Impact of the early and synsedimentary cretaceous fracturing on the final structuring of the Atlas folds of the Central-Southern Atlas, case of Jebel Meloussi (Central Tunisia)

Abstract

The aim of this work is to study the combined effects of early fracturing and synsedimentary tectonic activity on the current structuring in the Tunisian Atlas. The fieldwork carried out on Jebel Meloussi anticline, imposing structure in the Central-Southern Atlas, reveals significant variations in thicknesses and facies in the different Cretaceous units. These variations result from the reactivation of an ante-Cretaceous NE-SW to E-W preexisting fault, which has controlled the sedimentation of the Cretaceous series in an N–S direction. Likewise, this tectonic inheritance is associated to a well pronounced synsedimentary tectonic activity, which is clearly involved in the structuring of Upper Cretaceous mega-grabens. It can be deduced from this study that the current structuring of Jebel Meloussi is governed essentially by a set of WNW-ESE to submeridian synsedimentary faults, which are connected to the preexisting quasi-directional fault on which the main fold was developed during compressional events. The study of the activation and reactivation of these fractures since the Cretaceous provides details on lithostratigraphic features and tectonic movements.