AEROMAGNETIC ANOMALIES AND DISCORDANT LINEATIONS BENEATH THE NIGER DELTA - IMPLICATIONS FOR NEW FRACTURE-ZONES AND MULTIPLE SEA-FLOOR SPREADING DIRECTIONS IN THE MESO-ATLANTIC GULF OF GUINEA CUL-DE-SAC

An aeromagnetic contour map compiled over shallow water and onshore portions of the Nigerian continental margin, shows several elongate, long-wavelength anomaly closures with some alternating polarity, separated by steep gradient, NE lineations. The lineations are interpreted as new fracture zones or extensions of previously mapped ones. The NE trend in the western delta region is concordant with the fracture zone trends of the deeper Gulf of Guinea. Aeromagnetic lineations of the SE Niger Delta Basin however, discordantly trend ENE. Their termination against the former, is interpreted as evidence of early sea-floor spreading in a ENE-WSW direction in addition to the well documented NE-SW spreading of the Gulf of Guinea and the rest of the "meso-Atlantic" sea-floor. The geophysical crustal structure indicate the existence of two Early Cretaceous triple junctions beneath the Niger Delta Basin. The two triple-junctions further support the hypothesis that the African continent was a multi-plate system (in the Niger Delta region) during the early opening of the Atlantic.