Evaluation of provenance and weathering of beach sediments in the lower part of the Cameroonian coast
Arcange Duviol Tsanga, Armel Zacharie Ekoa Bessa, Gabriel Ngueutchoua, Gerardine Saurelle Ngokam, Same Moutongo Jacques-David, Victorine Ambassa Bela, Annick Kwewouo Janpou, Mohamed Abioui, John S. Armstrong‐Altrin
Abstract
The hinterland of Campo is marked by Archean, Paleoproterozoic, and Cretaceous geological formations. Petrographic, mineralogical and geochemical analyzes of beach sediment samples were performed to determine the origin, alteration, and paleoclimate of the various coastal sediment layers and to reconstruct the structural context of the source region. The beach sediments are fine to medium-grained in size. Morphoscopic examination showed a predominance of very angular and shiny quartz grains. These data reflect a relatively close source with transport in a fluvial environment. The Chemical Index of Alteration (CIA: average = 79.94%), Plagioclase Index of Alteration (PIA: average = 85.31%), as well as the A–CN–K and (A-K)-C-N triangular diagram, show that the weathering affected the source area rocks. The ratios of SiO2/Al2O3, K2O/Na2O, and the chemical composition variation index (ICV ∼ 1.32) show that the sediment samples are immature to mature in terms of texture and chemical composition. Al2O3/TiO2 ratio values ranged from 3.04 to 33.44, indicating an intermediate to felsic rock signature, confirmed by Zr vs TiO2, La/Sc, and Th/Co binary diagrams. Geochemical results reveal a passive marginal continental environment. The passive margin emerged during the opening of the South Atlantic Ocean, which is compatible with the overall geology and structural setting of the studied area.