Tectonometamorphic evolution of the Aracena metamorphic belt (SW Spain) resulting from ridge-trench interaction during Variscan plate convergence

The Aracena metamorphic belt is a high­temperature/low-pressure (HT/LP) band located at the southern end of the European Variscan chain. It marks a suture between Armorica and Avalonia. This belt is characterized by (1) the presence of mid-ocean ridge basalt-derived metabasites that were affected by an inverted HT/LP metamorphism related to SW verging thrusting, whose thermal peak diachronously migrated eastward; (2) the occurrence of a HT/LP metamorphism, related to an extensional event, affecting continental rocks belonging to the Ossa Morena zone with peak temperatures that are ~ 150°C higher than that recorded in the oceanic metabasites; and (3) the presence of near-trench magmatism with high-Mg andesite composition. These and other characteristics can be interpreted in terms of a ridge­trench-trench triple junction that migrated along the Armorican margin during Variscan oblique convergence.