Integrated Petrology, Geochronology and 3D Microstructural Analysis of Garnetiferous Micaschists: Insights Into the Tectono-Metamorphic Evolution of the Betic Cordillera

Abstract

Integration of microstructural, petrological and geochronological techniques has allowed detailed characterization of the timing and metamorphic features of deformation events in the Betic Cordillera. Phase equilibrium modelling, thermobarometric estimations, in situ U–Pb monazite geochronology and Ar–Ar geochronology (amphibole and micas) have been applied to key samples containing well-constrained deformation fabrics and garnet porphyroblasts of different timing that can be distinguished based on their specifically orientated inclusion trails. Our study helps constrain the timing and kinematics of initial crustal thickening stages in the Alpujárride complex, followed by orogenic collapse and renewed continental collision around 17 Ma. In the underlying Nevado-Filábride complex, multiple garnet generations coexisting in a single investigated sample record a similar history ending with garnet growth under low-pressure/high-temperature conditions around 13 Ma. New age constraints for microstructural trends fossilized within porphyroblasts refine the sequence of changing shortening directions previously linked to the plate-motion interplay between the Alborán Domain, Iberia and Africa from Eocene to Middle Miocene.