LA-ICP-MS zircon U-Pb age of Early Jurassic granite basement in Rencha Volca-nic Basin and its geological significance

Rencha basin is one of the typical Mesozoic-Cenozoic volcanic fault basins in northeast Guangdong. Drilling exploration reveals that its basement is mainly composed of Paleozoic metamorphic rocks and graphic granite. In order to further investigate the formation age of the basement rock masses and to improve the knowledge of geological evolution of the area, the authors conducted isotope dating of the samples of graphic granite basement from two drill holes in the basin. The ²⁰⁶Pb/²³⁸U measured ages of two groups of zircon by LA-ICP-MS are respectively 179±1Ma and 186Ma, suggesting that the formation age of the graphic granite basement of Rencha Volcanic Basin is late Early Jurassic, i.e., Rencha Basin was formed at the first episode of the Yanshanian mag-matic activity. These ages not only deepen the understanding of the formation and evolution of the Rencha Basin but also provide new chronologic data for the report that northeast Guangdong was lack of magmatic activity in Early Jurassic.