Late Paleozoic alkaline magmatism in Western Transbaikalia,Russia:Implications for magma sources and tectonic settings  

作　　者：Ivan Izbrodin Anna Doroshkevich Mikhail Rampilov Alexey Elbaev German Ripp 

机构地区：[1]Geological Institute,Siberian Branch of the Russian Academy of Sciences,Russia [2]V.S.Sobolev Institute of Geology and Mineralogy,Siberian Branch of the Russian Academy of Sciences,Russia

出　　处：《Geoscience Frontiers》2020年第4期1289-1303,共15页地学前缘（英文版）

基　　金：Mineralogical investigations were carried out using research project of the Geology Institute of SB RAS,NoAAAA-A16-116122110027-2;supported by the Russian Foundation for Basic Research (Project No.17-05-00309-a);supported by the Russian Science Foundation (Grant 19-17-00019)

摘　　要：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 western 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.The εNd(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 pronounced 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.

关 键 词：Nepheline-bearing and nepheline-free syenites Geochronological and isotope data Late paleozoic magmatism Sources Central Asian orogenic belt 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学] P534.4