Characterization of Metapelite and Metasiltstone as Uranium-REE hosted rocks in Rirang Area, West Kalimantan

Abstract

The Rirang River, Kalan, West Kalimantan has U and REE resources in the form of mineralization found at the intercalation of metapelite and metasiltstone. However, there are only a few studies about the characterization of U and REE-bearing host rocks in Indonesia. Determining the geological influence of the metasedimentary rock on the mineralization of U and REE is crucial. Thus, the characterization of metapelite and metasiltstone has been substantiated in this study to reveal the potency of the host rock in hosting the U and REE. Petrographic, micro-XRF, and AMICS methods were used to conduct mineralogical analysis. These two rocks share a mineral composition that includes clay minerals, hydrothermal alteration products, and several minerals that indicate metamorphism processes. The foliation structure with a spotted shale texture further indicates the metamorphism process in metapelite and metasiltstone. REE and trace elements associated with U are constituents of clay minerals such as wonesite, staurolite, montmorillonite, chlorite, illite, and kaolinite. The geochemical properties of metapelite and metasiltstone suggest that REE mineralization and trace elements associated with U come from hydrothermal alteration processes.