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Re-evaluation of the Western Alboran Basin History

Damien Do Couto, Christian Gorini, Laurent Jolivet, Jean-Luc Auxietre, Elia d'Acremont, Abdellah Ammar, and Haddou Jabour

Surrounded by the Betic and the Rif ranges, the Alboran domain is the result of crustal-scale processes (i.e. subduction, slab retreat). During the Neogene, several sedimentary basins formed on the Alboran metamorphic basement, mainly due to the extensional collapse of the previously thickened crust of the Betic-Rif belt. The major sedimentary depocentre, the Western Alboran Basin (WAB), is partly affected by shale tectonics and associated mud volcanism. Our study deals with the analysis of a dense network of vintage to recent 2D seismic profiles of the Alboran Sea.

The formation of the WAB began in the Early Miocene where a massive unit consisting of shales and olistostromes forms a thick mobile layer. From the Upper Langhian to the Upper Tortonian, the basin is filled by a thick sequence of siliciclastic deposits displaying a lot of sheeted turbidite geometries. Stratigraphic geometries identified on seismic data clearly indicate that only few extensional brittle deformations affected the basin during the Lower and Middle Miocene compared to its Late Miocene regional-scale compressional event. For the first time, a thick pre-rift sequence is identified under the Neogene sedimentary basin and is correlated to Mesozoic-Cenozoic sequences belonging to the Rif belt.

The thick basal unit mainly acts as a décollement layer which accommodates the deformation of the basin fill. The associated shale tectonics is related to a deeply rooted thrust systems. The shale tectonic deformation was reactivated recently, during the Messinian desiccation of the Mediterranean Sea (and the following catastrophic Pliocene reflooding) or during the Quaternary contourite deposition.

We present successive lithostratigraphic maps of the WAB and discuss the overall forearc geometry of the basin in the scope of the geodynamic evolution of the Alboran domain.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013