Petrological, geochemical and chronologic characteristics of the intrusive bodies on the south side of Karamaili ophiolite belt in eastern Junngar

There are many Carboniferous intrusive bodies on the south side of Karamaili ophiolite belt in eastern Junngar, which are mainly distributed in Wucaicheng area and Dishuiquan-Yemazhan zone. Based on the study of the characteristics of the intrusive bod-ies such as rock types, zircon geochronology and geochemistry, we can distinguish the early Carboniferous post-collisional I-type gra-nitic rocks from the late Carboniferous intra-continental bimodal rock associations (K-feldspar granite and hornblende-gabbro). Combined with the recently published data for Laoyaquan pluton, Huangyangshan pluton and volcanic rocks in Karamaili area, the au-thors have reached some new conclusions about the tectonic-magmatic evolution in Karamaili from Carboniferous to Permian. Firstly, the tectonic transition from post-collision to intra-continent extension may have occurred between early and late Carboniferous. The post-collisional igneous rocks are characterized by calc-alkaline I-type granite, basalt andesite and andesite, and the intra-continent extensional rock types are mainly composed of bimodal rock associations and A-type granite. Secondly, the granitoids in Karamaili are characterized by positive Nd values, suggesting that they were most probably from the young crust formed by depleted mantle.