Ferriplantites in the Bauxite-Bearing Lateritic Weathering Rocks (Futa Jallon-Mandingo Province, Africa): The Key Factors for Iron Accumulation

摘要

Investigation of the comprehensive geological material on the lateritic weathering rocks (Futa Jallon-Mandingo, Africa) led to original identification of a specific horizon of ferruginous laterites, namely ferriplantites, which lie between bauxites and saprolites. For these ferriplantites, the morphology, prevalence, physical and mechanical properties, as well as chemical and mineral composition were characterized. According to the results obtained, ferriplantites are formed under the influence of oxygen-containing surface waters; thus, ferriplantite beds should appear quite regularly in weathering profiles at the level of ground water table fluctuations. Therefore, it is possible to use ferriplantites as an indicator of oxygen-rich hydrological settings that indicate and determine the direction of the development of the lateritic weathering profiles.