Abstract Drainage systems are highly sensitive to landform changes, and their formation and evolution history are of great significance for understanding regional tectonic‐climatic processes and environmental changes. Since the Cenozoic, the uplift and expansion of the Tibetan Plateau have profoundly influenced the tectonic pattern and surface landscape of the surrounding regions. The Han River, one of the largest tributaries of the Yangtze River, drains the Qinling‐Daba Mountains located on the eastern margin of the Tibetan Plateau, and its evolution provides important clues for understanding the regional surface responses to the expansion of the Tibetan Plateau. In this study, a significant drainage reorganization of the upper Han River is reconstructed by combining information on fault kinematics, mapping of fluvial terraces, and quartz electron spin resonance dating with a comprehensive multi‐proxy provenance analysis based on K‐feldspar Pb isotope ratios and apatite and zircon fission track dating. These results suggest that before 0.4 Ma, the Paleo‐Han River flowed eastward through the Ankang Basin; between 0.4 and 0.15 Ma, continued left‐lateral strike‐slip motion on the Ankang Fault likely promoted vertical uplift at its restraining bend and favored southward diversion of the Han River along the northern edge of the Daba Mountains. This drainage reorganization event within the Qinling‐Daba Mountains is interpreted as a fluvial and geomorphic response to the outward expansion of the Tibetan Plateau.
Ju et al. (Fri,) studied this question.