HOW THE YARLUNG-TSANGPO CAPTURED THE UPPER INDUS: RIVERS AND LANDSCAPE EVOLUTION DUE TO A DYNAMIC UPLIFT WAVE IN SOUTHERN TIBET

The influence of dynamic topography on surface processes and landscape evolution in tectonically active regions is understudied compared to in tectonically inactive lowland areas. While barbed tributaries and paleocurrent data suggest that the headwaters of the Indus River in Southern Tibet have reversed course, the mechanism for this drainage reorganisation is unclear. We hypothesise that a wave of dynamic uplift along Southern Tibet in response to progressive mantle flow-driven Indian slab break off from ~ 26 to ~ 12 Ma provides a viable mechanism for the flow reversal of the Yarlung-Indus river network, which drains the India-Asia suture zone. Our numerical landscape evolution modelling shows that drainage divide relocation and associated river flow reversal could occur due to an eastward propagating wave of dynamic uplift. The dynamic uplift wave amplitude sufficient to cause drainage divide relocation and river flow reversal is proportional to the assumed regional tectonic uplift rate, that is only loosely constrained by thermochronological data. These findings suggest that dynamic topography may play a more significant control than previously thought on drainage reorganisation in tectonically active areas such as Southern Tibet.