晋陕峡谷大路梁黄土磁组构特征及其指示的古风向

Magnetic Fabrics of Daluliang Loess and the Paleowind Direction Indicated

在对晋陕峡谷厚41.2m的大路梁黄土剖面磁组构特征研究的基础上,恢复了该区0.9Ma以来的古风向。该剖面的磁组构特征与前人的研究结果有一些相似之处,但更具有其特殊性。几乎所有样品的磁面理值F都大于磁线理值L,各向异性度P与磁面理值F相关性较高,磁化率量值椭球体表现为压扁状。磁组构指示的古风向表明,本区的地面主导风向为NE-SW向,且0.9Ma以来在大的方向上没有显著改变。结合对主导风向变化驱动因子的分析表明,影响晋陕峡谷近地面主导风向的因子应该是南北走向的峡谷地形所致。

The essay reports the AMS-based reconstruction of the paleowind direction variations spanning the past 0. 9 Ma in the Jinshan Gorge. The results show that there is resemblance bet- ween the previous studies and this profile, while this profile has its special characteristics. The magnetic foliation （F） of almost all of the samples is higher than the magnetic lineation （L） and the degree of AMS （P） is correlative with F greatly, the shape parameter of the AMS ellipsoid is oblate. Magnetic fabrics indicated that a stable prevailing paleowind of NE-SW direction was established over the past 0. 9 Ma and the main direction did not have markedly transformed. This coincidence may imply that the north-south gorge topography might have causally related with the prevailing wind direction in the Jinshan Gorge.