Petrography and geochemistry of beach sediments along the central coast of Cameroon: constraints on paleoweathering, provenance, and tectonic setting

Abstract

The paleoweathering, provenance, and tectonic setting of the source region were determined with compositional and geochemical analyses of sediments obtained from the beach locations of Yoyo, Mouanko, and Mbiako along the central coast of Cameroon. The beach sediments are medium to coarse-grained and are brown to light brown. Their mineralogy is dominated by quartz and clay minerals with a medium amount of feldspars, rutile, goethite, hematite, and calcite. Moreover, their petrography is made up of quartz and feldspars, with low proportions of augite, apatite, biotite, and zircon. The sediments are classified as sublitharenite, and they are mostly made up of felsic rocks derived from the adjacent Neoproterozoic magmatic and gneissic basement rocks. Weathering indices such as the chemical index of alteration (CIA) and plagioclase index of alteration (PIA) indicated that in this study, the source area’s weathering intensity was moderate. The index of chemical variability (ICV) indicates a low maturity. The geochemistry data revealed passive and rift settings for the beach areas, which are congruent with the local geology.