The evolution of ocean chemistry during the Proterozoic eon (2.5–0.542 billion years ago) is thought to have played a central role in both the timing and rate of eukaryote evolution1,2. The timing of the deposition of iron formations implies that, early in the Earth’s history, oceans were predominantly anoxic and rich in dissolved iron3. However, global deposition of iron formations ceased about 1.84 billion years ago. This termination indicates a major upheaval in ocean chemistry4, but the precise nature of this change remains debated5,6,7,8. Here we use iron and sulphur systematics to reconstruct oceanic redox conditions from the 1.88- to 1.83-billion-year-old Animikie group from the Superior region, North America. We find that surface waters were oxygenated, whereas at mid-depths, anoxic and sulphidic (euxinic) conditions extended over 100 km from the palaeoshoreline. The spatial extent of euxinia varied through time, but deep ocean waters remained rich in dissolved iron. Widespread euxinia along continental margins would have removed dissolved iron from the water column through the precipitation of pyrite, which would have reduced the supply of dissolved iron and resulted in the global cessation of the deposition of ‘Superior-type’ iron formations. We suggest that incursions of sulphide from the mid-depths into overlying oxygenated surface waters may have placed severe constraints on eukaryotic evolution.
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Knoll, A. H. & Carroll, S. B. Early animal evolution: Emerging views from comparative biology and geology. Science 284, 2129–2137 (1999).
Anbar, A. D. & Knoll, A. H. Proterozoic ocean chemistry and evolution: A bioinorganic bridge? Science 297, 1137–1142 (2002).
Holland, H. D. The Chemical Evolution of the Atmosphere and Oceans (Princeton Univ. Press, 1984).
Isley, A. E. & Abbott, D. H. Plume-related mafic volcanism and the deposition of banded iron formation. J. Geophys. Res. 104, 15461–15477 (1999).
Canfield, D. E. A new model for Proterozoic ocean chemistry. Nature 396, 450–453 (1998).
Poulton, S. W., Fralick, P. W. & Canfield, D. E. The transition to a sulphidic ocean ∼1.84 billion years ago. Nature 431, 173–177 (2004).
Slack, J. F., Grenne, T., Bekker, A., Rouxel, O. J. & Lindberg, P. A. Suboxic deep seawater in the late Paleoproterozoic: Evidence from hematitic chert and iron formation related to seafloor-hydrothermal sulphide deposits, central Arizona, USA. Earth Planet. Sci. Lett. 255, 243–256 (2007).
Holland, H. D. The oxygenation of the atmosphere and oceans. Phil. Trans. R. Soc. 361, 903–915 (2006).
Canfield, D. E. The early history of atmospheric oxygen: Homage to Robert M. Garrels. Annu. Rev. Earth Planet. Sci. 33, 1–36 (2005).
Frei, R., Gaucher, C., Poulton, S. W. & Canfield, D. E. Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes. Nature 461, 250–253 (2009).
Shen, Y., Canfield, D. E. & Knoll, A. H. Middle Proterozoic ocean chemistry: Evidence from the McArthur basin, Northern Australia. Am. J. Sci. 302, 81–109 (2002).
Shen, Y., Knoll, A. H. & Walter, M. R. Evidence for low sulphate and anoxia in a mid-Proterozoic marine basin. Nature 423, 632–635 (2003).
Arnold, G. L., Anbar, A. D., Barling, J. & Lyons, T. W. Molybdenum isotope evidence for widespread anoxia in a mid-Proterozoic marine basin. Science 304, 87–90 (2004).
Scott, C. et al. Tracing the stepwise oxygenation of the Proterozoic ocean. Nature 452, 456–459 (2008).
Kendall, B., Creaser, R. A., Gordon, G. W. & Anbar, A. D. Re–Os and Mo isotope systematics of black shales from the Middle Proterozoic Velkerri and Wollogorang formations, McArthur basin, northern Australia. Geochim. Cosmochim. Acta 73, 2534–2558 (2009).
Fralick, P. W., Davis, D. W. & Kissin, S. A. The age of the Gunflint formation, Ontario, Canada: Single zircon U–Pb age determinations from reworked volcanic ash. Can. J. Earth. Sci. 39, 1085–1091 (2002).
Addison, W. D. et al. Discovery of distal ejecta from the Sudbury impact event. Geology 33, 193–196 (2005).
Morey, G. B. in Huronian Stratigraphy and Sedimentation. (ed. Young, G. M.) Geol. Assoc. Can. Spec. Pap. 12, 211–249 (1973).
Poulton, S. W. & Canfield, D. E. Development of a sequential extraction procedure for iron: Implications for iron partitioning in continentally derived particulates. Chem. Geol. 214, 209–221 (2005).
Poulton, S. W. & Raiswell, R. The low-temperature geochemical cycle of iron: From continental fluxes to marine sediment deposition. Am. J. Sci. 302, 774–805 (2002).
Lyons, T. W. & Severmann, S. A critical look at iron paleoredox proxies: New insights from modern euxinic basins. Geochim. Cosmochim. Acta 70, 5698–5722 (2006).
Slack, J. F. & Cannon, W. F. Extraterrestrial demise of banded iron formations 1.85 billion years ago. Geology 37, 1011–1014 (2009).
Johnston, D. T. et al. Evolution of the oceanic sulfur cycle at the end of the Paleoproterozoic. Geochim. Cosmochim. Acta 70, 5723–5739 (2006).
Habicht, K. S., Gade, M., Thamdrup, B., Berg, P. & Canfield, D. E. Calibration of sulphate levels in the Archean ocean. Science 298, 2372–2374 (2002).
Brocks, J. J. et al. Biomarker evidence for green and purple sulphur bacteria in a stratified Paleoproterozoic sea. Nature 437, 866–870 (2005).
Canfield, D. E. et al. Ferruginous conditions dominated later Neoproterozoic deep-water chemistry. Science 321, 949–952 (2008).
Johnston, D. T. et al. An emerging picture of Neoproterozoic ocean chemistry: Insights from the Chuar Group, Grand Canyon, USA. Earth Planet. Sci. Lett. 290, 64–73 (2010).
Li, C. et al. A stratified redox model for the Ediacaran ocean. Science 328, 80–83 (2010).
Canfield, D. E. The evolution of the Earth surface sulfur reservoir. Am. J. Sci. 304, 839–861 (2004).
Kump, L. R. & Seyfried, W. E. Jr Hydrothermal Fe fluxes during the Precambrian: Effect of low oceanic sulfate concentrations and low hydrostatic pressure on the composition of black smokers. Earth Planet. Sci. Lett. 235, 654–662 (2005).
We thank the staff at the Minnesota Geological Survey, the Minnesota Department of Natural Resources and the Department of Northern Development and Mines in Ontario for help in locating and accessing core material. Work was financially supported by a NERC Research Fellowship (S.W.P.), the Danish National Research Foundation (Danmarks Grundforskningsfond) and an NSERC Discovery Grant (P.W.F.). We are grateful to M. Hurtgen for constructive and supportive reviews.
The authors declare no competing financial interests.
About this article
Cite this article
Poulton, S., Fralick, P. & Canfield, D. Spatial variability in oceanic redox structure 1.8 billion years ago. Nature Geosci 3, 486–490 (2010). https://doi.org/10.1038/ngeo889
Differentiating between hydrothermal and diagenetic carbonate using rare earth element and yttrium (REE+Y) geochemistry: a case study from the Paleoproterozoic George Fisher massive sulfide Zn deposit, Mount Isa, Australia
Mineralium Deposita (2021)
Phosphorus-limited conditions in the early Neoproterozoic ocean maintained low levels of atmospheric oxygen
Nature Geoscience (2020)
Nature Geoscience (2020)