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The incision of the Sanmen Gorge marks the birth of the modern Yellow River, but its timing varies from the late Miocene-early Pliocene to the late Pleistocene (∼0.15 Ma), and the suggested forcing mechanisms vary from the uplift of the Tibetan Plateau to global climate change. Here, we report sedimentologic, geochronologic, and provenance data from a drill core near the Sanmen Gorge, the last gorge along the main course of the Yellow River. Our results indicate that typical river channel deposits, with detritus from the Ordos Block in the upstream regions, started to accumulate in the Sanmen Gorge at ∼1.25 Ma. When integrated with river terrace evidence from the upstream and downstream regions, the results provide robust evidence that the final integration of the modern Yellow River occurred at ∼1.25 Ma, consistent with the beginning of the Mid-Pleistocene transition (MPT). We propose that the accelerated lowering of eustatic sea level during the MPT may play as important a role as tectonism in driving the birth and evolution of the modern Yellow River., (Copyright © 2022 Science China Press. Published by Elsevier B.V. All rights reserved.)

Understanding the processes of fluvial geomorphic evolution is based on thorough evaluation of how rivers respond to tectonic activity and climatic change, with river terraces representing a key archive of alternating deposition and incision in response to such forcing, enabling an excellent means for correlation with tectonic and climatic records. An example presented here points to a difference in fluvial response to climate fluctuations along a trunk river and its tributary: the Yellow River and its tributary the Xike River, which has incised the Lajia Gorge to pirate the Zoige Basin, in the eastern Tibetan Plateau. Based on Accelerator Mass Spectrometry 14C dating, the chronological sequence of basin fill top and fluvial terraces below has been established, defining the drainage reorganization of the Yellow River excavation through the Zoige Basin since the Last Glacial Maximum. Spatial and stratigraphic comparison between the two fluvial sequences, combined with correlation with high-resolution climatic records, indicates that the tributary Xike River formed more terraces in response to trunk incision (base-level variation), climatic fluctuations, and underlying weak bedrock than the Yellow River. Thus, our results not only demonstrate a combined archive of climatic fluctuation and tectonic uplift recorded in the fluvial terrace sequences, but also suggest that the generation of fluvial terraces may be influenced by the underlying bedrock within the same tectonic and climatic settings. • The Yellow River excavating through the Zoige Basin is constrained before 19 ka. • Fast uplift drives a sensitive fluvial response to sub-orbital climatic cycles. • Drainage scale affects the sensitivity of fluvial response to climate change. • Fluvial terrace is archive of the coupling between uplift and climate change. [ABSTRACT FROM AUTHOR]

Continental-scale drainage reorganization is generally understood to result from landform evolution forced by the coupling between tectonic activity and climate change, attracting worldwide attention. Planation surfaces and river terraces constitute the most direct geomorphological archives for integrating the history of river systems and for reconstructing processes of drainage reorganization based on provenance analysis of the fluvial sediments. The Middle Yellow River has incised into the Ordos Block, which was previously levelled by a planation surface, creating the Jinshaan Gorge and linking the Hetao Basin to the north and the Fenwei Basin to the south. Multiple lines of evidence, from terraces correlation, sedimentary characteristics, and fluvial provenance, suggest that the Middle Yellow River catchment was occupied by fluvio-lacustrine systems before drainage integration, accumulating a sedimentary sequence derived from surrounding Red Clay and bedrocks during the period between 8.3 and 3.7 Ma. The planation surface was uplifted subsequently, forcing reorganization of the fluvio-lacustrine systems. Their integration resulted in the formation of the Jinshaan Gorge prior to 1.2 Ma. Numerous terraces were created during incision by the Middle Yellow River from north to south along the gorge. Our data, obtained from zircon U Pb dating and lithological composition of fluvial gravels, further points to a remarkable discrepancy in provenance between the fluvio-lacustrine systems overlying the planation surface and the terraces sequence formed by the integrated Middle Yellow River, confirming the drainage reorganization process constrained by the geomorphic records. • Fluvio-lacustrine systems occupied the Middle Yellow River before integration. • Yellow River terraces are different from fluvio-lacustrine systems in provenance. • The Middle Yellow River has been excavated and integrated during Plio–Pleistocene. [ABSTRACT FROM AUTHOR]

Strategic studies of gravel deposits, in particular using heavy-mineral analyses, have thrown light on the important unresolved question as to the timing of the initiation of the Yellow River drainage through the Sanmen Gorge, which linked the headwaters of that system in the Fenwei Basin and further upstream with the North China Plain and the Pacific Ocean in the east. Survey of the Sanmen Gorge reach revealed previously unrecognized gravel levels: a higher fifth terrace (T5) and a gravel that formed on a high-level planation surface that is preserved on the flanks of the gorge, below the Xiaoshan upland. This high-level gravel differs markedly from the Yellow River terraces, with a lack of material from the upstream catchment, and would appear to represent a small fluvial catchment that developed in the area during the formation of the planation surface, before the Sanmen Gorge was excavated. Comparison was also made with basin-fill gravels from the endorheic fluvio-lacustrine system that existed immediately upstream of the gorge, and was captured by the Yellow River when the latter was cut, and with the modern bedload gravel of the Yellow River in this reach. The former contains significant quantities of unstable hornblende, which implies more local derivation for the endorheic system, whereas the modern bedload resembles the terrace gravels in showing compositional maturity and long-distance transport from upstream within the catchment. The work reinforces a minimum age of 1.2 Ma for the formation of the Sanmen Gorge. • The gravel layer accumulated on the planation surface along the eastern front of the Xiaoshan represents a local river. • The local river sediments are different from the typical Yellow River gravels and the upper Sanmen Formation. • The Sanmen paleolake within the Fenwei basin was finally disrupted by the westward capture of this local river. • The Sanmen Gorge was excavated by the local river through the Xiaoshan separating the Fenwei basin and North China Plain. • The Yellow River integration may be attributed to the remarkable climatic fluctuation starting in the Mid-Pleistocene. [ABSTRACT FROM AUTHOR]

The eastern Altun Shan is a crucial part of the Altun orogenic belt within the Tibetan Plateau. Study of the uplift rate and the related features in this area provides important clues for understanding the uplift mechanism of the Tibetan Plateau as a whole. As an important geomorphic element in landscape development, the fluvial system can record the relationship between tectonic activity and climatic change. In recent years, studies of the Channel Steepness Index K sn , have been conducted by many researchers, using the geomorphological model of equilibrium channel longitudinal profiles, combining bedrock uplift and river incision and thus making it possible to extract rock uplift history from river profiles. This research show that regional rock uplift rate is a major factor in affecting the K sn index. Regional tectonic activity and intensity, therefore, can be evaluated from variation in the K sn index, which can provide a sensitive measure of uplift rate. In this paper, the Digital Elevation Map 'ASTER GDEM', with a spatial resolution of 30 m, was utilized as basic data, and combined with ArcGIS and MATLAB software to extract the K sn index from the equilibrium channel longitudinal profiles model. Meanwhile, we employed statistical methods to analyze the K sn index. Our results suggest that averaged K sn indices, obtained from the subrange A，B，C，D, and E of the eastern Altun Shan (from west to east), are 70.93, 139.03, 108.85, 134.44 and 165.39, respectively. Further analysis implies that the variation in this index can be correlated with the distribution pattern of uplift rates within different regions. Its value increases gradually from west to east, reflecting regional uplift rate. Along the western section of the eastern Altun Shan, the uplift rate is slower and characterized by strike-slip movements, while its eastern part has uplifted faster and is controlled by thrust fault systems. Moreover, in contrast with the southern Altun Shan, the uplift rate of the northern part is high. These variations in uplift rate seem to be linked with "the imbricated thrusting transformation-limited extrusion model" of the Tibetan Plateau. Our results can be correlated with previous work on the active characteristics along the eastern Altyn Tagh Fault (ATF). • Along the eastern Altun Shan, the obtained index K sn shows a rough tendency of increasing eastward. • The index K sn from the north front of the eastern Altun Shan is higher than that from the south flank. • This distribution pattern of the index K sn is translated into the different uplift along the eastern Altun Shan. • The difference in uplift rate can be evaluated well by the fluvial incision rate obtained by terrace archives. • The analysis of the index Ksn provides an excellent insight into the extrusion model of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Fluvial response to allogenic and autogenic controls concerns the understanding of landform evolution related to the interaction between tectonic movements, climate, surface process and human activity. Paleo-channels, as part of geomorphic archives, have been widely employed to study this issue during recent decades. Previous work has however concentrated on the mechanisms driving river migration. A new approach, in which multiple elements are considered, is employed here in the examination of paleo-channel formation in the Jiudong Basin, located at the northeastern margin of the Tibetan Plateau and characterized by active tectonic deformation, a dry climate and ancient human activity. Based on geomorphic and sedimentary analysis, eight paleo-channels formed by the Taolai and Hongshuiba rivers (two tributaries of the Beida River catchment) have been identified. AMS14C dating of the overlying lacustrine sediments defined their respective abandonment at ca. 22.2, 20.9, 15.3, 18.8, 13.9, 11.9, 3.5 and 1.1 cal. Ka BP. The migration histories of the two rivers have been reconstructed, and then well correlated with reference to archives of tectonic, climatic and human influence. Our results suggest that these controlling factors seem to be coupled and have a competitive relationship in driving river migration. In the northeastern margin of the Tibetan Plateau, channel migration can therefore be regarded as a result of fluvial response to the interaction between rapid tectonic activity, climatic fluctuation and human influence. • 8 paleo-channels have been identified in the northeastern margin of the Tibetan Plateau. • These paleo-channels have been constrained by AMS14C dating in the last glacial period. • These paleo-channels are coupled record of climate, tectonics and human influence. [ABSTRACT FROM AUTHOR]

[Display omitted] • The terrace sequences of Datong River were dated using multiple dating methods. • Tectonic-climate forcing triggered the formation of the Datong River before ∼1.1 Ma. • The Datong River has been more sensitive to climate changes than the Yellow River. The formation of river terraces has been related to climate changes and surface uplift in the mountain regions. Although the formation mechanism of river terraces in the northeastern Tibetan Plateau has been extensively studied, the difference between the large river (trunk stream of Yellow River) and small rivers (tributaries of Yellow River) responding to external forcing is still poorly understood. Here, we employ multiple dating methods to date the terrace sequence of the Datong River in the northeastern Tibetan Plateau and then further correlate it with tectonic activity and climate records. Our results show that the modern Datong River in the Babaochuan Basin formed between 1.5 Ma and 1.1 Ma in response to the coupled effects of Asian monsoon enhancement and intense regional uplift. To further evaluate the effect of tectonic–climatic forcing on rivers of different scales, detailed comparison of terrace formation was carried out between the Datong River and Yellow River in the Lanzhou Basin. The comparison results indicate that under the context of relatively slow surface uplift during 0.6–0.13 Ma, the Datong River created three terraces probably ascribed to the glacial–interglacial cycles with high-amplitude fluctuations, whereas no terraces formed along the Yellow River in the Lanzhou Basin during the same interval. We conclude that the Datong River, as a smaller river than the trunk Yellow River, is probably more sensitive to the climate change. [ABSTRACT FROM AUTHOR]