Geological-structural study of the activity phases of the main fault systems of the High Atlas (Morocco)
The project aims to study several major fault systems in the High Atlas of Morocco, whose long history of activation in diverse geodynamic contexts has characterized the entire evolution of the mountain range. The Atlas orogen is the product of a long history of reactivations in alternating transpressional and transtensional regimes of major lithospheric faults (the Tizi n'Test fault system in the western High Atlas, the South Meseta and South Atlas fault system in the central High Atlas). These same fault systems have acted over time through successive reactivations, controlling the opening and closing of sedimentary basins during the Paleozoic and subsequently during the Alpine orogeny.
The study of these fault systems aims to distinguish the oldest deformations from the more recent Alpine ones. To this end, the selected study areas fall within the axial zone of the High Atlas and are characterized by portions of Precambrian-Paleozoic basement outcropping beneath the Mesozoic-Cenozoic successions, thus allowing for a distinction between pre-Alpine and Alpine tectonic structures.
The fault system studied in this area corresponds to the South Meseta Fault (SMF) and the South Atlas Fault (SAF), structures thought to have been active since the Variscan orogeny and along which repeated openings and closures of pull-apart basins have occurred, starting from the Cambrian and continuing through the Triassic-Jurassic. The SMF/SAF system is still active, as evidenced by the widespread seismicity of the central High Atlas, with moderate magnitude earthquakes ranging from 4 to 5.3.
For a detailed study of the deformation history of the fault systems, it is essential to obtain temporal constraints on the various phases of recognized activity. To this end, one objective of the project is to collect samples for isotopic analyses aimed at obtaining data on the reactivation ages of the fault systems examined.