Mineralogical and Geochemical Features and Multistage Formation Model of the Verkhneashutskoe Karst Bauxite Deposit (Kazakhstan)

This paper presents the results of a comprehensive mineralogical and geochemical study of karst bauxites in the Verkhneashutskoe deposit (Amangeldy district, Kazakhstan). Modern analytical methods (X-ray fluorescence analysis, scanning electron microscopy with energy-dispersive spectroscopy, synchronous thermal analysis, and infrared spectroscopy) were used to investigate the material composition, textural and structural features, and formation conditions of ores. The GIS modeling established the fundamental role of the karst paleorelief as the main ore-controlling factor. The influence of organic matter (lignites) on the Fe redistribution and the formation of high-quality bauxites and refractory clays were revealed. The presence of biogenic forms of gibbsite and hematite is shown. A model for the multistage formation of the deposit is proposed, integrating the processes of lateritic weathering, karst formation, sedimentation, and diagenetic transformation of the sediment.