The crustal structure beneath the northeastern continental part of Algeria is still largely unknown. Here we use potential field data processing, modeling and interpretation in order to investigate the deep sedimentary layers of this area and the transition with the basement. Indeed the gravimetric and magnetic field maps unveil the main geological domains of North Algeria: the AlCaPeKa domain, the Tellian Nappes, the Atlas and the South-Atlasic Fault (SAF). Our modeling approach combines the prediction of gravimetric and magnetic field signals along 4 N–S profiles that cross those domains and using constraints from seismic lines. The resulting cross-sections reveal the roots of the main E-W tectonic detachments of this area: the northern Suture Zone, the Tell Front, and the SAF. It seems that they are all initiated in the lower crust, nearby the continental/oceanic crustal transition for the Suture Zone, and several tenths of kilometers south from this transition for the Tell Front and the SAF detachments. Using these detachments, the lower parts of the crust are sometimes uplifted to only 5 km deep in the crust, while the upper crust is sometimes thickened to reach 15 km of thickness. Large magnetization and density contrasts are observed right beneath the Suture Zone.