祁连山东北缘黄土磁组构记录的古风向重建

近年来，利用黄土磁化率各向异性/磁组构（AMS）研究古风向变化被广泛应用.在对祁连山东北缘厚755 m的中路黄土剖面岩石磁学和磁组构研究的基础上，恢复了该区14 Ma以来古风向变化序列.磁组构指示的古风向表明，在14～078 Ma期间，本区的地面主导风向为NW-SE；从078 Ma开始，地面主导风向逐渐向NE-SW过渡；至05 Ma时，该区地面主导风稳定为NE-SW向.对青藏高原隆升的研究显示，在12～08 Ma期间青藏高原发生过称为“昆黄运动”的大规模隆起.结合我们对主导风向变化驱动因子的分析表明，祁连山东北缘近地面主导风向的第一次转变很可能是同时期青藏高原构造强烈隆升对大气环流影响产生的环境后果.

Magnetic fabric-based reconstruction of the paleowind direction from a loess sequence in the northeastern flank of the Qilian Mountains

To reconstruct a continuous record of paleowind patterns from eolian sequences, low field anisotropy of magnetic susceptibility (AMS) is considered to be a useful paleowind retrieving proxy. This paper reports the AMS based reconstruction of the paleowind direction variations spanning the past 14 Ma (million years) in the northeastern flank of the Qilian Mountains. Our results suggest that a NW SE paleowind regime prevailed between 14 Ma and 078 Ma and a stable prevailing paleowind of NE SW direction was established around 05 Ma after a period of transition (078～05 Ma). The ending time of the earlier paleowind pattern (078 Ma) seems to be approximately coincident with the reported ending time of the reconstructed major tectonic uplift event occurred in 12～08 Ma. This coincidence may imply that the near surface atmospheric circulation pattern might have causally related with the Tibetan Plateau tectonic uplift.