Geochronology, detrital zircon sources and metamorphic evolution of the Sierra de Albarrana domain (SW Iberian Massif)

Résumé

The Iberian segment of the European Variscan belt shows an exceptional, and almost continuous, cross-section from the outer to the inner zones of the orogen. This segment comprises several terrains reflecting different stages of its tectonothermal history. The Sierra Albarrana Domain (SAD, SW Iberian Massif), which is the aim of this PhD thesis, is one of these terrains located in the central part of the Ossa-Morena Zone of the Iberian Massif. It preserves much of the original preorogenic features, including pre-Variscan tectonic fabrics, magmatism, and migmatization, and only experienced a limited record of deformation and metamorphism superimposed during the Variscan orogeny. This domain consists of a metasiliciclastic sequence, which includes several stratigraphic formations intruded by the La Cardenchosa pluton (LCP; a regional intrusion dominating the study area). Metamorphic conditions vary from highgrade gneisses and migmatites in the basal part, to low-grade slates in the upper part. The SAD is bounded by tectonic contacts with an overlying allochthon. Classically, it has been considered part of the Ossa-Morena Zone (OMZ). However, recent correlation studies suggest that, possibly, this domain could represent an autochthonous terrane outcropping below the high-pressure terrains of the Ossa-Morena Zone and thus, may be the southward continuation of the adjacent Central Iberian Zone (CIZ) exposed in the tectonic window. This research seeks to provide data to confirm or discard this hypothesis, as well as to enhance the temporal constraints of magmatism, migmatization and metamorphism of the SAD, together with a comprehensive provenance and thermobarometric study...