Drainage divide migration in response to strike-slip faulting: An example from northern Longmen Shan, eastern Tibet.

Drainage divides can become unstable due to tectonic disturbances and therefore can be used to constrain past tectonic activity. However, many studies have focused mainly on the influence of vertical motion with less attention on the drainage divide response to strike-slip faulting. How the drainage divide response to strike-slip faulting is still uninvestigated. Here we analyze the drainage divide stability along the Beichuan-Yingxiu Fault, an active dextral strike-slip fault with a reverse component in the Longmen Shan, on the eastern margin of the Tibetan Plateau. Based on activity of the Beichuan-Yingxiu Fault and response of the local landscape, we have identified a site in the Guixi area where a river capture event may occur in the near future, and a site in the Leigu area where a river capture event may have occurred. We used the χ-plot and Gilbert metrics methods to measure drainage divide stability at these two sites. The results show that (1) drainage divides near active strike-slip faults will be unstable before and after a capture event in response to strike-slip faulting and (2) before a capture event, the drainage divide on opposing sides of the strike-slip fault will migrate in opposite directions. This study systematically reveals the drainage divide migration generated in response to strike-slip faulting. We suggest that the drainage divide stability has the potential to be used to identify strike-slip fault activity and slip sense. • A model for drainage divide migration in response to strike-slip faulting. • Divide migration in response to strike-slip faulting in the northern Longmen Shan. • χ-plot and Gilbert metrics methods are used to reveal the drainage divide stability. • Divide migrates before and after a capture event caused by strike-slip faulting. • Divide migration can be used as evidence for strike-slip fault activity. [ABSTRACT FROM AUTHOR]