Las rocas básicas y ultrabásicas en el extremo occidental de la Sierra de Ávila (provincias de Ávila y Salamanca)

Zusammenfassung

Twenty-five outcrops of basic rocks located in the part of the province of Avila and the S.E. part of the province of Salamanca are described. Some of them have received attention in previous studies. P. FRANCO (1980) and the DEPARTMENT OF PETROLOGY AND GEOCHEMISTRY AT SALAMANCA UNIVERSITY (1980), included them in the «Appinitic» suite as genetically independent of the surrouding granitoids. They may intrude into the medium-to-high grade regional metamorphism, though more commonly they intrude in contact with or are within the «late granodiorite» whose characteristics correspond to the «Jungerer porphyrischer Granit» of SCHMIDT-THOMÉ (1945) and which are considered by us as S type and as the Ilmenite suite. The most probable hypothesis concerning their origin is that they evolved from large subjacent masses of mantle to a large extent responsible for the regional metamorphism and for originating and induced anatexis giving rise to granitoids partially uprroted from the anatecticzones, englobing during their ascent some of the basic and ultrabasic outcrops. The authors believe that the ascent of these small masses took place immediately prior (or almost simultaneously) to the development of migmatization and hence predate the ascent of the granitoids.