Extended Data Fig. 5: Cross-plots of Δ′17Osulfate, δ13Ccarb and δ18Osulfate.
From: Two-billion-year transitional oxygenation of the Earth’s surface
a, Δ′17Osulfate versus δ13Ccarb, showing positive correlations across all studied negative δ13Ccarb excursions. b, Δ′17Osulfate versus δ18Osulfate. The red solid line represents theoretical SO4-H2O isotope equilibrium line with the θ (=ln17α/ln18α; see “Oxygen isotope notation” in Methods) value set at 0.524 (ref. 54); the arrow and light-green shaded window indicate the direction and potential areas of increased mass-independent oxygen isotope signals in sulfate.
