Jurassic radiolarian-bearing series of Tunisia: biostratigraphy and significance to western Tethys correlations

Abstract

International audienceSince the 1970s, radiolarians have been used extensively to study and characterize basin successions from the peri-Mediterranean regions. However, no data was ever produced in Tunisia in spite of the occurrence of Jurassic siliceous series previously described by many authors. Our study presents the biostratigraphical results obtained on sections from the Jédidi Formation, which characterizes the basinal series of the Tunisian Trough. We provide new direct age determinations from the base, the middle part and the top of the formation, which ranges from the latest Bajocian–middle Bathonian to the Oxfordian (Tethyan biozones UAZ 5-6 to 8-9). The onset of these radiolarianbearing series of the Tunisian Trough, adjacent to partly coeval Ammonitico Rosso successions, is interpreted as resulting from regional palaeotopographical gradient and palaeoceanographical conditions. Inaccurately interpreted as “true” radiolarites, theses series are different from coeval radiolarites of the Maghrebian “Dorsale calcaire” and from more recent homologous deposits of the Flysch domain. They are instead correlative with series exposed in the Babors and the west-Numidian ranges of northern Algeria that belonged to the same Jurassic North African margin of western Tethys. During Alpine convergence s.l., this external domain was overthrust by nappe complexes of the Maghrebide inner zones and the Flysch domain units

Integrated biostratigraphy and regional correlations of Upper Jurassic–lowermost Cretaceous series in northern Tunisia

“…and Hybonoticeras hybonotum (Oppel) were registered. All these data are in accordance with the lower Tithonian H. hybonotum Zone, the lower part of which could (Boughdiri et al 2007). 1, nodular limestone; 2, siliceous marls; 3, siliceous limestone; 4, limestone.…”

“…Tazega of J. Lanasarine ( Fig. 1; Boughdiri et al 2007). At J. Jédidi and J. Chaabane, the sections are predominantly composed of thick red pelites alternating with thinly laminated siliceous limestone, dark brown to brick red with tints of yellow and green.…”

Cretaceous paleomargin tilted blocks geometry in northern Tunisia: stratigraphic consideration and fault kinematic analysis

“…The present-day structure of the Northern African margin in Tunisia results from a complex tectonic 31 evolution that operated since late Permian with the beginning of the breakup of Pangea and ended 32 with the Cenozoic Alpine orogeny of the Maghrebide chain. The geodynamic evolution of the 33 northern margin of Africa has been characterized by extension, crustal stretching and thinning, as 34 well as subsidence during the Mesozoic Tethyan rifting (Boughdiri et al, 2007;Gharbi et al, 2013;El Amari et al, 2016;Soussi et al 2017, Naji et al, 2018. The Mesozoic passive margin, where rifting 36 occurred, was followed by subsequent inversion during Late Cretaceous-Cenozoic subduction and 37 ended by Alpine collisional process (De Lamotte et al, 2009;Khomsi et al, 2016).…”

The Albian oceanic anoxic events record in central and northern Tunisia: Geochemical data and paleotectonic controls

“…In central and northern Tunisia, the Albian to Cenomanian successions are represented by cyclic alternations of thinly laminated carbonates with marls and shales that form the Fahdene Formation (Burollet, 1956). Tectonically, the Early Jurassic rifting phase in the southern Tethyan margin (Northern-central Tunisia; Boughdiri et al, 2007) was characterized during this period by the reactivation of the NE-SW to E-W ante-Latest Albian deep-seated structural accidents associated with evaporite Diapir movements and local tilted blocks (Burollet and Ellouz, 1986;Martinez et al, 1991;Zouari et al, 1999). The resulting basin was filled by organic-rich deposits, in association with a sea level rise and hyper silicious conditions, features that typify the Tethys Realm during Albian-Cenomanian times (Racki and Cordey, 2000).…”