SHRIMP ZIRCON U-PB DATING OF LAOJUNSHAN SYENITE
WAN Shaokai 1,2, XIA Bin1 and ZHANG Yuquan1 (1. CAS Key Laboratory of Marginal Sea Geology and Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, GD 510640, China; 2. Graduate School, Chinese Academy of Sciences, Beijing 100039, China)
Laojunshan syenite lies in the south segment of the Cenozoic potassic alkaline magmatic rock in Ailaoshan-Jinshajiang river. The SHRIMP zircon U-Pb dating results of Laojunshan Syenite are 34.8±1.6Ma(2σ),MSWD=0.38(probability= 0.96), which is consistant with the Oligocene epoch, belonging to Himalayas period. We will discuss its formation age of rocks and the cause formation of zircon by the SHRIMP zircon U-Pb analytical results of Laojunshan Syenite.