Palynostratigraphy of the numidian flysch of Northern Tunisia (Oligocene‐early Miocene)

Abstract

Diverse and relatively well preserved palynological assemblages from five outcrop sections sampled in the Numidian Flysch of northern Tunisia are presented and discussed. They provide valuable information for age determination and correlation within the Numidian succession. The dinoflagellate cyst zonation scheme of Wilpshaar et al. (1996) for the Oligocene through earliest Miocene of the central Mediterranean area is successfully applied. The basal portion of the Numidian Flysch, which exhibits a faulted contact with the underlying units, crops out in the El Gassaa and Tabarka sections and is dated as early Early Oligocene (Areosphaeridium diktyoplokum‐Reticulatosphaera actinocoronata Zones of Brinkhuis and Biffi, 1993), thus definitely older than previously inferred on the basis of scarce foraminiferal faunas. The youngest beds analysed in the Cap Serrat section are dated as Aquitanian in age (Membranilarnacia ?picena Zone of Brinkhuis et al., 1992) but, as the topmost portions of the Cap Serrat and Ras El Korane sections comprise palynologically barren sandstones and conglomerates cut by the topographic surface, accurate biostrati‐graphic information concerning the top of the Numidian Flysch is still lacking. Dinoflagellate cyst distribution in the examined sections suggests that the first appearance of Tuberculodinium vancampoae may be used as a confirmatory event for recognition of the Reticulatosphaera actinocoronata Zone of Brinkhuis and Biffi (1993) in the Early Oligocene at low paleolatitudes, whereas the extinction of Wetzeliella gochtii may be used for recognition of the Chiropteridium lobospinosum Zone of Wilpshaar et al. (1996). Furthermore, the first appearance of the trilete spore Magnastriadtes howardii Germeraad, Hopping & Müller 1968 and the abrupt increase of bisaccate pollen prove to be locally important for the delimitation of the Eocene/Oli‐gocene boundary.