| Abstract: | From the isotopic dating study of gneissic granodiorite, the authors discovered magmatism of the Jinning cycle. Intrusive rocks were formed in the Neoproterozoic, whose Pb-Pb ages range from (913±4) Ma to (1 011±4) Ma and U-Pb concordia age is (703± 15) Ma. The tectonic settings of the rocks are volcanic arc or syn-collision. After the formation of the intrusive rocks,these rocks also experienced reconstruction of Caledonian metamorphism. Based on the Ar-Ar dating of metamorphic mineral of muscovite, the metamorphic time is determined to range from (386. 84-0. 8) Ma to (389. 44±3. 70) Ma. |
