Zircon U-Pb age and Hf isotopes of the biotite plagioclase genesis in Duobagou area, Gansu Province

The LA-ICP-MS zircon U-Pb age and zircon Lu-Hf isotope were analyzed for biotite-plagioclase gneiss from Duoba-gou area, Dunhuang terrain, with the purpose of determining the formation age of the Dunhuang complex and discussing the crustal growth and evolution history of the Dunhuang terrain during Precambrian. Zircon U-Pb dating results indicate that the maximum depositional age of supracrustal rocks from the Dunhuang complex is ca. 710Ma. Additionally, the studied biotite-plagioclase gneiss indicates a metamorphic event at 422Ma, suggesting that the Precambrian Dunhuang terrain might have been involved in the subduc-tion-collision process of the Paleo-Asian Ocean during Early Paleozoic. Zircon Hf isotopes show that the Dunhuang terrain experi-enced episodic crustal growth events at ca. 2.7Ga, ca.2.5Ga, ca. 2.3Ga, ca. 2.0Ga and ca. 1.8Ga, suggesting episodic crustal growth. It is considered that the tectonic attribute could be compared with that of the Tarim craton during Neoproterozoic, as shown by the peak age at ca. 0.9Ga and ca. 0.8Ga.