Zircon U-Pb age, Sr-Nd isotopic characteristics and its geological significance of the granites from the Meixian zinc-lead polymetallic deposit, central Fujian Province

In order to discuss the genesis of the granites in the Meixian orefield of central Fujian Province, this paper reports petrography, geochronology and Sr-Nd isotope data. Zircon U-Pb dating yielded an age of 158±3Ma for the Xiaojiao granites, indicating that they were formed in Late Jurassic in the middle Yanshanian period. Isotopically, sample analyses show high and variable initial I_Sr ratios (0.707099~0.710082) but low and constant ε_Nd(t) (-9.79~-10.92), showing crust source characteristics obviously and indicating that Meixian granites are highly fractionated I-type granites. Combined with previous research results, it is held that the granites of the middle Yanshanian period in Meixian area were formed by the sub-reduction stretching and extension of the paleo-Pacific plate to the Eurasian plate, and were emplaced at the extention orogenic stage within the plate.