Structural Reconstruction of the Oligo–Early Miocene Basins of the Eastern Segment of Maghrebian Belt (Northern Tunisia): Influence of Subduction of the Fore-Arc Curvature

Abstract

Based on the field observations and tectono-sedimentary analysis, we suggest reconstruction of the geological evolution from case study of Northern Tunisia since the Eocene age. The reconstruction of the structural architecture of this region can be aided by knowing the spatiotemporal occurrence and the deformation of the Oligo‒Early Miocene deposits. In the research area, two depositional basin types that coexisted but in different tectonic settings were seen in the reconstruction of Oligo‒Early Miocene successions. In Northern Tunisia, the Late Eocene shortening episode led to a thin-skinned deformation that produced irregular basement topography. During the Oligo‒Early Miocene subduction process, the earliest lithofacies of the Maghrebian Numidian flysch deposited in deep marine offshore environment. Synchronously in the onshore, the second lithofacies of Fortuna were deposited in NW-trending extensional structures after a rifting episode that characterized north-eastern Tunisia (ante-nappes). During the Middle Miocene, the curving fore-arc of subduction between Africa and the Mesomediterranean Microplate dominated northern Tunisia. As a result, the Numidian basin was raised, resulting in thrust sheets in northwestern part of Tunisia, while the extensional structures supporting the Fortuna succession were closed and created push-up structures following transpressional deformation along the NW‒SE boundary faults. Continental collision has occurred in northern Tunisia since the Late Miocene, resulting in shortening structures, some elevated areas, and sedimentary gaps encompassing a substantial portion of the study area.