Petrogenesis of Fuye pluton in Rutog, Tibet: zircon U-Pb dating and Hf isotopic constraints

A Yanshanian magmatic arc was discovered in Rutog-Duolong area, in the western of Bangong-Nujiang metallogenic belt. It shows good ore-forming geological condition for several large and medium-size minerals had been found in recent years. Fuye pluton, locating in the west of the magmatic arc, is composed of diorite and diorite-porphyrite, with strong alteration. Primitive mantle-normalized spider diagram is loss Ba, Nb, Ta, Sr and Ti, enrichment Th, U and Pb. Chondrite-normalized REE pattern shows Slowly tilted to the right, and negative Eu anomalies. Zircon Lu-Hf isotope results of sample D1046 and D1049 show εHf(t)mainly focused at the range of-5.2 to-12.2, TDM1 model age concentrated in 0.98~1.28Ga. The 206Pb/238U weighted average age of sample D1046 and D1049 are 119.06±0.48Ma, and 120.03±0.68Ma, representing they formed in the middle age of Early Cretaceous. Combined with geochemical characteristics, it is I-type granitoid, and formed with both mantle and lower crust. According to these magmatic bodies' characteristics of this arc, Bangong-Nujiang Tethys ocean at least started northward subduction, in the Middle Jurassic. And it last to Early Cretaceous.