Drainage response to superimposed deformation of the Weiyuan anticline in the southwestern Sichuan Basin, China

The quantitative analysis of drainage landscapes utilizing digital elevation models (DEMs) has been widely adopted to effectively investigate structural development and evolution. However, the orientation of tectonic forces often exhibits intricate patterns and undergoes dynamic changes, leading to the superimposition of tectonic deformation and the emergence of complex structural styles. The response of drainage networks to these complex processes has been rarely documented. The Weiyuan anticline in the SW Sichuan Basin, China, serves as a case study to evaluate its applicability. Derived topographic metrics and geomorphic features indicates that deep tectonic deformation with an asymmetric uplift pattern results in contrasting tectonic activity on its flanks. The presently observed triangular distribution of anomalously high geomorphic indices in the central and northern regions suggest the presence of superimposed deformation. It is probable that the Weiyuan anticline has experienced two stages of tectonic shortening: an initial SE-directed basinward propagation of deformation from the Longmen Shan, followed by an east-west directed shortening due to the eastward extrusion of the Tibetan Plateau. Observed drainage patterns reveal that the current landscapes are undergoing transient adjustments. Quantitative morphotectonic analysis is proposed as a reliable and effective method for unravelling the complex history of structural superimposition.