Can REE-enriched carbonatites be mapped from space?

Rare Earth elements (REE) belong to the most strategic materials of the 21st century with steadily growing economic importance. PRISMA, the hyperspectral satellite data, is used for the very first time to test its capability of detecting REE contents from space using distinct subtle diagnostic spectral absorption features of REE. The PRISMA hyperspectral sensor acquired 234 spectral bands over VNIR/SWIR optical regions (400–2500 nm) of the electromagnetic spectrum at a spatial resolution of 30 m and a spectral resolution ranging from 11 to 15 nm. The carbonatite occurences within the Ondoto area in North Namibia were selected as the test site. To detect the REE-related diagnostic spectral absorption parameters (absorption wavelength position and depth) the in-house toolbox (QUANTools) developed at the Czech Geological Survey was tested and four absorption features placed within 700–900 nm range were found to correlate with the carbonatites containing high loads of REE. As a result, three perspective carbonatite areas were identified as the most promising, with one site validated using the laboratory geochemical data from collected samples. The results showed a good correlation between the high REE loads mapped using PRISMA data and the ground truth data highlighting the future potential of state-of-the-art satellite hyperspectral data to explore REE deposits using contactless Earth Observation data and methods.

Funded by the Czech Science Foundation project 19-29124X.