Abstract:
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.