CLAY MINERALOGY AND ORGANIZATION OF FINELY DISPERSED MATERIAL OF GILGAI SOILS (STAVROPOL KRAI)

The main properties, mineralogical composition of the clay fraction, a nd organization of fine-dispersed material were studied for gilgai soi ls using a combination of physical methods (X-ray diffractiometry, Moe ssbauer spectroscopy, and magnetic and thermomagnetic measurements) an d sequential selective dissolution of clay-aggregating agents. The mos t significant changes in clay mineralogy in comparison with the parent material were observed in the soil of a microdepression. Abrupt seaso nal changes in redox conditions resulted in the formation of a signifi cant amount of lepidocrocite in the A horizon of this soil. The organi zation of finely dispersed soil material is thought to be a feature pa rtly inherited from the parent rock and partly determined by the geoch emical conditions of soil formation.