Occurrence of palygorskite in soils of Ecija (Spain)

Abstract

Palygorskite has been characterized in soils classified as typic argixerolls, located in an extensive Quaternary zone in the north of Seville (Spain), where the geological and climatic conditions suggest its genesis. The soils contain a Ck horizon which has different textural characteristics to the other horizons in the profiles. The presence of large white calcareous nodules and cristobalite is the principal difference between them. The formation of palygorsltite at textural discontinuities is in agreement with the characteristics of these soils. Under the present conditions of the soils (pH, magnesium and silicon concentration and soluble salts), the alteration of palygorsltite to smectite is suggested. The sporadic nucleation of large fibres of palygorsltite on silica crystal suggests that this latter mineral could provide the necessary silicon for palygorsltite formation.