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Lower Sebtides Neogene exhumation and uplift in Ceuta and Cabo Negro areas (Internal Rif, Northern Morocco) : insights from medium- and low-temperature thermochronology

Abstract : The Rif Chain (Northern Morocco) belongs, with the Betic Cordillera (Southern Spain), to the western termination of the Alpine belt. Deepest units of the Rif Internal Zones (i.e. Lower Sebtides) outcrop in three areas, from North to South : Ceuta, Cabo Negro and Beni Bousera. The quick exhumation of these units during the Late Oligocene-Early Miocene is related with a crustal thinning and the Alboran Sea rifting. Despite Beni Bousera massif has been well investigated, no data are available in Ceuta and Cabo Negro areas. This study aims to constrain the last steps of cooling and exhumation in the Lower Sebtides using medium- and low-temperature thermochronological data. Combination of Ar-Ar on micas, fission tracks and (U-Th)/He on apatites (respectively AFT and AHe) from high-grade rocks allows understanding thermal history between 450-350°C and surface temperatures. These data suggest a similar cooling evolution of the Ceuta and Cabo Negro units. Ages obtained with all these methods are comprised in the same interval, between 22 and 18 Ma. These data record an almost instantaneous cooling (between 50 and 200°C/Ma) associated to final exhumation after the Oligo-Miocene thermal event affecting these units at shallow depths (10 km). Low-temperature data suggest that Ceuta and Cabo Negro units cooled at surface temperatures before Beni Bousera ones. Since the end of Burdigalian, the Rif internal zones vertical movements did not exceed 1km, even during the Messinian Salinity. AFT and AHe ages in the whole Sebtides are also slightly older than these obtained in their Spanish equivalent (Alpujarrides). The Gibraltar arc is divided into several independent crustal blocks separated by major fault zones perpendicular to the coast that could have induced independent vertical movements during the entire Neogene
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https://hal-insu.archives-ouvertes.fr/insu-01080768
Contributor : Isabelle Dubigeon <>
Submitted on : Thursday, November 6, 2014 - 11:14:05 AM
Last modification on : Tuesday, May 26, 2020 - 6:50:42 PM

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  • HAL Id : insu-01080768, version 1

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Adrien Romagny, Philippe Munch, Marc Jolivet, Michel Corsini. Lower Sebtides Neogene exhumation and uplift in Ceuta and Cabo Negro areas (Internal Rif, Northern Morocco) : insights from medium- and low-temperature thermochronology. 24 ème Réunion des sciences de la Terre 2014, Oct 2014, Pau, France. pp.182-183. ⟨insu-01080768⟩

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