Abstract:The Lintan—Tanchang fault zone is located between the east Kunlun fault and the northern margin of the West Qinling fault. As an important fault in the process of tectonic transformation and deformation transfer in the southeastern Gansu, China, its geometric distribution, new activity, and movement characteristics play a crucial role in earthquake preparation. Much investigation and research on the Lintan—Tanchang fault has been conducted, especially since the occurrence of the Minxian—Zhangxian MS6.6 earthquake. It has been thought that the activities of each segment of the fault had significant differences. With the exception of the southeast section of the main fault, the remaining secondary faults have been active since the late Quaternary. In this paper, we discovered geological and geomorphological evidence of late Quaternary activities along the southeast section of the Lintan—Tanchang main fault. As an important supplement of the structural features and activities of this fault, this discovery can help perfect the geometric images and motion characteristics of the regional structure, and it is vital in understanding the regional tectonic activities, tectonic transformation, and deformation transfer.