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Two-billion-year transitional oxygenation of the Earth’s surface

Nature volume 645, pages 665–671 (2025)Cite this article

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Abstract

Earth’s surface underwent stepwise oxygenation before persistently reaching modern levels late in its history1,2,3,4,5, but the details of this transition remain unclear5,6,7,8,9,10,11,12,13,14,15,16. Here we present a high-resolution 2.5-Gyr record of mass-independent oxygen isotopes in sedimentary sulfate (Δ′17Osulfate), a proxy linked to the atmospheric partial pressure of O2 (\({p}_{{{\rm{O}}}_{2}}\))17,18,19. This record, together with existing sedimentary Δ33S data20,21,22, demonstrates a 2-Gyr transition characterized by generally low, fluctuating \({p}_{{{\rm{O}}}_{2}}\) between an O2-free state before 2.4 billion years ago (Ga) and a modern \({p}_{{{\rm{O}}}_{2}}\) state after 0.41 Ga, with relatively elevated levels after 1.0 Ga. Our data also show coupled declines in Δ′17Osulfate and sulfate-δ34S during major negative carbonate-δ13C excursions in the Neoproterozoic. Quantitative biogeochemical modelling indicates that these isotopic couplings reflect the increasing \({p}_{{{\rm{O}}}_{2}}\), which may have driven episodic ocean oxygenation through an increased atmospheric O2 influx. This process intensified the oxidation of marine organics and reduced-sulfur species, while triggering temporary \({p}_{{{\rm{O}}}_{2}}\) drawdowns as negative feedback15. These findings support a dynamic, lengthy co-oxygenation history for the atmosphere and oceans—marked by long-term positive coupling and short-term negative feedbacks—offering a coherent explanation for the anomalous Neoproterozoic carbon cycles23,24 and the protracted, episodic rise of complex life25,26,27.

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Fig. 1: Sedimentary Δ33S and Δ′17O compilations illustrating a three-stage oxygenation of Earth’s atmosphere and links to the known atmospheric, oceanic and biological evolution.
Fig. 2: Comparison of Δ′17Osulfate record with modelled \({{\boldsymbol{p}}}_{{{\bf{O}}}_{{\bf{2}}}}\) evolution over the past 1,000 Ma.
Fig. 3: Temporal evolution of δ13Ccarb over the past 1,000 Ma and its coupling with Δ′17Osulfate and δ34Ssulfate variations during six major Neoproterozoic negative δ13Ccarb excursions.
Fig. 4: Modelled atmospheric O2 and \({{\boldsymbol{\Delta }}}^{{\prime} {\bf{17}}}{{\bf{O}}}_{{{\bf{O}}}_{{\bf{2}}}}\) evolution, and comparison with δ13Ccarb record, ocean redox and life history from 1,000 Ma to 500 Ma.

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All data generated or analysed during this study are included in this published article and its Supplementary Information files.

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Acknowledgements

We thank P. Peng, X. Wang, G. Jiang, B. Chen, Z. Han, M. Liu, D. Xu, K. Dai, F. Tong, Z. Wang, H. Yan, X. Chen, T. Ma, L. Liu, H. Liu, H. Song and Y. Fan for their assistance with field sampling, data measurements and scientific discussions. C.L. acknowledges support from the National Natural Science Foundation of China (grant numbers 42425002 and 42488201). Y.P. and C.L. acknowledge support from the National Key Research and Development Program of China (grant numbers 2022YFF0800303 and 2022YFF0800100). Additional financial support was provided by the National Natural Science Foundation of China (grant numbers 42494851 to H.B., 42103072 to H.W., 42372351 to J.Z., 42072335 to M.C. and 92479205 to Y.P.), and by the Fundamental Research Funds for the Central Universities (0206/14380204 and 0206/14380232 to Y.P.). This research is also supported by Open Research Fund (2025-Z03) of State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits, Nanjing University, and by the New Cornerstone Science Foundation through the XPLORER PRIZE (to Y.P.). The authors acknowledge the Northern Territory Geological Survey for providing drill-core samples from the Alice Springs Core Facility.

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Authors and Affiliations

  1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation and Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China

    Haiyang Wang, Chao Li, Meng Cheng, Zihu Zhang & Mingcai Hou

  2. International Center for Isotope Effects Research, State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China

    Haiyang Wang, Yongbo Peng, Xiaobin Cao & Huiming Bao

  3. Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources, Chengdu University of Technology, Chengdu, China

    Haiyang Wang, Chao Li, Meng Cheng, Zihu Zhang & Mingcai Hou

  4. International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China

    Haiyang Wang, Chao Li, Meng Cheng & Zihu Zhang

  5. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China

    Junpeng Zhang & Wenkun Qie

  6. School of Earth and Oceans, University of Western Australia, Perth, Western Australia, Australia

    Matthew S. Dodd

  7. School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia

    Malcolm Wallace & Ashleigh v. S. Hood

  8. Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA

    Timothy W. Lyons

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Contributions

C.L. led the research. C.L., Y.P., H.B. and H.W. designed the research. H.W., C.L., Y.P., Z.Z., J.Z., W.Q., M.S.D., M.W., M.H. and A.v.S.H. collected and provided the samples. H.W. prepared the samples for geochemical analysis. H.W., Y.P. and Z.Z. conducted the isotopic analyses. J.Z., H.W. and X.C. performed the model simulations. H.W. drew the figures with input from C.L., Y.P., M.C. and J.Z. All authors contributed to data interpretation, with major input from H.W., C.L., Y.P., H.B., J.Z., M.C., X.C., Z.Z., M.S.D., M.H. and T.W.L. H.W. and C.L. wrote the paper, with substantial input and discussion from all co-authors, especially Y.P., H.B. and T.L.

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Correspondence to Chao Li or Yongbo Peng.

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Extended data figures and tables

Extended Data Fig. 1 Schematic presentation of sulfate formation incorporating mass-independent oxygen isotope signatures.

Mass-independent 17O-depleted O2 is generated during photochemical reactions of O2, O3 and CO2 in the stratosphere, which is incorporated into sulfate during reduced-sulfur oxidation in the oceans and/or pyrite oxidative weathering on land.

Extended Data Fig. 2 The relationship between Δ′17\({{\bf{O}}}_{{{\bf{O}}}_{{\bf{2}}}}\) and \({{\boldsymbol{p}}}_{{{\bf{O}}}_{{\bf{2}}}}/{{\boldsymbol{p}}}_{{{\bf{CO}}}_{{\bf{2}}}}\), as well as \({{\boldsymbol{p}}}_{{{\bf{O}}}_{{\bf{2}}}}\)/GPP, at steady state19.

It shows a general trend of increasing \({p}_{{{\rm{O}}}_{2}}\), which corresponds to the three major shifts in Δ′17Osulfate, highlighted by the circled numbers ‘1-3’ in Fig. 1b. The ultra-low, anomalous Δ′17Osulfate values observed immediately after the Marinoan could be associated with extremely high \({p}_{{{\rm{CO}}}_{2}}\) levels and potentially reduced GPP. PAL: present atmospheric level; GOE: Great Oxidation Event; GPP: gross primary productivity.

Extended Data Fig. 3 Statistical distribution of Δ′17Osulfate across geological time.

a, Relative frequency histogram of Δ′17Osulfate values. b, Box plots of Δ′17Osulfate grouped by geological intervals. Dashed lines in both panels indicate the mean and the cumulative distribution function (CDF) value of 0.5 (median). A pronounced increase in 17O depletion occurred after ~2.1 Ga, likely driven by rising \({p}_{{{\rm{O}}}_{2}}\) levels, enhanced ozone formation, and intensified O2-O3-CO2 photochemical reactions. As \({p}_{{{\rm{O}}}_{2}}\) and resultant \({p}_{{{\rm{O}}}_{2}}/{p}_{{{\rm{CO}}}_{2}}\) ratios continued to increase, the extent of 17O depletion progressively diminished, eventually resembling the pattern before 2.1 Ga.

Extended Data Fig. 4 Co-variation between Δ′17Osulfate and δ13Ccarb across major negative carbon isotope excursions.

a-f, Majiatun (940 Ma), BSA (Bitter Springs Anomaly; 805 Ma), Trezona (643 Ma), CANCE (CAp carbonate Negative Carbon isotope Excursion; 635 Ma), SE (Shuram Excursion; 570 Ma), and BACE (BAsal Cambrian Carbon isotope Excursion; 539 Ma). All data are newly reported in this study, except for SE records, which are compiled from ref. 38 (circles, South China; triangles, South Australia). Dashed lines represent LOWESS fits. Analytical uncertainty (1σ) is shown only for Δ′17Osulfate; uncertainties for δ13Ccarb are smaller than the symbol size.

Extended Data Fig. 5 Cross-plots of Δ′17Osulfate, δ13Ccarb and δ18Osulfate.

a, Δ′17Osulfate versus δ13Ccarb, showing positive correlations across all studied negative δ13Ccarb excursions. b, Δ′17Osulfate versus δ18Osulfate. The red solid line represents theoretical SO4-H2O isotope equilibrium line with the θ (=ln17α/ln18α; see “Oxygen isotope notation” in Methods) value set at 0.524 (ref. 54); the arrow and light-green shaded window indicate the direction and potential areas of increased mass-independent oxygen isotope signals in sulfate.

Extended Data Fig. 6 Sedimentary phosphorus concentrations and inferred gross primary productivity from 1,000 to 500 Ma.

a, Temporal distribution of sedimentary phosphorus contents, compiled from ref. 67. b, Estimated gross primary productivity relative to the present-day oceanic level (POL; red line), calculated from the LOWESS fit of phosphorus data. The blue and red lines represent gross productivity levels used as model inputs—together with \({p}_{{{\rm{O}}}_{2}}/{p}_{{{\rm{CO}}}_{2}}\) ratios from the NEOCARBSULF model—to simulate atmospheric ∆′17\({{\rm{O}}}_{{{\rm{O}}}_{2}}\) evolution.

Extended Data Fig. 7 NEOCARBSULF-∆′17O model results from 1,000 to 500 Ma.

a, Model input of δ13Ccarb record. Black circles denote data from this study; the dark-grey dashed line shows the moving average, and the light grey band indicates ±1 s.d. b, Model output of \({p}_{{{\rm{O}}}_{2}}/{p}_{{{\rm{CO}}}_{2}}\) ratios. The black line represents the mean result of 1,000 model runs, with the grey shaded band denoting ±1 s.d. c, Model input of gross productivity. Scenario 1 (solid line) assumes constant productivity; Scenario 2 (dashed line) represents time-dependent estimates based on sedimentary phosphorus concentrations (see Extended Data Fig. 6). d, Modelled O2 residence time, calculated as the ratio of \({p}_{{{\rm{O}}}_{2}}\) to productivity. Dark-blue and light-blue lines denote the respective mean values under Scenario 1 and Scenario 2 assumptions, respectively. e, Modelled ∆′17\({{\rm{O}}}_{{{\rm{O}}}_{2}}\) values. Light and dark-blue lines represent the mean values for the two scenarios, with shaded envelopes indicating ±1 s.d. The model shows that during all major negative δ13Ccarb excursions, \({p}_{{{\rm{O}}}_{2}}/{p}_{{{\rm{CO}}}_{2}}\) ratios dropped by roughly an order of magnitude, mostly from about 10 to about 1, accompanied by parallel decreases in O2 residence time. Except for the SE, other δ13Ccarb excursions, specifically the Majiatun, BSA, Trezona, CANCE, and BACE, exhibited increased ∆′17\({{\rm{O}}}_{{{\rm{O}}}_{2}}\) values.

Extended Data Fig. 8 NEOCARBSULF model simulations of marine sulfur cycling in response to changes in pyrite burial.

All panels show mean outputs from 1,000 Monte Carlo simulations, with shaded bands (in various colours) denoting ±1 s.d. a, Model input of δ13Ccarb record. b, Modelled fraction of total sulfur buried as pyrite, showing transient declines during major negative δ13Ccarb excursions. c, Simulated δ34Ssulfate compared with new measurements from this study. d, Modelled oceanic sulfate concentrations. It shows transient increases during negative δ13Ccarb excursions, peaking during the SE in line with previous model estimates38,68. Pyrite burial parameters were scaled to reflect ∆′17Osulfate-based evidence for episodic ocean oxygenation. The model reproduces the direction and magnitude of δ34Ssulfate shifts, though baseline values remain uncertain owing to assumptions about apparent sulfur isotope fractionation (Δ34S = δ34Ssulfate – δ34Spyrite) and spatial heterogeneity in Neoproterozoic seawater δ34Ssulfate38,68.

Supplementary information

Supplementary Table 1 (download XLSX )

Δ′17Osulfate, δ18Osulfate, δ34Ssulfate and δ13Ccarb data reported in this study and compiled from literature.

Supplementary Table 2 (download XLSX )

Parameters used to drive the NEOCARBSULF-Δ′17O model in this study.

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Wang, H., Li, C., Peng, Y. et al. Two-billion-year transitional oxygenation of the Earth’s surface. Nature 645, 665–671 (2025). https://doi.org/10.1038/s41586-025-09471-4

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