Raman spectroscopic study of zircons in the Jinshuikou gneissic Al-rich granite in east Golmud, East Kunlun.

Studies of the macroscopic morphology of zircons in the Jinshuikou gneissic Al-rich granite and the characteristics of the micro-area Raman spectra show that zircons in this gneissic granite mainly have two types: relatively small, simple zircon and relatively big, complex zircon. Complex zircon consists of three parts: a smaller relict core, a light-colored part and a brown part. Simple zircon and the smaller relict core in complex zircon are both of metamorphic origin. The light-colored and brown parts in complex zircon are both magmatic zircon. On that basis, combined with a study of the zircon Raman spectra, a reinterpretation of the available zircon U-Pb age of the Jinshuikou gneissic Al-rich granite has been made. The authors think that 390-414 Ma might represent the formation age of the magmatic zircon of the light-colored part or the brown part in complex zircon, while 1600-1800 Ma might represent the age of the metamorphic event in the relict core in complex zircon.