Extended Data Figure 1 : Relationships between Fe3+/ΣFe, total iron, and sample age.

From: A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts

Extended Data Figure 1

a, Fe3+/ΣFe versus total Fe for all ophiolite basalt data. The regression line (dotted grey line) is a linear regression through all data with a 95% confidence interval shaded in grey. b, Total Fe versus age for all ophiolite data. The regression line (dotted grey line) is a linear regression through all data with a 95% confidence interval shaded in grey. Combination of the regression lines in a and b indicates a maximum shift in Fe3+/ΣFe ratios over the past 3.5 billion years of 0.04 ± 0.03 (2σ).