Study of relief changes related to active doming in the eastern Moroccan Rif (Morocco) using geomorphological indices

Abstract This work studies the influence of active tectonics in the drainage networks and topography of the eastern Rif belt, eastern Middle Atlas, and Rekkame high plateau. We have performed a trend-topographic surface analysis at small to medium scales, several landscape analyses at medium scale, and the slope analysis of the relief. Furthermore, we have determined several geomorphic indices in the drainage networks of the study area: hypsometric curve analysis and normalised stream-length gradient (SLk) estimations. The trend-topography surface analysis identifies a NE–SW trending undulation that correspond to the positive topography of the Middle and High Atlas mountain ranges and the Rekkame high plateau as well as an E–W elongated dome in the eastern Rif-Beni Snassen massif. The geomorphologic indices indicate that drainage network is strongly deformed in the vicinity of the Trougout-Nekor active fault system. Furthermore, the Oued Molouya catchment is deformed in the northern limit of the Beni Snassen massif by active deformations accommodating a roughly N–S shortening. According to the available geochronological data from volcanic rocks as well as from Neogene to Quaternary sediments, the most likely age for the deformation of the drainage network producing the anomalous high geomorphic indexes was Placenzian to Present.