Diachronous Cretaceous Closure of the Bangong‐Nujiang‐Shyok Ocean (Westernmost Central Tibet)

Abstract Precisely reconstructing the diachroneity of continental collision along various Paleo‐, Meso‐, and Neo‐Tethyan branches has proved to be challenging, which limited our understanding of the dynamics of terrane suturing and associated topographic inheritance in the Tibetan Plateau. In this study, we present stratigraphic and sedimentological evidence to support, for the first time, the presence of a late Early Cretaceous remnant deep‐water basin active at least until 110 Ma in the westernmost Bangong‐Nujiang suture in central Tibet. This basin was confined by shallow‐marine deposition in the north, east, and southeast, as indicated by obitolinid biostratigraphy and maximum depositional ages for six lithostratigraphic units, while the corresponding ocean had already closed in the east by Aptian‐Albian time. Detrital zircon U‐Pb age data (n = 965), forward numerical mixture modeling, and in situ εHf(t) values point at syn‐collisional magmatic rocks along strike in the east as the main sediment source, with additional variable input from uplifted Jurassic‐lowermost Cretaceous turbidites. Our paleogeographic reconstruction indicates that the closure of the Bangong‐Nujiang Ocean progressed markedly diachronously from east to west, culminating in the final closure of the Shyok oceanic branch during the Late Cretaceous (probably by 95 and no later than 85 Ma). This westward‐younging ocean closure corresponds to a shorter duration of continental convergence in the west, resulting in less crustal shortening and tectonic uplift than in the east. This may have played a pivotal role in shaping Cenozoic topography, characterized by higher elevations in the east compared to the west along the Bangong‐Nujiang‐suture valley.