The Geological Setting of the Moroccan High Atlas and Its Plate Tectonics Context

In this introductory chapter we summarize the geological evolution of the atlasic domain, making reference to many (not all) of the significant previous works carried out in the area. The geological setting of the Moroccan Central High Atlas is characterized by a complex Mesozoic-Cenozoic evolution that included (i) an extensional to transtensional stage during the Mesozoic, in which episodes with intense magmatic activity (forming lava flows, dykes and intrusion) and salt-driven movements took place and (ii) a compressional stage that generated well developed fold-and-thrust systems in the northern and southern basin and upright folds and tightening of previously formed structures (both extensional and diapiric) in the central part of the basin. The sedimentary sequence characteristic of the Central High Atlas is the frame for the structural observations and the magnetic techniques applied elsewhere in this book. It consists of a thick (Permo)Triassic (red beds) and Jurassic (mainly limestones and marls) syn-rift sequences reaching thickness of more than 7 km in the basin center. Facies changes in the Jurassic sequence indicate deepening conditions towards the central part of the domain. Conversely, the Cretaceous and Cenozoic materials crop out discontinuously in the studied domain. Particularly significant from the structural and geophysical points of view are the incompetent levels (mainly Upper Triassic) and the igneous rocks of Triassic and Jurassic age.