Genesis of Clastic Dykes and Soft-Sediment Deformation Structures in the Mamfe Basin, South-West Region, Cameroon: Field Geology Approach

Abstract

This paper aims to investigate the genesis of clastic dykes and soft-sediment deformation structures in the Mamfe Basin, South West-Region, Cameroon. Results from this study portray the following: (1) The clastic dykes are extrusive and were generated from preexisting soft-sediments that penetrate fissures caused by seismic activity. It can be concluded that clastic dykes originate from seismic shacking, probably induced by volcanic-tectonic activity and magmatic dykes that cut across the Precambrian and Cretaceous formations of the Mamfe Basin. (2) The soft-sediment deformation structures (flexures, sheared foliations, anticlinal folds, load casts, and flame structures) are likely triggered by seismic shocks. The inferred influence of seismic activity results from rifting and rapid subsidence of basin-fill during the Cretaceous. Some of these soft-sediment deformation structures (SSDS) are induced by fluidization and liquefaction triggered by rapid sedimentation within tectonically active settings, as well as density variations illustrated by local occurrence of load casts with weak lateral extensions. (3) The synsedimentary features (joints, faults, filled fractures) are related to local stress triggered by gravitational sliding, because the fractures were filled by unconsolidated clastic materials.