The plateau of Meknes and its borders shows a great geological diversity. The plateau is formed by a cover of marls, fawn sands and lacustrine limestones. The geological formations of the borders are composed of dolomitic limestones and marls of Jurassic age. The quarries of the plateau of Meknes and its borders are of diversified geological nature. In this region, the problem of increased demand for building materials causes excessive overexploitation, without taking account of quality and rational use measures. This problem requires a study of the state of the quality of these materials to guide the entrepreneurs towards the places where the quarries are of quality required by the standards of the field of the BTP, and on the other hand to control over the abuse user of these building materials and its influence on the environment. For these aims, a study of mineralogical and chemical analyzes by X-ray diffraction and by ICP-AES was carried on the samples taken from four quarries of materials used in this region. Thus, the physical and mechanical parameters of the materials are measured according to the most fundamental geotechnical protocols in the construction geomaterials. These analytical results have allowed to class spatially of the mineralogical, geochemical and geotechnical quality of this material in comparison with the standards.
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La lagune de Nador est située à l'extrémité est du Rif nord-oriental. Elle est entourée par un ensemble de reliefs à lithofaciès très variés volcaniques et sédimentaires. Le bassin versant, d'une superficie de 2200 km 2 , est drainé par un réseau hydrographique dense. La superficie du bassin lagunaire est de 115 km 2 (25 x 7.5 km) et de 8 m de profondeur maximale ; il est séparé de la mer par une barrière littorale de 25 km de longueur et de 350 m de largeur maximale.La fraction carbonatée est une composante importante de la sédimentation actuelle de la lagune de Nador. Elle constitue 13 à 48 % du sédiment total. Sa répartition au sein de la lagune reflète celle des apports des bassins versants marin et continental. La fraction carbonatée est composée de quatre minéraux, formés par ordre d'importance de calcite, de calcite magnésienne, de dolomite et d'aragonite. Les signatures isotopiques de Sr des carbonates des sédiments lagunaires montrent qu'ils sont constitués en grande partie des carbonates marins actuels qui se déposent sous forme biogène et éventuellement par précipitation chimique. A ces carbonates marins s'ajoutent ceux d'origine externe moins radiogéniques issus des aérosols et des carbonates plus anciens apportés par les oueds. En allant du N-W au S-E, la concentration en Sr de ces carbonates lagunaires augmente, indiquant un faible taux de renouvellement des eaux dans la zone SE, du fait de son éloignement de la passe de communication.Abstract. -The Nador lagoon is the largest one in Morocco and along the Mediterranean. It is located on the northeastern coast near the Rif chain (North Morocco), and it is surrounded by volcanic and sedimentary rocks of various lithofacies. The watershed has an area of about 2200 km 2 and is drained by a dense river network. The lagoon dimension is of 115 km 2 (25 x 7.5 km) with a depth not exceeding 8 m. The island barrier is 25 km in length and 350 m in average width.The carbonate fraction is the dominant component of the present-day sedimentation in the Nador lagoon. It represents 13 to 48 % of total sediments. Its distribution within the lagoon reflects the nature of marine and continental watershed.The carbonate fraction is composed, in decreasing order of importance, of calcite, magnesium calcite, dolomite and aragonite. The Sr isotopic signatures of lagoonal carbonates sediments show that they are dominated by marine biogenic sediments deposited, and by chemical precipitation. In addition, other carbonates of external origin and less radiogenic Sr isotopic are also present, coming from aerosols and ancient carbonates and transported by streams and rivers. From northwest to southeast, the Sr concentration of these lagoon carbonates increases, showing a slow renewal of waters in the southeastern zone because of its remoteness from communication with sea.
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