Impacts of late Miocene normal faulting on Yarlung Tsangpo River evolution, southeastern Tibet

Abstract The Jiacha Gorge in southeastern Tibet is the second-largest deeply incised gorge of Yarlung-Tsangpo River, after Tsangpo Gorge. A late Cenozoic N-S–trending normal fault, Woka Rift coincides with western limit gorge. However, relationship between formation gorge, drainage evolution, and rift activity remains unclear. Analysis river long profile suggests that developed as a ~45-km-wide knickzone, rather than local knickpoint. Projection tributary stream profiles indicate significantly deeper incision downstream area, suggesting different controls on incision. Thermochronological data collected along two age-elevation footwall record rapid cooling at ca. 12–10 Ma followed by moderate 10 7 Ma, additional accelerated 5 We interpret Miocene (ca. Ma) to reflect onset east-west extension faulting Rift, whereas Pliocene (post–ca. inferred be driven Geomorphic sedimentologic observations suggest diversion River through Gorge, from an earlier more southerly course, rifting. Therefore, we anchored knickzone its shoulder, while uplift led enhanced incision, forming steepest channel upstream Tangpo River.