Reconstructing Extensional Basin Architecture and Provenance in the Marrakech High Atlas of Morocco: Implications for Rift Basins and Inversion Tectonics

Abstract

AbstractThe Moroccan Atlas developed through a multiphase tectonic history including Permian‐Jurassic continental rifting and Cretaceous‐Cenozoic intracontinental shortening. New detrital zircon (DZ) U–Pb geochronologic results from the Ourika‐Zat region in the Marrakech High Atlas constrain the sediment provenance of prerift sediment sources and synrift and postrift basin fill. Prerift Precambrian‐Cambrian units contain Neoproterozoic DZ from the Pan‐African orogeny. Ordovician rocks contain diagnostic 0.95‐ to 1.28‐Ga DZ that are absent in the West African Craton, suggesting distal sediment sources. Permian rift basin fill contains Permian zircons that constrain maximum deposition age and diagnostic of northern Meseta domain sediment sources. New mapping and cross‐section construction demonstrate that Permian basin fill accumulated in a half‐graben above a southward dipping normal fault that likely guided subsequent inversion. Triassic rift basin fill thickens southward, above a likely northward dipping normal fault. The change in rift basin geometry was accompanied by catchment reorganization, the introduction of southern rift flank sediment sources, and subbasin integration. The southern catchment expanded to encompass Meso‐Archean rocks of the Reguibat Shield situated >800 km southward. Existing and new provenance results from postrift strata document onset of recycling of Atlas rift basin fill during the mid‐Cretaceous and before the onset of compressional inversion. These results highlight the interaction between deformation and sediment routing in an extensional basin and sediment dispersal patterns across continental margins during multiphase deformation. Stratigraphic, structural, and provenance characteristics reveal that the Atlas rift shares similarities with high‐angle and supradetachment basin models, emphasizing the diverse nature of extensional styles.