末次冰期以来柴达木盆地沙漠形成与演化

Desert Formation and Evolution in Qaidam Basin since the Last Glacial Epoch

通过热释光测年,结合剖面岩性岩相特征、粒度等环境指标的综合分析,对柴达木盆地各地形面上古风成砂剖面进行了详细分析研究。将柴达木盆地沙漠形成与演化划分为3个阶段:21～15 kaBP的末次盛冰期是柴达木盆地大规模沙漠活动时期;15～10 kaBP的晚冰期柴达木盆地沙漠经历了多次扩展和固定缩小的波动演化;10 kaBP以来的全新世盆地沙漠经历了固定缩小和再次扩张的演化过程。自21 kaBP末次盛冰期以来,随着全球气候的波动变化,盆地沙漠虽经历了多次扩展与固定缩小的两相组合式波动演化过程,但流沙活动至今尚未完全停止过。现今盆地流沙活动是末次盛冰期以来沙漠演化过程中新近经历的又一阶段,是末次盛冰期流沙活动的承袭。

The Qaidam Basin is one of the areas where the deserts of the Qinghai-Xizang Plateau are mainly distributed. These deserts are mainly found in the southern margin and southeastern part of the Qaidam Basin, and areas around the three lakes, that is, east Taijinaier lake, west Taijinaier lake, and Dabuxun lake. The extensively distributed desert and loess recorded the environmental evolution history in this region. According to the environmental records and TL-date from stratigraphy of different types of loess, eolian sand sections in southeastern margin of the Qaidam Basin, we studied the processes of desert evolution in the concerned area since the last glacial epoch. The extensive desert which appeared 21-15 kaBP indicated that the desert was intensified in the last maximum glacial epoch. The eolian sand, loess, and paleosol layers of 15-10 kaBP are overlapped in sections, which indicated that the positive and reverse changes from the occurrence of the shifting sand to the spread and the fixation have taken place many times. Since 10 kaBP the desert had experienced fluctuating evolution process of reduction and expansion along with the global environmental changes and sand-drifting still continued at present day. The modern sand-drifting activities are another episode of desert evolution process since the last maximum glacial epoch, and the subsequent activities of drifting sand of the last maximum glacial epoch in the Qaidam Basin.