Figure 3: Average Mn/Fe ratios under different redox conditions.
From: Low-oxygen waters limited habitable space for early animals
Mn/Fe ratios for samples identified as manganous (positive Ce/Ce* and low FeT or oxic Fe-speciation signals), ferruginous (anoxic Fe-speciation signals) and oxic (oxic Fe-speciation signals, no positive Ce anomaly). Mn/Fe is enriched in manganous samples compared with global carbonate (0.29; ref. 70). Bars represent median values. Red outlines indicate dolomitized samples. Arrows indicate samples with exceptionally high Mn/Fe ratios that lie above the limit of the y axis.
