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Title: A preliminary analysis of the basement structure of the Cenozoic Niger Delta basin : insights from high-resolution potential field data
Author: Onuba, Leonard Nnaemeka
ISNI:       0000 0004 6353 2127
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2016
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The crustal structure beneath the Cenozoic Niger Delta Basin has remained controversial and a challenging problem for regional basin evaluation. The high-resolution potential field data were evaluated using analytical, statistical and 2D forward modelling techniques with the aim of developing a better understanding of the origin and nature of the crustal structure and the location of the continent-ocean boundary (COB) within the Niger Delta. The analytical evaluations suggest that basement lineament trends of NE-SW, NNE-SSW and NW-SE in the study area are similar to the trends of the Pan-African events/orogeny (< 800 Ma). Two new intra-basement features were recognized, the Udi-Burutu and the Okigwe-Middleton intra-basement features, which provide fresh insights into the crustal nature of the Niger Delta. These features could have influenced the main boundary faults that provide migratory pathways for hydrocarbon or hydrothermal fluids. Mapping of the basement using a statistical method indicates that the thickness of the Cenozoic sediments varies from 10 km to less than 6.5 km with an average of 8 km. The average heat flow value (67 mWm⁻²) calculated in the Niger Delta area from geothermal gradient data, and thermal conductivity data lies within the average global heat flow for a typical continental crust. The 2D forward models show that the crustal thickness varies from 12 km at Okigwe area (NE) to about to about 24 km beneath Patani area at the centre of the delta to 12 km at Pennington area (SW) near the coastline of the delta. The depth to Moho estimated in the study area ranges from about 24 km at Okigwe area to more than 30 km at Patani area and to about 25 km at Pennington area. The Okigwe and/or Pennington area could mark the start of hyper-extended/transitional crust that lies beneath the Niger Delta. Thus, it is hereby suggested that the onshore Niger Delta Basin generally is underlain by thin continental crust and not oceanic crust as previously argued and the COB is observed at the offshore segment of the delta. This implies that the Onshore-offshore portion of the Niger Delta is underlain by the continent-ocean transition (COT) structure. The crustal structure of the Cenozoic Niger Delta Basin suggests post-rift stage characteristics similar to the pure shear model mechanism for the evolution passive continental margins. In reconstruction of the South Atlantic, the Chain and Charcot fracture zones beneath the Niger Delta exhibit dextral shear movement thereby suggesting a right-angled bend connecting Africa and South America continental margin due to pre-existing stress patterns within this part of Gondwanaland.
Supervisor: Not available Sponsor: Tertiary Education Trust Fund (Nigeria) ; Anambra State University
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Geology ; Stratigraphic ; Basins (Geology) ; Niger River Delta (Nigeria)