Spatiotemporal Evolution of Tectonic Stresses During the High Atlas Cenozoic Basin Inversion: Impact of Plate Kinematics and Structural Inheritance
Hamza Skikra, Riccardo Lanari, Abderrahmane Soulaı̈mani, Muhammad Ouabid, Otmane Raji, Khalid Amrouch
Abstract
Abstract The Moroccan High Atlas is a key region for understanding the complexities of tectonic interactions within intracontinental settings. However, the spatial distribution of stress fields and strain partitioning between the basement and cover during the basin inversion remain poorly understood, posing challenges for unraveling the geodynamic evolution of the region and assessing geohazards. This study employs joint paleostress inversion of mesostructures to analyze the spatiotemporal variation of tectonic stresses during the inversion of the High Atlas basin. An initial phase of layer‐parallel shortening occurred between the Eocene and Middle Miocene, characterized by NNE–SSW compression. A subsequent phase of layer‐parallel shortening, with NW–SE compression initiated the main Mio‐Pliocene shortening of the range. Both phases are marked by a prominent strike‐slip tectonic regime. The shift from NNE–SSW to NW–SE compression likely reflects changes in plate kinematics during the Late Cenozoic. A post‐folding NW–SE compression phase, dominated by thrust faulting, occurred during fold tightening in the Late Pliocene‐Quaternary. West of the range, reactivation of basement fault altered the remote stress field, resulting in both clockwise and anticlockwise rotation of σ H , and inducing a pronounced strike‐slip and oblique‐slip regime. Inversion of focal mechanisms data reveals a NW–SE‐striking σ 1 driven by the continuous oblique convergence of Africa and Europe. The consistency of the NW–SE compression determined from the paleo and present‐day stresses suggests uniformity in stress fields from the Neogene to the present. The spatiotemporal evolution of tectonic stresses in the High Atlas is primarily controlled by plate kinematics, while basement fault reactivation induces second and third‐order stresses. In the western segment, stress field modification is facilitated by the obliquity of faults to the remote stress and the presence of hot mantle beneath the range, which promotes friction reduction and reactivation of steeply dipping faults.