Multi-scale and multi-source remote sensing of REEs in southern Africa

Technological advancements have led to an increased demand for rare earth elements (REEs), resulting in them becoming crucial to ensure the transformation towards green technologies (Dutta et al., 2016). At the same time, the world’s REE supply is monopolized by a limited number of countries (Simandl, 2014). A renewed and sustainable exploration approach is required to ensure a more ethical and global supply of REEs. For this, we suggest the use of a multi-scale and multi-source remote sensing workflow. Conventional exploration methods typically involve extensive field work and geochemical lab work supported by geophysical surveying. This approach, however, can be constrained by several factors such as the area size and accessibility, climate, finances as well as the lack of a social licence to operate. The suggested multi-scale, multi-source approach uses optical remote sensing data from multiple platforms with increasing spatial resolution. We utilize multispectral satellite data, plane-based hyperspectral data, unmanned aerial vehicle (UAV)-based hyperspectral data and validate the findings with in-situ measurements. Our suggested method can mitigate the disadvantages of traditional exploration techniques by allowing for fast, systematic and dense surveying, particularly in inaccessible and remote areas with little infrastructure. Additionally, a generally less-invasive technique garners a higher social acceptance for the mining and exploration community. We demonstrate our approach on a few, selected carbonatite complexes in southern Africa: the Marinkas Quellen carbonatite complex and the Lofdal carbonatite complex in Namibia.