Structural evolution of Rides Prerifaines (Morocco): structural and seismic interpretation and analogue modelling experiments

The Rides Prerifaines (RP) of Morocco constitute the leading edge of the Rif chain. They involve a Triassic-Palaeocene succession deposited on a peneplained Palaeozoic fold belt and accumulated in basins delimited by NE-SW-trending normal fault systems. A significant hiatus separates an overlying Middle Miocene-Upper Miocene foredeep sequence. The reconstruction of the complex structural evolution of the RP during the later compressive phases that affected the Rif chain since Middle Miocene time has been the aim of this paper. We integrated field structural analyses, seismic line interpretation, and analogue modelling in order to evaluate the control exerted by the Late Triassic-Jurassic normal fault systems onto the later compressive tectonics. The maximum compression direction associated with the first compressive phase is roughly NE-SW to ENE-WSW oriented. During this phase the Mesozoic basin fill was scooped-out from the graben and the main decollement level were the Triassic evaporites. Since Pliocene times the maximum compression direction was oriented roughly N-S. During this phase the RP assumed their present structural setting. The earlier normal faults delimiting the Mesozoic graben were reactivated in a strike-slip mode also involving the Palaeozoic basement. The analogue modelling experiments demonstrated that the basement reactivation promoted salt tectonics and favoured fluid circulation.