In this paper, we collected the gabbro samples from Kare near Qushui county in the middle segment of the Gangdese belt, and conducted an integrated study including petrological, elemental geochemical analyses and LA- ICP- MS zircon dating, aiming at understanding their petrogenesis and the implications for tectonic evolution. speaking, Gabbro is lithologically composed of clinopyroxene and plagioclases. Chemically, the gabbro has low SiO2 and K2O+Na2O，but high Al2O3 contents, and is enriched in LREEs and LILEs, depleted in HFSEs, showing the chemical features similar to the high- alumina basalts of island arcs and continental margins. The geochemical characteristics indicate the gabbro has subduction- reformed lithospheric mantle- derived primary magma that was contaminated by upper crustal materials during its evolution. The LA- ICP- MS U- Pb age of zircon is 49. 01+0. 51 Ma (MSWD=0. 41), indicating the Eocene formation age. The Kare gabbro has highly depleted zircon Hf isotopic compositions，with εHf(t) values of +10. 88~+13. 71. The integrated lithologic and chemical compositions suggest that the gabbros were generated by the hydrous partial melting of depleted mantle metasomatized by fluids released from subducted oceanic slab. Combining with the regional tectonic evolution history, strong magmatic underplating and crust- mantle magmatic mixing might be occur during the Eocene in the southern margin of Gangdese belt.