La Lobe Early Cretaceous fan-delta (Cameroon Atlantic basin)

Abstract

From the Campo onshore to the Malabo-Victoria volcanic line, the Cameroon Atlantic Basin comprises two main segments: the Ekité-Kordofan transform-fault basin and the Wouri-Yassem deep-graben structure separated by the Yassoukou-Tissongo-Ossa reverse fault. The major morphologic features of the Ekité-Kordofan transform-fault basin are Kribi-Campo half-graben and the Elombo-Nkoundou internal shear zone. Detailed analyses of long offset pre-stack depth migrated seismic sections enabled mapping of buried fan-delta at approximately 20 km southwest of the Kribi-La Lobe river mouth. The fan is up to 25 km wide, 4km thick and is morphologically expressed in the form of bank clinoform sequences. By correlation of seismic records with borehole data from adjacent areas, it appears that the fan is divided in two morphologic divisions (upper and lower fan). The lower fan uniformly returns transparent weak seismic record, with intermittent internal reflections. In contrast, the upper fan is characterized by acoustically high amplitude clinoform reflections. Within this package, listric growth faults are common, and the fan tends to mound up were salt domes are present beneath Bedoulian-Aptian boundary. These results opened up Aptian-Albian fan-delta play of the Cameroon Atlantic Basin and help to introduce new hydrocarbon concepts and exploration opportunities.