1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, Shandong, China

Petrography, chronology and geochemistry of volcanic rocks in Quanshuicun Formation in Yanbian area have been used to constrain the tectonic evolution in this area. The volcanic rocks in Quanshuicun Formation are divided into two sections, of which the upper section comprises rhyolite,rhyolitic tuff and rhyolite breccia, whereas the lower section consists of andesite and andesitic breccia. There are two eruption cycles running from eruption facies to flooding facies. LA-ICP-MS zircon U-Pb dating indicates that the formation age of the rhyolitic tuff in Quanshuicun Formation is (115±5.3) Ma,which is the late stage of Early Cretaceous, and its geochemical characters indicate that the primary magma could be mainly derived from partial melting of the crust. The geochemical characters of andesite indicate that the magma is derived from partial melting of the mantle wedge resulted from the metasomatism of the subduction fluid and is mixed with crustal materials at the same time, showing the characteristics of magmatic rocks formed under the active continental margin. Combined with other evidence, it is concluded that the paleo-Pacific plate, subducted to the eastern region of Jilin and Heilongjiang in the Early-Middle Jurassic, and the subduction was weakened in Late Jurassic-Early Cretaceous, but resumed again in the late stage of Early Cretaceous.