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The evolution of the marine carbonate factory


Calcium carbonate formation is the primary pathway by which carbon is returned from the ocean–atmosphere system to the solid Earth1,2. The removal of dissolved inorganic carbon from seawater by precipitation of carbonate minerals—the marine carbonate factory—plays a critical role in shaping marine biogeochemical cycling1,2. A paucity of empirical constraints has led to widely divergent views on how the marine carbonate factory has changed over time3,4,5. Here we use geochemical insights from stable strontium isotopes to provide a new perspective on the evolution of the marine carbonate factory and carbonate mineral saturation states. Although the production of carbonates in the surface ocean and in shallow seafloor settings have been widely considered the predominant carbonate sinks for most of the history of the Earth6, we propose that alternative processes—such as porewater production of authigenic carbonates—may have represented a major carbonate sink throughout the Precambrian. Our results also suggest that the rise of the skeletal carbonate factory decreased seawater carbonate saturation states.

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Fig. 1: Strontium isotope records in marine carbonates through the history of the Earth.
Fig. 2: Density plots of δ88/86Sr records in different time intervals.
Fig. 3: Mass balance regulating the impact of seawater saturation state and variable partitioning between a shallow marine (platform, ramp and reef) carbonate burial sink and an inferred isotopically depleted sink on carbonate Sr isotope fractionation.
Fig. 4: Carbonate relative abundance in preserved sedimentary rocks through time.

Data availability

All data are available in the main text or the Supplementary Information. All data are also reposited in EarthChem (

Code availability

We used the open-source language R (version 4.1.1) to analyse the measured data, analyse the EarthChem ( and Macrostrat ( datasets, and generate all plots. All equations for the mass-balance model are listed in the Supplementary Information and all associated code is deposited on GitHub (


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We thank S. Nicolescu, B. Kalderon-Asael and Y. Wang for facilitating access to the Yale Peabody Museum and Woods Hole Oceanographic Institution collections and for assistance with sample selection; D. Asael for assistance with MC-ICP-MS method development; R. P. Reid and E. P. Suosaari for access to the Hamelin Pool stromatolite samples; S. Ye for assistance with the Macrostrat database; and D. Schrag, M. Arthur, K. Bergmann, Z. Zhang and Y. Cui for helpful discussions. This study is supported by an Agouron Geobiology Postdoctoral Fellowship to J.W. and National Aeronautics and Space Administration Interdisciplinary Consortia for Astrobiology Research grant (NNA15BB03A) to N.J.P.

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Authors and Affiliations



J.W., L.G.T. and N.J.P. conceived the study and acquired funding. J.W., L.G.T., A.D.J. and N.J.P. developed the methodology. J.W. performed mass spectrometry analyses. J.W. and L.G.T. conducted the statistical analyses. J.W. and L.G.T. wrote the paper, with input from A.D.J., A.M.O. and N.J.P. J.W., L.G.T., A.D.J., A.M.O. and N.J.P. all contributed to the interpretation of the results and editing the manuscript.

Corresponding authors

Correspondence to Jiuyuan Wang or Lidya G. Tarhan.

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The authors declare no competing interests.

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Nature thanks Adina Paytan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Marine carbonate strontium isotope records through the history of the Earth.

a, Summary of δ88/86Sr values measured in marine calcites and dolomites. New data from this study (n = 139) are colour-contoured to indicate corresponding radiogenic Sr isotope ratios (87Sr/86Sr) generated from the same samples: circles, calcite; diamonds, dolomite; ×, calcite with abnormally high 87Sr/86Sr ratios. Error bars represent the long-term external reproducibility of δ88/86Sr (2σSD = ±0.03‰, n = 273). Purple crosses denote duplicate measurements of the same sample (see Methods for description of duplicate strategy). The gold line illustrates the δ88/86Sr value of bulk silicate Earth (0.27‰)27. The dashed blue line represents the δ88/86Sr value of modern marine carbonate63. Other symbols represent published data from other studies (n = 299; see Methods): pink squares, non-skeletal carbonate; grey gridded squares, cap carbonate; grey triangles, bulk skeletal calcite; grey crosses, belemnite; grey inverted triangles, brachiopod. b, Marine carbonate 87Sr/86Sr ratios. New data from this study are denoted by coloured symbols: circles, calcite; diamonds, dolomite; ×, calcite with abnormally high 87Sr/86Sr ratios. The grey circles represent Precambrian carbonate 87Sr/86Sr records (n = 1,494)23. The dashed curve denotes the LOESS fit of the lowest 10% of Precambrian 87Sr/86Sr ratios23 and the solid curve denotes the LOESS fit of the Phanerozoic 87Sr/86Sr record64.

Extended Data Fig. 2 Histograms of measured and bootstrap-resampled Precambrian calcite and dolomite δ88/86Sr values.

a, Measured Precambrian calcite (red) and dolomite (yellow) δ88/86Sr values. b, Bootstrap-resampled (n = 10,000) Precambrian calcite (red) and dolomite (yellow) δ88/86Sr values. All Precambrian calcite and dolomite δ88/86Sr values are from this study. The purple and green curves represent density distributions of δ88/86Sr in Precambrian calcites (purple, n = 72) and dolomites (green, n = 43).

Extended Data Fig. 3 The relationship between δ88/86Sr and 87Sr/86Sr in analysed dolomites.

a, The stable and radiogenic Sr isotope relationship for all analysed dolomites (n = 43). A SMA regression model yields R2 = 0.223 and P = 0.001. b, The stable and radiogenic Sr isotopic values of less-altered dolomite samples from this dataset, that is, samples characterized by 87Sr/86Sr values less than 0.708, the inferred value of Ediacaran seawater64.

Extended Data Fig. 4 Cross-plots of δ88/86Sr versus different elemental contents and ratios.

a, δ88/86Sr versus CaCO3 weight percentage (wt%). Carbonate wt% calculated using calcium content assuming stoichiometric CaCO3. b, δ88/86Sr versus Sr contents. c, δ88/86Sr versus Mn/Sr. d, δ88/86Sr versus Rb contents. e, δ88/86Sr versus Ti contents. f, δ88/86Sr versus Pb contents. δ88/86Sr values are given in ‰, normalized to NIST 987; all elemental concentrations are in ppm except when noted otherwise. An SMA regression model was used to evaluate the statistical significance of each correlation. R2 and P-values are listed at the top of each panel. No statistical correlations are observed at the significance level of 0.01.

Extended Data Fig. 5 Box plot of δ88/86Sr values for skeletal (green), microbial (red) and non-skeletal, non-microbial carbonate (blue) for modern, Permian–Triassic and Precambrian deposits.

In the box plot, the centre line represents the median of the data (50th percentile), box limits represent the upper and lower quartiles (75th and 25th percentiles), whiskers represent 1.5 times the interquartile range, blank points represent outliers and coloured points represent all data. These data indicate that the notably higher δ88/86Sr values characterizing Precambrian calcites cannot be attributed to differences between microbial and non-microbial pathways of carbonate precipitation and that, similarly, the shift between elevated Precambrian and less-elevated Phanerozoic δ88/86Sr values cannot be readily attributed to differences between skeletal and non-skeletal pathways of carbonate precipitation. The modern δ88/86Sr records are from Stevenson et al.20 (skeletal n = 10) and this study (microbial n = 5; non-skeletal, non-microbial n = 8); the Permian–Triassic δ88/86Sr records (skeletal n = 6; microbial n = 8; non-skeletal, non-microbial n = 20) are from Wang et al.24; the Precambrian calcite (microbial calcite n = 12; non-skeletal, non-microbial calcite n = 47) and dolomite (microbial dolomite n = 6; non-skeletal, non-microbial dolomite n = 37) δ88/86Sr records are from this study.

Supplementary information

Supplementary Information

This file contains Supplementary Discussion, Supplementary References and Supplementary Figs. 1 and 2.

Reporting Summary

Supplementary Table 1

Descriptions and geochemistry of analysed Precambrian carbonate samples.

Supplementary Table 2

Descriptions and Sr isotope ratios of analysed modern and palaeogene carbonate samples.

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Wang, J., Tarhan, L.G., Jacobson, A.D. et al. The evolution of the marine carbonate factory. Nature 615, 265–269 (2023).

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