The Yushu ophiolite mélange, which has preserved important record concerning the evolution of the Palo-Tethys Ocean, is mainly composed of pillow basalts, diabases, gabrros and ultramafic rocks. The zircon SHRIMP U-Pb age of Rangnianggongba gabbro in this mélange is 258.4±2.9 Ma, suggesting that the emplacement age of the rock is Late Permian. Petrologic and geochemical studies suggest that the gabbro is alkaline and has characteristics of high Ti and Fe. All the rock samples have relatively high REE abundances, and are enriched in LREE . The rock is enriched in large ion lithophile elements (LILE: Rb,Ba,Th,K) and some high field strength elements (HFSE: Nb, Ta, Zr, Hf). These data indicate that the Rangnianggongba gabbro was derived mainly from the enriched mantle. According to geochemical characteristics, the authors have concluded that the gabbro was formed in an oceanic island setting. The age dating and geochemical data indicate that an oceanic crust was already existent at least in the Late Permian. Moreover, the existence of large-scale Paleozoic Plume activities on the southwest margin of Yangtze block has been extensively reported. It is considered that the emplacement of the Rangnianggongba gabbro was related probably to activities of the Plume.