Fault reactivation study of the long-lived major fault systems of the High Atlas belt (Morocco)

The bilateral project aims to study the main fault systems of the High Atlas in Morocco, whose long history of activation in different geodynamic contexts characterized the overall evolution of the mountain belt. The Atlas orogen resulted from a long history of reactivations in alternating transtensional–transpressional tectonic regimes of lithospheric faults (Tizi n'Test fault system in the western High Atlas, South Meseta and South Atlas fault systems in the central High Atlas). These same fault systems acted over time through subsequent reactivations, controlling the opening and closing of sedimentary basins during the Paleozoic and after during the Alpine orogenesis. The study of these fault systems has the aim to distinguish the oldest deformations from the younger Alpine ones. For this purpose, the selected study areas fall in the axial area of the High Atlas belt, and are characterized by the Precambrian-Paleozoic basement outcropping below the Mesozoic-Cenozoic successions. These reciprocal relationships should allow discrimination between the pre-Alpine and the Alpine tectonic structures. The studied fault systems include the South Meseta Fault (SMF) and the South Atlas Fault (SAF), structures that have been hypothesized to be active since the Varisic orogenesis and along which openings and closures of pull-apart basins occurred, starting from the Cambrian, up to the Triassic-Jurassic interval. The SMF/SAF system is still active as evidenced by the widespread seismicity of the central High Atlas, with earthquakes of moderate magnitude, between 4 and 5.3. For a comprehensive study of the deformation history of the fault systems, it is essential to obtain time constraints of the different phases of reactivaction. Consequently, a goal of the project is to collect rocky samples for isotopic analyses aimed at obtaining data on the reactivation ages of the studied fault systems.

Partner Italy: Dr. Alessandro Ellero, CNR-IGG (alessandro.ellero(at)
Partner Morocco: Prof. Hassan Ouanaimi, Ecole Normale Supérieure, Université Cadi Ayyad, Marrakech.