The Suoerbasitawu quartz diorite in the Yemaquan area of East Junggar, Xinjiang, has a zircon U-Pb age of 442.5±5.6 Ma. The quartz diorite has the data SiO₂=63.75%~65.40%, Al₂O₃=17.07%~18.00%, Na₂O/K₂O=5.28~6.82, and MgO=1.11%~1.35%. They are characterized by enrichment of large ion lithophile elements (LILEs, such as K, Rb, Ba, and Sr), and depletion of high field strength elements (HFSEs, such as Ta, Nb, Zr, and Ti) and P. They also have the data Sr=783×10^-6~1 030×10^-6, Y=8.10×10^-6~10.80×10^-6, Yb=0.84×10^-6~1.04×10^-6, and Sr/Y=82.59~112.32, showing typical characteristics of adakitic rocks. The rocks have relatively low (⁸⁷Sr/⁸⁶Sr)_i (0.703 77~0.704 04) and high εNd(t) (+6.9~+7.2), and relatively high zircon εHf(t) (+10.7~+13.7), indicating that the magma was probably derived from an depleted juvenile mantle, similar to the adakitic rocks formed by the partial melting of subducted oceanic crust. In combination with the regional geological background, the authors hold that the Suoerbasitawu quartz diorite was formed by the partial melting of subducted oceanic slab edge heated by the asthenospheric mantle, which was the magmatic arc formed by the southward subduction of the Paleo-Asian oceanic crust in the early Silurian period.