医巫闾山变质核杂岩中岩脉热液锆石的类型及成因分析

he Yiwulvshan metamorphic core complex in western Liaoning has experienced two stages of extensional evolution from late Jurassic an annular ductile shear zone (called Yiwulvshan shear zone) developed around the central Yiwulvshan pluton to early Cretaceous overprinted by the well-known NNE-striking Waziyu ductile shear zone in the west. A large amount of late Jurassic granitic dikes, containing several types of zircons including old inherited zircons, new magmatic zircons and hydrothermal zircons, intruded in the Yiwulvshan shear zone and its deformed footwall. According to the characteristics of cathodoluminescence image, REE pattern and U, Th, Pb content, these hydrothermal zircons could be divided into three genetic types: dissolution-reprecipitation, direct crystallization by a zircon-saturated aqueous fluid and metasomatic alteration in hydrothermal fluid. These three types of hydrothermal zircons recorded a complex fluid during extension of the Yiwulvshan mcc, gave a effective geochemical evidence for analysing the extensional events in this area.