تشكيل، طبقه‌بندي و كاني شناسي خاك‌هاي تشكيل شده از مواد مادري گوناگون در شمال استان چهارمحال و بختياري

Genesis, Classification and Mineralogy of Soils Formed on Various Parent Materials in the North of Chaharmahal-Va-Bakhtiari Province

Parent material is considered as the most important soil forming factor in arid and semiarid regions. This study was carried out to determine the effect of different parent materials composition on physico-chemical and mineralogical properties of soils and also soil classification in the north of Chaharmahal-Va-Bakhtiari province. Seven different kinds of parent materials including granite, basalt, limestone, shale, mica-schist, gneiss and amphibolite were chosen and three different locations were selected for excavation and description of soil profiles. Then, soil samples were taken and soil physico-chemical and mineralogical properties were determined for representative profiles of each site and their related parent rocks. Results showed that physico-chemical properties, clay mineralogy and soil classification have been considerably affected by parent materials. Most of the soils in the region had only A and BC horizons and classified as Entisols but the soils derived from shale and gneiss rocks are classified as Inceptisols because of the existence of the diagnostic B horizon. Soil taxonomy from subgroup or family level clearly shows the difference among the soils studied which indicates the importance of soil classification at the lower levels for management purposes. Clay mineralogy showed that chlorite, kaolinite and Mica (except surface horizon of the soil developed over basalt rock and rock sample of shale) were present in all the soils studied and seem to be inherited only from parent materials. Smectite has pedogenic origin in the basaltic and the granitic soils. These clay minerals show lithologic origin in the soils derived from limestone whereas both lithologic and pedogenic origins seem for the soil derived from gneiss rock. Vermiculite seems to be lithologic in the soil developed over amphibolite and pedogenic in the soil derived from shale and mica-schist rocks. Keywords: Parent material, Soil physical and chemical properties, Clay mineralogy, Soil taxonomy