Study on the mineralogical and geochemical characteristics within sediments in southwestern Taiwan

Rare earth elements are important resources and they can be widely used in smart phones, electric vehicles, and smart home appliances, etc. Recently, countries around the world pay attentions to their own rare earth resources and set policies to cope with the country's future development. Therefore, rare earth resources have obviously become valuable strategic materials. Rare earth minerals are mainly occurred in placer depositions in Taiwan. The literature on rare earth resources in Taiwan is quite limited; there are only a few studies on the characteristics of heavy sand deposits, and only a few about the distribution of heavy minerals in southwestern Taiwan. Therefore, this study utilizes the drainage basin of Zengwun River (the upstream, midstream and downstream of the river) as the study site for rare earth resources in southwestern Taiwan. Using the sediments in the river and offshore as study samples, the systematic investigation on the properties of rare earth minerals in river sands and sea sands will be deeply studied. This study aims to investigate the relevant characteristics of rare earth resources (microstructure, types of rare earth minerals, and concentrations of rare earth elements, etc.) and to provide the comprehensive results pertaining to the potential placer rare earth ore in the drainage basin of Zengwun River of southwestern Taiwan. The XRD data indicated that the samples contained major minerals of quartz, feldspar, muscovite/illite, kaolinite, and chlorite; some minor minerals of rutile, calcite, and monazite (rare earth mineral). The SEM results showed that these monazites can be divided into detrital and aggregated monazites. The aggregated monazite presented two different occurrences. Type I aggregated monazite displayed a skeletal morphology associated with quartz and feldspar inclusions. Type II aggregated monazite was symbiotic with allanites or TiO₂ polymorphs. The REE concentration in this study area will be evaluated and compared with the UCC average and active REE mining countries.