Transforming the Miocene Altyn Tagh fault slip into shortening of the north-western Qilian Shan: insights from the drainage basin geometry

Although it has long been proposed that active crustal shortening within the Qilian Shan accommodates slip along the Altyn Tagh fault, questions regarding the temporal and spatial amount of slip transfer remain debated. Traditional shortening calculations cannot yet be made accurately, because the geology is not known well enough. Following the view that long, linear drainage basins in the north-western Qilian Shan developed in response to internal shortening associated with slip transfer along the Altyn Tagh fault, we targeted this special irregular drainage basin geometry to develop an alternative way to estimate shortening. We infer a total of ~66km of shortening in the western Qilian Shan with a north-eastward decrease in the magnitude of shortening. This ~39% shortening strain is comparable to previous estimates. Estimates of dates of initiation support the view that significant shortening and topographical growth within the north-western Qilian Shan occurred in post-Middle Miocene time.