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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]

Determining the provenance of Cenozoic strata in the Qaidam Basin is key to understanding the basin-mountain coupling history in the northern Tibetan Plateau (TP). However, the specific source areas of Cenozoic strata in the northern Qaidam Basin remain highly debated. Here, we combine analyses of detrital zircons U Pb geochronology for recent and ancient fluvial sediments from the northern Qaidam Basin to trace source areas of Cenozoic strata and reconstruct related mountain-building processes. The results indicate that the diagnostic 270–240 Ma zircon U Pb peak, which was previously recognized as the unique input of a southern source area, is widespread in the recent fluvial sediments of the northern Qaidam Basin. Given our new zircon U Pb data, the source-to-sink transport processes of Cenozoic sediments in the northern Qaidam Basin can be summarized as follows. (1) The northern Qaidam Basin has received the eroded detrital material from a dominantly northern source throughout the Cenozoic. (2) The Qaidam BeiShan was uplifted already at least by the early Eocene and served as the single contributor of detritus to the Dahonggou (DHG) region, suggesting that far-field stress due to the India-Asia collision had been propagated to this region as early as the early Eocene. (3) An abrupt change in provenance is observed in the DHG region during 46.5–43.7 Ma. We interpret this middle Eocene source change as reflecting the onset of growth of the North Altyn Tagh Range, implying that the North Altyn Tagh Range was already serving as an important source area for the DHG region by the middle Eocene. (4) The South Qilian Range served again as the dominant source area for the DHG region after 24.6 Ma. The shift in provenance from the North Altyn Tagh Range to the South Qilian Range can be attributed to the uplift of the Saishiteng Shan. • Cenozoic detritus in northern Qaidam Basin exclusively from northward source • 270–240 Ma zircon U Pb peak widely seen in recent fluvial sediments in north basin • The Qaidam BeiShan had uplifted already at least in the early Eocene. • North Altyn Tagh and South Qilian ranges provide dominant sources. • Multiple source-to-sink stages of northern Qaidam Basin from ~>50.4 to 10.8 Ma [ABSTRACT FROM AUTHOR]

Research on the dynamics of body-size changes in varied water depths can provide important insights into the evolution of palaeoenvironments through time. This paper attempts to investigate how the body sizes of two most commonly found chonetid brachiopod species in the uppermost Permian in South China varied with palaeo-bathymetry. The result shows that there is a broadly negative correlation between the latest Permian brachiopod body size and water depth. There is no simple singular variable that could explain this correlation because bathymetry is correlated, either linearly or nonlinearly, to food availability, redox condition and habitat temperature, as well as substrate conditions. Overall, we found that both oxygen and food availability played a more important role in controlling the differences of body sizes, and specifically several depressed factors (low food availability, anoxia, or abnormal temperature) have compounded and caused small body sizes in deeper waters during the latest Permian. We propose that the brachiopod miniaturization during the Permian-Triassic crisis in South China was collectively driven by anoxia, food restriction and high temperature. [ABSTRACT FROM AUTHOR]