Mineralogy and geochemistry of the Ossa lake Complex sediments, Southern Cameroon: implications for paleoweathering and provenance

Abstract

This study investigates the provenance, paleoweathering, and paleoclimate of the Ossa lake sediments, based on the mineralogy and geochemistry data. Ossa lake sediments are characterized by silt and clay with high content of total organic carbon (TOC). Clay minerals are identified as kaolinite and illite types. Other dominant minerals identified are quartz, zircon, rutile, goethite, gibbsite, feldspar, and accessory vivianite. The major, trace, and rare earth element concentrations indicate that the sediments were derived from felsic rocks, such as gneisses and granitoids. The tectonic discrimination diagrams revealed an active margin setting. Weathering indices such as the chemical index of alteration (CIA), the plagioclase index of alteration (PIA), and chemical index of weathering (CIW) suggest intense chemical weathering in the source area. K2O/Na2O ratio and index of compositional variation (ICV) are consistent with high maturity of the sediments. The mineral assemblages and trace elemental ratios and climatic index “C” of the Ossa Lake sediments suggest a warm to semi-humid climate and deposition in an oxic shallow environment.