Tropical chemical weathering of a garnet rich micaschist in the rainforest zone of Cameroon

Abstract

Article Info Received : 22.03.2016 Accepted : 17.05.2016 Soils developed on garnet-rich micaschist in the Southern Cameroon plateau were investigated. Morphologically, two weathering materials constituted the study profile, fine earth and nodules. Each material has a singular evolution from the coarse saprolite to the upper set of clayey and loose horizons. There is Al2O3 enrichment in the fine earth concomitantly to Fe2O3, Na2O and K2O enrichment in nodules in major elementAl2O3 variation diagrams. A-CN-K and A-CNK-FM diagrams show a progressive depletion of Al in nodules concomitantly to an enrichment of this element in the fine earth. Three pedogenetic processes emerge from the evolution of weathering products. There is a ferruginization process whose importance increases from the coarse saprolite to the upper set of clayey and loose horizons, giving rise to the formation of dense nodules composed of hematite, goethite and gibbsite. This ferruginization occurs concomitantly with a desaluminization process, which causes Al2O3 depletion in nodules. These nodules are formed by the process of induration where the hydrated amorphous hydroxide and oxides are dehydrated to their crystalline oxide form, due to condensation. In addition, there is aluminization, which occurs in the fine earth, leading to the development of a red clayey material composed of kaolinite and gibbsite.

Chemical weathering in hardened volcanic horizons (tepetates) of the State of Mexico

“…Tzozué y Yongue-Fouateu (2017) reported that the Mineralogical Index of Alteration (MIA) is used to evaluate the mineralogical weathering degree. The values obtained in profiles 1, 2, and 3 (Table 4) indicate that the mineralogical alteration is incipient, while in hardened horizons of profiles 4, 5, 6 and 7 it is considered as weakly developed (Tsozué and Yongue-Fouateu, 2017).…”

Assessment of Soils Developed on Various Formations in Maroua (Far North, Cameroon) for Production of Compressed Earth Bricks

“…According to [1], soils are a result of the influence of climate, topographic factors, organisms, and parent materials that interact over time. They repeatedly undergo maturity by way of numerous physical, chemical, and biological processes, including weathering with associated erosion [2] [3]. As reported by [4] [5] [6], most minerals in the soil originate from the bedrock, and their spatial distribution is significantly influenced by this bedrock.…”