The late Miocene Mediterranean-Atlantic connections through the North Rifian Corridor: New insights from the Boudinar and Arbaa Taourirt basins (northeastern Rif, Morocco)
Résumé
New data from the Neogene Boudinar and Arbaa Taourirt basins (northeastern Morocco) provide constraints on the late Miocene evolution of the North Rifian Corridor. The chronostratigraphy of these basins is clarified on the basis of biostratigraphic (planktonic foraminifers, calcareous nannoplankton) and radio-isotope ages. Marine sedimentation in the Boudinar Basin began during the early Tortonian at ~ 10 Ma and persisted until the late-early Messinian at ~ 6.1 Ma. In the Arbaa Taourirt basin, it occurred between the late Tortonian and the earliest Messinian. Paleoenvironmental data (benthic foraminifera and pollen grains) record a major drowning in association with extensive tectonism in the Boudinar basin during the early Messinian (~ 7.2 Ma). Synchronously, there was a major sedimentological change in the Arbaa Taourirt basin with progradation of conglomerates and sandstones over late Tortonian marls. Large-scale cross-bedded sandstones indicate paleo-currents flowing from the Atlantic Ocean toward the Mediterranean Sea. During the late-early Messinian, a shallowing trend occurred, culminating with the progradation of reefal carbonates. Our findings indicate that the North Rifian Corridor opened at ~ 7.2 Ma ensuring Atlantic-Mediterranean connections. The Corridor was progressively restricted during the late-early Messinian with complete closure by ~ 6.1 Ma. The results of this study thus question existing hypotheses for the timing and nature of Atlantic-Mediterranean connections during the late Messinian.