Structural Characterisation of the Nigerian Sector of the Dahomey Basin using Geopotential Field Attributes
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Date
2014-03
Authors
Oladele, S.
Ayolabi, E. A.
Olobaniyi, S. B.
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Abstract
The structural dispositions of the Nigerian sector of the Dahomey Basin have been investigated
using attributes of geomagnetic and gravimetric fields. Aeromagnetic anomalies were reduced to
the equator to improve the correspondence of the anomalies with the causative bodies. The residual,
upward continued, Analytic signal, tilt and horizontal derivatives, and pseudogravity transformation
of geopotential attributes and forward models of both geomagnetic and gravimetric anomalies were
computed to accentuate geological features including regional faults and fracture network,
basement block pattern and depth to magnetic basement. The results show that the basement of the
Dahomey Basin ranges from continental to oceanic crust. Some shallow and deep structural
lineaments show significant degree of correlation suggesting that some deep lineaments propagate
to the surface. Sinistral and dextral faults were mapped. The dominant trends of structures are the
NE-SW, NW-SE, N-S and E-W trends. Basement architecture is essentially of horst and grab en
architecture with Lagos and Badagry grabens-which straddle the coastline- showing high petroleum
prospectivity in that they host significantly thick sediments. Two NE-SW deep seated regional
fracture zones extending from the Atlantic Ocean demarcate the western and eastern boundary of
the basin. Possible release of stress along these regional fractures may trigger trembling in the
subsurface. The implication is that this region may not be totally immune to earthquakes. The
geometry of the coastline; Lekki and Lagos Lagoons were suspected to have been influenced by
reactivation of Pan African weak zones. Major surface features are deduced to be structurally
controlled. Maximum depth to magnetic basement in parts of the grab en is interpreted to be 6387
m. This study has shown the capabilities of geopotential filed attributes in imaging the structural
plumbing of sedimentary basins. This knowledge will aid the understanding of the geology of the
basin and its resources.
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Keywords
Structural characterisation , Benin Basin , Nigeria
Citation
Oladele, S., Ayolabi, E. A. and Olobaniyi, S. B. (2014), Structural Characterisation of the Nigerian Sector of the Dahomey Basin using Geopotential Field Attributes. Being a paper presented at the 50th Annual International Conference and Exhibitions