Peridotites and basalts reveal broad congruence between two independent records of mantle fO2 despite local redox heterogeneity

- We determine the fO2 of co-located mid-ocean ridge peridotites and basalts.
- We project the recorded fO2 of each lithology back to source conditions.
- Basalts and peridotites from the same segment record the same average source fO2.
- However, basalt fO2 is fairly homogeneous, while peridotite fO2 is highly variable.
- The MORB source mantle, on average, lies at the QFM buffer.