Basement inherited structures and their control on overburden sediments deformation: A study in the Eastern High Atlas and its northern foreland basins, Morocco

Abstract

Inherited structures are widely recognized as one of the major factors that govern rift systems localizations, acting as weakening zones and influencing the subsequent inversion style during compression events, as well as controlling the deformation of overburden sediments. The High Atlas intermountain belt in Morocco, interpreted as evolution controlled by Paleozoic inherited structures, comprises Mesozoic and Cenozoic sediments overlying a Paleozoic and Precambrian basement. Exploring these structures is crucial for understanding the evolution of the belts and for assessing seismic hazards. Surface studies are often insufficient to unveil the complete image of the subsurface structural setting, as illustrated by the Mw 7 Al Haouz earthquake, which is interpreted as being linked to a blind fault (William et al., 2023; Cheloni et al., 2024). In this context, geophysical studies are indispensable to bridge this gap. Here, we present a 3D model depicting the morphology of the metasedimentary basement in the Eastern High Atlas and its northern foreland basins. This model is constrained through the inversion of gravity and aeromagnetic data, supported by seismic sections, borehole, and field data. Preliminary findings from fieldwork denote a series of large NE-SW to E-W structures, predominantly comprising reverse and thrust faults that have governed the deformation of Mesozoic-Cenozoic sediments. The depth of both outcropping and non-outcropping structures, along with their tectonic implications during the Alpine inversion, will be derived through the analysis of geophysical data. Keywords: Inherited structures, High Atlas, basement, 3D model, inversion, geophysical data.