The mio-plio-quaternary Volubilis basin evolution (prerif ridges, NW Morocco):contribution of geophysical imagery

Abstract The Prerif Ridges, part of the south Rifain corridor, are structured during the upper Miocene. The Volubilis basin fill is characterized by the Mio-Plio-Quaternary marine and continental deposit. This study aims is to describe the Neogene evolution of the central part of the Volubilis basin and its relationships to the growth of the bordering Ridges. The database used consists of 107 Vertical Electrical Sounding (VES),calibrated with hydrogeological drilling and wire line logging. The approach used allowed to establish a new three-dimensional model of the top of the Burdigalien substratum, new geo-electrical cross sections and isopach maps of the two most important resistive levels. The most important evidenced structures are the northward prolongation of the N–S Ain Orma fault and a newly NW-SE lineament that crosses the central part of Volubilis plain. This approach leads also to a better understanding of the related environmental issues of sediments deposits. Their migration activities could be synchronous with the growing phases of the eastern and western Ridges. The obtained results allowed us to recognize the Miocene orogeny effects during the south rifain seaway closure.