Biostratigraphy of the Numidian Formation and its underlying Tellian unit, based on calcareous nannofossils in Northern Tunisia: Implication on their stratigraphic vs. tectonic relationships

Ilef Belhajtaher, Emanuela Mattioli, Mohamed Soussi, Najeh Ben Chaabane

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A detailed biostratigraphic study, based on calcareous nannofossils, was performed to re-evaluate the stratigraphic interpretation of the Numidian Formation and its structural relationship with the underlying El Haria, Boudabbous and Souar formations Tellian units (i.e., stratigraphic vs. tectonic). The new biostratigraphic results indicate that the Numidian Formation is not restricted to a Miocene age as considered in some recent works but spans from Oligocene (Rupelian and Chattian, NP23 to NP25) to early Miocene (Aquitanian and Burdigalian, NN1 to NN3). The Cap Serrat succession can be retained as the type section for the Tunisian Numidian Formation, where both the Chattian-Aquitanian (Oligocene/Miocene boundary) and the Aquitanian-Burdigalian transitions have been characterized. Based on the new calcareous nannofossil findings, several duplications of the sedimentary succession were identified. They include the thick shales and marls of El Haria (Maastrichtian-Paleocene) and Souar (Eocene) formations, thrusted by the Numidian Formation. The updated regional structural cross-sections, confirm that the Numidian Formation is currently juxtaposed by southward major thrust contact to the underlying Kasseb structural unit in the studied area. The latter is intensively affected by poly-phased tectonics, resulting in the thrust events associated with the Alpine phase inversion. This has to be taken into consideration in oil and gas exploration in the area of the fold-thrust belt system, in both onshore and offshore Northern Tunisia.
Original languageEnglish (US)
Pages (from-to)104896
JournalJournal of African Earth Sciences
StatePublished - Mar 2 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-03-15
Acknowledgements: This study is part of the ongoing Ph.D. work of IB which is in the frame of collaboration between the University of Tunis El Manar (Sedimentary Basins and Petroleum Geology) and the Claude Bernard University (Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement). Our sincere thanks go to Dr. Riahi Sami for his assistance during the investigation of the Oued Jabeur/Sidi Chaieb section. We also thank Drs K. Boukhalfa and K. Laridhi for the constructive discussions on the same section, Alessandro Menini for fertile exchanges on nannofossil taxonomy, Ali Kchira and Abdelbasset Tounekti for their technical assistance and fruitful discussions. We thank Dr. Dhouha Jomaa Salmouna for the English improvement of the Manuscript. We are grateful to the three anonymous reviewers and the Editor for their constructive and helpful comments that greatly improved the manuscript. This work is funded by the Minister of High Education and Research of Tunisia. It is dedicated to the soul of Manel Chnayna, a Ph.D. student in our laboratory, who died on December 31, 2022.


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