Arc-related high-K magmatism in the Ceuta Peninsula (Internal Rif, Spain): discovery and consequences - Observatoire de la Cote d'Azur Accéder directement au contenu
Article Dans Une Revue Geological Magazine Année : 2019

Arc-related high-K magmatism in the Ceuta Peninsula (Internal Rif, Spain): discovery and consequences

Emmanuelle Homonnay
  • Fonction : Auteur
Jean-Marc Lardeaux
Michel Corsini
Asmae El Bakili
Delphine Bosch
Olivier Bruguier
  • Fonction : Auteur
  • PersonId : 981411

Résumé

We document the occurrence of micro-diorite magmatic sills, with magmatic enclaves, in the Ceuta Peninsula within metapelites from the Lower Sebtides units (Internal Rif). All magmatic rocks show a primary magmatic mineralogy and geochemical signature diagnostic for high-K calc-alkaline to shoshonitic island arc magmatism. Moreover, these rocks are significantly affected by secondary metamorphic transformations under greenschist-to amphibolite-facies conditions, regionally dated at c. 21 Ma. Geometric relationships between the sills and the main regional foliation, developed under intermediate-pressure granulite-facies conditions at c. 28 Ma, demonstrate that the sills emplaced during the late stage of this main tectonic event. New U-Pb in situ analyses of monazite performed on the micro-diorite sills provide an age of 20.64 ± 0.19 Ma, coherent with this chronological framework and interpreted as the age of greenschist-facies re-equilibration. The discovery of pre-Miocene high-K calc-alkaline to shoshonitic arc-related magmatism is clearly consistent with the subduction context proposed for the Alboran Basin evolution, according to geophysical investigations. In this framework, the Lower Sebtides units could be considered as part of the upper plate of the subduction system, while the Upper Sebtides must be regarded as the lower subducted plate.
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Dates et versions

hal-03018035 , version 1 (21-11-2020)

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Emmanuelle Homonnay, Jean-Marc Lardeaux, Michel Corsini, Asmae El Bakili, Delphine Bosch, et al.. Arc-related high-K magmatism in the Ceuta Peninsula (Internal Rif, Spain): discovery and consequences. Geological Magazine, 2019, ⟨10.1017/S0016756818000717⟩. ⟨hal-03018035⟩
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