微量元素记录的毛乌素沙漠全新世气候波动--以萨拉乌苏流域DGS1层段为例

选取毛乌素沙漠东南缘萨拉乌苏河流域具有代表性的滴哨沟湾剖面全新统(DGS1层段),结合微量元素与测年分析结果,探讨了该地全新世千年尺度的气候波动.结果表明,P、V、Cu、Zn、Sr、Ni、As、Cr、Pb属于易迁移-较稳定元素,其含量在沉积相中主要呈现为古土壤< 沙丘砂 <湖沼相,Co、Rb、Nb、Ba、Cl、Zr属于稳定-惰性元素,主要呈现为古土壤 >沙丘砂 >湖沼相,说明沙丘砂是冬季风主导下的沉积,古土壤和湖沼相是夏季风主导下的沉积.以Rb和Sr两种元素在垂向上峰谷交替的变化特征为依据,将DGS1记录的全新世气候分为升温期(11 000~10 130 a B.P.)、大暖期(10 130~6 590 a B.P.)、降温期(6 590~3 760 a B.P.)和寒冷期(3 760~0 a B.P.)四个阶段,这与国内外的相关研究结果一致,表明萨拉乌苏河流域全新世的气候变化是全球环境变化影响下的结果.

Holocene Climate Fluctuations from the Record of Trace Elements in the Mu Us Desert: Evidence from the DGS1 segment of the Salawusu River Valley

The DGS1 segment of the Dishaogouwan section in the Salawusu River Valley on the southeast edge of the Mu Us Desert is selected to study the climate fluctuations on millennium-scale during the Holocene. Based on the trace elements analysis and age determination, we find that the contents of P, V, Cu, Zn, Sr, Ni, As, Cr, Pb are least in the paleosols, less in the dune sands than that in the lacustrine facies, because they are easy to migrate and slightly stable; the contents of Co, Rb, Nb, Ba, Cl, Zr, are most in the paleosols, more in the dune sands than that in the lacustrine facies, because they are stable inert elements. The results suggest that the dune sands are mainly the aeolian sediments in the dominance of the winter monsoon, and the paleosols and lacustrine facies are the sediments in the dominance of the summer monsoon. According to the changes in the alternations of peaks and valleys of these trace elements, the DGS1 is divided into four periods: warming period(11 000~10 130 a B.P.), Megathermal period(10 130~6 590 a B.P.), cooling period (6 590~3 760 a B.P.)and cold period(3 760~0 a B.P.), which are consistent with the related research results abroad and domestic. It reveals that the climate variations in the Salawusu River Valley are subject to the global environmental changes.