Abstract

Palynological analysis were performed on 49 samples of cuttings from the interval 6020' to 4460 ' of an oil well Dino -1x located on Abidjan offshore margin in Côte d'Ivoire. This study proposed a palynostratigraphy and inferred a depositional environment, of which 1,560 feet thickness ismainly of gray clays. The samples first described for a lithological synthesis were then subjected to conventional chemical treatment with strong acids. The interval consisted of dark-gray clay becoming slightly calcareous towards the top. Incidentally, the glauconite and pyrite were observed. Palynological species identified revealed three intervals namely Maastrichtian, Paleocene and Eocene. Vertical distribution of this palynoflora shows two depositional environments: the first of marine neritic type with predominantly marine dinocysts from Maastrichtian to the base of Eocene, and the second of nearshore type with dominant terrestrial spores and pollen (Upper part of Eocene). The poor preservation of dinocysts along the interval was interpreted as related to many factors (physical and chemical conditions). Presence of calcareous dinoflagellates assemblages indicates a relatively warmer climate from Maastrichtian to the base of Eocene and a colder one during Upper part of Eocene whereas pollen of palms suggested tropical humid climate.

Key words: Palynostratigraphy, palaeoenvironment, Maastrichtian, Palaeocene, Eocene, sedimentary basin, Côte d'Ivoire.