【摘要】 对陇西盆地六盘山西侧山麓剥蚀面上厚约223 m的断岘黄土-古土壤剖面的古地磁、磁化率和粒度进行分析,该剖面具有1.8 Ma以来完整的风成沉积旋回。主要应用砂粒百分含量(>63μm)作为指示风成物质来源区沙漠范围和气候干旱的直接指标,初步发现腾格里沙漠自1.8 Ma以来至少有2次大的扩张与变化过程,分别发生在1.1和0.8 MaBP前后,表明腾格里沙漠的扩张与变化可能同全球性的冰量增加和冬季风增强以及区域性的青藏高原隆升有成因上的联系。更多还原

【Abstract】 Analyses of paleomagnetic polarity reversals,magnetic susceptibility and grain size on the loess-paleosol sequence of Duanxian section,about 223 m thick,at a pediment of Longxi basin lying to the west of Liupan Mountain,show that this sequence contains most of the stratigraphic units recorded in the standard loess-paleosol section in the China Loess Plateau over the past 1.8 MaBP.Using sand particle percentage(>63 μm%) of the eolian sequence as a proxy indicator of desert extent and aridity in the dust source regions,the authors preliminarily found that during the past 1.8 Ma,there were two important climatic events indicating the advance of the Tengger Desert.The events occurred around 1.1 and 0.8 MaBP,respectively.The stepwise advance and changes of the Tengger Desert may have a close relation with the increase in global ice volume and monsoon change and uplift of the Tibetan Plateau in the late Cenozoic.更多还原