Petrografía de los depósitos arenosos fluviales y costeros en la península de Tánger: implicaciones sobre la dinámica fluvial y litoral

Abstract

The present paper deals with the petrological study of fluvial and littoral deposits of the Tangier Peninsula Atlantic catchments (Morocco). It allowed us to establish relationships between littoral and fluvial dynamic in the Rif Cordillera geological frame and, further on, to compare it with equivalent sediments on the Betic Cordillera (Iberian Peninsula). Fluvial basins are elongated following the range main thrust structures, and enlarge towards the South, according to the Rif arch expansion. Fluvial sands are quarzolitic, with a maturity increase downstream, showing its origin in the Rif Internal Domain and Numidic flysch. Carbonate enrichment occurs on river mouths, as rivers incise on the Pleistocene lumaquelic platforms. Beach sands mineralogy, on the other hand, is homogeneous and mature, due to the strong Atlantic Ocean dynamic. This petrofacies is similar to the Betic fluvial and littoral sands ones, even though the Iberian sands are rich in feldspars as result of their granitic and metamorphic rocks provenance. Atlantic coastal sands are rather similar on both sides of the Gibraltar strait, by opposite to the poor mineralogical maturity of Betic Mediterranean sands related to a weak coastal dynamic.