Role of an advanced gravity data analysis in improving the geologic understanding of the northern Tebessa region, Northeastern Algeria

Abstract

The Tebessa region in the extreme northeastern part of the Saharan Atlas of Algeria is characterized by a succession of anticline and syncline structures, diapirs, grabens, and a thick sedimentary cover underlying the Paleozoic basement. The region constitutes a complex structural system. The extensional structures (i.e., grabens and basins) in the Tebessa region belong to the foreland grabens of the North Africa Alpine Belt and their evolution is related to the tectonic history of the western Mediterranean region. The Tebessa region has been the subject of several geologic studies in the last decades. However, the subsurface structural configuration remains unknown, resulting in uncertainty about the exact origin of the grabens present in the Tebessa region.The current research involves gravity data analysis in order to understand the geologic subsurface system. Accordingly, gravity data are used to delineate the fault systems and the tectonic framework by using the 2-D Source Edge Detection (SED) technique, Centre for Exploration Targeting (CET) grid analysis, Euler Deconvolution, multiscale edge detection method (Worming), and 3-D modeling.Results indicate that the main tectonic trends within the study area are NE-SW, E-W, ENE-WNW, and NW-SE directions, making the northern Tebessa a complex structural region. The eastern part of the Tebessa region is characterized by a basement uplift which contributes to the positive gravity anomalies of the diapirs. In addition, the grabens have a sedimentary deposit thickness of about 2–8 km and underlain by Triassic evaporite layers that facilitated their opening by providing rheological weakness.The grabens in the Tebessa region have different mechanisms that have been responsible for their formation. However, the Early Mesozoic extensional tectonic regime initiated some grabens by creating the bounding normal faults, followed by Cenozoic strike-slip motions, when grabens opened as pull-apart basins.