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Ecostratigraphy, Climate Stratigraphy and Eutastic Signals of the Ceneozic Sediments, Niger Delta of Nigeria: A Key for Regional Exploration

Adojoh, Onema C.¹; Osterloff, Peter L.²
¹Earth of Earth Science, University of Plymouth, Plymouth, United Kingdom.
²Geosolution, Shell Petroleum Development Company, Warri, Nigeria.

High-resolution biostratigraphy have significantly improved routine sequence stratigraphic studies, which is controlled by factors such as eustacy, climate, orography, edaphic conditions, and depositional settings. This paper studies the distributions of palynomorphs across subset of 30 wells in the onshore and shallow offshore depobelts in order to obtain data highlighting the variability of species abundance trends with age (Pliocene - Eocene). Sixteen palaeoecological groupings were established from marine influenced realm to the onshore realm.

In the latest Eocene - mid Oligocene, the Northern Delta Depobelt wells suggest abundances of Operculodinium spp. (Marine Microplankton), Acrostichum aureum, (Mangrove Swamp), Striatricolpites catatumbus, Racemonocolpites hians (Fresh Water Swamp), Praedapollis flexibilis, Verrucatosporites usmensis (Lowland Rainforest), Retitriporites boltenhagenii, Proteacidites cooksonii (Savanna group).

During latest Oligocene - mid Miocene sequences in the Greater Ughelli Depobelt, dominance of Zonocostites ramonae (Mangrove Swamp), Praedapollis africanus (Lowland Rainforest), Verrutricolporites rotundiporis (Coastal Swamp), Retricolporites irregularis (Riverine), Psydrax subcordata, (Open Forest), Cicatricosisporites dorogensis (Montane), Retibrevitricolporites obodoensis, Monoporites annulatus (Savanna group) were observed along with fungal hyphae and brackish water algae across the Central Swamp Depobelt in the Middle Miocene wells suggests further subtle environment controlled changes.

During the Pliocene - Middle Miocene, Coastal Swamp and Shallow Offshore depobelts demonstrate similar evolution of Verrutricolporites rotundiporis, Echiperiporites estalae (Coastal Swamp), Zonocostites ramonae (Mangrove Swamp), Magnastriatites howardi, Nymphaea lotus type, Cyperus type, Pachydemites diederixi (Fresh Water Swamp). Each of these key taxa mapped into the depositional settings will ultimately refine existing depositional models, which will enhance the understanding of the depositional history that can be linked to the development of existing fields and future exploration campaigns on a regional scale.

 

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012