Landscape processes and erosion in the Ordos Loess Plateau, central China: topographic response to the Cenozoic uplift of the Tibetan Plateau and climate change

The Cenozoic uplift of the Tibetan Plateau leads to eastward lateral extrusion of fault-bounded blocks, which caused large surface uplift. To the northeast of the Tibetan Plateau, the development of the particular fluvial incision landscape on the internally stable Ordos Loess Plateau reflects the lateral extrusion and thrust loading by the adjacent Liupanshan Mts. in the west. In this study, we investigated the climate-mediated temporal evolution of surface uplift and the effect of activity along confining faults on the morphological evolution of the Ordos Loess Plateau by fieldwork, morphological analysis and integration of results from numerous previous studies. Field surveys show that the boundaries of the Ordos Loess Plateau are still tectonically active and fluvial channels are in a state of morphological disequilibrium, with steep channel segments towards the Weihe Graben and meandering low-gradient rivers in the central Ordos Loess Plateau. Morphological analysis shows that the shape of the longitudinal channel profile is straight and deviates from typical longitudinal channel profiles and the degree of erosion and plateau incision is more pronounced in the southeastern Ordos Loess Plateau. We conclude that the northeastern expansion of the Tibetan Plateau activated the boundary faults around the tectonically stable, craton-like Ordos Loess Plateau, which caused the drainage basins to tilt towards the overthrusting Liupanshan Mts in the southwest. The drainage systems reorganized to a principal southern flow direction towards the Weihe Graben caused by the ongoing E-W shortening and ca. N-S extension and thereby progressively incising in the Ordos Loess Plateau.