TIME OF SINGLE-ACT METAMORPHISM OF SEDIMENTARY ROCKS OF THE YENISEI COMPLEX (ANGARA-KAN BLOCK) BASED ON U—Pb DATING OF MONAZITE

The rocks of the Yenisey complex form an extensive metamorphic belt along the western margin of the Angara-Kan block (south-western Siberian craton), forming a series of tectonic blocks in the Yenisey fault zone. This complex is represented by metasedimentary and metavolcanic rocks and differs from the granulites of the Kan complex by a lower degree of metamorphism. The timing of the formation of the Yenisey metamorphic complex is key to understanding the Proterozoic geodynamic events on the southwestern margin of the Siberian craton. This paper presents the first results of LA-ICP-MS dating of monazite from metasedimentary rocks of the Yenisey Complex. These rocks were found to have undergone single-act metamorphism in the range of 716–750 Ma. The PT-parameters of the metamorphism of the garnet-biotite schists are estimated to be about P = 7.2 - 8.2 kbar and T = 700 - 730°C and are in good agreement with those previously obtained for metavolcanic rocks of the Yenisey Complex.