Contribution of aeromagnetic cartography and lithostratigraphic studies to the identification of blind faults and the Cambrian deposits geometry in Jbel Saghro (eastern Anti-Atlas, Morocco)

The study area corresponds to the Jbel Saghro mountain range located in the Moroccan eastern Anti-Atlas. The area landscape shows a Palaeozoic cover, overlying a Neoproterozoic basement. The Cambrian series present lateral thinning from east to west; this thinning is related to the rifting events occurring during the late Neoproterozoic-Cambrian period. The rifting transformed the Anti-Atlas into horsts and grabens. The grabens recorded important sedimentation through the Lower and Middle Cambrian, while at the horsts, it remained reduced. Four lithological sections were examined: Boumalne, Imiter, Taghazout West, and Taghazout, distributed respectively from west to east. The Lower Cambrian is absent in the Boumalne and Imiter, while the Middle Cambrian series show a thickening from west to east. The rifting was generalised in the Anti-Atlas domain, and produced by NE-SW trending faults. The aim of this work is to identify the deepening of these faults, relying on field and geomagnetic examinations. Several treatments were applied to the Jbel-Saghro residual magnetic field map: reduction-to-pole, horizontal gradient, and Euler's deconvolution. Numerous faults were revealed, including a NE-SW trending system interpreted as Cambrian rifting faults, and a NW-SE trending system described as late Neoproterozoic extension faults. These fault systems are considered responsible for the thickness variations of the Cambrian series along the northern flank of Jbel Saghro.