LA-ICP-MS zircon U-Pb dating and geological implications for the Xinhuoshan granites in Jiulong, Western Sichuan

The LA-ICP-MS zircon U-Pb dating is made for the Xinhuoshan granites in Jiulong, Western Sichuan. The selected zircon grains from the granites display well-defined girdle structures in the cathodoluminescence images and higher Th-U ratios (more than 0.13) characteristic of magmatic origin. The ²⁰⁶Pb/²³⁸Pb weighted average age of 181.2±1.4 Ma (Early Jurassic) for the Xinhuoshan granites (MSWD=3.3) represents the age of crystallinization of the Xinhuoshan granites, and an important phase of the Yanshanian magmatism in the SongpanGarze orogenic zone. The findings in this study may serve as the circumstantial evidence for better understanding of the granitic magmatism and dynamic settings in the Songpan-Garze orogenic zone druing the Yanshanian.