Abstract:

Abstract: Taipingchuan large porphyritic granite pluton was developed in the Erguna Massif in the northern Great Xingan Range, NE China. The precise age of the formation and genesis of this pluton are unclear. The authors have carried out zircon UPb dating and Hf isotope studies by means of LAICPMS. Zircon UPb dating results revealed that the age of Taipingchuan granite is 791.4 Ma. Zircon Hf isotope characteristics indicate that the zircon εHf（t）values of the granite range from 1.4 to 6.4, implying that the depletedmantlederived juvenile crustal material played an  important role in the formation of the granite magma. The 2stage model ages tDM of 1.091.28 Ga, as revealed by Hf composition in zircon, showed rather large interval with the formation age 791.4 Ma of the granite. It indicates that the parental magma of the granitic rock in this region was derived from the partial melting of the crustal material which had a long resident time within the crust. Combined with the previous zircon Hf isotope data obtained from Erguna Massif, the authors hold that there had been crustal accretion event in Erguna Massif in the late Mesoproterozoic time and the 1.091.28 Ga late Mesoproterozoic accretional crust had existed.

Key words:  Taipingchuan large porphyritic granite, zircon UPb age, Hf isotope, Erguna Massif