Significado petrológico de cordierita, sillimanita y andalucita en migmatitas y granitos de Plasencia-Béjar y áreas adyacentes (Salamanca-Cáceres)

Abstract

This paper deals with the most important petrographical aspects of sillimanite, cordierita and andalucite in granites and migmatites from the Béjar-Plasencia zone. Conclusions are that cordierite and sillimanite are developped under progresive metamorphic conditions and its occurrence in granites has two different significations. In some cases they are "resisters" to the anatectic process and in others they occur as xenocrists. Andalucite occurs as partly derived from cordierite breakdown caused by a potassium metasomatism and partly from a possible magmatic cristalization. In an isolated case andalucite is apparently related with staurolite breakdown.