Événements diagénétiques carbonatés, marqueurs de l'évolution géodynamique du Moyen Atlas (Maroc)

Abstract

Carbonate diagenetic events, markers of the geodynamical evolution in the Middle Atlas (Morocco). The carbonate episodes dated from Lias to Paleogene in the Middle Atlas and the High Moulouya areas, have recorded many diagenetic events of which the main markers are grouped in two categories that are significant to the geodynamical evolution of these regions. Then, the sedimento-diagenectic markers represented by earlies cementation and dolomitiza-tion, characterize the eogenectic domain, reflect the sedimentological and paleogeographical dynamic environnements and correspond to the period of stability dated from Lower and Middle Lias. The dynamo-diagenetic markers of mesogenetic and telogenetic domains, materialized by a compaction, a later dolomitization, a tectonic fissuration which is associated with a later cementation and a meteoric dissolution, reflect the geodynamic of these sectors : during the Toarcian and Dogger, the period of filling (burial of liasic carbonate deposits), is expressed by the lithostatic compaction and the burial dolomite ; the intracontinental stage of the atlasic chain is the result of the atlasic compression since Cretaceous, it is materialized by tectonic fissuration and later dolomitization ; finally, the formation of the continental chain with the exhumation of former buried deposits, lead to their partial dissolution by meteoric waters.