Diapirs of the eastern Maghreb; the role of Alpine deformations and of initial Cretaceous and Eocene structures in the present forms

The present geometry of the diapirs in the NE Maghreb (Tebessa region in eastern Algeria and the diapir zone in Tunisia) results partly from the initial shape of the primary structures, and partly from the deformations resulting from Alpine compressions. Their size depends on the location of these primary structures within the Maghrebian orogen. In the simplest cases, classical salt dome bodies--emplaced in one or several phases during the Cretaceous and/or Eocene--can be reconstructed when the present structures are unfolded. The individual geometries of the present diapirs are related to the local or regional structural environment. The wide extension of some of these diapiric structures is consistent with this polyphase structural evolution.