Origen y significado de los gabros anortosíticos bandeados de Castillo de las Guardas, batolito de la Sierra Norte de Sevilla

Zusammenfassung

The Seville Range batholith is characterized by the high proportion of basic and intermediate rocks to granites comparated with other batholiths of inner areas of Iberian Massif. Cumulate rocks with olivine and/or plagioclase cumulus appear within basic rock massifs, suggesting as fractional crystallization was effective during magma crystallization. Cumulate rocks with plagioclase are layered, with parallel and cross-bedding, and unconformity contacts. A section of 6,5 cm wide of anortositic gabbros of representative of layered gabbros outcropping at Castillo de las Guardas massif has been studied. The studied section consists of an alternance of 1) anortositic layers with adcumulate texture, 2) pyroxene leucogabbronorite layers with mesoadcumulate and orthoacumulate textures, 3) amphibole-piroxene gabbronorite layers with orthocumulate texture, and occasionally 4) olivine and clinopyroxene layers very altereted. Plagioclase cumulus is common in all the layer excepting the last one. Field relationships, petrographic variations. An content of plagioclase and Al iv, Mg/(Mg+Fe2+), Ti in pyroxenes and amphiboles of studied section are consistent with a crystallization model of static and dynamic alternate stages of a basaltic magma.