Zircon U/Pb ages for gniess from Qianshan, Anhui

Zircon U/Pb ages were measured for Qianshan gneiss at the ultrahigh pressur e metamorphic (UHPM) complex in the Southern Dabie Terrain (SDT). According to morphology, Th and U contents of eight fractions of zircon and data dis tribution on the discordia, it is indicated that they should be treated as metamorphic overgrowth mixing zircons, in which the cores mainly are magmat ic and the outers were metamorphic. The intercept ages show that the gneiss underwent UHPM. There is no direct correlation for zircon between morpholo gical feature and genesis.