Tectonic inversion of Late Miocene extensional deformations in northeastern Tunisia (Cap Bon Peninsula–Sahel area)

Abstract

: The tectonic inversion of the Miocene extensional basins (Cap Bon Peninsula–Sahel area, northeastern Tunisia) is an important process that accommodates the crustal shortening in the northeastern Tunisian edge with the ongoing collision between the African and European plates. Field observations and microtectonic measurements have revealed two main Late Miocene tectonic events: (1) A NE–SW trending extensional tectonic event that would create titled blocks, horsts, and grabens, as well as slump features. These structures were controlled by numerous conjugate systems of syndepositional normal faults. On a regional scale, the NW-trending faults controlled the Miocene sedimentation and subsidence rate in the Takelsa, Dakhla, Saouaf, and Zeramdine syn-rift grabens and (2) the NW-directed post-Tortonian compression, the so-called “Alpine/Atlasic event” that was identified by NE–SW-oriented reverse slip movements and associated folds. The latter compressional event began in the latest Miocene and continued through the Plio–Quaternary, which thus led to the complete inversion of the Miocene basins by the ongoing African and European plates’ convergence. A significant neotectonic uplift of the Abderrahmane, Korbus, and Skanes areas recorded the switch from Late Miocene crustal extension to post-Tortonian to Quaternary compressional tectonics. In fact, the present-day petroleum trap configuration of the northeastern offshore Tunisia is highly controlled to the Miocene–Quaternary tectonic inversion. The sandy levels along the thick Tortonian section provided the most preferred target for petroleum exploration. They exhibit considerable variations in thickness controlled by Late Miocene to Quaternary tectonic trends.