腾格里沙漠南缘土门剖面TMS5e层段由16层风成砂、11层湖积黄土和5层湖相沉积构成,其年代相当于深海氧同位素5e。分析结果表明,TMS5e的10种微量元素的含量依次为P>Mn>Sr>Rb>V>Cr>Zn>Ni>Cu >Nb。就平均值来看,古流动沙丘砂的各微量元素含量最低,其次为古半固定-固定沙丘砂,但两者的各微量元素含量都明显低于整个TMS5e层段相应平均值;黄土状亚砂土微量元素含量稍低于整个TMS5e层段相应平均值;湖相沉积和湖积黄土的各微量元素含量相差较小,且明显都高于整个TMS5e层段、古流动沙丘砂和黄土状亚砂土的平均值。土门剖面TMS5e层段的微量元素指示的MIS5e腾格里沙漠南缘的气候是不稳定的,经历了14. 5次暖湿与冷干交替的气候波动,且可划分为 TMS5e5(139?129. 30 ka BP)、TMS5e4(129. 30~124 ka BP)、TMS5e3 (124~119. 50 ka BP)、TMS5e2(119. 5?116. 5 ka BP)和 TMS5e1(116. 5~113. 70 ka BP)等5个亚段,分别可与格陵兰GRIP冰芯氧同位素所反映的MIS5e5、MIS5e4、MIS5e3、MIS5e2、MIS5el等气候波动在性质和相位上相对应。
英文摘要:
The TMS5e sequence from the Tumen Section, at the southern edge of Tengger Desert in the northwestern China, is synchronous with Marine Isotope Stage 5e (MIS5e). It consists of 16 layers of aeolian dune sands, 11 layers of lacustrine loess-like facies, and 5 layers of lacustrine facies. The results of trace elements analysis shows that the concentrations of 10 trace elements in TMS5e varies as P>Mn>Sr>Rb> V>Cr>Zn>Ni>Cu>Nb. The palaeo-mobile dune sands and palaeo-fixed to semi-fixed dune sands have lower contents of trace elements than those of the whole TMS5e sequence. The loess-like sandy loams also have slightly lower contents of trace elements than those of the whole TMS5e sequence. The average contents of the lacustrine loess-like faciesare similar to those of lacustrine facies, both of which have higher contents than those of the three aeolian dune sands. The contents of trace elements in the TMS5e sequence indicate that the climate in southern Tengger Desert during MIS5e significantly varied within at least 14. 5 warm-cold fluctuations. Such variations could be divided into five stages: TMS5e5 (139. 0 129. 3 ka BP), TMS5e4 (129.3- 124 ka BP), TMS5e3 (124.0 119.5 ka BP), TMS5e2 (119.5 116.5 ka BP), and TMS5el (116. 5-113. 7 ka BP), roughly consistent with MIS5e5, MIS5e4, MIS5e3, MIS5e2 and MIS5el in the GRIP ice core record, respectively.