Scanning Electron Microscopy (SEM) Character of Metamorphic-hosted Bauxite Mineralization in Eastern Taurus Orogenic Belt

Abstract

One of the main tectonic belts in Türkiye is the Taurus Orogenic Belt, where significant bauxite mineralizations are observed. The bauxite deposits in Doğanşehir (Malatya, Türkiye) occur as massive bodies and lenses within the carbonate rocks of the Permian-Triassic Malatya Metamorphics in the Eastern Taurus Orogenic Belt. The region’s geological foundation comprises lithologies belonging to the Malatya Metamorphics. This unit consists primarily of schists, calc-schists, and marble, which are overlain by the Late Cretaceous-Eocene Berit Metaophiolite, Eocene Maden Complex, Early-Middle Eocene Doğanşehir Granitoid, and Plio-Quaternary cover sedimentary units. Oolitic and pisolitic bauxite mineralizations are present within the Permian-Triassic carbonate rocks (Malatya Metamorphics). These mineralizations occur in carbonate rocks that contain fossils and are observed in the form of lenses. The bauxite lenses are overlain by relatively thin, middle-layered Permian-Triassic carbonate rocks (Malatya Metamorphics). With the advancement of technology, Scanning Electron Microscopy (SEM) has been used for the analysis of bauxite ores to determine the presence of elements within their crystal lattice structure. The point analysis and mapping method were employed to identify the elements that could be present within the crystal lattice structure of the bauxite ores. The SEM analysis of the samples using the mapping method revealed the distribution of Fe, Ti, Si, Al, and O elements before and after activation. The images indicate that bauxite exhibits a broad grain distribution, both below and above 50 um. The elemental spectrum diagram shows the presence of O, Al, and Si in the sample. Additionally, Fe, Ti, C, K, and Mg were also detected. Using SEM analysis of the same samples and the mapping method, the distribution of Fe, Ti, Si, Al, and O elements in the structure was examined before and after activation. As seen from the images, the elements Al, O, and Si exhibit high density in certain areas before activation show a more homogeneous distribution and similar structures after activation. Fe, Mg, and K display a similar distribution pattern, while Ti and C exhibit different characteristics.