Subsidence and uplift during the Plio-Quaternary in the Oued Laou andTirinesse sectors (Internal Rif, Morocco) Subsidencia y levantamiento durante el Plio-Cuaternario en los sectores de Oued Laou yTirinesse (Zona Interna Rifeña, Marruecos)

TheOuedLaouareaandtheTirinessebasinarefilledwithearlyPliocene (Zanclean)marinesedimentsveryslightlydeformedbutcurrentlyoutcropping at different altitudes. In Tirinesse area Zanclean sediments reach high altitudes(+600m),whereascoevalsedimentsappearnearthecoastallevel in Oued Laou area and even more than 100 m under the sea level in a borehole near the coast. The difference of altitudes is explained by two successive processes. First there was an important regional subsidence permitting sedimentation. Moreover, in the Tirinesse basin, due to the combined movement of the two SW-NE conjugated normal faults, an additional tectonic subsidence took place. Later, a regional and not homogenousuplift,progressivelymoreimportanttothewest,occurredinthe Rifian Internal Zone, then surpassing the effects of the subsidence. Differential vertical displacements also existed in a N-S direction.