A preliminary study on timing of the oldest Pleistocene glaciation in Qinghai–Tibetan Plateau

Abstract

The Qinghai–Tibetan Plateau consists of broad planation surfaces, basins, and mountain ranges. Research in the past several decades has argued that Quaternary glaciations developed only around the high mountains on the Plateau, not the whole plateau surface. In recent years we and other researchers have dated the oldest moraines in several mountain ranges using ESR. The relative age of these moraines was first confirmed based on their geomorphological position and degree of weathering. The results show that the oldest glaciation, the Zhonglianggan glaciation, in the Qilian Mountains, occurred at about 463 ka, and the high elevation moraines of the Wangfeng glaciation, the oldest ones in the Tianshan Mountains, was dated at 477 and 460 ka. The oldest glaciation in the Hengduan Mountains, the Daocheng glaciation, which is characterized by moraines with deeply weathered red soils, was dated at ∼570 ka. This is reconfirmed by an age of ∼590 ka on the oldest moraine at Yulong Shan in the southern Hengduan Mountains. The Wangkun glaciation, the oldest in the Kunlun Shan Pass, was dated at 710 ka using ESR. This is similar to the 36Cl age of the bottom ice layer of a 309 m ice core of Guliya Ice Cap, western Kunlun Shan. These dates of the oldest moraines in several mountain ranges suggest that glaciers began to develop during MIS-12 in the Qilian and Tianshan Mountains, MIS-16 in the Hengduan Mountains and perhaps MIS-18 in the Kunlun and Nyainqentanglha Mountains. A widespread, rapid uplift of Qinghai–Tibetan Plateau (Kunlun-Huanghe Tectonic Movement) was determined to have occurred between 1.1 and 0.6 Ma. Thus, it is reasonable that uplift of mountain ranges on the Tibetan plateau during this time initiated widespread mountain glaciations in ice ages.