Title

L.B. MAKAREV, A.A. RASSOLOV, E.V. MORGUN, P.A. LVOV (VSEGEI), S.A. SERGEEV (VSEGEI, IES SPSU), L.N. SHARPENOK (VSEGEI)

New data on the age and the composition of Borgoyskiy complex and Alentuy-­Sogotinskaya volcano-­plutonic assotiation of Western­Transbaikalian belt (Tashirskaya Area, Republic of Buriatia)

Early­-Permian age for Borgoyskiy complex and Alentuy­Sogotinskaya volcano­plutonic association are being substantiated on the newest geochronological data. Borgoyskiy nepheline and alkaline syenite complex (subsynchronic Borgoyskiy and Botziyskiy complexes), considered as Early-­Carbonian, has a later age of 280±3 million years and is the latest in Paleozoic magmatism general sequence in Western-­Transbaikalian volcano­plutonic belt territory. The close determined forming time of Alentuyskaya formation volcanic (292±2 million years) and subvolcanic (289±2 million years) structures and also Sogotinskiy complex granitoids (286±2 million years) is the evidence of forming sequence and comagmaticity of Alentuy-­Sogotinskaya volcano­plutonic association.
Keywords: Western-­Transbaikalian volcano­plutonic belt, Borgoyskiy nepheline and alkaline syenite complex, Alentuy­Sogotinskaya volcano­plutonic association, U­Pb isotopic dating, zircon, SIMS SHRIMP