STUDY ON THE CHRONOLOGY OF GRANITIC PORPHYRY IN HORQIN YOUYI ZHONGQI, INNER MONGOLIA

The isotopic chronological study indicates that the LA-ICP-MS zircon U-Pb weighted-average age of the granitic porphyry in Horqin Youyi Zhongqi, Inner Mongolia, is 163.3±2.9 Ma, suggesting the rock body emplaced at the late period of Middle Jurassic. Characterized by A-type granite, the granitic porphyry represents extensional tectonic magmatic activity. Combining the regional geological data and previous research, the Middle Jurassic granitic porphyry is possibly the product of post-orogenic extensional environment. The determination of its phases can provide new data for the formation and evolution of Songliao Basin.