Fig. 3: Conceptual model and biogeochemical indicators following the Sturtian deglaciation.
a Vigorous weathering induced eutrophication after the Sturtian deglaciation. b Expansion of euxinia on productive margins owing to excess of H2S over iron. c Continuous atmospheric CO2 drawdown led to subdued weathering, cooling and shallow seawater oxygenation. In (a–c), the thicknesses of arrows indicate the relative magnitude of fluxes, and the sizes of ellipses represent the relative sizes of reservoirs. d Global length of continental arcs74 and mid-ocean ridges75,101. The blue band indicates the studied interval. e Occurrences of biomarkers9. f Possible evolution of atmospheric CO2 and global mean surface temperature9. g–l Compilation of carbon, strontium, sulfur, uranium isotopes and iron speciation records (modified after ref. 9). Solid lines in (g, h, j, k) represent the LOESS (locally estimated scatterplot smoothing) fitting curves, and the shaded area represents 1σ (68%) confidence interval. The dashed lines in (j) indicate the major range of δ34Spy. In (l), each boxplot represents the distribution of global Fepy/FeHR data in each one-million-year time bin. The light shade of pale red band indicates the second stage. The age model of (e–l) is based on model A of ref. 9 (see Supplementary Fig. 2 for the alternative age model D). OM organic matter burial, Fepy pyrite burial, DOC dissolved organic carbon pool, PAL present atmospheric level, Min. minimum, Max. maximum.
