Triassic–early Liassic extensional systems and their Tertiary inversion, Essaouira Basin (Morocco)

Abstract

NNE–SSW striking late Triassic–early Liassic half-grabens of the Essaouira Basin and the adjacent High Atlas are linked by roughly EW-striking transfer faults. They are overlain by a wide, considerably less faulted, evaporitic sag basin and extensive basalt flows. A Pre-Pliensbachian unconformity truncates the Triassic–early Liassic sequences on the E and NE margin of the basin and is overlain by a mid-Liassic to Cretaceous platform sequence. In the Cap Sim-Necnafa depression Jurassic and early Cretaceous salt tectonics caused widespread salt withdrawal structures. Tertiary NNW to SSE compression caused the inversion of NE and NNE-striking structures and⧸or the formation of salt anticlines. The same compression formed EW-striking reverse faults and anticlines, suggesting the reactivation of late Triassic–early Liassic transfer faults.