Paleomagnetic dating of the Jiuquan Gravel in the Hexi Corridor: Implication on mid-Pleistocene uplift of the Qinghai-Tibetan Plateau

The sediments in the foreland basins around the Qinghai-Tibetan Plateau preserved crucial information to reveal its tectonic history. In the Hexi Corridor, north periphery of the Qinghai-Tibetan Plateau, the angular unconformity between the Jiuquan Gravel and the Yumen Conglomerate has been well known to represent an intensive tectonic event of the plateau. However, its age is poorly constrained. Our paleomagnetic dating at the Laojunmiao section in the Jiuxi Basin show that the bottom of the Jiuquan Gravel reaches 0.84 MaBP, the top of the Yumen Conglomerate is about 0.93 MaBP. This result clearly demonstrates that the northern Qinghai-Tibetan Plateau experienced an intensive movement at mid-Pleistocene.