The role of clay mineralogy properties in the subsidence intensity of the land of Abarkuh plain in Yazd

This study was done in Abarkuh plain where the disasters of land subsidence and land slide have been reported in some sites. The current study is limited to the land slide on a farm near Abarkuh. After taking an inventory of morphological properties, soil sampling from land subsidence locations was done. Routine physical and chemical analyses of the soils and depositions were also done. Advanced analyses such as spectrometry, x-ray fluorescence and x-ray diffraction were conducted on the clay fractions and the soil. One of the new concepts of this research was the dolomitic bed rock that has been confirmed after chemical and x-ray diffraction analyses to rarely form karst in arid climates. Therefore, karst cannot be a serious agent for land slide in these areas. The second new concept in this research was that interlayer random mixed minerals of illite and smectite can be intensifier agents for land depression and slide. Also, ground water table fluctuation together with downward level of groundwater can be the third factor for land sliding. As a suggestion, adding calcium compounds to soil can decrease the activity of clay to increase soil stability against soil divergence. More detailed stratigraphy in this area for surveying hazard maps of land subsidence leads to more logical land management and ground water utility.