Rare earth elements in Greenland; known and new targets identified and characterised by regional stream sediment data

Increasing demand for lanthanides encouraged inspection of stream sediment data for Greenland. The database of the Geological Survey of Denmark and Greenland contains analytical data for c. 10600 samples covering 70% of the ice-free margin of Greenland. Data for La, Eu and Yb are considered representative for the suite of seven rare earth elements (REEs) determined in the samples, and spatial distribution of background values as well as of anomalies (La>364 ppm, Eu>7.4 ppm, Yb>16 ppm) shows that certain provinces are enriched in one, two or all three elements. Stream sediment REE-anomalous samples from South Greenland derived from the most important rock associations hosting REE deposits, i.e. carbonatite, peralkaline syenite, alkaline granite or non-alkaline granite, show that the REE fractionation for samples derived from each of these rock associations is distinct and can form the basis for defining screens. When applied to data from the whole of Greenland it is possible to identify samples likely derived from the same associations. Samples from diverse lithologies also occupy distinct parts in diagrams of La-Yb, Yb-Eu and La/Yb-Eu/Yb variation. Stream sediment REE properties reflect those of source rocks because REE are preferably contained in minerals that survive in the stream sediment environment.