LAUSR

Abstract The Retortillo Syncline is part of a major late-Variscan structure that runs for > 120 km from Figueira de Castelo Rodrigo (Portugal) to Tamames (Spain), affecting Neoproterozoic and Lower Paleozoic metasediments in the Central Iberian Zone, and delineated by the Armorican Quartzite. This tectono-metamorphic study gives new insights on the Variscan evolution of this region, showing that it was affected at least by two contractional Variscan stages (C 1 and C 3 ) and by one extensional (E 1 ). The first contractional event (C 1 ), and perhaps an overriding thrust sheet (C 2 ), presently eroded, produced a low-grade Barrovian assemblage (M 1 ) and induced enough load to trigger the formation of high temperature–low pressure (HT-LP) thermal domes (M 2 ) that characterize the regional syn-orogenic extensional event (E 1 ). This allowed the appearance of typical minerals such as andalusite, biotite and/or cordierite. Later, during the C 3 stage, the HT-LP isograds were folded and sheared together with the metasediments and a new axial planar slaty cleavage developed surrounding the M 2 blasts. Finally a late- to post-kinematic thermal (M T ) event associated with the intrusion of a late-Variscan granodiorite led to the growth of new HT-LP minerals and rim overgrowths around previously formed porphyroblasts in a contact metamorphic aureole. The fabric-porphyroblast relations confirm that the Retortillo syncline forms part of a major C 3 fold. Interestingly, it is located at the hinge zone of and arcuate structure whose existence is currently under discussion, the Central Iberian Orocline.