Heavy Minerals in Beach Sediments Along the Gulf of Guinea, Cameroon: Clues on Weathering Condition and Provenance

Abstract

A mineralogical survey was conducted in the Gulf of Guinea beach sediments to assess the transport history, depositional environment, weathering conditions, and provenance. Heavy mineral assemblages are abundant in augite, followed by opaque minerals, diopside, zoisite, enstatite, tourmaline, zircon, rutile, sillimanite, garnet, apatite, hornblende, epidote, kyanite, chloritoid, and staurolite. The variety of this minerals shows that the sands studied come from the igneous source rocks, mainly from a metamorphic source, in particular the gneisses and basalts, which is consistent with the geology of the study area. The bulk mineralogy detected using XRD and the chemical properties obtained by SEM–EDS reveals that the sands were dominated by quartz. Nineteen microtextures were observed on heavy minerals like hornblende, chloritoid, sillimanite, garnet, augite and staurolite, which were subsequently classified as mechanical (13 features), chemical (4 features), and combined mechanical and chemical (2 features) origins. The dominance of mechanical features suggests that the grains underwent high-energy transport. The abundance of angular and subangular heavy minerals indicate a nearby source. The mineral composition suggests that the source rocks underwent a moderate weathering. The sub-rounded and rounded heavy minerals indicate a long transport. The predominance of heavy minerals in sediments suggests that the nearby source rocks are rich in heavy minerals.