Mineralogia y sedimentologia del yacimiento de Saponita de Yuncos (Toledo)

Abstract

Mineralogy and textures of saponite-bearing bentonites and related facies have been studied in quarries located southwest of Yuncos village in the Madrid Neogene Basin. Results allow three stages related to the evolution of sedimentary environments to be established, in which bentonite deposits (middle stage) are at the boundary between lacustrine (lower stage) and distal alluvial facies (upper stage). Sedimentary facies and clay mineral associations are descirbed. Illite, dioctahedral smectite, kaolinite and chlorite are interpreted as inherited clay minerals, whilst saponite and sepiolite are of authigenic origin. Saponite origin is early diagenetic, by dioctahedral smectite transformation and neoformation. -from Authors