Resumen de Structure and evolution of topography during the Cenozoic in the central and eastern Anti-Atlas (Morocco)
Jordi Guimerà, María Luisa Arboleya, Antonio Teixell Cacharo
The Anti-Atlas extends WSW-ENE South of the High Atlas, both mountain belts being separated by the Souss and Warzazat basins. Extensive areas of the Anti-Atlas exceed 1500 m of elevation, reaching 3304 m in Jebel Sirwa. Such elevations are the signal of recent uplift. Cretaceous and Neogene (sedimentary and volcanic) rocks are found North and inside the Anti-Atlas; moreover, a poligenic erosional surface (HES) developed in this area before the Miocene. Reverse faults of decakilometric to kilometric scale and E-W trend involve the Neogene rocks. The major structures related to the uplift of the Anti-Atlas, have been analysed drawing contour maps of the basal unconformity of Cretaceous and Neogene rocks, as well as of the erosional surface. Generalized geological cross-sections have also been drawn. Very gentle hectokilometric WSW-ENE-trending anticlines have been recognized as the major contributors to the uplift of the Anti-Atlas, producing a horizontal shortening which does not reach 1%. A structural depression resulting from the lowering of the Eastern Anti-Atlas anticline hinge allowed the formation of the Warzazat basin, which was endorheic during the Neogene, to overflow to the South. Two stages of deformation have been recognized: a first one of pre-mid-late Miocene age (?) and a second one postdating the Miocene and Pliocene rocks.
