Fig. 1
Tectonic and geochemical evidence for an Ediacaran oxygenation. a Total global subduction-zone length as a proxy for CO2 input rate, derived from the PALEOMAP project37. Error estimations in grey based on observations, timing of collisions and relative plate motions (see Mills et al.37 Methods). Also shown are the cumulative proportion of young zircon grains (red triangles), indicative of continental arc environments33. b, c Proxy compilations for the oxygenation state of the Neoproterozoic ocean: b Less positive selenium isotope ratios recorded in marine shales15 (δ82/76Se; red triangles) indicate more oxic conditions in the global ocean. Stronger negative cerium anomalies recorded in marine cements20 (Ceanom; pale blue dots), defined as Ceanom < 1, are indicative of more oxygenated regional to basin-scale conditions (the blue line is a fit through the Ceanom data). Both proxies suggest a trend towards more oxygenated ocean conditions during the Ediacaran period. c A summary of redox sensitive element (RSE; magenta) enrichment data (Mo, U, Re, V, Cr) from black shales, indicating intervals of widespread ocean oxygenation16,17,22,23. Below this is a summary of iron-speciation proxy data24,25, which records localised redox conditions, hence is divided by depth range. The intervals of the Sturtian, Marinoan and Gaskiers glaciations are also indicated. These redox proxies suggest a series of transient oxygenation events during the Cryogenian and Ediacaran periods
