Late Maastrichtian (68 Ma) Dilamu Trench Succession in the Yarlung–Zangpo Suture Zone, Bainang: New Provenance Constraints on Pre‐Collisional Gangdese Uplift and a Single‐Stage India–Asia Collision

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ABSTRACT In the Yarlung–Zangpo Suture Zone (YZSZ), the absence of a Latest Cretaceous sedimentary record hinders a comprehensive understanding of the depositional evolution in the suture zone and its adjacent terranes across the subduction–collision transition. In this study, we present results from field mapping combined with U‒Pb dating of tuff and detrital zircons from the Dilamu Formation, which is exposed as a Latest Cretaceous (68 Ma) trench deposit in the central YZSZ (Xigaze area). Provenance analysis indicates that the Dilamu Formation has a strong affinity with the Lhasa Terrane and correlates with the Upper Ngamring and Shexing formations. Based on regional stratigraphic data, we confirm the correlation of sediment sources between the basins on both sides of the Gangdese Arc and the suture zone and indicate that the evolution of detrital provenance is closely related to the uplift of the Gangdese Arc and the Lhasa Terrane. With the regional geographical changes during the Latest Cretaceous, the sediment provenance of the trench basin and Xigaze Forearc Basin became increasingly consistent, and the ‘isolation’ between them disappeared. Furthermore, these lines of evidence tend to support a single‐stage model of India–Eurasia Plate evolution during the Late Cretaceous–Palaeocene interval.

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