60ka来腾格里沙漠东南缘风成沉积与沙漠演化

Aeolian Deposits on the Southeastern Margin of Tengger Desert and Desert Evolution during the Last 60 000 Years

对腾格里沙漠东南缘风成沉积相典型剖面 (中卫南山剖面 )年代的测定 ,建立了 60 ka以来腾格里沙漠演化的时间序列 ,并结合各地层粒度组分分析结果认为 60 ka以来腾格里沙漠演化共经历了 5个阶段。 60～ 2 0 ka B.P.,腾格里沙漠的范围远没有到达现在的位置 ;2 0～ 10 ka B.P.,沙漠向东南方向大规模扩展 ,奠定了东南缘现代沙漠环境的格局 ;8.1～ 5 .2 ka B.P.,沙漠东南部得到固定 ,沙漠范围缩小 ;11～ 8.1ka B.P.与 5 .2 ka B.P.至现代两阶段和现代沙漠环境接近。

The ancient aeolian sand and dust has been thought of as the indicator that can indicate the formation and evolution of the desert within the past time. The signals of the desert evolution were well preserved in the aeolian deposits on the margin of desert,so these records are effective to reconstruct the desert evolution pattern. Moreover,the variation of grain size of the aeolian deposits may be caused by the strength of the wind which might result in the extension of the desert. Hence,the particle distrbution of the different layers can reflect the desert extension during the different periods. \;The typical stratum profile, named Zhongwei Nanshan section,can stand for the facie of aeolian deposits on the southeastern margin of Tengger Desert. Through TL and \{\}\+\{14\}C dating samples and grain size analyses, the temporal sequence of Tengger Desert evolution was established, which combined with the particle distribution, the temporal and spatial pattern of the desert evolution over the past \{60 000\} years can be reached. Namely, The extent of Tengger Desert did not reach its current position during the period of 60~20 ka B.P., however, it seriously extended southeastward within 20~11 ka B.P.. The southeastern desert was fixed and its extent shrank from 8\^1 ka B.P. to 5\^2 ka B.P.. During the periods of 11~8\^1 ka B.P. and 5\^2~0 ka B.P., the desert extent was similar to the current.