地理学报 ›› 2021, Vol. 76 ›› Issue (3): 612-625.doi: 10.11821/dlxb202103009

• 气候变化与地表过程 • 上一篇    下一篇

若尔盖盆地河流古洪水沉积及其对黄河水系演变问题的启示

黄春长()   

  1. 陕西师范大学地理科学与旅游学院,西安 710062
  • 收稿日期:2019-12-02 修回日期:2020-12-07 出版日期:2021-03-25 发布日期:2021-05-25
  • 作者简介:黄春长(1953-), 男, 陕西彬县人, 教授, 博士生导师, 中国地理学会会员(S110000052M), 主要从事环境演变与灾害研究。E-mail: cchuang@snnu.edu.cn
  • 基金资助:
    国家自然科学基金项目(41971116);国家自然科学基金项目(41801060)

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 Published:2021-03-25 Online:2021-05-25
  • Supported by:
    National Natural Science Foundation of China(41971116);National Natural Science Foundation of China(41801060)

摘要:

青藏高原东部若尔盖盆地古湖泊消亡、黄河贯穿盆地、黄河源区现代水系格局形成,是黄河发育演变史上的重要事件,也是青藏高原东部水文环境变化的转折点。关于其发生年代问题,目前尚无确切结论。本文根据野外考察所获资料和实验室测试分析数据,结合历年来前人多方面研究的结果,针对若尔盖盆地古湖泊消亡与黄河贯穿盆地的年代问题,进行比较全面的分析论述与展望。其中在玛曲—欧拉秀玛河段的最新研究,发现由古洪水沉积物记录的黄河特大洪水事件,发生在OSL年龄(13590±1200)~(12980±1090) a期间,其洪水主要来自于若尔盖盆地上游广泛分布的高山冰川的冰雪融水。这证明在末次冰消期Bolling-Allerod全球性相对温暖阶段,黄河就已经贯通若尔盖盆地,流经玛曲—欧拉秀玛断陷谷地,并且发生了若干次特大洪水事件。可见从河流古洪水沉积学、年代学与水文学新途径的研究,将会为解决黄河贯通若尔盖盆地的年代问题提供直接的证据。

关键词: 黄河源, 若尔盖盆地, 河湖演变, 古洪水, 水系形成, 末次冰消期

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