Fig. 2

Density histograms that show the deviations of modelled REE from measured REE (ID-modified) in mafic and ultramafic rock samples from the screened PetDB dataset (https://search.earthchem.org/). The histogram data is normalised to densities. The orange lines give the kernel density estimation curves. Cerium and Eu were excluded 1,292 times as anomalies during modelling. (A) The histogram for all REEs shows a skewness of 0.63, a kurtosis of 6.99. 90% and the data points range between −5.4% and 7.2% (5%–95% percentile; SD = 4). (B) The histogram for the removed Pr, Tb, Ho and Tm shows a skewness of 0.46, a kurtosis of 5.17. 90% and the data points range between −6.9% and 9.7% (5%–95% percentile; SD = 5.4).