Describe REE patterns of the lichen samples and PAAS. What are its key features (enrichments, anomalies, etc.) and what do they say about the continental crust?

Looking at Figure 5, one can observe that most samples are enriched in $SiO_2$, $Al_2O_3$ and $Fe_2O_3$. The other elements have similar concentrations in both Lichen and PAAS samples. There is an enrichment of $Na_2O$ in almost all the samples, including PAAS, which would be typical of continental crust close to an ocean or seawater of some kind. There is also an anomaly in the Sand Lichen sample, where it has low $SiO_2$ and $MnO$ concentrations, which could mean that it was leached out more readily from the lichen, or that it was in a different area than the other rock samples and just didn't get as much of these REEs.