GU Feng-hua^1,2, ZHANG Yong-mei², LIU Rui-ping², SUN Xuan², YANG Wei-long², WANG Jia-lin²
1. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;
2. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China

Abstract: It is recognized that the genesis of granite is closely associated with its mafic microgranular enclaves (MMEs). The Shadegai granite is a representative intrusion of the Indosinian granite belt on the northern margin of the North China Craton. Petrographic and geochemical studies have been carried on Shadegai granite and its MMEs in order to understand the genesis of granite. The result shows that the enclaves are characterized by various shapes, strong plastic nature, typical magmatic textures and abundance of acicular apatite. Major element concentrations of the MMEs and their host granite commonly show linear correlations in the Harker diagrams, indicating the genesis of magma mixing. Similar distribution patterns of trace elements and REEs of both host granite and MMEs suggest material exchanges between two magmas. The Nb/Ta ratios of granite and MMEs indicate that they derived from the lower crust and mantle, respectively. It is thus suggested that the Shadegai granite was generated by mixed mantle-crust magmas in a post-collisional extension setting.

Keywords: magma mixing mafic microgranular enclaves K-feldspar granite Shadegai Inner Mongolia