The continental arc belt,located at the frontier margin of convergent plate,records the subduction of oceanic lithosphere and the continental crustal growth processes.In addition, the continental arc is the best laboratory to address the interaction between crust and mantle.Increasing number of studies reveal that the growth and emplacement of continental arc magmatism shows episodic patterns,rather than a steady or continuous process.Compared with the magmatic lull,the magmatic flare-up is characterized by high magma addition rates (MARs) and magma focusing,which is favorable for the formation of big arc batholith,such as the Sierra Nevada and Peninsular Ranges batholiths in the Cordilleran orogen,western North America.The Gangdese arc belt is located along the southern margin of the Lhasa terrane, belonging to the overlying plate of the Indo-Asian collisional zone.The Gangdese arc belt is separated from the southern Himalayan terranes by the Indus-Yarlung Tsangpo suture zone.The arc magmatism of the Gangdese arc persisted from ~240 to ~50 Ma,and is closely related to northward subduction of the Neotethyan oceanic lithosphere beneath the southern margin of the Lhasa terrane.Thus,the on-going studies on the magmatism of the Gangdese arc will help us to better understand the Gangdese arc tempos,the subduction of the Neotethys,as well as the crust-mantle interaction.In the present study,we have collected manyzircon U-Pb ages and Lu-Hf isotopes of igneous rocks from the Gangdese arc,and detrital zircon U-Pb ages and Lu-Hf isotopes from forearc and foreland basins.Thiscompiled data,in combination with regional geology,leads to the following conclusions:1)the magmatism of the Gangdese arc shows episodic features,with magmatic flare-ups culminating at 100~80 Ma and 65~40 Ma,respectively;2)the magmatic flare-up is favorable for the formation of big batholiths with depleted isotopes,implying significant involvement of mantle material;and 3)the magmatic flare-ups are coincidently synchronous with the crustal thickening events,indicatingthat the magmatic flare-up contributed greatly to the crustal thickening.