The Oligocene-Miocene Numidian Complex forms the highest structural unit in the Mahgreb fold and thrust belt, which extends along the northern coast of Africa Major tectonic activity along this belt occurred during Miocene time. The Mahgreb orogenic belt trends east-west in Algeria and turns northeastward in Tunisia. Only the most external and less complex parts of the orogen are exposed in Tunisia, because the fold belt is south vergent; structural complexity increases toward Algeria, where more internal parts of the belt are exposed.
Considerable difference of opinion exists concerning the structural position, the stratigraphic relationship, and the style and nature of emplacement of the Numidian Complex in Tunisia. In the western Mogod Mountains (Fig. 1), rocks of the Numidian Complex generally overlie older, Maestrichtian to Eocene limestone and marl, classically termed the Tellian sequence by French and Tunisian geologists. This arrangement of younger over older rocks has resulted in a controversy about whether the Numidian is allochthonous or autochthonous that has been difficult resolve in this region.