Acta Geographica Sinica ›› 2021, Vol. 76 ›› Issue (3): 612-625.doi: 10.11821/dlxb202103009

• Climate Change and Land Surface Processes • Previous Articles     Next Articles

Palaeoflood deposits in the Zoige Basin and the enlightening on the formation of the Yellow River drainage systemon the Tibetan Plateau

HUANG Chunchang()   

  1. School of Geography and Tourism, Shaanxi Normal University, Xi'an 710062, China
  • Received:2019-12-02 Revised:2020-12-07 Online:2021-03-25 Published:2021-05-25
  • Supported by:
    National Natural Science Foundation of China(41971116);National Natural Science Foundation of China(41801060)

Abstract:

The lake environment in the Zoige Basin of the Tibetan Plateau persisted for a long time in the Quaternary. It represents a great turning point of environmental change over the eastern Tibetan Plateau when the basin was dissected, the lake disappeared and the Yellow River course formed. The ages of these important events are very complicated and therefore still controversial, which requires further research and discussion. This paper provides an overall review and perspective of these issues. An in-depth study of the accumulation of the palaeoflood deposits, chronology and hydrology will facilitate the establishment of a continuous sequence of palaeoflood events of the Yellow River on the Zoige Basin. The direct evidence of the extinction of the palaeo-lake and the appearance of the course of the Yellow River drainage basin will be obtained by identification of the stratigraphic unconformity between the earliest palaeoflood deposit and the palaeo-lake deposit. The age of these remarkable events can be achieved by using AMS- 14C and OSL dating methods. In combination with the analysis of environmental change, especially the evolution of geomorphology and hydro-climatology, this paper reveals the mechanisms of the dissection and the formation of the Yellow River course, and the disappearance of the palaeo-lake. Our latest investigation indicates that extraordinary palaeoflood events occurred during OSL age 13590±1200 a to 12980±1090 a along the Maqu reach of the Yellow River in the downstream of the Zoige Basin. The floodwater came from the melting of mountain glaciers surrounding the basin during the Bolling-Allerod warm phase of the last deglacition. This means that the palaeo-lake had disappeared and the course of the Yellow River had formed through the Zoige Basin. These results are of great significance in understanding the formation of the Yellow River course, and enriching the theory of environmental evolution over the Tibetan Plateau.

Key words: palaeoflood, lake-river evolution, drainage system, last deglaciation, Zoige Basin, Yellow River source region