The Plio-Pleistocene evolution of the Southern Middle Atlas Fault Zone (SMAFZ) front of Morocco

Abstract

International audienceThe South Middle Atlas front constitutes a northeast-trending shear zone, located north of the Neogene Missour basin adn east of the Taza Guercif basin. This paper analyses the Southern Middle Atlas Fault Zone (SMAFZ) deformation since the Pliocene. The set of structures observed suggests that reverse and thrust faulting along the central part of the SMARZ are combined with left-lateral slip along N-S striking faults of its south-western termination and right-lateral faulting along E-NE striking faults of the east-northeast termination. Thrust and oblique trust-related anticlines of the two lateral ramps partly accommodate north-west directed motion of the Afican plate. The Thrusts probably resulted from rejuvenation of Jurassic normal fault ; they were active durin the Upper Miocene-Pliocene and the Pleistocene. The géometries of positive inversion structures and buttressing effects are clearly dependent on the geometry and sedimentology of the original basin-controlling fault system and on the presence of a décollement level. Field mapping is integrated with Landsat imagery and a digital elevation model to investigate the morphotectonic evolution of the south-eastern range front of the Middle Atlas. Geomorphological features provide significant information on the processes that govern lateral propagation of active anticlines. Both suggest the deformation front may have been active since Pliocene

Recent spatial and temporal changes in the stress regime along the southern Tunisian Atlas front and the Gulf of Gabes: New insights from fault kinematics analysis and seismic profiles

“…The geodynamic history of the Tunisian Atlas is divided into two major periods: the first one corresponds to the rifting stage dominated by an extensional tectonic regime in relation with normal faulting that produces a variable sediment A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 thickness and distribution of facies during Mesozoic times (Piqué et al, 2002;Guiraud et al, 2005. In contrast during Cenozoic-Quaternary period, the collision of Nubia and Europe induced a compressional tectonic regime characterized by folds combined with reverse and strike slip faults (Gomez et al, 1998;Bouaziz et al, 2002;Piqué et al, 2002;Laville et al, 2007;Frizon de Lamotte et al, 2000;2009).…”

Morphotectonic evolution of the Jebel Bou Naceur in the South Middle Atlas Fault Zone (Morocco)

“…1). The set of structures observed suggests that reverse and thrust faulting along the central part of the SMAFZ are combined with left-lateral slip along north-south striking faults of its southwest termination and right-lateral faulting along east-northeast striking faults of the east-northeast termination [16]. Quaternary activity has been previously discussed by Gomez et al [12].…”

“…The Late Neogene deformation of active foreland basins and intermontane basins is dominated by thrusting and fault-related folding [3,10,16]. Novel studies of tectonic geomorphology have focused folding and deformation/erosion balance in tectonically active mountain belts [2,7,8,14,20,22].…”

“…Le réseau de drainage développé sur le front du SMAFZ enregistre une activité néotectonique déjà reconnue [12,16]. Dans cette zone, l'oued du Beni Ouriach (BO) et ses affluents incisent vigoureusement le versant sud du djebel Bou Naceur, tandis que son bassin versant s'accroît radialement, au détriment des bassins adjacents ( Fig.…”

The Atlas System

“…The studies by Krijgsman et al (1999) and Zizi (1996Zizi ( , 2002, which concern the stratigraphy and structural geology of the Guercif Basin, led to a better understanding of the timing of deformation in the Middle Atlas. The Plio-Pleistocene evolution of the southeastern Middle Atlas front has been analysed by Laville et al (2007).…”