LA-ICP-MS zircons U-Pb ages and geological characteristics of EarlyMiddle Jurassic volcanic rocks in the Qingyuan area, Zhejiang Province

The Early-Middle Jurassic volcanic rocks were discovered for the first time in Qingyuan area of southern Zhejiang Prov-ince, where the Cretaceous volcanism was intense. They consist of rhyodacite and rhyolitic ignimbrite and can be assigned to Ma-onong Formation. Their LA-ICP-MS zircon U-Pb ages are 176.5±0.7Ma and 169.1±3.3Ma respectively. Combined with Middle Jurassic volcanic rocks in northern Fujian Province, it is inferred that southeast coastal areas began to enter the paleo-Pacific plate sub-duction system in Early-Middle Jurassic.