Provenance evolution of Late Mesozoic clastic rocks in the Qamdo Basin of eastern Qinghai-Tibet Plateau: Sedimentary response to the Lhasa and Qiangtang terranes collision

• Sedimentary rocks in Qamdo show collision response to the Lhasa-Qiangtang block. • The source rocks in the Qamdo Basin are mainly intermediate-felsic igneous rocks. • The collision of the Lhasa-Qiangtang block occurred in the late Early Cretaceous. The Mesozoic tectonic movements of the Qinghai-Tibet Plateau are crucial for understanding the evolution of the Meso-Tethys Ocean. Up to now, the central segment of the Meso-Tethys tectonic belt has been extensively studied, but some viewpoints remain highly controversial, such as the timing of the Lhasa-Qiangtang terranes collision. The exceptionally thick Late Mesozoic sedimentary strata (>10 km) in the Qamdo Basin have significant potential to record the collision event between the Lhasa-Qiangtang terranes and the closure processes of the Meso-Tethys Ocean. This study selected four Late Mesozoic sedimentary sections in the Qamdo Basin for petrological research, with whole-rock geochemical data of silicate components, heavy mineral assemblages from sandstone samples, and Sr-Nd isotopic compositions of mudstone samples. The results show that the 87 Sr/ 86 Sr ratios of the Late Mesozoic mudstones in the Qamdo Basin range from 0.710309 to 0.745580, with relatively low εNd(0) values (−16.77 to −9.41). The U-Pb ages of detrital zircons from sandstones (437 Ma to 187 Ma) exhibit significant similarity in peak age to zircons from surrounding igneous rocks (237 Ma to 187 Ma). Provenance analysis indicates that the Late Mesozoic sedimentary rocks in the Qamdo Basin are dominated by intermediate-acidic igneous rocks of the Jiangda-Weixi volcanic arc belt, Yidun island arc belt, and Jitang-Lancangjiang volcanic arc belt. Triassic sedimentary rocks in the northern Qamdo Basin also contributed significantly to its provenance. Moreover, the high-resolution geochemical records from the Markam section demonstrate significant variations in Ra/Sr and Na/Ti ratios across the Jurassic-Cretaceous boundary. The ZTR index of heavy minerals exhibits a pronounced decline to 43.61 % during this transition period. These sedimentary proxies, integrated with existing constraints on the Meso-Tethys tectonic evolution, provide compelling evidence for a distinct sedimentary response in the Qamdo Basin to the late Early Cretaceous collision event between the Lhasa and Qiangtang terranes.