Fig. 2: Trace element data for different grains-size fractions normalized to the average concentrations of the upper continental crust85.

a < 2 μm fractions, b 2–20 μm fractions and c bulk sediments. Most sediments show similar patterns according to the respective size fractions although proportions vary greatly from site to site. Clear differences exist between the 2–20 μm size fractions with positive Hf and Zr anomalies and the <2 μm fractions with negative anomalies in Sr, Zr, and Hf. The differences are due to different mineralogy in the two fractions.