陇西六盘山黄土及最近1.8Ma B.P.以来的构造运动与气候变化

Liupanshan Loess Since Last 1.8Ma B.P.on Longxi Basin of Western China and Its Response to Tectonic Movement and Climate

对陇西盆地六盘山西侧山麓剥蚀面上断岘剖面的古地磁、磁化率和粒度分析表明,该剖面具有1.8 M a B.P.以来完整的黄土-古土壤沉积序列。断岘剖面以下7级黄河阶地的发育形成以及在1.1和0.8 M a B.P.前后所指示的腾格里沙漠扩张变化,反映了第四纪早更新世以来青藏高原阶段性隆升对黄土高原西部环境变化影响,以及在青藏高原隆升过程中构造与气候的变化与耦合响应。

Analyses of paleomagnetic polarity reversals, magnetic susceptibility and grain size on the loess-paleosol sequence of Duanxian section, 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 of section on the China Loess Plateau over the past 1.8Ma. Research suggests that the loess-paleosol sequence of Duanxian section has seven terraces and a preliminary study on it finds that during the past 1.8Ma, there were two important climatic events indicating the advance of Tengger Desert. The events occurred at about 1. land 0.8 Ma B. P. , respectively. These not only reflect effect of uplift of the Tibetan Plateau in the late Cenozoic on the environment of the western Loess Plateau, but also record details of the coupling effect between tectonics and climate responses of this area to the East Asian monsoon.