Role of Faulting and Salt Tectonics in the Tectono-Sedimentary Evolution of the Ait Ourir Basin, High Atlas Mountains of Marrakesh, Morocco

This paper investigates the structure and evolution of diapirism in the Ait Ourir Basin, located in the High Atlas of Morocco, using structural and sedimentological fieldwork integrated with field mapping. A tectonic-sedimentological study of the Mesozoic cover of the Ait Ourir Basin area revealed that these units were subjected to important saccadic halokinetic activity, reflected by anticline structures associated with regional faults that created several synclinal mini-basins. However, the absence of seismic coverage in the study area makes the proposed interpretation reliant on extrapolations from surface observations. In this work, we suggest that faults and salt activity led to the formation of different structures within the studied area. The growth of Triassic evaporites during various stages of the Mesozoic era is evident through the presence of both progressive and localized unconformities, each with distinct ages recorded. These geological features gave rise to elevated diapiric zones that saw reduced sedimentation, leading to abrupt lateral variations in thickness in multiple areas where this geological activity took place. This phenomenon is particularly well-documented in the mini-basins of Wanina and Jbel Sour, where a Senonian angular unconformity is clearly observed over the entire sedimentary cover, spanning from the Liassic to the Turonian period. The diapirism associated with the major faults, especially encountered between the basins, is often accompanied by late Triassic volcanic material. This diapir-fault relationship resulted in shallow and often depocentric zones in a pull-apart system within a distensive context.