Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The Angara-Kan block is an outcrop of the southwestern margin of the Siberian Craton, it is mostly composed of rocks of the Kan granulite complex and the Yenisey metavolcanic-metasedimentary complex. In this work we present the new data on composition, metamorphic condition and age of zircon and monazite of garnet-biotite schists of the Yenisey complex. Textural features, geochemical composition and wide range of zircon ages indicate formation of garnet-biotite schists during single-act metamorphism of terrigenous rocks. PT-conditions of metamorphism of garnet-biotite schists and garnet amphibolites are about P=7.2-8.2 kbar, T=700-730°C, they are similar to those of metavolanic rocks of the Yenisey complex. The age of metamorphic generation of zircons and monazites from garnet-biotite schists in the range of 720-730 million years correlates with the time of Neoproterozoic metamorphism of volcanic rocks of the Yenisei complex. The age spectra of Paleoproterozoic detrital zircons from garnet-biotite schists indicate two maxima: ca. 1.86 and ca. 1.78 Ga. The probable source of detrital zircons were granulites of the Kan complex, which underwent two stages of high-grade metamorphism at 1.89–1.85 and 1.8–1.77 Ga, respectively. The accumulation of terrigenous sediments was probably close in time to the formation of volcanics of the Yenisei complex at ⁓ 1.74 Ga. It is assumed that most sedimentary rocks of the Yenisei series were formed after the main orogenic events in the Angara-Kan block.