Evidence of Upper Tortonian Wedge-Top deposits on the Northern Rif Numidian Sequence (External Domain, Northern Rif, Morocco): Geodynamic implications for the Neogene evolution of Rif belt

We report on new stratigraphic data concerning Upper Miocene deposits outcropping in the Northwestern Rif Belt. We analyzed sections located in the Dar Zhiro-Bougdour and Saf Lahmam-Seguedla areas, 30 km to the south of Tanger City. In these areas, sandy-clayey deposits unconformably overlie the Numidian Sandstones pertaining to the External Tanger Intrarif sub-domain. In turn, the External Tanger Intrarif is part of the External Rif domain (ER). The tectono-stratigraphic features of the studied areas, e.g. the basal unconformity and the slight compressional deformation with respect to the substratum, let us to refer them to a wedge-top basin recording the compressional deformation of ER domains. Dar Zhiro-Bougdour and Saf Lahmam-Seguedla sections are both represented mainly by dm-thick turbiditic strata interbedded with light-colored and bluish/pinkish marls. These successions show sulfur nodules, glauconie, and deep marine environment ichnofacies. Biostratigraphic quantitative analyses, performed on calcareous nannofossil assemblages, provided ages ranging from early Tortonian for Seguedla area, and late Tortonian-Messinian for Dar Zhiro-Bougdour- Saf Lahmam. The new stratigraphic results are a major constraint for the closure timing of the Maghrebian Flysch Basin and its tectono-sedimentary evolution, which is coeval with the internal part of the Intrarif sub-domain. Particularly, they point out the latest collisional and docking stages of the whole Rif nappe-stack onto the African plate in the Gibraltar Arc system.