Geochronology, Geochemistry and Tectonic Interpretation of Akebulake Plutons in Qinghe County, Northern Xinjiang

The Akebulake plutons, outcropped in Qingeli River in Qinghe County of southern margin of Altay orogenic belt, are mainly granodiorite. LA-ICP-MS zircon U-Pb indicates that the plutons were formed in the early Devonian (397.6±5.2Ma), which is a large scale magmatic event in the Altay orogenic belt in Devonian. The SiO₂ contents range from 69.17% to 74.70% and A/CNK from 0.97 to 1.09, indicating that the plutons are metaluminou, mid-high K calc-alkaline series rock. In addition, the plutons are enriched in K, Rb, Th, La, Ce and Nd, obvious negative anomaly in Ba, Nb, Ta, Ti, Sr and Eu (δEu=0.58-1.23), which are consistant with the characteristics of granitoid rocks formed in island-arc. Based on the previous studies, this paper suggests that the Akebulake plutons were generated from the tectonic environments of continental margin arc by the subduction of the Paleo-Asian Ocean plate. Dark-coloured inclusion bodies in the rocks and the geochemical properties suggest that the plutons are the mixing and differentiation of the mantle magma melting the lower crust.