Structural modeling of the hidden parts of a Paleozoic belt: Insights from gravity and aeromagnetic data (Tadla Basin and Phosphates Plateau, Morocco)

Abstract

Gravity and aeromagnetic potential methods are proven to be adequate geophysical techniques for studying the subsurface structure of continental basement areas hidden beneath sedimentary basin. In this study, we present the study of that large part of the Moroccan Western Meseta which is hidden beneath the Phosphates Plateau and Tadla Basin, based on gravity and aeromagnetic data analysis and interpretation. A subsurface structural map of the study area has been established. This reference map shows how the subsurface structural lineaments deduced from the gravity and aeromagnetic data can be continued into the regional crustal-scale faults outcropping around the study area in the Rehamna, Jebilet and Central Massifs. The analysis of this map reveals that: i) the area is predominantly controlled by faults having NE and NW major trends, with E-W and N-S minor trends; ii) these trends are associated with the main phases of deformation that the area underwent during the Variscan Orogeny, the Triassic-Jurassic rifting, and the Atlas tectonic inversion, respectively; iii) many faults already highlighted by previous geophysical investigations are confirmed, and some new crustal-scale structures are revealed; iv) the subsurface continuity of the major, Variscan crustal-scale faults such as the West Meseta Shear Zone, the Smaala-Oulmes Fault Zone and the Fkih Ben Salah Fault is evidenced, and v) the Khouribga-Oulmes Anticlinorium appears to be bounded to the south by a newly described, NW-striking Phosphate Plateau Fault.