Abstract:
The global REE deposits are mostly associated with carbonatites, alkaline igneous rocks, ion
adsorption clay deposits and placers. In this context, previous geochemical studies of alluvial
beds in Sri Lanka have disclosed significant concentrations of REEs. Moreover, the Walawe
river basin is located at the boundary between Highland Complex and Vijayan Complex,
which is a highly mineralized belt. Therefore, this study is focused on assessing the REE
potential of stream sediments in Samanala-wewa reservoir and its upstream and
downstream areas (i.e. Walawe river basin). The collected samples (n=26, covering 9
locations associated with Walawe river, Belihul Oya, Hiriketi Oya and Denagan Oya) were
processed (< 63 μm grain size) and analyzed using XRD to identify their mineralogy.
Monazite, bastnaesite, loparite and xenotime are the major RE minerals found in these
samples. Additionally, the sampling locations were confined to six stream paths and a
correlation was found between the stream order, and the number of REEs present at the
location. Overall, this study provides a qualitative interpretation of the REEs present in the
stream sediments of the study area. However, detailed quantitative analyses are required to
further assess the true REE potential in this prospect.
