Post early Cretaceous evolution of the Cévenol fault system according to U-Pb geochronology

The Le Teil (Rhône Valley) earthquake of magnitude 4.9 on November 11, 2019, located on the Cévennes fault system has raised many questions about how regional intraplate structures may be reactivated and how they could potentially trigger strong and shallow earthquakes. This study aims to better understand the geodynamic evolution of this major structure of France’s geology over geological time. A structural study was carried out between Alès and Cruas localities, and synkinematic calcite samples were collected on fault planes and dated using the U-Pb method at LA-HR-ICPMS. Four major geodynamic episodes between 110 and 25 Ma were identified. In addition to recording tectonic events related to plate boundary geodynamics, the Cévenol Fault System appears to be a key structure in accommodating vertical motion differentials between the Massif Central, the Pyrenean domain and the South-East basin.