The Cambro-Ordovician Ollo de Sapo magmatism in the Iberian Massif and its Variscan evolution: A review

摘要: Abstract We present here a comprehensive and updated review on the gneissic Ollo de Sapo Formation (OSF) in Iberian Massif discuss multiple aspects (lithostratigraphy, petrography, geochemistry, geochronology, partial melting relationships) of its evolution through time. These arise from superposition multi-magmatic Cambro-Ordovician assemblage complex Variscan metamorphic overprint. The OSF comprises plutonic, subvolcanic, volcanic, volcaniclastic units fel peraluminous compositions calcalkaline affinity Upper Cambrian to Lower Ordovician age (495–470 Ma), which crops out at core 600-km-long antiform Domain are overlain by Armorican Quartzite. most striking petrographic features large phenocrysts K-feldspar, plagioclase, blue quartz, giving name “Ollo Sapo” (toad's eyes), fraction inherited zircons Ediacaran or older ages. Geochemical indicators point medium-P, high-T event Neoproterozoic metasedimentary rocks, probably Schist Greywacke Complex, subsequent rapid ascent melts. Augen gneisses mostly plutonic origin, similar age, geochemistry emplaced same sedimentary sequences but lower stratigraphic levels than classical Domain, also exist. augen considered be genetically related OSF. magmatic that produced equivalent Massif, as well other European Belts, has been supposedly opening Rheic Ocean northern margin Gondwana. metamorphism affected variable degrees, low-grade anatectic conditions, clockwise P-T-t path, characteristic foliation. No model for generation unanimously accepted yet because several, often contradictory, geodynamic scenarios suggested geochemical characteristics, further complicated current debates paleogeography Gondwana terranes. stepwise investigation this formation allows general time, is presented here.