Upper Albian planktic foraminifera and radiolarian biostratigraphy (Nebeur – northern Tunisia)

Preliminary lithostratigraphic and biostratigraphic data recovered from Upper Albian pelagic successions of the Jebel Srassif area (Tunisian trough) reveal the presence of a moderately well preserved radiolarian fauna. This fauna is fossilized in blackshale beds of Rotalipora subticinensis, R. ticinensis and the lower part of the R. appenninica foraminifer zones. Thirty-five radiolarian morphotypes were identified. A correlation established with foraminifer planktic biochronology allows us to distinguish three radiolarian assemblages. The close association between organic-rich deposits and the radiolarian bloom can be interpreted as productivity proxy triggered by semi-enclosed basin configuration and an intensified upwelling currents provided by a possibly halokinetic-induced hydrothermalism.