Análisis de los procesos de formación de minerales de la unidad de arcosas de la cuenca del tajo

Abstract

A mineralogic study of the Tajo Basin's Arcoses Unit has been realized from borehole's data. The mineralogy of these sediments corresponds mainly to in herited phases resulting from alteration of granite. Biotite and muscovite micas are transformed to smectites (ferriferous beidellites and to a lesser extent montmorillonites), mixed-layer l-Sm and illites, at the source area. Feldspars alter mainly to dioctahedrical smectites an minor kaolinite. Electronic microscopy observations of micas transforming to illite-smectite and the presence of mixed-layer Cl-Sm, suggest that part of the transformations continued within the basin after sedimentation