Geochronology of the Iberian Pyrite Belt and the Sierra Norte Batholith: lower plate magmatism during supercontinent amalgamation?

Abstract

Abstract Protracted magmatism has long been recognized in the exotic South Portuguese Zone of southern Iberia where Early–Late Devonian volcano-sedimentary successions potentially record processes associated with ocean closure and continental collision associated with the formation of Pangaea. Collectively, these rocks represent a bimodal, predominantly submarine volcanic succession with massive sulfides spatially associated with basalts and rhyolites. Volcanic rocks are intruded by the voluminous Sierra Norte Batholith. Although the region hosts some of the world's largest ore deposits, the temporal and genetic relationships between the Iberian Pyrite Belt, the Sierra Norte Batholith and the evolution of the Variscan Orogen remain enigmatic. In an attempt to better understand these complexities, field investigations and targeted geochronology were completed throughout the volcanic and sedimentary rocks of the Iberian Pyrite Belt, and the plutonic rocks of the proximal Sierra Norte Batholith. Our results suggest that the emplacement of the pyrite belt was both pre- and syncollisional, and was initiated primarily by lithospheric delamination related to tectonic escape and crustal thinning of the lower plate. In this scenario, protracted magmatism occurred in both subaerial and subaqueous settings from c. 370 to 338 Ma.