Estudio petrológico del Complejo Anatécnico de la Peña Negra (Batolito de Ávila, España central)

Abstract

A large migmatitic-anatectic complex, called Complejo Anatéctico de la Peña Negra (CAPN), outcrops in the Central-North area of Sierra de Gredos. The CAPN have a subhorizontal geometry and is limited by several granitic massifs which range from concordant to intrusive. The CAPN "regional rock" are diatexitic migmatites of granodioritoid composition -called "mesocratic migmatites"- which include the rest of lithologies. All the CAPN granites are anatectic. Large sub horizontal sheets of megacrystic granodiorites and monzogranites stand out. The CAPN migmatites have been generated from the CXG and Cambric rocks that, in this area, are very rich in orthoderived quarzfeldspatic material. It is not possible to see a thermal gradient in the migmatitic series of the Peña Negra, excluding a punctual thermal focus. We think the increase of T comes from decreasing the dissipation capacity of the radiogenic heat due to crustal thickening because of the hercynian folding. The increase of quazfeldspatic component in the metasedimentary series is the responsible of the increase in radiogenic heat-producers isotopes.