Bandas miloníticas y filoníticas en las áreas suroccidentales de Segovia (Guadarrama central)

Abstract

According to N-S direction some milonitic and phyllonitic bands appear in agreement to the structure of the wall metamorphic series. They have been originated by sinmetamorphic dúctil shear, perhaps tardi FrF2 (catazonal milonites), or later (retrograde phyllonites). The milonitic bands show a great litological heterogenety. They became of shearing of levels of Serie Fémica Heterogénea (schists, marbles, calc-silicates); and also of quartzfeldspathic orthogneises, leucogneises and augengneises, with different degree of milonitization. We have no found any rock they were out of the bands, except intrusion and skarn phenomena. The lithologies in both sides of the bands are similar. There are coincidence between the apparition of kyanite (in rock, with no clear geochemical control), and these corridors of milonitic rock. This points out interesting problems of metamorphic discordance. The phylonitic bands outcrop on the east side of the area. They show retromorphic gneises, with widespread phenomena of cataclasis and metamorphic blastesis of volatile-rich minerals: micas, turmaline, apatite, fluorite,... These proccesses are caused by the hydrous mesozonal metamorphism affecting the rocks.