Discovery of active fault at the western margin of Wenshushan uplift in Hexi Corridor

Abstract

The Wenshushan uplift is located at the western end of the Hexi Corridor，dividing the Jiuxi basin and Jiudong basin. It is one of the three major uplift zones within the Hexi Corridor. Based on high-resolution satellite image interpretation and field investigations，we found that there were multiple fault scarps on the western margin of the Wenshushan uplift，with a length of about 3 km. The scarps are relatively continuous and exhibit complex combination characteristics of alternating forward and reverse scarps. Through unmanned aerial vehicle photogrammetric technique and optically stimulated luminescence dating，a comprehensive study was conducted on the fault scarps. The fault scarps developed in different periods of alluvial fans in front of the mountain. Based on the accumulated fault scarp heights of 4.9～5.6 m and corresponding age of （37.3 ± 1.7） ka on the early alluvial fan，the vertical slip rate has been determined to be approximately 0.15 mm/a since the Late Pleistocene. The latest seismic activity occurred during the Holocene，which was a Holocene active fault with fault scarp heights of 0.5～0.7 m. According to data analysis，the formations of the fault scarps are the results of the uplift and expansion of the Wenshushan anticline.

Keywords

• wenshushan uplift
• fault scarp
• slip rate
• hexi corridor