A review on two types of mantle domains of the Permian large igneous province in Tarim and the western section of Central Asian orogenic belt. Geological Bulletin of China

A comprehensive analysis on the reported geological, geochronological and ochemical data of the Permian basaltic rocks in Tarim and the western section of the Central Asian orogenic belt (CAOB) indicates that the volume, petrography and their peaking activity at 275 Ma are orrelated with those characteristics of other large igneous provinces (LIPs) in the world and we termed it as Bachu LIP. Elements and Sr-Nd isotopic compositions of the basalts in Tarim suggest that they may originate from partial melting of a long-term enriched lithospheric mantle at 60-80 km depth, while the mafic dykes and ultramafic-mafic intrusions in Tarim most possibly originated from asthospheric mantle (OIB-like). On the other hand, the basaltic rocks from the CAOB predominantly originated from partial melting of a subduction-released fluid (and/or melts) metasomatized lithospheric mantle involved with variable OIB-like basaltic magma addition, e.g., the high-Ti series basaltic rocks in southern Altaid and Eastern Tianshan areas. Thus based on geochemical data of major and trace elements, two different mantle domains can be divided within Bachu LIP, i.e., a long-term enriched Tarim domain and a subduction-metasomatized depleted CAOB domain. These two mantle domains have different metalogenesis types, i.e., the metalogenesis in Tarim is dominated by V-Ti magnetite mineralization, while in CAOB, dominated by Cu-Ni-PGE sulphide and co-genesis of Cu-Ni-PGE sulphide and V-Ti magnetite mineralization. The metallgenetic difference between in Tarim and in the western section of the CAOB is concurrent with the two different mantle domains. By integrating geological, geochronlogical, metallgenetic and geochemical data, we conclude that the formation of Bachu LIP is closely linked with a Permian mantle plume, which we term it as Bachu plume.