ORIGIN OF CONTINENTAL SEDIMENTARY BASINS IN CAMEROON. CASE STUDY: KOUM BASIN

ABSTRACT

Cameroon is underlain by Precambrain rocks, cretaceous sediments and Cenozoic sedimentary  and volcanic formation. Large parts of the Precambrian are undifferentiated gneisses and migmatite. The continental sedimentary basins in Cameroon owe their origin to the opening of the South Atlantic. These were formed during geodynamic processes between the period of Cretaceous to the Neogeene. In northern Cameroon the sedimentary facies of the Cretaceous is mainly continental.

This study is a contribution to the planning of hydrocarbon exploration program of the Koum sedimentary basin in North Cameroon.The Koum basin confirms that the basin is developed as a half graben bounded by sub-vertical faults. The thickness of the Cenozoic sediments is about 1.5 km in the eastern part and reaches 4.5 km in the western part of the basin.

The Koum basin is one among numerous Northern Cameroon intra-continental rifts which belong to the West and Central African Rift Systems (WCARS). The lithostratigraphic unit comprises an association of alternating sequences of sandstones, marlstones and shales. The basin lies unconformably on a plutonic and metamorphic Neoproterozoïc basement. Lithofacies of this unit contain fossils such as dinosaur footprints, bivalves, conchostracans, ostracods, insects, ichnofacies, silicified wood and other plants fossils. The basin which measures about 4300 m thick has regionally been deformed into a monoclinal structure with the occurrence of localized syn-sedimentary deformational structures. The strike of beds trends at N92°E, with an average dip of 12° towards the north. The facies association of the Koum basin indicates deposition in a fluvio-lacustrine paleoenvironment. The formation is cross-cut by volcanic rocks.

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