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Geochemical mapping of river sands in the Manufahi area of Timor-Leste revealed potential areas for future mineral exploration. River sand samples from the study area were collected and geochemically analyzed to identify anomalous concentration distributions of several valuable elements and locate potential target areas and geological formations that may host mineral deposits. The 26 major and minor elements were identified using wavelength-dispersive X-ray fluorescence. The river sands exhibited varying elemental concentrations, with Cr, Cu, Zn, and Ba showing deviations from the normal distribution patterns. Identification of geochemical anomalies is an important task in mineral exploration geochemistry. The mean+2 standard deviations (mean+2STD), median+2 median absolute deviations (median+2MAD), and Tukey’s inner fence (TIF) methods were used to determine the geochemical thresholds. This study shows that TIF and principal component analysis (PCA) methods are highly effective in calculating appropriate threshold values and identifying relevant elemental associations. These approaches have proven useful for delineating target areas for mineral deposits, resulting in reliable outcomes. Four predicted target areas with high potential for deposits and mineralization anomalies of Cr, Cu, Ni, and Ba were delineated in the study area.

A geochemical mapping of regional modern river-sand is performed to clarify geological information in the study area of Timor-Leste. Several areas of Timor-Leste including the study area in particular have limited geological information due to limited accessibility and dense vegetation coverage, and deformed, weathered, and erosion-covered materials. A total of 53 modern river sand samples were collected and analyzed. Ten major elements were determined by using wavelength-dispersive X-ray fluorescence. Areas characterized by clastic sedimentary rocks are recognized clearly by elevated concentrations of SiO2, Al2O3, and K2O. Meanwhile, areas covered by carbonate sedimentary rocks are detected by significant concentrations of CaO and MnO. The occurrences of the altered clastic and carbonate sedimentary rocks of the Wailuli and Aitutu Formations due to metamorphic, silicification and other alteration processes were responsible for the elevated concentrations and positive correlation between SiO2, CaO, K2O, and MnO, and CaO, TiO2, and MnO in the midstream and near the downstream areas of the Clerec and Sahe River catchments. The positive correlation observed between TiO2, CaO and MnO may be ascribed to the presence of carbonate components associated with secondary Ti-bearing minerals, which are potentially formed through hydrothermal alteration processes.