Caractérisation physico-chimique des argiles fibreuses de « Souk el Arbaa » du Gharb, Maroc

Le présent travail s’intéresse à l’étude de la qualité industrielle des argiles fibreuses de ‘Souk El Arbaa’ du Gharb appartenant à l’étage géologique Eocène-Miocène. Cette étude a révélé à travers l’analyse d’une vingtaine d’échantillons, prélevés sur des niveaux marneux variés, par spectrométrie à fluorescence X une carence en fer, une richesse en CaO, des taux plus ou moins élevés en Al2O3. La diffractométrie aux rayons X a permis de mettre en évidence une composition minéralogique assez variée dans les différents échantillons analysées, dominée par la présence de paragenèses minéralogiques composées de calcite, dolomite, quartz, sépiolite et attapulgite (argiles fibreuses). Ainsi, le chimisme des échantillons analysés indique d’une façon inéluctable que les argiles de ‘Souk El Arbaa’ du Gharb nécessitent un traitement afin de les rendre exploitables pour la production de céramique d’excellente qualité.Mots-clés : qualité industrielle, argiles fibreuses, Eocène-Miocène, céramique, Maroc

Unravelling the Temporal and Chemical Evolution of a Mineralizing Fluid in Karst-Hosted Deposits: A Record from Goethite in the High Atlas Foreland (Morocco)

Timing and duration of ore deposit formation are crucial to understanding the mineralization process. To address this, the geochronological (U-Th)/He method, geochemical and H- and O-isotope compositions of pure goethite formed in the Imini karst-hosted Mn district (High Atlas, Morocco) were examined in detail. Two main generations of cavity-filling and fracture-filling goethite are identified, and both precipitated prior to the massive Mn oxide ore. The δD and δ18O values reveal that the mineralizing fluid of cavity and fracture-filling goethite is meteoric-derived but enriched in 18O due to fluid–rock interactions with the host rock dolostone or mixing with O2-rich surface water resident in an open karst system. The cavity-filling goethite precipitated between 95 to 80 Ma, whereas fracture-filling goethite formed between 80 to 50 Ma. Ore deposition occurred discontinuously during the early Atlas doming associated with one or more early compressional events in the Atlas tectonism. The increase in δD values and depletion in U content result from a change in the mineralizing fluid within the karst system. At about 50 Ma, the fluid is notably enriched in U, Cu and trace metals

Influence of cutting time interval and season on productivity, nutrient partitioning, and forage quality of blue panicgrass (Panicum antidotale Retz.) under saline irrigation in Southern region of Morocco

Salinity has become a major issue in various parts of the world negatively impacting agricultural activities and leading to diminished crop potential and lower yields. Such situation calls for urgent interventions such as adopting salt-tolerant crops to fill the gap in food and feed availability. Blue panicgrass (Panicum antidotale Retz.) is a promising salt-tolerant forage crop that has shown an appropriate adaptation and performance in the saline, arid, and desertic environments of southern Morocco. However, for obtaining a highest forage productivity with nutritional quality, optimization of the cutting interval is required. Thus, the objective of this study was to determine the optimal cutting time interval allowing high forage production and quality under high salinity conditions. This experiment was conducted over one entire year covering the summer and winter seasons. The effect of five cutting time intervals on selected agro-morphological traits, crop productivity, mineral nutrient accumulation, and forage quality of blue panicgrass in the region of Laayoune, southern Morocco. The finding of this study recommend that cutting blue panicgrass every 40 days maximized the annual fresh and dry forage yield as well as the protein yield, which reached 74, 22, and 2.9 t/ha, respectively. This study also revealed a significant effect of the season on both productivity and quality. However, forage yield declined during the winter and increased during the summer, while protein content increased during winter compared to summer. The mineral nutrient partitioning between shoots and roots, especially the K+/Na+ ratio, indicated that blue panicgrass has salt tolerance mechanism as it excluded sodium from the roots and compartmentalized it in the leaves. In conclusion, there is a potential of blue panicgrass on sustaining forage production under salt-affected drylands, as demonstrated by the response to two key questions: (a) a technical question to farmers for its adoption such as at which interval should blue panicgrass be harvested maximizing both forage yield and quality? And (b) a scientific question on how does blue panicgrass maintain high K+/Na+ ratio to cope with salinity stress

Diagenetic evolution of lower Jurassic platform carbonates flanking the Tazoult salt wall (Central High Atlas, Morocco)

Platform carbonates diagenesis in salt basins could be complex due to potential alterations of fluids related and non‐related to diapirism. This paper presents the diagenetic history of the Hettangian to Pliensbachian platform carbonates from the Tazoult salt wall area (central High Atlas, Morocco). Low structural relief and outcrop conditions allowed to define the entire diagenetic evolution occurred in the High Atlas diapiric basins since early stages of the diapiric activity up to their tectonic inversion. Precipitation of dolomite and calcite from both warmed marine‐derived and meteoric fluids characterised diagenetic stages during Pliensbachian, when the carbonate platforms were exposed and karstified. Burial diagenesis occurred from Toarcian to Middle Jurassic, due to changes of salt‐induced dynamic related to increase in siliciclastic input, fast diapir rise and rapid burial of Pliensbachian platforms. During this stage, the diapir acted as a physical barrier for fluid circulation between the core and the flanking sediments. In the carbonates and breccias flanking the structures, dolomite and calcite precipitated from basinal brines, whereas carbonate slivers located in the core of the structure, were affected by the circulation of Mn‐rich fluids. The final diagenetic event is characterised by the income of meteoric fluids into the system during uplift caused by Alpine orogeny. These results highlight the relevant influence of diapirism on the diagenetic modifications in salt‐related basins in terms of diagenetic events and involved fluids

How Does Organic Amendment Improve Quinoa Growth and Productivity under Saline Conditions?

Nowadays, salinization is becoming a serious problem affecting several agricultural areas, especially irrigated ones. A field experiment was conducted in Foum El Oued, south of Morocco, testing quinoa responses to three irrigation-water salinities (4, 12, and 20 dS/m) combined with nine organic amendments. The obtained results indicate that most of the growth and productivity parameters were negatively affected by salinity, while the effect of organic amendment varied from one salinity level to another. Under high salinity, sheep manure, compost, and insects improved quinoa seed yield by 157, 110, and 83%, respectively, compared to the control. The findings of this study recommend that organic amendment could be a judicious practice to improve quinoa yield under saline conditions

Integrated Agronomic Practices to Enhance Forage Productivity and Quality of Blue Panicum (Panicum antidotale Retz.) under Saline and Arid Conditions in the South of Morocco

Soil salinity and drought are the two major challenges agriculture is facing in marginal environments, such as desert areas, which limit the growth and productivity of traditional cultivated crop species. In the Sahara Desert of the southern region of Morocco, livestock is the major agricultural activity, and forage supply is severely affecting livestock production. Blue panicum (Panicum antidotale Retz.) is an alternative salt-tolerant crop recently introduced to Morocco’s Sahara to enhance forage availability for livestock. The aim of this study was to increase the productivity and nutritional quality of blue panicum through the use of integrated agronomic practices, such as planting methods (bed or flat), crop establishment (direct seeding, transplantation, and rhizome propagation), organic and/or mineral amendments, and grass–legumes intercropping. The preliminary results showed that in the highly saline conditions, the combined application of organic amendments, seedling transplanting, and bed planting method gave the highest production (56 t/ha/year) of fresh biomass, which is higher than 50% compared to the control. This study suggests that in the southern region of Morocco and the Sahara Desert, the adoption of the blue panicum with integrated agronomic practices sustains livestock production

Volcanic sequences, lithostratigraphy and geochemistry of altered rocks at the Jbel Malek deposit : clues for the origins of a Neoproterozoic deposit, High Atlas, Morocco

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