Influence of Geological Material in the Composition of Surface Waters of Galicia (Nw Spain). Genesis of Clay Minerals

Abstract

AbstractThe composition of fluvial waters can be used to predict the processes of formation and evolution of secondary minerals in Galician soils. These processes are similar in areas with different rocks, from acid to basic, the only exception being strongly serpentinized materials. In general, the nature of the rock has less influence than the characteristics of the alteration system, which is always open, acid and freely draining. Mineral neoformation is always of the monosialitic type, having different degrees of evolution. The incipient phases tend to form gibbsite as a more stable mineral, and halloysite, allophanes and imogolite as metastable forms. With time, a crystalline kaolinite would be the only stable species. These results agree with the mineralogy and the andic or ferralic properties of the soils.