Drainage network patterns influence the hydrological response of the watersheds and must be taken into account in the management of the water resource. In this context, it is important to identify the factors that control the configuration of drainage networks in and beyond specific climatic conditions. Here, we study 318 basins spread over three sectors (arid, semi-arid, and semi-humid) of Morocco where seven drainage network patterns have been identified. From each basin, 14 parameters were extracted, describing the relief, geology, morphometry, drainage network, land cover, precipitation, and time of concentration (Tc). Principal component analysis (PCA) and discriminant analysis (DA) processing were performed on the entire database and on each sector separately. The results show that the drainage network pattern is a feature of the landscape that contributes significantly to the variance of the basins. They suggest that the distribution of network patterns is controlled by the relationship between the different parameters, mainly those related to the relief, more than by the variations of each parameter taken individually. The network discrimination rate is 63.8%, which improves when each sector is treated separately. Confusion in discrimination are similar across all sectors and can be explained by similar conditions (active tectonic, deformation, and uplift) or transitions from one network pattern to another, due to the landscape evolution of certain sectors. A contribution of climatic variables appears locally but was attributed to a statistical coincidence, these parameters presenting a distribution close to that of the relief and geology variables.
The Mississippian (Tournaisian–Visean) of the Jbel Asdaf area in the Tisdafine Basin (Eastern Anti-Atlas, Morocco) has been, for the first time, the subject of a palynological study. This work aims first to describe the lithological and the paleontological composition of the Aït Yalla and Tinerhir Formations, then to refine the age, reconstruct the paleoenvironment and assess the thermal maturity of the organic matter. The studied section is subdivided, from oldest to youngest, into three intervals, according to their lithological and paleontological compositions. Lithologically, the lower interval (lower part of the Aït Yalla Formation) and middle interval (upper part of the Aït Yalla Formation and basal part of the Tinerhir Formation) consist mostly of clay shales and green shales, respectively, both alternating with limestone or sandstone beds. The upper interval (upper part of the Tinerhir Formation) is dominated by sandstones, also alternating with pelitic-sandstone or limestone beds. The kerogen delivered by the analyzed samples is mostly of continental origin, composed mainly of opaque phytoclasts, while translucent phytoclasts and miospores are less represented. Marine fraction, consisting mainly of granular amorphous organic matter and some phytoplankton, are rare. Biostratigraphically, the late Visean Tripartites vetustus–Rotaspora fracta (VF) miospore Zone of the Western Europe biozonal scheme is recognized with some regards in the Tinerhir Formation, based on the first occurrence of the miospore Rotaspora cf. knoxi. Vallatisporites aff. ciliaris is another biostratigraphic marker taxon of the assemblage, whose the last occurrence marks the end of the VF Biozone at the top of the analyzed section. Qualitative and quantitative parameters of the different palynofacies constituents (e.g., shape, size, % of opaque and translucent phytoclasts) show, from the base to the top of the section, a gradual transition from a distal marine environment generally recognized in the Aït Yalla Formation towards an intermediate marine environment in the Tinerhir Formation, suggesting a sea-level fall. Optical analyses performed on the color of palynomorphs, mainly spores, suggest a thermal maturity, ranging from late mature to early post-mature stage for most of the analysed samples, with a burial depth and a temperature of at least 3300 m and 90 °C, respectively.
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