Step-like landform system of the Gonghe basin and the uplift of the Qinghai-Tibet Plateau and development of the Yellow River

Abstract：Based on the satellite images, combined with field surveys and thermoluminescence dating of Quaternary sediments, the authors explain and analyze the step-like landform system of the Gonghe basin. Study shows that the landform system consists of the piedmont denudation surface, proluvial fan surface, basin surface and terrace surface. Its spatial structure and material composition clearly record the early Early Pleistocene C phase of the Qinghai-Tibet orogeny and late Middle Pleistocene Gonghe orogeny. Phase C of the Qinghai-Tibet orogeny witnessed the disintegration of the main planation surface during the differential uplift of the plateau, with a vertical displacement of as high as 1700 m. The Gonghe orogeny caused the Yellow River to enter the Gonghe basin at 0.11 Ma. Since then, substantial down-cutting of the basin surface has continued to the present at an average rate of 3.5 mm/a. At the same time, the piedmont paleo-proluvial fan at the margin of the basin has been elevated at about the same rate. Ultimately, a step-like landform system with a height difference of about 2000 m appeared.