Relationship between Magmatic, Metamorphic, and Hydrothermal Processes within the Baikal–Muya Terrane (Eastern Siberia): Constraints from High-Precision Geochronological Study of the Kedrovskii Granitoid Massif

Resumo

High-precision dating of granitoids is of key significance for age identification of the main stages of crust formation in various blocks of the continental crust. Here we demonstrate geochronological results for of the Kedrovskii diorite–granodiorite massif localized within the South Muya block of the Baikal–Muya accretionary terrane (BMT) (Eastern Siberia) among Neoproterozoic gabbroids of the Kedrovskii complex and metasedimentary rocks of the Kedrovskaya Formation. The results of U–Pb (ID TIMS) and ³⁹Ar/⁴⁰Ar geochronological studies of the Kedrovskii massif are discussed. The crystallization of the massif (781 ± 3 Ma) occurred at an early stage of formation of the Proterozoic continental crust of the BMT during accretion of Baikalids with the Siberian craton margin. A later thermal event (626 ± 11 Ma) that took place at the Ediacaran stage of the BMT evolution resulted in the formation of a series of transverse biotite–quartz–feldspar veins cutting through the granitoids of the Kedrovskii massif. The geochronological data obtained show that the gold mineralization of the Kedrovskoe deposit (273 ± 4 Ma) was not generated by granitoids of the Kedrovskii massif.