Determine whether UV-driven manganese oxidation left a measurable chromium-isotope signal

Determine whether a UV-driven manganese-oxide source operated on the early Earth at rates sufficient to leave a measurable chromium-isotope signal.

Background

The paper discusses how surface ultraviolet radiation may have driven abiotic mineral reactions on the early Earth, including the photooxidation of rhodochrosite to manganite and hydrogen. Manganite can oxidize chromium(III) to chromium(VI) under laboratory conditions, raising the possibility that a UV-driven manganese-oxide pathway influenced the chromium-isotope record.

The authors explicitly identify as unresolved whether this process operated at a sufficiently high rate to produce a measurable geological signal. Resolving this question would help assess the use of chromium isotopes as an oxygenation proxy across the Great Oxidation Event.

References

To our knowledge, whether a UV-driven Mn-oxide source ever operated at rates sufficient to leave a measurable Cr-isotope signal on the early Earth is an open question, but it is one worth noting alongside the use of Cr isotopes as an oxygenation proxy across the GOE.

— Simulations of the Evolving Ozone Layer: Implications for the Early Earth, Exoplanets, and the Search For Life  (2610.18864 - Kumar et al., 13 Oct 2026) in Section 5.2, “Implications for early Earth”