The geochemical study of the sequences of 3rd order of the East of the margin of Abidjan permitted to identify the source rocks of the albian deposits. The pyrolytic methods applied to 30 samples of cuttings, from the drillings Freedom 1 and 2, revealed three types of organic matter at the early of maturity, the types III, II/III and II in the sequences. The variation of the origin of the organic matter in the systems tracts of the sequences testifies a change in the environment of deposit in phase with the eustatic fluctuations. The passage from the type III or II/III to the type II, eventually coupled with a rise of the values of the TOC and/or S2, in this study, evokes a rise in the marine level which would support the good conditions of safeguarding of the organic matter. The albian source rocks in the drilling Freedom 1 are bad source rocks whereas those in the drilling Freedom 2 are good producing source rocks of oil and/or gas hydrocarbon.

The trace of the Lagoons’ Fault permitted to understand the distribution of bitumen in the onshore sedimentary basin in South-east of Ivory Coast. The bituminous formations met are made up mainly of bituminous sandstone which are sometimes associated with other bituminous formations (microconglomerats, sands, kaolins, glaucony, marly limestones and fossiliferous rocks). The bituminous sandstones are quartz wackes resulting from the consolidation of old quartzose sands by the bitumen. There are nano-vacuums between the grains quartz and the bitumen of these sandstones. This bitumen comes from the hydrocarbons which were formed in South of the Lagoons’ Fault in the surroundings of Eboïnda. They were spread by diffusion through paleo-beaches and communicating paleo-channels before reaching the layout of the Lagoons’ Fault and its satellite faults. It is thanks to these faults and to other communicating paleo-channels that the bitumen could migrate to North of the Lagoons’ Fault between Samo and Grand-Bassam even beyond on a distance of at least 75 km. The bitumen is trapped in the form of lenses in fluviatile paleo-channels and paleo-beaches located between Eboïnda and Grand-Bassam. The migration was done from East to West. The bituminous sandstones are in outcrop, subsurfaces and in the sublagoonals; that involves a contamination of soils, phreatic water table and lagoons surrounding.

The petrography of Miocene ferruginous muddy sandstones of Bingerville permitted to understand the transformation of muddy sands to muddy sandstones. The muddy sands lithification starts during the rainy seasons which distribute the iron hydroxides in the kaolin of muddy sands. During the evaporation of pore waters during the arid seasons, the iron hydroxides lose their water. These hydroxides are transformed into iron oxides supporting the transformation of muddy sands to muddy sandstones thanks to ferruginous cement. This cement derives from the total oxidation of the ochreous matrix. This matrix is a mixture of kaolinite and iron oxides. These muddy sandstones are quartz wackes with ferruginous cement. There are always nano-vacuums between the grains of quartz and ferruginous cement which surrounds them. These nano-vacuums are the spaces left after the evaporation of pore waters which surrounded the grains of quartz. Quartz of quartz wackes are transformed into iron oxides through their weakness zones. That is supported by the lot of iron oxides in the sedimentation environment. The muddy sands lithification of Miocene took place at Holocene thanks to their exposure in subaerial environment and/or aerial.