Assessment of subsurface lithology in mountain environments using 2D resistivity imaging
Assessment of subsurface lithology in mountain environments using 2D resistivity imaging
复制标题
DOI：
10.1016/j.geomorph.2005.09.012
复制
发表时间：
2006-10
期刊：
影响因子：
3.9
通讯作者：
C. Kneisel
中科院分区：
文献类型：
--
作者：
C. Kneisel
中纬度高山和高纬度亚北极冰缘环境的不同案例研究显示了使用二维电阻率成像研究典型冰缘现象。山地环境地貌研究需要确定的重要参数是多年冻土的位置和范围及其特征、活动层的空间变化以及不同冰缘地貌的内部结构。对不同典型冰周特征的研究表明，二维电阻率成像是一种以适当精度检测永久冻土的合适方法。活性层厚度的描绘是可能的，但取决于活性层和下面的永久冻土之间的电阻率对比。由于Wenner阵列的平滑效应以及高接地电阻和弱信号强度不允许Dipole-Dipole阵列成功应用，一些典型冰缘地貌内部结构的小尺度变化的检测受到限制。因此，冰缘山区环境中崎岖的地形条件可能会导致地电方法应用的限制，因为电极和地面之间良好的电耦合是地电测量的先决条件。然而，事实证明，即使在崎岖的地形条件下，二维电阻率成像也可以成功地获得可重复的结果，这是使用视电阻率测量的变化来监测地下电阻率分布的变化，从而监测永久冻土的加剧和退化所需要的。
The use of 2D resistivity imaging for the investigation of typical periglacial phenomena is shown on different case studies from a mid-latitude high-alpine and a high-latitude subarctic periglacial environment. Important parameters that need to be determined for geomorphological studies in mountain environments are the location and extent of permafrost and its characteristics, the spatial variability of the active layer as well as the internal structure of different periglacial landforms. The investigations on different typical periglacial features demonstrate that 2D electrical resistivity imaging is a suitable method to detect permafrost with an appropriate accuracy. Delineation of active-layer thickness is possible but depends on the contrast in resistivity between the active layer and the permafrost underneath. The detection of small-scale variability within the internal structure of some typical periglacial landforms can be limited because of the smoothing effect of the Wenner array and the high ground resistances and weak signal strength which do not allow the successful application of the Dipole–Dipole array. Hence, limitations of application of geoelectric methods can arise from the rugged terrain conditions in periglacial mountain environments since good electrical coupling between the electrodes and the ground is a prerequisite for geoelectrical surveys. Nevertheless, it is demonstrated that even on rough terrain conditions 2D electrical resistivity imaging could be used successfully to obtain reproducible results which are required to use changes in the apparent resistivity measurements to monitor changes in the subsurface resistivity distribution, and hence, permafrost aggradation and degradation.