Petrology and geochemistry of the Az Zabirah south zone bauxite deposit at Al Ba’itha mine, north-central Saudi Arabia

Abstract

In the central north of Saudi Arabia, outcrop samples from the Cretaceous bauxite profile deposits in the Az Zabirah area were subjected to a comprehensive evaluation aimed at investigating their petrographical and geochemical characteristics using X-ray diffraction analysis (XRD), Scanning electron microscope (SEM) coupled with Energy dispersive (EDS) analysis, and X-ray fluorescence spectrometer (XRF) analysis. These bauxite deposits in the Az Zabirah area comprises of three main zones: the South zone, the Central zone, and the North zone. Petrologically, the bauxite samples predominantly consist of oolitic to pisolitic grains that are bound together by a matrix comprising bauxitic materials, iron oxides, calcite, and/or kaolinite. Mineralogical investigations indicate that the primary mineral composition of the bauxite includes gibbsite, boehmite, diaspore (kaolinite), hematite, quartz, and calcite. XRF showed that the dominant chemical components of the bauxite samples are Al₂O₃, SiO₂, and Fe₂O₃. When considering the collective data from the rare earth elements (REEs) analysis (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and chemical weathering indices such as the Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Weathering Index of Parker (WIP), it becomes evident that the Az Zabirah South Zone bauxite laterite profile at Al Ba’itha mine was formed under the influence of significant and persistent weathering conditions. The findings and methods used in this study are considered beneficial and valuable as they support mineral exploration in arid and semi-arid environments.