Geoquímica, petrología y geocronología de rocas plutónicas Carboníferas del Macizo de Évora (Zona de Ossa-Morena, Portugal). Un caso de repetido reciclaje cortical e influencia mantélica

Abstract

The Alto São Bento outcrops (Évora Massif, Ossa-Morena Zone, Portugal) offer a possibility to study diverse types of magma and their genetic relations regarding the evolution of the Variscan belt. The main types of plutonic rocks are layers of two- mica granites and porphyritic granites including foliated enclaves of sanukitoids and monzogranites. Representative samples of each lithology have been geochemically and petrologically studied, and have been dated establishing a succession of magmatic events: 335 ± 3 Ma for the monzogranitic enclaves, 328 ± 3 Ma for the enclave of sanukitoids, and 316 ± 8 Ma for the porphyritic granite hosting the enclaves. The correlation of new ages is useful to improve the timing of the Carboniferous tectono-thermal evolution of the Évora Massif. The first and second magmatic events are coetaneous with the ductile exten- sional deformation D2, whereas the third magmatic event occurred along the transition from the extensional deformation D2 to contractional deformation D3. The finding of sanukitoids is a key factor to better understanding the calc-alkaline magma genesis in subduction zones and the implication of mantle sources in the magmatism of the region.