An Early Cretaceous radiolarian assemblage from the strata south to the Zhongba microterrane in the Zhongba area, southern Tibet

The presence of the Zhongba microterrane causes the Yarlung–Tsangpo suture zone to be bifurcated into two parts in its western segment: the Northern Ophiolitic Belt and Southern Ophiolitic Belt. This indicates that the evolution of the Neo-Tethys Ocean in the western segment is more complex than previous interpretation. Between the Southern Ophiolitic Belt and the Zhongba microterrane, there exists a successive stratigraphic sequence. In this study, a total of 15 genera belonging to 20 species of radiolarians were identified from the siliceous strata of the Dangxin Formation within this sequence, constraining the age of the Dangxin Formation to the Barremian, Early Cretaceous. Additionally, a stratigraphic column was constructed based on the basic understanding of this stratigraphic sequence from regional geological surveys, and it was compared with deep-water sediments in the Tethyan Himalaya. The results show that this sequence can be correlated with the Rilang, Duobeng, Chuangde, and Zongzhuo formations, which were deposited on the passive margin of the Indian plate.