Weathering mechanisms and their effects on landsliding in pelitic schist |
| |
| Authors: | Shintaro Yamasaki Masahiro Chigira |
| |
| Institution: | 1. Disaster Prevention Research Institute, Kyoto University, Kyoto, JapanCurrent Address at: Department of Civil and Environmental Engineering, Kitami Institute of Technology;2. Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan |
| |
| Abstract: | Physical, chemical, and mineralogical analyses of undisturbed drill cores of pelitic schist from a landslide area in Japan clarified the mechanisms of chemical weathering of pelitic schist. Oxidizing surface water percolates downward and reaches an oxidation front, where chlorite is altered to Al‐vermiculite, graphite and pyrite are oxidized and depleted, and goethite precipitates. Oxidation of pyrite also occurs just below the oxidation front, probably by ferric iron. Pyrite oxidation yields sulphuric acid, which penetrates further downward, interacting with and weakening the rocks. In addition to this chemical weakening, stress release and shearing along schistosities form an incipient shear zone, which propagates to a sliding zone that forms the rupture surface of a landslide. Once a sliding zone has developed, it inhibits downward groundwater flow across it because of its low permeability, slowing the downward propagation of the weathering zone until this filtration barrier is broken by landslide movement. Copyright © 2010 John Wiley & Sons, Ltd. |
| |
| Keywords: | landslide oxidation front pelitic schist pyrite weathering |
|
|
