Tracking the Late Devonian high-P metamorphic belt in the Variscan Orogen: New constraints on the PT evolution of eclogites from the Cubito-Moura Unit (SW Iberian Massif)

摘要: Abstract The Cubito-Moura Unit is a high-P metamorphic succession that occurs in the southern part of Ossa-Morena Complex (SW Iberian Massif). It includes series metasedimentary, metafelsic and metamafic rocks affected by high-P, low to intermediate-T event during Late Devonian times. Geochemistry metabasic reveals generation protoliths occurred supra-subduction zone setting Ediacaran Early Ordovician times, either back-arc or fore-arc context. eclogites contain atoll-like garnets, omphacite, amphibole, phengite (up Si = 3.38 apfu), paragonite, rutile quartz. Thermodynamic modelling MnNCKFMASTH system indicates at ~24 kbar and ~ 585 °C followed thermal peak ~19 kbar and ~ 630 °C, subsequent exhumation ~15 kbar. This P-T path deep subduction c. 370 Ma this arc-related section. lithostratigraphy tectonothermal evolution are equivalent number units along Iberian, Armorican Bohemian massifs can be correlated as same Basal Allochthonous Terrane. These define single low- belt developed first stages Variscan Orogeny.