咸阳市区黄土显微结构研究

Study on Micro-structures of Loess in the Xianyang Downtown Area

应用扫描电镜对咸阳市区黄土微结构进行研究,发现市区黄土的微结构特征在平面上随地形地貌不同而异,在剖面上随土层及深度不同而变化。在同一剖面上,黄土层与古土壤层的微结构差异最为明显,黄土层以支架大孔一镶嵌微孔半胶结式结构为主,古土壤以絮凝一凝块胶结式结构为主。在地貌单元上,渭河三级阶地、二级阶地黄土微结构较为疏松,主要为支架大孔一镶嵌微孔半胶结结构,一级阶地黄土微结构较为致密,主要为镶嵌微孔胶结式结构和絮凝胶结式结构。黄土微结构特征沿黄土剖面垂直方向上及沿地貌单元平面上的变化,主要是受黄土堆积环境、成土环境及埋藏环境共同作用的结果。

Micro-structural characteristics of bess in the Xianyang downtown area were revealed using scanning electron microscope. Results show that loess microstructures are horizontally different with different landscape units, and vertically vary with different loess layers. The micro-structural difference between loess layers and paleosols in a given profile is most obvious. Loess layers mainly have supporting-macrospore and mosaic-microspore semi-cementation structures, whereas paleosols mainly have flocculent and coagulum cementation structures. Within a landscape unit, loess in the third and second terraces of the Weihe River is mainly characterized by supportingmacrospore and mosaic-microspore semi-cementation structures, and loess in the first terrace, by mosaic-microspore and flocculent cementation structures. Structure characteristics are mainly controlled by the environments of sedimentation, soil formation and loess burying.