Figure 6
From: Rare earth element geochemistry of outcrop and core samples from the Marcellus Shale
Distribution of total REE and degree of fractionation in samples with and without major fractions of illite or calcite. Distributions are depicted as standard boxplots [41], where the thick, black line depicts the median; the boxed range represents the 25th–75th percentile, or inter-quartile range (IQR); and the thin whiskers denote all measurements within 1.5 times the IQR above or below. Individual values of all observations are shown as blue dots. Statistically significant differences were found via the Wilcoxon rank sum test (H0: no difference in medians, P < 0.05) between groups for both variables and both minerals, as discussed in the text.