The Role of the Atlas Mountains (Northwest Africa) within the African-Eurasian Plate Boundary Zone

Francisco Gomez, Muawia Barazangi, *Weldon Beauchamp
Institute for the Study of the Continents and Department of Geological Sciences, Cornell University, Ithaca, Snee Hall, New York  14853

    Constraints on the magnitude and timing of deformation in the Atlas Mountains of North Africa suggest that the mountain belts have been an integral part of the African-Eurasian plate boundary zone in the Western Mediterranean during the Cenozoic.  Although considered intracontinental in nature, the tectonic evolution of the Atlas Mountains is closely tied with nearby plate interactions.  Shortening directions in the Atlas are generally consistent with ongoing plate convergence.  In Morocco, shortening of the Atlas Mountains accommodates 17 - 45% of the total African-Eurasian plate convergence since the Early Miocene.  The majority of the plate convergence is accommodated  in the Rif-Betic-Alboran region which also appears to have been affected by additional geodynamic processes, as the Alboran Sea exhibits extension contemporaneously with plate convergence.  However, the Atlas Mountains do not show the influence of these additional processes.  In the framework of plate tectonics, the western Mediterranean region, including the “intracontinental” Atlas system, should be regarded as a diffuse plate boundary in which the Atlas Mountains comprise narrow deformable zones bounding larger, relatively rigid crustal blocks.  The deformable zones in between rigid blocks reflect the influence of crustal structures inherited from a major Early Mesozoic episode of intracontinental rifting in the Atlas.
 

* Presently at ARCO International Oil and Gas Company, Plano, Texas