Fig. 5 | Nature Communications

Fig. 5

From: Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing

Fig. 5

COPSE model with the addition of the evolution of bioturbation. Scenario 1 shows the effect of the sedimentary response that scales linearly with bioturbation intensity. Scenarios 2 and 3 assume that the effects of bioturbation on sediment geochemistry occur non-linearly (strong response for low levels of bioturbation), where Scenario 2 follows a gradual increase of the areal extent of bioturbation and Scenario 3 shows the maximum effect at the Ediacaran-Cambrian boundary (see panels g, n, u). a, h, o Atmospheric CO2. b, i, p Average sulphate δ34S of seawater. c, j, q Pyrite fraction of sulphur burial. d, k, r Average δ13C of carbonate. e, l, s Degree of ocean anoxia. Model outcomes (in red) are fitted to the δ13Ccarb and δ13SSO4 proxies (grey dotted line represents a LOESS fit), predictions for the relative importance of pyrite for the total sulphur burial rate (blue dotted lines represent the range of model results presented in ref. 44) and compared to a summary of the evolution of sedimentary Mo concentrations over time (f, m, t). Solid lines represent the model outcomes with anoxia feedback, dashed lines represent the model outcomes without anoxia feedback. Grey shaded areas indicate the Cambrian explosion (540–521 Ma) and the Great Ordovician Biodiversification Event (GOBE; 470–450 Ma). Blue shaded line indicates the Hirnantian glaciation

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