Arfaoui, A.,  Soumaya, A.,  Ben Ayed, N.,  Delvaux, D.,  Ghanmi, M.,  Kadri, A. & Zargouni, F. 2017. ‘Role of strike-slip fault system in structuring of Northeast Tunisia; geodynamic implications’. Journal of African Earth Sciences. Elsevier. DOI: 10.1016/j.jafrearsci.2017.01.013. URL: http://dx.doi.org/10.1016/j.jafrearsci.2017.01.013  I.F. 1.326.

Article in a scientific Journal / Article in a Journal

Two major compressional events characterized by folding, thrusting and strike-slip faulting occurred in the Eocene and Late Miocene along the NE Tunisian domain between Bou Kornine-Ressas-Msella and Cap Bon Peninsula. Using existing tectonic and geophysical data supplemented by new fault-kinematic observations, we show that Cenozoic deformation of the Mesozoic sedimentary sequences is dominated by first order N-S faults and a sinistral wrench system responsible for the formation of strike-slip duplexes, thrusts, folds and grabens. Following our new structural interpretation, the two major faults of Bou Kornine-Ressas-Msella (MRB) and Hammamet-Korbous (HK) form an N-S first order compressive relay within a strike-slip duplex. The N-S master MRB fault is dominated by contractional imbricate fans, while the parallel HK fault is characterized by a trailing of extensional imbricate fans (i.e., Nabeul graben). The Eocene and Miocene compression phases in the study area caused sinistral strike-slip reactivation of pre-existing N-S faults, reverse reactivation of NE-SW trending faults and normal-oblique reactivation of NW-SE faults, creating a NE-SW to N-S trending system of east-verging folds and overlaps. The MRB major strike-slip system is dominated by positive flower structures, overlaps and some NW-trending rifts such as the Mornag graben while the HK strike-slip system is associated with NW-trending rifts as the Grombalia and Nabeul grabens along both their northern and southern edges and negative flower structures. Within the central compressional relay, the seismic profile shows ENE trending Eocene reverse faults. In this context, the NW-SE SHmax trajectory was reoriented in the contractional duplex to become perpendicular to major strike-slip of MRB and form the main submeridian thrusts and folds in this region. Existing seismic tomography images suggest a key role for the lithospheric subvertical tear or STEP fault (Slab Transfer Edge Propagator) evidenced below this region on the development of the MRB and the HK relay zone. The presence of extensive syntectonic Pliocene on top of this crustal scale fault may be the result of a recent lithospheric vertical kinematic of this STEP fault, due to the rollback and lateral migration of the Calabrian slab eastward.