Drainage reorganization near the eastern margin of the Tibetan Plateau as a result of fluvial response to differential uplift enhanced by isostatic compensation

Drainage reorganization is affected by the relationships between tectonically driven rock uplift, climatically modulated denudation, and isostatic (atectonic) compensation, conveying signals of tectonic and climatic changes into processes of landscape evolution. Drainage-divide migration as a marker of drainage reorganization is a key to understanding these processes; however, previous studies on the differential rock uplift seem to have overlooked the contributions from surface erosion and isostatic compensation, due to a lack of natural archives for further verification. We have therefore conducted a combined study of geomorphological indices and natural records to categorize a remarkable case of drainage-divide migration between the Jialing and Min rivers near the eastern margin of the Tibetan Plateau, characterized by active tectonic deformation and significant spatial difference in denudation. Reconstruction of this drainage change is based on multiple geomorphological indices, including normalized channel steepness and χ-map, in combination with constraining the timing of drainage-divide migration to <11.1 ka, using cosmogenic radionuclide exposure dating. Our results attribute divide migration at the eastern margin of the Tibetan Plateau primarily to differential tectonic uplift, which may have been further enhanced by isostatic compensation in response to uneven distribution of denudation induced by differences in precipitation and landslides, thus implying the coupling between crustal processes and climate in driving landscape evolution.