5 research outputs found
Caractérisation physico-chimique des argiles fibreuses de « Souk el Arbaa » du Gharb, Maroc
Le prĂ©sent travail sâintĂ©resse Ă lâĂ©tude de la qualitĂ© industrielle des argiles fibreuses de âSouk El Arbaaâ du Gharb appartenant Ă lâĂ©tage gĂ©ologique EocĂšne-MiocĂšne. Cette Ă©tude a rĂ©vĂ©lĂ© Ă travers lâanalyse dâune vingtaine dâĂ©chantillons, prĂ©levĂ©s sur des niveaux marneux variĂ©s, par spectromĂ©trie Ă fluorescence X une carence en fer, une richesse en CaO, des taux plus ou moins Ă©levĂ©s en Al2O3. La diffractomĂ©trie aux rayons X a permis de mettre en Ă©vidence une composition minĂ©ralogique assez variĂ©e dans les diffĂ©rents Ă©chantillons analysĂ©es, dominĂ©e par la prĂ©sence de paragenĂšses minĂ©ralogiques composĂ©es de calcite, dolomite, quartz, sĂ©piolite et attapulgite (argiles fibreuses). Ainsi, le chimisme des Ă©chantillons analysĂ©s indique dâune façon inĂ©luctable que les argiles de âSouk El Arbaaâ du Gharb nĂ©cessitent un traitement afin de les rendre exploitables pour la production de cĂ©ramique dâexcellente qualitĂ©.Mots-clĂ©s : qualitĂ© industrielle, argiles fibreuses, EocĂšne-MiocĂšne, cĂ©ramique, Maroc
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 nonârelated 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 marineâderived 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 saltâinduced 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 Mnârich 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 saltârelated basins in terms of diagenetic events and involved fluids