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A comprehensive study of the sediment source-to-sink history of basins arranged along the Bangong-Nujiang Suture Zone (BNSZ) is critical for understanding the early Cenozoic topography and drainage systems of central Tibet and its implications for the uplift history of the Tibetan Plateau. Nevertheless, previous provenance analyses work mainly focused on the middle-eastern segment of the BNSZ, those Paleogene basins in the western segment have received less attention, which hinders a full understanding of the early Cenozoic topography of central Tibet. In this study, based on a chronostratigraphic framework developed for the lower Cenozoic continental redbeds of the Gaize Basin, we applied detrital zircon U-Pb geochronology to the well-exposed Paleogene Suonahu Formation in order to reconstruct the basin's source-to-sink history. Integrating these new data with detrital zircon U-Pb results from the underlying Kangtuo Formation, we recognize a major secular shift in sediment provenance characterized by inputs of Lhasa-derived clasts during the Late Eocene. Moreover, we applied statistical analysis to compare the U-Pb age spectra of Eocene strata in the Gaize-Nima-Lunpola basins in order to assess similarities between them and potential source regions. Our study confirms a paleogeographic scenario in which these Paleogene basins most likely were part of a low-elevation intermontane valley. • Analysis of detrital zircon U-Pb geochronology of Paleogene strata in Gaize Basin. • A major shift in provenance occurred between the Kangtuo and Suonahu formations. • Cenozoic clastic strata in the Gaize-Nima-Lunpola basins share a similar provenance. • The Gaize-Nima-Lunpola basins belonged to a Paleogene low-elevation valley. [ABSTRACT FROM AUTHOR]

The Beishan Orogen, located in the southernmost Central Asian Orogenic Belt, is a key area for research on accretionary orogens. The formation of the Beishan Orogen is closely related to the evolution of the Paleo-Asian Ocean, but the closure time of a significant branch of the Paleo-Asian Ocean in the Beishan area, i.e., the Hongliuhe–Niujuanzi–Xichangjing (HNX) Ocean, remains controversial. This study investigates the sedimentary sequences of Baihu Basin adjacent to the HNX suture zone and presents new detrital zircon U Pb geochronology and whole-rock geochemistry data to reveal depositional ages, provenance variations, paleogeography changes and attributes of Baihu Basin. Detrital zircon ages indicate that deposition began in the Permian and lasted until the Triassic. Two coarse sandstones in Member 1 and one siltstone in Member 2 contain abundant detrital zircons older than 700 Ma, in addition to the typical age peak that characterises the Gongpoquan Arc at ca. 450 Ma, while two sandstones in Member 3 contain rare detrital zircons older than 700 Ma. The whole-rock geochemistry shows that the lower part of the Hongyanjing Formation possesses numerous old components and higher chemical index of alteration values. The sediment in the lower part of the Hongyanjing Formation was derived from both the Gongpoquan Arc, mainly comprising Palaeozoic arc-related magmatic rocks, and the Shuangyingshan Arc, including large quantities of Precambrian meta-sedimentary rocks. The upper part originated solely from the juvenile Gongpoquan Arc. During the collision, the Shuangyingshan Arc played a role similar to a craton. Craton-derived source rocks and fining-upward sequences in the lower part indicate uplift of the Shuangyingshan Arc, which may represent the development of a forebulge and foredeep. In the upper part, the source rocks were derived from the Gongpoquan Arc and accretionary wedges, with coarsening-upward sequences reflecting the springback of the Shuangyingshan Arc and disappearance of the forebulge. Based on the sedimentary sequences, provenance variations, and paleogeographic changes, we suggest that Baihu Basin is a foreland basin associated with the collision between the Gongpoquan Arc and Shuangyingshan Arc, marking the final closure of the HNX Ocean from the Late Permian to Early Triassic. We investigate the closure of the HNX Ocean and reconstruct the evolution of the central Beishan Orogen in the youngest Palaeozoic. • Baihu Basin adjacent to the Niujuanzi suture zone is proved to be a foreland basin. • Baihu foreland basin began to form in the Permian and lasted until the Triassic. • In the early stage, sediments derived from two arcs and accretionary wedge. • In the late stage, the source areas were mainly the Gongpoquan Arc and wedge. [ABSTRACT FROM AUTHOR]