Tectono-sedimentary evolution of the Senhaja Basin (Western Meseta, Morocco) and its implication for understanding the late Variscan tectonic processes

During the final stage of the Variscan Orogeny, a series of intermontane basins developed along the present-day northwestern margin of Africa, predominantly within the Western (Moroccan) Meseta. Among them, the Senhaja Basin, located in the eastern Jebilet Massif, plays a key role in interpreting diachronous evolution of those basins. Whilst traditionally considered to have formed synchronously under similar geodynamic conditions, recent evidence suggests a more complex and diachronous development.

The depositional environment of the Senhaja Basin is dominated by a fluvial system, characterized by a diversity of facies ranging from the alluvial fans in its proximal part to lacustrine deposits in its distal part. The alluvial-fan gravels feature the coarsest material deposited within the Senhaja Basin.

Integration of sedimentological and structural data supports the interpretation of the Senhaja Basin as a pull-apart basin formed in response to NE–SW compression, accompanied by localized NW–SE extension. Comparative analysis with other Late Paleozoic basins in Morocco reveals the existence of two distinct generations of basins that evolved diachronously under varying tectonic regimes–ranging from compressional to extensional settings–whilst exhibiting similarities in sedimentary infill. These findings contribute to the broader discussion on the geodynamic evolution of late orogenic basins in the Moroccan Meseta and their implications for Late-Variscan tectonic reorganization.