Unraveling the Mechanisms of Elemental Mobilization and Supergene Enrichment in Lateritization: An Experiment Study

Chemical weathering carves earth surface by elemental mobilisation and supergene enrichment. Laterization is one of such process. Laterites result from intense chemical weathering, dominantly in tropical and subtropical climates. Leaching of mobile elements results concentration of iron (Fe) and aluminum (Al) as oxides or oxyhydroxides. The selective mobilization and retention of immobile elements during extreme weathering provides valuable proxies for paleoenvironmental investigations. The enrichment of immobile elements (Fe and Al) in laterite is a dichotomy needing deeper mechanistic insights to understand the origin. To investigate the mechanism of elemental mobilisation and enrichment near earth surface, multiple sets of experiments have been conducted in this study. The effect of drainage conditions and organic ligands of soil have been investigated. Custom made experimental setup of rock leaching significant amount of iron mobilisation with oxalic acid, reaching upto 0.175 mg per day from 1 gm of basalt. SEM and TEM investigation of solid precipitates from the leachants confirmed amorphous Fe-phases. Deeper investigation from molecular perspective using X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR) are under progress to unveil the mineralogical mysteries with implication towards lateritisation. Furthermore, the integration of reactive transport modeling into these experimental frameworks aims to enhance our understanding of the diverse phases and associated complexes formed during weathering, thereby providing critical insights into paleoenvironmental conditions. This approach will also facilitate the simulation, how various factors influence elemental mobility and enrichment in lateritic profiles.