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Late Variscan metamorphism in the Iberian Massif is characterized by high-T and low-P associations overprinting a Barrovian zonation developed during -and partly following- crustal thickening related to the Variscan collision. The highgrade rocks, commonly reaching sillimanite-K feldsparmuscovite out parageneses and locally even granulitic (biotite out) conditions, crop out at the core of gneiss domes where partial melting, migmatite development and syn-kinematic granitoids are abundant. Gneiss domes are often bounded on top by ductile detachments that, like the domes, formed during an extensional phase of deformation reflecting thermal relaxation and the subsequent collapse of the thickened continental crust, Departamento de Geología, Universidad de Salamanca, España, Instituto Geológico y Minero de España, España, Unidad de Salamanca, Instituto Geológico y Minero de España, España, Department of Geosciences, Penn State, Estados Unidos

During the TopoIberia experiment, a total of 26 seismic broadband stations were recording in northern Morocco, providing for the first time extended regional coverage for investigating structure and seismotectonics of the southern branch of the Betic-Rif arc, its foreland, and the Atlas domain. Here, we analyze P-to-S converted waves in teleseismic receiver functions to infer gross crustal properties as thickness and Vp/Vs ratio. Strong lateral variations of the crustal thickness are observed throughout the region. Crustal thicknesses vary between 22 and 44 km and display a simple geographic pattern that divides the study area into three domains: entire northwestern Morocco underlain by a thickened crust with crustal thicknesses between 35 and 44 km; northeastern Morocco affected by significant crustal thinning, with crustal thicknesses ranging from 22 to 30 km, with the shallowest Moho along the Mediterranean coast; and an extended domain of 27–34 km thick crust, farther south which includes the Atlas domain and its foreland regions. Vp/Vs ratios show normal values of 1.75 for most stations except for the Atlas domain, where several stations give low Vp/Vs ratios of around 1.71. The very sharp transition from thick crust in northwestern Morocco to thin crust in northeastern Morocco is attributed to regional geodynamics, possibly the realm of present-day subcrustal dynamics in the final stage of western Mediterranean subduction. Crustal thicknesses just slightly above 30 km in the southern domain are intriguing, showing that high topography in this region is not isostatically compensated at crustal level., Instituto Andaluz de Geofísica, Universidad de Granada, España, Departamento de Física Teórica y del Cosmos, Universidad de Granada, España, Departamento de Geofisica, Universidade Federal do Rio Grande do Norte, Brasil, Programa de Pós-graduacão em Geodinâmica e Geofísica, Universidade Federal do Rio Grande do Norte, Brasil, Instituto de Ciencias de la Tierra Jaume Almera, España, Real Observatorio de La Armada, España, Departamento de Geofísica, Universidad Complutense de Madrid, España, Departamento de Geología, Universidad de Oviedo, España, Instituto Geológico y Minero de España, España, Institut Scientifique, Université Mohammed V, Marruecos, Departamento de Geodinámica, Universidad de Granada, España

England and Thompson (1984) and Peacock (1989) developed a method to produce thermal models of the pressuretemperature-time (P-T-t) paths of regional metamorphism in thickened continental crust. Their models place the physical conditions undergone by rocks initially at different depths in a temporal frame and permit a better understanding of the orogenic processes involved. One common response to thickening that is observed in orogenic belts is the formation of gneiss domes (Whitney et al., 2004). Gneiss domes are an important feature of the Iberian crust affected by the Variscan orogeny and are abundant in the core of the Central Iberian arc (Martínez Catalán, 2011). Recent investigations (Rubio Pascua,l 2012) in the Central Iberian zone (CIZ) provide data that can be used to constrain thermal models and to evaluate the model response to changes in basic parameters and in the geometry of structural evolution, Department of Geosciences, Penn State, Estados Unidos, Instituto Geológico y Minero de España, España, Departamento de Geología, Universidad de Salamanca, España, Unidad de Salamanca, Instituto Geológico y Minero de España, España, Departamento de Petrología y Geoquímica, Universidad Complutense de Madrid, España, Instituto de Geociencias, Consejo Superior de Investigaciones Científicas, España, Instituto de Geociencias, Universidad Complutense de Madrid, España