This contribution reports on the field mapping of 9 exceptionally well-exposed channel-levée complexes from Taza-Guercif Basin (NE Morocco), belonging to the Late Miocene Tachrift turbidite system. Separated from each another by hemipelagic marlstones, the mapped channel-levée complexes exhibit thicknesses in the range of 5-25 m. Four main sedimentary facies associations were mapped, including channel-fill sandstones, levée thin-bedded heterolithics, chaotic mass transport deposits, and hemipelagic marlstones. In addition, two end-member styles of channel-fills spatial stacking were recognized, reflecting different modes of channel belt development and/or location along the slope profile, namely: (a) a lateral-migration pattern, resulting from lateral migration of high-sinuosity levéed channel belts, as opposed to (b) a vertically stacked pattern, interpreted to reflect the vertical aggradation of levéed channel belts with a relatively low sinuosity. The geological map accompanying this contribution provides the basis for more in-depth sedimentological investigations on the channels of the Tachrift turbidite system.

New Palaeogene vertebrate localities were recently reported in the southern Dakhla area (southwestern Morocco). The Eocene sediment strata crops out on cliffs along the Atlantic Ocean coast. Vertebrate remains come from five conglomeratic sandstone beds and are principally represented by isolated teeth belonging to micromammals, selachians and bony fishes, a proboscidean assigned to ?Numidotheriumsp. and many remains of archaeocete whales (Basilosauridae). From fieldwork five lithostratigraphic sections were described, essentially based on the lithological characteristic of sediments. Despite the lateral variations of facies, correlations between these five sections were possible on the basis of fossil-bearing beds (A1, B1, B2, C1 and C2) and five lithological units were identified. The lower part of the section consists of rhythmically bedded, chert-rich marine siltstones and marls with thin black phosphorite with organic matter at the base. The overlying units include coarse-grained to microconglomeratic sandstones interbedded with silts, indicating deposition in a shallow-marine environment with fluvial influence. The natural remanence magnetization of a total of 50 samples was measured; the intensity of most of the samples is too weak however, before or after the first step of demagnetization. The palaeomagnetic data from the samples are very unstable, except for eight from three similar sandstone levels which show a normal polarity. Matched with biostratigraphic data on rodents, primates, the selachian, sirenian and cetacean faunas, the new carbon isotope chemostratigraphy on organics (1) refines the age of the uppermost C2 fossil-bearing bed to earliest Oligocene time and (2) confirms the Priabonian age of the B1 to C1 levels.

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This work performed by considering two complementary approaches for investigating the Karst system of Ras El Ma source: (1) The structural approach based on field studies, (2) The functional approach requiring inputs data (precipitations) as well as output data at the exit of the karstic system. The choice of the Ras El Ma source is justified by the fact that it constitutes the main outlet of the Liassic aquifer at the Southwest of Taza town. The structural approach highlighted that the impact of South Rifan and North Middle Atlas faults, oriented mainly NE-SW to ENE-WSW and NW-SE, tectonically linked to the Hercynian and late-Hercynian phases; these faults compartmentalized the karst into panels. The functioning of this karst system is based on the coupling of inputs and outputs, the analysis of interannual hydrograph, flood hydrographs, the recession curves and the analysis of hydrogeochemical results. Respectively, the obtained results are presented as follows: A close relationship between flow rates and precipitation, interannual hydrographs marked by a contrasting variation in flow rates and a periodicity that occurs between low water and high-water years. Concerning flood hydrographs, there are two types, a unit modal hydrographs type which generally occurs following time concentrated rainfall and a second multi modal hydrographs type which follows the repetitive rainfall in the basin. The study of recession curves reveals a clear complexity of the systems supplying the source. However, due to the low drying-off coefficients (7.66•10 -4 ), the aquifer seems to have a poorly developed drainage network in a flooded area. According to the Mangin method [1975], this karstic system is classified in the category of poor or complex karst systems taking into accounts two parameters (i) and (K), which characterize the functioning of the infiltration zone and the volume of flooded karst, respectively. The physicochemical parameters study highlighted the nature of drained rock by the sources. The correlation between conductivity and different chemical elements shows that bicarbonates and calcium are responsible for the mineralization of the waters of this source. It can be concluded that the low values of mineralization occur during the winter and spring floods. The spring regains its normal mineralization during the summer period.

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