ELTALIBI, Hajar Abdelmalek Essaâdi University - Faculty of Sciences and Techniques of Tangier - Department of Earth Sciences, Morocco , ZAGHLOUL, Mohamed Najib Abdelmalek Essaâdi University - Faculty of Sciences and Techniques of Tangier - Department of Earth Sciences, Morocco , EL MOUSSAOUI, Said Abdelmalek Essaâdi University - Faculty of Sciences and Techniques of Tangier - Department of Earth Sciences, Morocco , EL OURAGLI, Bilal Abdelmalek Essaâdi University - Faculty of Sciences and Techniques of Tangier - Department of Earth Sciences, Morocco , BOUAZZA, Noureddine LAFARGE Cements II - Department of quarry, quality and environment, Morocco

Petrography and geochemistry of Triassic-Early Jurassic successions of El Haouz “Dorsale Calcaire” (northern Rif, Morocco): A preliminary assessment for cement production suitability

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The “Dorsale Calcaire” of the El Haouz chain constitutes the frontal part of the Internal Rif Domain. It is mainly made of carbonate lithofacies. At El Mashar cement quarry, the limestone is well exposed and being worked for Tetouan cement manufactory (LAFARGE Cements II). In this study, petrographic and geochemical analysis of fifteen limestone samples were carried out. The aims of this study is to examine the major oxides in the limestone exposed in the quarry, using the X–Ray Fluorescence Spectrophotometer (XRF), and to do a preliminary assessment of these carbonates for a possible cement production. A petrographic study was also carried out, in order to characterize their mineralogical composition and the nature of the associated biogenic fraction. Results of the geochemical analysis allow to determinate three main petrofacies, mainly composed of calcite, dolomite and seldom quartz. The identified petrofacies in El Mashar quarry are: i) micritic and sparitic limestones, ii) dolomitic limestones, and iii) cherty limestones with cryptocrystalline irregular chert nodules. These analysis show also a wide range of variations in LOI (29.94% to 40.64%), SiO_2 (6.14% to 27.18%), CaO (37.93% to 50.78%), Al_2O_3 (0.49% to 2.27%), Fe_2O_3 (0.28% to 2.4%) and MgO (0.24% to 25.19%); K_2O and Na_2O are present in traces. The high CaO (47.17%) indicates that calcite is the principal carbonate mineral. Fe_2O_3 with average of 0.50% indicates low oxidizing conditions and that the pH of the water was not favorable for formation of Iron III oxides. Low alumina (Al_2O_3: 1.07%) probably reflects a low energy environment. CaO with LOI shows a positive correlation, whereas CaO with SiO_2 shows a negative correlation because of mineralogical factors. The low MgO contents in massive and siliceous limestones suggest a lack of dolomitization process, while it’s show a high concentration in dolomitic limestone. These results suggest that theses carbonaceous rocks are suitable for the cement industry.

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EL Mashar quarry , geochemistry , limestone , petrography , major oxides , northern Rif , Moroc

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