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A global transition to ferruginous conditions in the early Neoproterozoic oceans


Eukaryotic life expanded during the Proterozoic eon1, 2.5 to 0.542 billion years ago, against a background of fluctuating ocean chemistry2,3,4. After about 1.8 billion years ago, the global ocean is thought to have been characterized by oxygenated surface waters, with anoxic and sulphidic waters in middle depths along productive continental margins and anoxic and iron-containing (ferruginous) deeper waters5,6,7. The spatial extent of sulphidic waters probably varied through time5,6, but this surface-to-deep redox structure is suggested to have persisted until the first Neoproterozoic glaciation about 717 million years ago8,9,10,11. Here we report an analysis of ocean redox conditions throughout the Proterozoic using new and existing iron speciation and sulphur isotope data from multiple cores and outcrops. We find a global transition from sulphidic to ferruginous mid-depth waters in the earliest Neoproterozoic, coincident with the amalgamation of the supercontinent Rodinia at low latitudes. We suggest that ferruginous conditions were initiated by an increase in the oceanic influx of highly reactive iron relative to sulphate, driven by a change in weathering regime and the uptake of sulphate by extensive continental evaporites on Rodinia. We propose that this transition essentially detoxified ocean margin settings, allowing for expanded opportunities for eukaryote diversification following a prolonged evolutionary stasis before one billion years ago.

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Figure 1: Stratigraphy and geochemical analyses for the 1.0 Ga Huainan succession.
Figure 2: Fe speciation data for the 1.0 Ga Huainan Basin, the 0.89–0.79 Ga Amundsen Basin, the 0.84–0.77 Ga Amadeus and Officer basins, and the 0.74 Ga Svalbard Basin.
Figure 3: Data compilation from 2 Ga to the Sturtian glaciation.


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We are grateful to P. Green, J. Davis and E. Avbelj for technical support. We thank S. Bottrell and R. Newton for constructive discussions. This work was supported by NERC through its research program ‘Long-term Co-evolution of Life and the Planet’ (Project NE/I005978/1), and the 973 program of the Ministry of Science and Technology of China (2013CB835000).

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Authors and Affiliations



R.G., S.W.P., G.A.S-Z. and M.Z. collected samples. R.G. analysed samples and interpreted data. R.G. and S.W.P. wrote the manuscript, with significant contributions from all co-authors.

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Correspondence to Romain Guilbaud.

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Guilbaud, R., Poulton, S., Butterfield, N. et al. A global transition to ferruginous conditions in the early Neoproterozoic oceans. Nature Geosci 8, 466–470 (2015).

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