LA-ICP-MS zircon U-Pb age of Late Carboniferous quartz diorite in Yiwu area of Xinjiang and its geological significance

The Late Carboniferous intrusions in Yiwu region of Xinjiang were produced in the eastern section of TianshanXingmeng orogenic belt. LA-ICP-MS technological analysis shows that the quartz diorite zircon ²⁰⁶Pb/²³⁸U age of the study area is 312.4±1.5Ma (MSWD=0.18, n=30), suggesting Late Carboniferous epoch. The petrochemical data show that the late Carboniferous intrusive rocks in Yiwu region belong to aluminum alkaline rock series characterized by LREE enrichment and HREE flat type, with moderate Eu negative anomaly. Trace elements in rocks are characterized by enrichment of light rare earth elements and large ion lithophile elements such as Ba and Th, and the relative loss of Nb, Ti and P; strong P element loss may be associated with apatite crystallization separation. These elements and the continental crust material have an obvious affinity. These data reveal that the Yiwu region was in a post-collision tectonic environment in the Late Carboniferous.