Late Paleozoic alkaline magmatism in Western Transbaikalia, Russia:Implications for magma sources an

• 作 者: Ivan Izbrodin Anna Doroshkevich Mikhail Rampilov Alexey Elbaev German Ripp
• 机 构: Geological Institute, Siberian Branch of the Russian Academy of Sciences, Russia“,”V.S. Sobolev Inst
• 出 处: 地学前缘（英文版）
• 发表日期: 2020年4期
• 关键词: Nepheline-bearing and nepheline-free syenites Geochronological and isotope data

This paper presents the results of geochronological (40Ar-39Ar, U–Pb SHRIMP II), petrological and geochemical studies of the Late Paleozoic complexes of alkaline rocks (Zimovechinsky, Tuchinsky and Koma) located within the Vitim Plateau (the west part of the Mongol-Okhotsk Orogenic Belt). The rocks were formed at 310–280 Ma. It is coeval with Late Paleozoic magmatism within the Central Asian Orogenic Belt. TheεNd(T) values show large variations from -2.1 to +3.3 as well as the initial Sr(I) isotopic ratios from 0.7042 to 0.7138, that demonstrate strong isotopic heterogeneity of the magmatic source. The geochemical characteristics of the rocks show pro-nounced positive Pb and negative Ti, Zr–Hf anomalies that can be explained by involvement of the subducted component in primary melts. The rocks intruded in a setting of extension at the active continental margin of the Siberian Craton during subduction of Mongol-Okhotsk oceanic crust under the Siberian Craton.