South Portuguese Terrane: A Continental Affinity Exotic Unit

Abstract

The South Portuguese Terrane encompasses three major pre-orogenic mega-sequences: the Phyllite-Quartzite Group and the Tercenas Fm., the Volcanic-sedimentary Complex, and the Carrapateira Group, all three overlain by the syn-orogenic Baixo Alentejo Flysch Group, dealt with in Chap. 11. During the Mid-Late Devonian all the three mega-sequences belonged to an epicontinental sea. From the late Devonian to late Visean major changes took place: the region that became the IPB Domain was the locus of important lithospheric extension that led to the emplacement of important volumes of igneous rocks associated to a Volcanic-Sedimentary Complex, to which the VHMS ore deposits are associated; in Southwest Portugal the Tercenas Fm. shallow water sediments changed to a mixed-siliciclastic-carbonate shelf succession (Carrapateira Group); during the late Visean the extensional regime changed to crustal compression that caused the onset of huge deposits of flysch sediments (Baixo Alentejo Flysch Group) in successive depocenters migrating southward until the late Moscovian.