Temporal and spatial changes of the submarine Cretaceous paleoslope in Northern Tunisia, inferred from slump folds analysis

Chahreddine Naji , Mohamed Gharbi , Zayneb Amri , Amara Masrouhi , Olivier Bellier (1)

1 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement

This paper presents the first comprehensive, non-exhaustive, study of the genetic relationship between slump folds and the synsedimentary paleoslope during Cretaceous time in northern Tunisia. Slump folds occur mainly in the Cretaceous marl-dominated lithofacies, which exposes numerous slump folds structures. In addition, fault kinematic analysis is conducted to define the paleostress fields and the stress states characterizing the Cretaceous extension that triggers soft-sediment deformation and slumping. The MAM and the APM methods are used to deduce the paleoslope in several localities. The calculated values of paleoslope trend derived from MAM and APM methods precise the variation of the paleoslope trend during Cretaceous times in northern Tunisia. This paleoslope is similar to NW-dipping during Berriasian, similar to SSW-dipping during Valanginian, similar to NW-dipping during the Barremian and similar to N- to similar to NNE or similar to S- to similar to SSW-dipping during Aptian-Albian period. The results of the back-tilted fault diagram show a North to Northeast-trending tectonics extension. The back-tilting of Cenomanian slump axis and poles of axial planes (MAM and APM methods) give close results with similar to Southward or Northward-dipping paleoslope. The restored fault diagrams show similar to North to similar to Northeast-trending extension during Cenomanian times. Coniacian-Santonian marls deposits seal all the gravity-driven deformation structures. North Tunisian area exposes evidences for abundant soft-sediment deformation and slumping atop a northward facing submarine slope, which was probably dominant from the Early Cretaceous to Santonian with similar to North-South tectonic extension related to the Southern Tethyan rifted continental margin evolution. (C) 2017 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.

Mots clés: Cretaceous; submarine paleoslope; slump folds; Tunisia

Domaines: Tectonique

Chahreddine Naji, Mohamed Gharbi, Zayneb Amri, Amara Masrouhi, Olivier Bellier. Temporal and spatial changes of the submarine Cretaceous paleoslope in Northern Tunisia, inferred from slump folds analysis. Proceedings of the Geologists' Association, 2018, 129 (1), pp.40-56. ⟨10.1016/j.pgeola.2017.10.006⟩. ⟨hal-01882007⟩