Dispersal Patterns of the Late Cretaceous to Early-Tertiary Sediments in the Southern Anambra Basin, Southeastern Nigeria
- 1 Department of Geoscience, Federal University of Technology, Owerri, Nigeria
- 2 Department of Geoscience, Federal University of Technology, Owerri, Nigeria
- 3 Department of Geoscience, Federal University of Technology, Owerri, Nigeria
- 4 Department of Geoscience, Federal University of Technology, Owerri, Nigeria
- 5 Department of Geoscience, Federal University of Technology, Owerri, Nigeria; First Exploration and Petroleum Development Company Limited, Ikoyi Lagos, Nigeria
Abstract
The dispersal patterns of the Late Cretaceous to Early Tertiary sediments in southern Anambra Basin were studied to delineate spatial facies distributions for improved mapping and hydrocarbon prospectivity. Seven lithofacies distin guished from eleven outcrop sections aided the interpretation of depositional environments for the different depositional units. Interpreted paleoenvironments ranged from estuarine/lagoonal to tidal delta and shallow marine depositional en vironments. Sequence stratigraphic interpretation of the deposits using vertical relationships between the delineated facies and foraminiferal and palynofacies assemblages and the interpreted environmental setting identified two com p lete sequences (SEQ-1 and -2) and two incomplete sequences (SEQ-3 and -4) in the study area. The sequiences are enveloped by three Type-1 Sequence Boundaries (SB), two Transgressive Surfaces of Erosion (TSE) and four Maxi mum Flooding Surfaces (MFS). The identified surfaces were used to delineate formation boundaries and as such would assist in the improved mapping of the Anambra Basin and adjoining depocenters. The massive sand units of the High stand and Transgressive Systems Tracts constitute good (potential) reservoirs, while the transgressive shales would con stitute seals for potential traps in the study area. The delineation of these petroleum system elements, especially those associated with the Transgressive and Highstand Systems Tracts has conferred great hydrocarbon prospectivity potential on the sedimentary sequences in the Basin. The absence of deep marine and slope complexes of the Lowstand Systems Tract (LST) in the interpreted sequences is indicative that the study area is the up-dip section of the Anambra Basin.
- C. S. Nwajide, “Anambra Basin of Nigeria-Synoptic Basin Analysis as a Basis for Evaluating Its Hydrocarbon Prospectivity,” In: C. O. Okogbue, Ed., Hydrocarbon Potentials of the Anambra Basin, Great AP Express Publishers Limited, Nigeria, 2005, pp. 1-46.
- G. J. Genik, “Petroleum Geology of Cretaceous-Tertiary Rift Basins in Niger, Chad and Central African Republic,” AAPG Bull, Vol. 77, No. 8, 1993, pp. 1405-1434.
- K. Burke, “Longshore Drift Submarine Canyons and Submarine Fans in Development of Niger Delta,” American Association of Petroleum Geologists, Vol. 56, No. 1, 1972, pp. 1975-1983.
- J. C. Van Wagoner, H. W. Posamentier, R. M. Mitchum, P. R. Vail, J. F. Sarg, T. S. Loutit and J. Hardenbol, “An Overview of Sequence Stratigraphy and Key Definitions, In: C. W. Wilgus, Ed., Sea Level Changes: An Integrated Approach, Society of Economic Paleontologists and Mineralogists, Vol. 42, 1988, pp. 39-45.
- C. M. Ekweozor, “Searching for Petroleum in the Anambra Basin,” In: C. O. Okogbue, Ed., Hydrocarbon Potentials of the Anambra Basin, Great AP Express Publishers Ltd., Nigeria, 2005, pp. 1-110.
- S. O. Onyekuru and C. J. Iwuagwu, “Depositional Environments and Sequence Stratigraphic Interpretation of the Campano-Maastrichtian Nkporo Shale Group and Mamu Formation Exposures at Leru-Okigwe axis, Anambra Basin, Southeastern Nigeria,” Australian Journal of Basic Applied Sciences, Vol. 4, No. 12, 2010, pp. 6623-6640.
- C. E. Bassey and A. O. Ojesina, “Sequence Stratigraic Interpretation of E-Bock in Western Offshore, Niger Delta, Nigeria,” Global Journal of Applied Science, Vol. 5, 1999, pp. 227-233.
- J. Neal, D. Risch and P. Vail, “Sequence Stratigraphy—A Global Theory for Local Success,” Oilfield Review, Vol. 2, No. 1, 1993, pp. 51-62.
- C. E. Okezie, “Geological Map of Nigeria,” Geological Survey of Nigeria, 1974.
- J. Benkhelil, “Structure and Geodynamic Evolution of Intracontinental Benue Trough (Nigeria),” Doctoral Thesis, University of Nice, ELF Nigeria, 1986.
- H. Doust and E. Omatsola, “Niger Delta,” In: J. D. Edwards and P. A. Santogrossi, Eds., Divergent/Passive Margin Basins, American Association of Petroleum Geologists, Tulsa, Vol. 48, pp. 201-238.
- O. J. Ojo, U. K. Ajibola and S. O. Akande, “Depositional Environments, Organic Richness and Petroleum Generating Potential of the Campanian to Maastrichtian Enugu Formation, Anambra Basin, Nigeria,” Pacific Journal of Scientific Technology, Vol. 10, No. 1, 2009, pp. 614-628.