///Zircon U-Pb dating by LA-ICP-MS shows that Sankeyushu Formation trachyte in southern Jilin area formed in 118 Ma of late Early Cretaceous. Study of petrogeochemistry suggests that SiO2 contents from Sanke-yushu Formation trachyte are 65.11%-~65.61%, rich in alkali. It belongs to shoshonite series with weak peraluminous (A/CNK=1.05-1.12) and low Mg index. The total amount of rare earth elements is relatively high. Light and weight lanthanon differentiation evidence is noticeable.Eu negative anomaly is weak. The trace elements Rb, Th, Zr and K enrichment, Nb, Ta and Sr obvious depletion, show the emblematical character of continent lithosphere. The above characteristics indicate that the Early Cretaceous trachyte in the study area mainly came from Paleoproterozoic lithosphere partial melting and was formed in an extensional tectonic environment.oft-com:office:office" />