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The Bayin River, the largest river in the northeastern Qaidam basin, plays an important role in the source‐to‐sink system and landscape evolution at the basin‐mountain boundary between the Qilian Mountains and the Qaidam basin in the northern Tibetan Plateau. In this study, we conduct field observation, topographic analysis, zircon U–Pb dating, and apatite (U–Th)/He dating to constrain the landscape and tectonic evolution of the Bayin River watershed. Bedrock zircon U–Pb dating indicates the age group of 420–450 Ma for far‐source sediments and the age group of >1,700 Ma for near‐source sediments in the Bayin River watershed. Detrital zircon U–Pb dating results from the Mesozoic and Cenozoic strata in the Bayin River watershed reveal that the most important source transition occurred during the Cretaceous. The Zongwulong Mountains gradually uplifted throughout the Cenozoic, along with decreasing far source and increasing near source based on detrital zircon U–Pb dating. Rapid uplift occurred across the Qilian Mountains during the late Cenozoic, leading to high normalized steepness indices, young apatite (U–Th)/He ages, and deep incised valleys at the basin‐mountain transition zone. The knickpoints caused by the latest headward erosion just reach an elevation of ~3,800 m on the river longitudinal profiles, indicating that the latest uplift magnitude is ~300–400 m relative to the basin surface of the Qaidam basin. Elevation distribution and apatite (U–Th)/He ages reveal that river incision leads to high relief in the Zongwulong Mountains and influences its tectonic evolution. Key Points: The tectonic setting of Bayin River watershed significantly changed from Jurassic to Cretaceous based on detrital zircon U‐Pb age spectrumSlight erosion in central Qilian Mountains and intense erosion at the basin‐mountain transition zone are revealed by apatite (U–Th)/HeRiver incision leads to high relief of the Zongwulong Mountains related to the central Qilian Mountains [ABSTRACT FROM AUTHOR]

The Denan Depression is a unique depression in the northeastern Qaidam basin, with a maximum Cenozoic sedimentary thickness of ~ 5 km. Detailed field work, interpretation of seismic profiles and analyzation of well data were conducted to define the Cenozoic tectonic evolution of the northeastern Qaidam basin. All geological evidences indicate that the Denan Depression is controlled by the northeast-directed Olongbulak Thrust at its southern boundary. The Denan Depression grew in concert with the development of the northeast-directed Olongbulak Thrust at least since it began to accept the Xiaganchaigou Formation, supporting the early Cenozoic growth of the northern Tibetan Plateau. Surface and subsurface data both point to enhanced tectonic activity since the Quaternary in the northeastern Qaidam basin, leading to a more individual Denan Depression relative to the main Qaidam basin. The northern boundary of the Denan Depression is a passive boundary, and no foreland developed at the northern slope of the Denan Depression. [ABSTRACT FROM AUTHOR]