Variscan intracrustal recycling by melting of Carboniferous arc-like igneous protoliths (Évora Massif, Iberian Variscan belt)

Abstract Bulk rock geochemistry and sensitive high-resolution ion microprobe zircon geochronology of igneous metaigneous rocks the Évora gneiss dome, located to north reworked Rheic Ocean suture zone in southwest Iberian Variscan belt, reveal a succession magmatic melting events lasting ~30 m.y. between ca. 341–314 Ma. The study detailed field relationships orthomigmatites (i.e., migmatites from protoliths) host granitic proved be crucial reconstruct complex sequence tectono-thermal dome. older protoliths, with marked geochemical arc-like signatures, are represented by 338 ± 3 Ma tonalites 336 diorites. These diorites appear as mesosomes containing new melts (leucosomes) monzogranite composition silica-poor trondhjemites formed episode at 329 4/6 327 absence peritectic phases (e.g., pyroxene), together shearing associated migmatization, imply existence water-rich fluids during This event is coeval second dome neighboring Pavia pluton. A porphyritic dated 314 4 defines later event. encloses large blocks contains mafic enclaves (autoliths) 337 that ~23 than rock. All studied show arc-like, calc-alkaline signatures. Our results support recycling intermediate-mafic plutonic rocks, representing root an early arc time Gondwana-Laurussia convergence (after closure Ocean) subduction Paleotethys. geodynamic model involving ridge proposed explain Early Carboniferous intra-orogenic crustal extension, formation, exhumation high-grade compositional variations magmatism formation which, signatures were inherited source.