LA-ICP-MS ZIRCON U-Pb DATING,Hf ISOTOPIC COMPOSITIONS AND ITS GEOLOGICAL SIGNIFICANCE OF THE LATE JURASSIC GRANITE PORPHYRY IN HOUSHANDIAN REGION,CENTRAL ZHEJIANG PROVINCE

Late Mesozoic intrusive rocks distributed in whole Zhejiang Province are located in the southeastern margin of the Eurasian plate,and mostly concentrated in the Cretaceous period,as products of Late Yanshanian magmatic activity,and rarely reported for the record of the Early Yanshanian Period.LA-ICP-MS U-Pb dating and Lu-Hf isotopic analysis of zircons are carried out from representative rock samples of Houshandian granite porphyry pluton in central of Zhejiang Province.Weighted average ages of(148.5±1.2)Ma(MSWD=1.4)is interpreted as the formation time of the granite porphyry,indicating the existence of Late Jurassic intrusive rocks in central Zhejiang,which are formed by late stage of Early Yanshanian magmatic activity.The time of rock formation may represent a transitional phase from intraplate magmatism to continental margin arc by Paleo-Pacific tectonic domain.ZirconeHf(t)values of the granite porphyry are all negative(-10.3to-3.5),and two-stage Hf model ages(tHf2)range from 1 400 Ma to 1 829 Ma,suggesting that the granite porphyry is originated from remelting of the Mesoproterozoic lowercrust basement materials,and there are mantle-derived components participated during diagenesis.