Abstract:

A set of mélange is exposed in Sangdanlin, Gyirong, south to the Yarlung-Zangbo Suture (YZS). The measured Sangdanlin section is lithostratigraphically divided into Zongzhuo Formation, Sangdanlin Formation and Zheya Formation from bottom to top. Abound radiolarian fossils were gained from the mélange and 72 species of 50 genera were identified, which allows the recognizing of four radiolarian assemblages: Immersothorax cyclops, Spongurus irregularis, Buryella dumitricai and Phormocyrtis turgida zones. The radiolarian assemblage points to a late Cretaceous to early Eocene age for the strata of the Sangdanlin section. The research results provide the important paleontologic evidence to restore the stratigraphic sequence of “mélange” in the southern margin of YZS, and they also explore the evolution of the Neotethys and reveal the comprehensive collision process between the India and the Asia plates.

Key words: Neotethys, Yarlung-Zangbo Suture, Sangdanlin, radiolarian