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Earth’s missing argon paradox resolved by recycling of oceanic crust

Nature Geoscience volume 15, pages 85–90 (2022)Cite this article

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Abstract

The extent to which primordial mantle domains have survived billions of years of convective mixing is a fundamental question in mantle dynamics and geochemistry. The observation that around half of Earth’s 40Ar is missing from the atmosphere has been used to argue for a largely primordial, convectively isolated lower mantle. This hypothesis is apparently supported by lower 40Ar/36Ar ratios in the mantle source of ocean-island basalts compared with mid-ocean-ridge basalts. However, strongly layered convection is contradicted by seismic tomographic observations and geodynamic constraints. Using joint geodynamic–geochemical modelling of mantle convection, we show that high 40Ar concentrations associated with K-rich subducted oceanic crust plus unmelted material dispersed throughout the mantle can fully account for Earth’s 40Ar budget. This solution to the missing Ar paradox requires neither a substantial reduction in Earth’s assumed K concentration nor large isolated domains in the mantle. We additionally show that subducted atmosphere-derived Ar has little effect on the mantle 40Ar budget but can substantially reduce mantle 40Ar/36Ar ratios. Unlike He and Ne isotope systems, whose variations reflect primarily incorporation of primordial material, mantle 40Ar/36Ar ratios may instead result from subduction of atmosphere-derived Ar into the deep mantle.

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Fig. 1: Tracer distribution and compositions in the final model time step (4.55 Gyr).
Fig. 2: Fraction of melted mantle mass, degassed 40Ar and subducted mantle Ar in the five best-fit models.
Fig. 3: Comparison of models with constant convective vigour and enhanced early convective vigour.

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Data availability

No new data were collected as part of this study. All data used in this study are available from the cited references.

Code availability

The geodynamic and geochemical model codes are available from the authors upon request. The code used for MCMC sampling is available from https://github.com/dfm/emcee.

References

  1. Turcotte, D. L. & Schubert, G. Tectonic implications of radiogenic noble gases in planetary atmospheres. Icarus 74, 36–46 (1988).

    Article  Google Scholar 

  2. Allègre, C. J., Hofmann, A. & O’Nions, K. The argon constraints on mantle structure. Geophys. Res. Lett. 23, 3555–3557 (1996).

    Article  Google Scholar 

  3. Parai, R., Mukhopadhyay, S., Tucker, J. M. & Pető, M. K. The emerging portrait of an ancient, heterogeneous and continuously evolving mantle plume source. Lithos 346, 105153 (2019).

    Article  Google Scholar 

  4. Kárason, H. & van der Hilst, R. D. Constraints on mantle convection from seismic tomography. Geophys. Monogr. 121, 277–288 (2000).

    Google Scholar 

  5. French, S. W. & Romanowicz, B. Broad plumes rooted at the base of the Earth’s mantle beneath major hotspots. Nature 525, 95–99 (2015).

    Article  Google Scholar 

  6. Spohn, T. & Schubert, G. Modes of mantle convection and the removal of heat from the Earth’s interior. J. Geophys. Res. Solid Earth 87, 4682–4696 (1982).

    Article  Google Scholar 

  7. Davies, G. F. Geophysical and isotopic constraints on mantle convection: an interim synthesis. J. Geophys. Res. Solid Earth 89, 6017–6040 (1984).

    Article  Google Scholar 

  8. McNamara, A. K. & van Keken, P. E. Cooling of the Earth: a parameterized convection study of whole versus layered models. Geochem. Geophys. Geosyst. 1, 2000GC000045 (2000).

    Article  Google Scholar 

  9. Xie, S. & Tackley, P. J. Evolution of helium and argon isotopes in a convecting mantle. Phys. Earth Planet. Inter. 146, 417–439 (2004).

    Article  Google Scholar 

  10. Gonnermann, H. M. & Mukhopadhyay, S. Preserving noble gases in a convecting mantle. Nature 459, 560–563 (2009).

    Article  Google Scholar 

  11. Albarède, F. Time-dependent models of U–Th–He and K–Ar evolution and the layering of mantle convection. Chem. Geol. 145, 413–429 (1998).

    Article  Google Scholar 

  12. Davies, G. F. Geophysically constrained mantle mass flows and the 40Ar budget: a degassed lower mantle? Earth Planet. Sci. Lett. 166, 149–162 (1999).

    Article  Google Scholar 

  13. Lassiter, J. C. Role of recycled oceanic crust in the potassium and argon budget of the Earth: toward a resolution of the ‘missing argon’ problem. Geochem. Geophys. Geosyst. 5, Q11012 (2004).

    Article  Google Scholar 

  14. Brandenburg, J. P., Hauri, E. H., van Keken, P. E. & Ballentine, C. J. A multiple-system study of the geochemical evolution of the mantle with force-balanced plates and thermochemical effects. Earth Planet. Sci. Lett. 276, 1–13 (2008).

    Article  Google Scholar 

  15. Jones, T. D., Maguire, R. R., van Keken, P. E., Ritsema, J. & Koelemeijer, P. Subducted oceanic crust as the origin of seismically slow lower-mantle structures. Prog. Earth Planet. Sci. 7, 17 (2020).

    Article  Google Scholar 

  16. Ringwood, A. E. Phase transformations and differentiation in subducted lithosphere: Implications for mantle dynamics, basalt petrogenesis, and crustal evolution. J. Geol. 90, 611–643 (1982).

    Article  Google Scholar 

  17. Hofmann, A. W. & White, W. M. Mantle plumes from ancient oceanic crust. Earth Planet. Sci. Lett. 57, 421–436 (1982).

    Article  Google Scholar 

  18. Zindler, A. & Hart, S. Chemical geodynamics. Annu. Rev. Earth Planet. Sci. 14, 493–571 (1986).

    Article  Google Scholar 

  19. Tucker, J. M., van Keken, P. E., Jones, R. E. & Ballentine, C. J. A role for subducted oceanic crust in generating the depleted mid-ocean ridge basalt mantle. Geochem. Geophys. Geosyst. 21, e2020GC009148 (2020).

    Article  Google Scholar 

  20. Jarrard, R. D. Subduction fluxes of water, carbon dioxide, chlorine, and potassium. Geochem. Geophys. Geosyst. 4, 8905 (2003).

    Article  Google Scholar 

  21. Syracuse, E. M., van Keken, P. E. & Abers, G. A. The global range of subduction zone thermal models. Phys. Earth Planet. Int. 183, 73–90 (2010).

    Article  Google Scholar 

  22. Pujol, M., Marty, B., Burgess, R., Turner, G. & Philippot, P. Argon isotopic composition of Archaean atmosphere probes early Earth geodynamics. Nature 498, 87–90 (2013).

    Article  Google Scholar 

  23. Guo, M. & Korenaga, J. Argon constraints on the early growth of felsic continental crust. Sci. Adv. 6, eaaz6234 (2020).

    Article  Google Scholar 

  24. Dhuime, B., Wuestefeld, A. & Hawkesworth, C. J. Emergence of modern continental crust about 3 billion years ago. Nat. Geosci. 8, 552–555 (2015).

    Article  Google Scholar 

  25. Tang, M., Chen, K. & Rudnick, R. L. Archean upper crust transition from mafic to felsic marks the onset of plate tectonics. Science 351, 372–375 (2016).

    Article  Google Scholar 

  26. Coltice, N., Albarède, F. & Gillet, F. 40K–40Ar constraints on recycling continental crust into the mantle. Science 288, 845–847 (2000).

    Article  Google Scholar 

  27. van Keken, P. E., Ballentine, C. J. & Porcelli, D. A dynamical investigation of the heat and helium imbalance. Earth Planet. Sci. Lett. 188, 421–434 (2001).

    Article  Google Scholar 

  28. Tolstikhin, I. & Hofmann, A. W. Early crust on top of the Earth’s core. Phys. Earth Planet. Int. 148, 109–130 (2005).

    Article  Google Scholar 

  29. Labrosse, S., Hernlund, J. W. & Coltice, N. A crystallizing dense magma ocean at the base of the Earth’s mantle. Nature 450, 866–869 (2007).

    Article  Google Scholar 

  30. Ballmer, M. D., Houser, C., Hernlund, J. W., Wentzcovitch, R. M. & Hirose, K. Persistence of strong silica-enriched domains in the Earth’s lower mantle. Nat. Geosci. 10, 236–240 (2017).

    Article  Google Scholar 

  31. Jochum, K. P., Hofmann, A. W., Ito, E., Seufert, H. M. & White, W. M. K. U and Th in mid-ocean ridge basalt glasses and heat production, K/U and K/Rb in the mantle. Nature 306, 431–436 (1983).

    Article  Google Scholar 

  32. Gale, A., Dalton, C. A., Langmuir, C. H., Su, Y. & Schilling, J. G. The mean composition of ocean ridge basalts. Geochem. Geophys. Geosyst. 14, 489–518 (2013).

    Article  Google Scholar 

  33. Allègre, C. J., Staudacher, T. & Sarda, P. Rare gas systematics: formation of the atmosphere, evolution and structure of the Earth’s mantle. Earth Planet. Sci. Lett. 81, 127–150 (1987).

    Article  Google Scholar 

  34. Porcelli, D. & Wasserburg, G. J. Mass transfer of helium, neon, argon, and xenon through a steady-state upper mantle. Geochim. Cosmochim. Acta 59, 4921–4937 (1995).

    Article  Google Scholar 

  35. Sarda, P., Moreira, M. & Staudacher, T. Argon–lead isotopic correlation in Mid-Atlantic Ridge basalts. Science 283, 666–668 (1999).

    Article  Google Scholar 

  36. Holland, G. & Ballentine, C. J. Seawater subduction controls the heavy noble gas composition of the mantle. Nature 441, 186–191 (2006).

    Article  Google Scholar 

  37. Parai, R., Mukhopadhyay, S. & Standish, J. J. Heterogeneous upper mantle Ne, Ar and Xe isotopic compositions and a possible Dupal noble gas signature recorded in basalts from the Southwest Indian Ridge. Earth Planet. Sci. Lett. 359, 227–239 (2012).

    Article  Google Scholar 

  38. Tucker, J. M., Mukhopadhyay, S. & Schilling, J. G. The heavy noble gas composition of the depleted MORB mantle (DMM) and its implications for the preservation of heterogeneities in the mantle. Earth Planet. Sci. Lett. 355, 244–254 (2012).

    Article  Google Scholar 

  39. Kendrick, M. A., Scambelluri, M., Honda, M. & Phillips, D. High abundances of noble gas and chlorine delivered to the mantle by serpentinite subduction. Nat. Geosci. 4, 807–812 (2011).

    Article  Google Scholar 

  40. Jackson, C. R. M., Parman, S. W., Kelley, S. P. & Cooper, R. F. Noble gas transport into the mantle facilitated by high solubility in amphibole. Nat. Geosci. 6, 562–565 (2013).

    Article  Google Scholar 

  41. Staudacher, T. & Allègre, C. J. Recycling of oceanic crust and sediments: the noble gas subduction barrier. Earth Planet. Sci. Lett. 89, 173–183 (1988).

    Article  Google Scholar 

  42. Burnard, P. G. Origin of argon–lead isotopic correlation in basalts. Science 286, 871 (1999).

    Article  Google Scholar 

  43. Matsumoto, T., Chen, Y. & Matsuda, J. Concomitant occurrence of primordial and recycled noble gases in the Earth’s mantle. Earth Planet. Sci. Lett. 185, 35–47 (2001).

    Article  Google Scholar 

  44. Honda, M. & McDougall, I. Primordial helium and neon in the Earth—a speculation on early degassing. Geophys. Res. Lett. 25, 1951–1954 (1998).

    Article  Google Scholar 

  45. Tucker, J. M. & Mukhopadhyay, S. Evidence for multiple magma ocean outgassing and atmospheric loss episodes from mantle noble gases. Earth Planet. Sci. Lett. 393, 254–265 (2014).

    Article  Google Scholar 

  46. Sarda, P., Staudacher, T. & Allègre, C. J. 40Ar/36Ar in MORB glasses: constraints on atmosphere and mantle evolution. Earth Planet. Sci. Lett. 72, 357–375 (1985).

    Article  Google Scholar 

  47. Staudacher, T. & Allègre, C. J. Terrestrial xenology. Earth Planet. Sci. Lett. 60, 389–406 (1982).

    Article  Google Scholar 

  48. Porcelli, D., Woolum, D. & Cassen, P. Deep Earth rare gases: initial inventories, capture from the solar nebula, and losses during Moon formation. Earth Planet. Sci. Lett. 193, 237–251 (2001).

    Article  Google Scholar 

  49. Drake, M. J. & Righter, K. Determining the composition of the Earth. Nature 416, 39–44 (2002).

    Article  Google Scholar 

  50. Hirschmann, M. M. Constraints on the early delivery and fractionation of Earth’s major volatiles from C/H, C/N, and C/S ratios. Am. Mineral. 101, 540–553 (2016).

    Article  Google Scholar 

  51. Hanes, J. A., York, D. & Hall, C. M. An 40Ar/39Ar geochronological and electron microprobe investigation of an Archean pyroxenite and its bearing on ancient atmospheric compositions. Can. J. Earth Sci. 22, 947–958 (1985).

    Article  Google Scholar 

  52. Stuart, F. M., Mark, D. F., Gandanger, P. & McConville, P. Earth–atmosphere evolution based on new determination of Devonian atmosphere Ar isotopic composition. Earth Planet. Sci. Lett. 446, 21–26 (2016).

    Article  Google Scholar 

  53. Coltice, N., Marty, B. & Yokochi, R. Xenon isotope constraints on the thermal evolution of the early Earth. Chem. Geol. 266, 4–9 (2009).

    Article  Google Scholar 

  54. Parai, R. & Mukhopadhyay, S. Xenon isotopic constraints on the history of volatile recycling into the mantle. Nature 560, 223–227 (2018).

    Article  Google Scholar 

  55. Jones, T. D., Sime, N. & van Keken, P. E. Burying Earth’s primitive mantle in the slab graveyard. Geochem. Geophys. Geosyst. 22, e2020GC009396 (2021).

    Article  Google Scholar 

  56. Jones, R. E. et al. Origins of the terrestrial Hf–Nd mantle array: evidence from a combined geodynamical–geochemical approach. Earth Planet. Sci. Lett. 518, 26–39 (2019).

    Article  Google Scholar 

  57. van Keken, P. Cylindrical scaling for dynamical cooling models of the Earth. Phys. Earth Planet. Inter. 124, 119–130 (2001).

    Article  Google Scholar 

  58. Gable, C. W., O’Connell, R. J. & Travis, B. J. Convection in three dimensions with surface plates: generation of toroidal flow. J. Geophys. Res. Solid Earth 96, 8391–8405 (1991).

    Article  Google Scholar 

  59. Christensen, U. R. & Hofmann, A. W. Segregation of subducted oceanic crust in the convecting mantle. J. Geophys. Res. Solid Earth 99, 19867–19884 (1994).

    Article  Google Scholar 

  60. Lithgow-Bertelloni, C. & Richards, M. A. The dynamics of Cenozoic and Mesozoic plate motions. Rev. Geophys. 36, 27–78 (1998).

    Article  Google Scholar 

  61. Pollack, H. N., Hurter, S. J. & Johnson, J. R. Heat flow from the Earth’s interior: analysis of the global data set. Rev. Geophys. 31, 267–280 (1993).

    Article  Google Scholar 

  62. Dasgupta, R. & Hirschmann, M. M. Melting in the Earth’s deep upper mantle caused by carbon dioxide. Nature 440, 659–662 (2006).

    Article  Google Scholar 

  63. Nakagawa, T. & Tackley, P. J. Influence of initial CMB temperature and other parameters on the thermal evolution of Earth’s core resulting from thermochemical spherical mantle convection. Geochem. Geophys. Geosys. 11, Q06001 (2010).

    Article  Google Scholar 

  64. Nakagawa, T., Tackley, P. J., Deschamps, F. & Connolly, J. A. D. The influence of MORB and harzburgite composition on thermo-chemical mantle convection in a 3-D spherical shell with self-consistently calculated mineral physics. Earth Planet. Sci. Lett. 296, 403–412 (2010).

    Article  Google Scholar 

  65. Brandenburg, J. P. & van Keken, P. E. Deep storage of oceanic crust in a vigorously convecting mantle. J. Geophys. Res. 112, B06403 (2007).

    Google Scholar 

  66. Li, M., McNamara, A. K. & Garnero, E. J. Chemical complexity of hotspots caused by cycling oceanic crust through mantle reservoirs. Nat. Geosci. 7, 366–370 (2014).

    Article  Google Scholar 

  67. Billen, M. I. Modeling the dynamics of subducting slabs. Annu. Rev. Earth Planet. Sci. 36, 325–356 (2008).

    Article  Google Scholar 

  68. Hurley, P. M. & Rand, J. R. Pre-drift continental nuclei. Science 164, 1229–1242 (1969).

    Article  Google Scholar 

  69. Porcelli, D., Ballentine, C. J. & Wieler, R. An overview of noble gas geochemistry and cosmochemistry. Rev. Mineral. Geochem. 47, 1–19 (2002).

    Article  Google Scholar 

  70. Lee, J. Y. et al. A redetermination of the isotopic abundances of atmospheric Ar. Geochim. Cosmochim. Acta 70, 4507–4512 (2006).

    Article  Google Scholar 

  71. Halliday, A. N. The origins of volatiles in the terrestrial planets. Geochim. Cosmochim. Acta 105, 146–171 (2013).

    Article  Google Scholar 

  72. Turekian, K. K. The terrestrial economy of helium and argon. Geochim. Cosmochim. Acta 17, 37–43 (1959).

    Article  Google Scholar 

  73. Rudnick, R. L. & Gao, S. in Treatise on Geochemistry 2nd edn, Vol. 4 (ed. Rudnick, R. L.) 1–51 (Elsevier, 2014).

  74. Goodman, J. & Weare, J. Ensemble samplers with affine invariance. Comm. Appl. Math. Comp. Sci. 5, 65–80 (2010).

    Article  Google Scholar 

  75. Foreman-Mackey, D., Hogg, D. W., Lang, D. & Goodman, J. emcee: the MCMC hammer. Publ. Astron. Soc. Pac. 125, 306–312 (2013).

    Article  Google Scholar 

  76. Kurz, M. D., Jenkins, W. J. & Hart, S. R. Helium isotopic systematics of oceanic islands and mantle heterogeneity. Nature 297, 43–47 (1982).

    Article  Google Scholar 

  77. Kelley, K. A., Plank, T., Farr, L., Ludden, J. & Staudigel, H. Subduction cycling of U, Th, and Pb. Earth Planet. Sci. Lett. 234, 369–383 (2005).

    Article  Google Scholar 

  78. Allègre, C. J., Poirier, J. P., Humler, E. & Hofmann, A. W. The chemical composition of the Earth. Earth Planet. Sci. Lett. 134, 515–526 (1995).

    Article  Google Scholar 

  79. Hart, S. R. & Zindler, A. In search of a bulk-Earth composition. Chem. Geol. 57, 247–267 (1986).

    Article  Google Scholar 

  80. Jagoutz, E. et al. The abundances of major, minor and trace elements in the Earth’s mantle as derived from primitive ultramafic nodules. In Proc. 10th Lunar and Planetary Science Conference 2031–2050 (Pergamon Press, 1979).

  81. Lyubetskaya, T. & Korenaga, J. Chemical composition of Earth’s primitive mantle and its variance: 1. Methods and results. J. Geophys. Res. Solid Earth 112, B03211 (2007).

    Google Scholar 

  82. McDonough, W. F. & Sun, S. S. The composition of the Earth. Chem. Geol. 120, 223–253 (1995).

    Article  Google Scholar 

  83. Palme, H. & O’Neill, H. St. C. in Treatise on Geochemistry 2nd edn, Vol. 3 (ed. Carlson, R. W.) 1–39 (Elsevier, 2014).

  84. Huang, Y., Chubakov, V., Mantovani, F., Rudnick, R. L. & McDonough, W. F. A reference Earth model for the heat-producing elements and associated geoneutrino flux. Geochem. Geophys. Geosyst. 14, 2003–2029 (2013).

    Article  Google Scholar 

  85. Plank, T. in Treatise on Geochemistry 2nd edn, Vol. 4 (ed. Rudnick, R. L.) 607–629 (Elsevier, 2014).

  86. Turner, S. J. & Langmuir, C. H. The global chemical systematics of arc front stratovolcanoes: evaluating the role of crustal processes. Earth Planet. Sci. Lett. 422, 182–193 (2015).

    Article  Google Scholar 

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Acknowledgements

J.M.T. and P.E.v.K. acknowledge funding from NSF CSEDI grant 1664642. J.M.T. acknowledges support from a Peter Buck Postdoctoral Fellowship. C.J.B. acknowledges funding from the NERC Deep Mantle Volatiles consortium, NE/M000427/1.

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Authors and Affiliations

  1. Earth and Planets Laboratory, Carnegie Institution for Science, Washington DC, USA

    Jonathan M. Tucker & Peter E. van Keken

  2. Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington DC, USA

    Jonathan M. Tucker

  3. Department of Earth Sciences, University of Oxford, Oxford, UK

    Chris J. Ballentine

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Contributions

P.E.v.K. developed the geodynamic models; J.M.T. and P.E.v.K. developed the geochemical models with input from C.J.B.; all authors analysed the results; J.M.T. wrote the manuscript with input from P.E.v.K. and C.J.B.

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Correspondence to Jonathan M. Tucker.

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Nature Geoscience thanks Philippe Sarda and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Rebecca Neely.

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Extended data

Extended Data Fig. 1 Fraction of terrestrial 40Ar in the atmosphere for different BSE K concentrations (red line).

The other colored lines assume that all 40Ar produced before the specified time is lost to space, for example by impacts. Due to the long half-life of 40K, the amount of 40Ar produced and lost even after 200 Ma hardly affects the terrestrial 40Ar budget and the missing Ar paradox. Furthermore, these calculations assume efficient degassing such that all 40Ar produced within the specified time is subject to atmospheric loss. Any 40Ar retained within the Earth would reduce the effect. A95 = Allègre et al.78; HZ86 = Hart and Zindler79; J79 = Jagoutz et al.80 LK07 = Lyubetskaya and Korenaga81; MS95 = McDonough and Sun82; PO03 = Palme and O’Neill83.

Extended Data Fig. 2 K/U ratios in the upper mantle and continental crust.

Bulk continental crust is \({1160{0}_{-2500}}^{+3500}\) ref. 84); sediments are 10600 ± 900 (2.21 ± 0.14$% K2O, 1.73 ± 0.09 ppm U; ref. 85); arc lavas are \({1100{0}_{-2900}}^{+9700}\) based on the median and 1 − σ range of arc segment averages86; MORB is 12300 ± 400 (ref. 32). The similarity between K/U ratios of the upper mantle and continental crust suggest that K/U fractionation during subduction does not substantially alter the global K and U budgets, and that MORBs provide a reasonable estimate for the BSE.

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Tucker, J.M., van Keken, P.E. & Ballentine, C.J. Earth’s missing argon paradox resolved by recycling of oceanic crust. Nat. Geosci. 15, 85–90 (2022). https://doi.org/10.1038/s41561-021-00870-6

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