Shortening rate and kinematics of the active Huoshaogou Anticline, northern margin of the Tibetan Plateau, inferred from deformed fluvial terraces

Abstract

Active thrusting and folding at the foot of the Qilian Shan Mountains has accommodated the northward growth of the Tibetan Plateau. However, the slip history of individual thrusts and fault-related folds over different timescales remain largely unknown. In particular, the growth of a series of active fault-related folds suggests a relatively young deformation history in the sedimentary basin of the Hexi corridor. Here, we show the kinematics of the active Huoshaogou Anticline (HSGA) through stratigraphic sequences, and the shortening rate of the anticline using a balanced cross-section in the Jiuxi Basin, located at the western end of the Hexi Corridor. The total shortening rate (0.91 ± 0.37 mm/a) was estimated from deformed fluvial terraces, including the shortening of folding (0.74 ± 0.34 mm/a) and the shortening of the Xinminpu Fault (0.16 ± 0.07 mm/a) within the HSGA region. The results show that the shortening of fold deformation is more significant than the shortening of the fault dislocation. This indicates that the northward growth of the Tibetan Plateau not only affects the mountain foot of the Qilian Shan but also cross the Hexi Corridor to the southern boundary of the Gobi-Alashan Block.