EARLY PALEOGENE DINOFLAGELLATE CYSTS FROM NIGERIA AND ODP HOLE 959D (LEG159): IMPLICATIONS FOR THE BIOSTRATIGRAPHY OF TROPICAL AREAS

 

Hernan Antolinez

Department of Geological Sciences and Engineering, University of Missouri-Rolla,

Rolla, Missouri USA

Email: [email protected]

 

A set of forty four samples from the early Paleogene interval of Alo-1 well in Anambra State, Nigeria and ODP Hole 959D (Leg 159) in the Côte d'Ivoire-Ghana Transform Margin were analyzed for their dinocyst contents. Dinocyst recovery is very good to moderate, and the specimens are commonly well preserved. The stratigraphic and quantitative data were compared with detailed and well calibrated dinocyst distributions from north-western Europe and southern Hemisphere, Tasmania and New Zealand.

Five informal zones (A to E) were identified in this study. Zone A is the stratigraphically oldest and is characterized by the consistent occurrence of Areoligera senonensis, Areoligera coronata, Palaeocystodinium bulliforme, and Hafniasphaera septata. Characteristic of Zone B is the occurrence of Damassadinium cf. D. heterospinosum in combination with abundant Fibrocysta/Lanternosphaeridium spp., and Cordosphaeridium spp. The dinocyst assemblages in zone C are characterized by the co-occurrence of abundant Apectodinium spp., and Adnatosphaeridium spp. Zone D consists of common occurrence of Glaphyrocysta ordinata, Glaphyrocysta divaricata, Polysphaeridium subtile, Spiniferites microceras, and Adnatosphaeridium spp. Finally, Zone E is characterized by the occurrence of Homotriblium abreviatum, Homotriblium cf. H. oceanicum, and H. pallidum.

Results from this study can have an impact on hydrocarbon exploration in tropical areas such as southeastern Nigeria and the Equatorial Atlantic where important hydrocarbon reservoirs occur in Paleocene and Eocene continental and marginal marine rocks and subsidence curves, thermal maturation histories and timing of oil migration rely heavily on ages directly derived from palynological zones.