Tectonic and sedimentary evolution of the Northern Cameroon Cretaceous rift basins: A study of the Babouri-Figuil and Mayo Oulo-Lere basins

Abstract

The Babouri-Figuil and Mayo Oulo-Lere basins located in Northern Cameroon are small elongated sedimentary asymmetric half-grabens associated with the development of the West and Central African Rift System (WCARS). The evolution of these basins began during the Precambrian pre-rift period and continued through the Late Jurassic - Early Cretaceous periods, although details of their development remain unclear. The aim of this study is to understand the evolution and development of the border faults and their control on syn-rift geometry, accommodation space, and the resulting stratigraphic architecture. Using a combination of multiples surface and subsurface well logs data, we demonstrate the relationship and evolution of various stages of rifting and the associated sedimentary architecture. The basin is composed of an alluvial to lacustrine succession that developed during its tectonic evolution. A 3-stage tectonic model is proposed for the evolution of the basin that uses fault propagation analysis to describe the sedimentary architecture and evolution of basin geometry. The three stages of the model are the early rift, rift climax, and late rift; here, the early rifting phase is marked by the reactivation of faults in the Lower Cretaceous. The rift climax phase resulted in the interconnection of small segmented border faults leading to the high rate of activation of major border faults and to the development of the half graben structure of the basins. The late rift stage is marked by a decrease in border fault activity and accommodation. Sediment distribution and the facies architecture are controlled by tectonic subsidence created throughout the rifting phases. The stratigraphic signature of the Babouri-Figuil and Mayo Oulo-Lere basins are punctuated by the lacustrine water transgression-regression cycles, and controlled by the balance between the rate of sediment supply and tectonic accommodation. The progressive change between overfilled to starved sedimentary architecture is illustrated by this stratigraphic succession. Additional age assessment and sub-surface data in future work could help confirm the structures identified on the surface.