A new Geodynamic Model for the Betic Cordilleras based on T-tpaths and Structural data from the Eastern Betic.

Abstract

This study presents a new geodynamie model for the teetonie evolution of the Betie Cordilleras from the Cretaceous to the Miocenebased on an integrated(micro) structural, petrological aud geochronological study of the eastern l3etic Zone. Early Cretaceous subduction in the Betic Zone was initiated in thc Jurassie transtensional Africa-Eurasiaplate boundary, whichwasstronglyweakened by extensional tectonics and strike-slip fautting, whieh persisted until the onset of subduction. Compression in the Africa-Eurasia plate boundary and initation of subduetion in the Betic Zone resulted from ESE-ward motion of Iberia due to oceanie spreading in the AtianticOcean and the Bay of Biscay to theW and NWofIberia during the 119-80 Ma period. Following subduetion the high pressure metamorphieBede nappeswere partially exhumed during extension and extreme duetile thinning, whieh also affected the Malaguide Complex in the upper pinte. Early to Middle Eocene northward thrusting of the entire and partially struetured Betie Zone over the southernmost part of the External Zone, the former rifted Betie margin, resulted inHP/LT metamorphism in the overthrust and buried part and flexural bulgingin the part ofthe ExternalZone which was notoverthrust andwheresedimentation continued. During the Late Oligocene and younger tectonie evolution extension and crustal shortening followed eaeh olber rapidly during continuing Africa-Eurasia convergence, * Presentaddress:InstitiitdeGeodynamiqiie, Universite de Nice, URA. CNRS 1279, Parc Valrosee, 06034 Mce Cedex. France. Fisica de la Tierra, nY 4, 77-107, Editorial Complutense, Madrid, 1992