Clastic record from Northern Tethyan Himalaya: Implication for the initial India-Asian collision in the western Yarlung-Zangpo suture zone, South Tibet

The suturing process between the Indian and Asian continents in the western part of the Yarlung-Zangpo Suture Zone (YZSZ) remains unclear due to the challenging environment and the complex geological background. The bilateral material of two continents provides robust evidence for constraining the timing of the continental collision. In this study, we conducted field mapping, geochronology and provenance analyses on sandstones from the Weimei, Rilang and Denggang formations (Upper Jurassic to Eocene) within a same section in the Zhongba area. The Weimei and Rilang formations exhibit typical characteristics of Tethyan Himalayan provenance, recording the evolution of the northern margin of the Indian continent during Late Jurassic - Cretaceous. The Paleocene - Eocene Denggang formation displays a provenance distinct from the Tethyan Himalayan strata, closely aligning with the Asian deposits in the YZSZ. In the Tethyan Himalaya area, the appearance of Asian debris in the Denggang formation indicates that the collision between India and Eurasia had occurred. The maximum depositional ages of the sandstones from the Denggang formation constrain the collision between the Indian and Asian continents in the western YZSZ to no later than 56 Ma - 54 Ma.