Petrology and geochronology of Asuo ophiolite in central Tibetan Plateau

Asuo ophiolite belongs to Shiquanhe-Yongzhu-Jiali ophiolite zone, located in southwestern Asuo County. The rock combination is complete, and consists from the bottom to the top of serentine, pyroxenite, cumulate gabbro, mafic dyke swarms and volcanic lava, with the existence of sedimentary rocks overlying ophiolite. In this paper, LA-ICP-MS U-Pb dating was carried out for the zircons of the gabbro dyke of Asuo ophiolite. LA-ICP-MS zircon U-Pb dating of gabbro dyke yielded a concordant age of 117.54±0.58Ma, indicating that it was formed in the Early Cretaceous.The ophiolite of Shiquanhe-Yongzhu-Jiali ophiolite zone was formed in Late Triassic to Early Cretaceous and mainly distributed in three age groups of 219~178Ma, 165~149Ma and 117~114Ma, representing the ocean expansion, subduction and back-arc extension respectively.