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Type of clay minerals determines the stage of soil evolution. Palygorskite is a dominant clay mineral in soils of arid and semi-arid regions. This study aims to identify the distribution and genesis of palygorskite in some soils developed on Tertiary parent materials in the Isfahan Province. Six soil profiles and their Tertiary parent materials were studied, described and sampled for X-ray diffraction analysis and scanning electron microscopy examinations. Physico-chemical characteristics of both soils and parent materials were also determined. Different quantities of palygorskite were found in soils and parent materials. The highest amount of palygorskite was found in soils and parent materials where both gypsum and carbonates precipitated. Much less quantity of palygorskite was found in salic and calcic horizons. Results revealed that occurrence of palygorskite in the studied soils are mainly related to the inheritance from parent Tertiary sediments. Besides, it seems that palygorskite has partly been formed through pedogenesis processes. Using principal component analysis, the Mg/Ca ratio, pH, H₄SiO₄ and gypsum contents were identified as the most important factors affecting the distribution and genesis of palygorskite in the soils and parent materials. This may suggests that the neoformation of palygorskite by precipitation from solution can take place where the evaporation fluxes are very high.

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Halakabad is located about 30 km south of Sabzevar. Basalt, andesite, hornblende andesite and hornblende dacite are the oldest volcanic rocks cropping out in the study area. Monzodiorite, quartz diorite, quartz monzodiorite, quartz monzonite, and hornblende quartz monzodiorite intruded the volcanic rocks. Application of component analysis is one of the methods that can help to reveal simpler patterns within a complex set of variables. In mineral exploration, the most common application of this multivariate analysis method is to characterize and map interrelationship within high volume surface geochemical data sets. Application of component analysis in Halakabad shows that the most variable can be categorized in five components. Results for geochemical data show first component has positive loading for Cu, Zn, Co, V as well as Li, Th, Cs, Sr and negative loading for Pb, Ba, Rb and Nb. Second component has negative loading for Rb, Sr, Th, Ba and positive loading for other elements. Association of Zn with Pb and F demonstrates another mineral paragenesis in the area. Third component has positive loadings for Ni, Co, Cr and Zn. The chemical elements with positive loadings of the second component are associated with alteration and subvolcanic rocks. Principal component analysis in Halakabad area demonstrated at least two type of Cu and Zn mineralization.

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Having specific properties, clay minerals including palygorskite have considerable influence on soil physico-chemical characteristics as well as the stage of soil development. The objectives of current study were to determine the distribution, origin and formation conditions of palygorskite in the Tertiary sediments and associated soils in Darab, Fars Province. Based on the field observations and geological maps, six rock and soil samples from different Tertiary epochs were selected. The clay size samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Based on clay mineralogy of parent materials and soils as well as quantity and morphology of clay minerals, three origins were distinguished for palygorskite including inherited, pedogenic and detrital. Using principal component analysis (PCA), smectite, gypsum, EC, illite, soluble Ca and Mg and soluble Mg/Ca ratio were identified as the most important factors affecting the distribution and genesis of palygorskite in the studied soils which in turn show the pedogenic and in situ formation of palygorskite from soil solution under high evaporation.