochemical characteristic between I and S- type granite (0.70795 < 87Sr/86Sri < 0.71606; - 6.3 < еNd (880 Ma) < - 5.2; TDM = 1.9 - 2.0 Ga). Within accretionary Central Taimyr belt in the north-western margin of the Siberian craton there are two Mamont-Shrenk and Faddey terranes with granitoids of 940-850 Ma. The plutons occur in late Mesoproterozoic/early Neoproterozoic amphibolite facies metamorphic sedimentary rocks. These granites have S-type (0.71088< 87Sr/86Sri < 0.72163; - 7.1< еNd (940-850 Ma)< - 4.5; TDM = 1.8-2.0 Ga) as well as H-type (0.70585 < 87Sr/86Sri < 0.71920; - 2.1 < еNd (890-850 Ma)< + 0.6; TDM = 1.5-1.6 Ga) characteristics. At present, we cannot say on which continent or microcontinent the 940-850 Ma granitoids formed. Supposedly it were emplaced outside of the Siberian craton during formation of the Rodinia supercontinent. The Central Angara, Mamont-Shrenk and Faddey terranes which have similar characteristics of the NP1 granites and the surrounding metamorphic country rocks were united before they collided with Siberia. Our investigations confirm a common nature of the NP1 collisional granitoids from Central Angara, Mamont-Shrenk and Faddey terranes which were formed as a results collision events within a indivisible tectonic block. Subsequently considered terranes were separated and then included in the structures of the Neoproterozoic accretional belts of Siberian craton.1.Vernikovsky, V. & Vernikovskaya A. 2001. Precambrian Research, 110, 127-141.2. Pease V., Gee, D., Vernikovsky, V. et al. 2001. Terra Nova, 13, 4, 270-280.3. Vernikovskaya, A., Vernikovsky, V., Sal'nikova, E. et al. 2002. Russian Geology & Geophysics, 43, 3, 259-272.4. Vernikovsky, V., Vernikovskaya, A., Kotov, A. et al. 2003. Tectonophysics, 375,1-4, 147-168.
