Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Deep roots for mid-ocean-ridge volcanoes revealed by plagioclase-hosted melt inclusions


The global mid-ocean ridge system is the most extensive magmatic system on our planet and is the site of 75 per cent of Earth’s volcanism1. The vertical extent of mid-ocean-ridge magmatic systems has been considered to be restricted: even at the ultraslow-spreading Gakkel mid-ocean ridge under the Arctic Ocean, where the lithosphere is thickest, crystallization depths of magmas that feed eruptions are thought to be less than nine kilometres2. These depths were determined using the volatile-element contents of melt inclusions, which are small volumes of magma that become trapped within crystallizing minerals. In studies of basaltic magmatic systems, olivine is the mineral of choice for this approach2,3,4,5,6. However, pressures derived from olivine-hosted melt inclusions are at odds with pressures derived from basalt major-element barometers7 and geophysical measurements of lithospheric thickness8. Here we present a comparative study of olivine- and plagioclase-hosted melt inclusions from the Gakkel mid-ocean ridge. We show that the volatile contents of plagioclase-hosted melt inclusions correspond to much higher crystallization pressures (with a mean value of 270 megapascals) than olivine-hosted melt inclusions (with a mean value of 145 megapascals). The highest recorded pressure that we find equates to a depth 16.4 kilometres below the seafloor. Such higher depths are consistent with both the thickness of the Gakkel mid-ocean ridge lithosphere and with pressures reconstructed from glass compositions. In contrast to previous studies using olivine-hosted melt inclusions, our results demonstrate that mid-ocean-ridge volcanoes may have magmatic roots deep in the lithospheric mantle, at least at ultraslow-spreading ridges.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Textural complexity of olivine and plagioclase and melt-inclusion distribution and associations.
Fig. 2: Volatile contents of Gakkel Ridge olivine- and plagioclase-hosted melt inclusions.
Fig. 3: Compositional relationships of plagioclase- and olivine-hosted melt inclusions.
Fig. 4: Crystallization depth and pressures recorded in olivine.
Fig. 5: Comparison of crystallization depths recorded in melt inclusions.

Data availability

Source Data for all figures are provided with the paper and also in the Supplementary Information tables. The data are also available from EarthChem at


  1. Crisp, J. A. Rates of magma emplacement and volcanic output. J. Volcanol. Geotherm. Res. 20, 177–211 (1984).

    Article  ADS  Google Scholar 

  2. Shaw, A. M., Behn, M. D., Humphris, S. E., Sohn, R. A. & Gregg, P. M. Deep pooling of low degree melts and volatile fluxes at the 85°E segment of the Gakkel Ridge: evidence from olivine-hosted melt inclusions and glasses. Earth Planet. Sci. Lett. 289, 311–322 (2010).

    Article  ADS  CAS  Google Scholar 

  3. Wanless, V. D., Behn, M. D., Shaw, A. M. & Plank, T. Variations in melting dynamics and mantle compositions along the Eastern Volcanic Zone of the Gakkel Ridge: insights from olivine-hosted melt inclusions. Contrib. Mineral. Petrol. 167, 1005 (2014).

    Article  ADS  Google Scholar 

  4. Colman, A., Sinton, J. M. & Wanless, V. D. Constraints from melt inclusions on depths of magma residence at intermediate magma supply along the Galápagos spreading center. Earth Planet. Sci. Lett. 412, 122–131 (2015).

    Article  ADS  CAS  Google Scholar 

  5. Wanless, V. D. & Shaw, A. M. Lower crustal crystallization and melt evolution at mid-ocean ridges. Nat. Geosci. 5, 651–655 (2012).

    Article  ADS  CAS  Google Scholar 

  6. Wanless, V. D. et al. Magmatic plumbing at Lucky Strike volcano based on olivine-hosted melt inclusion compositions. Geochem. Geophys. Geosyst. 16, 126–147 (2015).

    Article  ADS  CAS  Google Scholar 

  7. Wanless, V. D. & Behn, M. D. Spreading rate-dependent variations in crystallization along the global mid-ocean ridge system. Geochem. Geophys. Geosyst. 18, 3016–3033 (2017).

    Article  ADS  Google Scholar 

  8. Schlindwein, V. & Schmid, F. Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere. Nature 535, 276–279 (2016).

    Article  ADS  CAS  Google Scholar 

  9. Chen, Y. J. & Lin, J. High sensitivity of ocean ridge thermal structure to changes in magma supply: the Galápagos spreading center. Earth Planet. Sci. Lett. 221, 263–273 (2004).

    Article  ADS  CAS  Google Scholar 

  10. Phipps Morgan, J. & Chen, Y. J. The genesis of oceanic crust: magma injection, hydrothermal circulation, and crustal flow. J. Geophys. Res. 98, 6283–6297 (1993).

    Article  ADS  Google Scholar 

  11. Lissenberg, C. J. & MacLeod, C. J. A reactive porous flow control on mid-ocean ridge magmatic evolution. J. Petrol. 57, 2195–2220 (2016).

    Article  ADS  CAS  Google Scholar 

  12. Kent, A. J. R. Melt inclusions in basaltic and related volcanic rocks. Rev. Mineral. Geochem. 69, 273–331 (2008).

    Article  CAS  Google Scholar 

  13. Kress, V. C. & Ghiorso, M. S. Thermodynamic modeling of post-entrapment crystallization in igneous phases. J. Volcanol. Geotherm. Res. 137, 247–260 (2004).

    Article  ADS  CAS  Google Scholar 

  14. Neave, D. A., Hartley, M. E., Maclennan, J., Edmonds, M. & Thordarson, T. Volatile and light lithophile elements in high-anorthite plagioclase-hosted melt inclusions from Iceland. Geochim. Cosmochim. Acta 205, 100–118 (2017).

    Article  ADS  CAS  Google Scholar 

  15. Maclennan, J. Bubble formation and decrepitation control the CO2 content of olivine-hosted melt inclusions. Geochem. Geophys. Geosyst. 18, 597–616 (2017).

    Article  ADS  CAS  Google Scholar 

  16. Grove, T. L., Baker, M. B. & Kinzler, R. J. Coupled CaAl-NaSi diffusion in plagioclase feldspar: experiments and applications to cooling rate speedometry. Geochim. Cosmochim. Acta 48, 2113–2121 (1984).

    Article  ADS  CAS  Google Scholar 

  17. Chakraborty, S. Rates and mechanisms of Fe-Mg interdiffusion in olivine at 980°–1300 °C. J. Geophys. Res. 102, 12317 (1997).

    Article  ADS  CAS  Google Scholar 

  18. Bryan, W. B. Systematics of modal phenocryst assemblages in submarine basalts: petrologic implications. Contrib. Mineral. Petrol. 83, 62–74 (1983).

    Article  ADS  CAS  Google Scholar 

  19. Welsch, B., Hammer, J. & Hellebrand, E. Phosphorus zoning reveals dendritic architecture of olivine. Geology 42, 867–870 (2014).

    Article  ADS  CAS  Google Scholar 

  20. Matthews, S., Shorttle, O., Rudge, J. F. & Maclennan, J. Constraining mantle carbon: CO2-trace element systematics in basalts and the roles of magma mixing and degassing. Earth Planet. Sci. Lett. 480, 1–14 (2017).

    Article  ADS  CAS  Google Scholar 

  21. Lowenstern, J. B. in Magmas, Fluids and Ore Deposits Vol. 23, 71–99 (Mineralogical Society of Canada, 1995).

  22. Anderson, A. T. & Brown, G. G. CO2 contents and formation pressures of some Kilauean melt inclusions. Am. Mineral. 78, 794–803 (1993).

    CAS  Google Scholar 

  23. Wallace, P. J., Kamenetsky, V. S. & Cervantes, P. Melt inclusion CO2 contents, pressures of olivine crystallization, and the problem of shrinkage bubbles. Am. Mineral. 100, 787–794 (2015).

    Article  ADS  Google Scholar 

  24. Roedder, E. Liquid CO2 inclusions in olivine-bearing nodules and phenocrysts from basalts. Am. Mineral. 50, 356–366 (1965).

    Google Scholar 

  25. Portnyagin, M. V., Plechov, P. Y., Matveev, S. V., Osipenko, A. B. & Mironov, N. L. Petrology of avachites, high-magnesian basalts of Avachinsky volcano, Kamchatka: I. General characteristics and composition of rocks and minerals. Petrologiya 13, 99–121 (2005).

    Google Scholar 

  26. Roedder, E. Fluid Inclusions (Mineralogical Society of America, 1984).

  27. Helo, C., Longpré, M.-A., Shimizu, N., Clague, D. A. & Stix, J. Explosive eruptions at mid-ocean ridges driven by CO2-rich magmas. Nat. Geosci. 4, 260–263 (2011).

    Article  ADS  CAS  Google Scholar 

  28. Michael, P. J. & Graham, D. W. The behavior and concentration of CO2 in the suboceanic mantle: inferences from undegassed ocean ridge and ocean island basalts. Lithos 236–237, 338–351 (2015).

    Article  ADS  Google Scholar 

  29. Hartley, M. E., Maclennan, J., Edmonds, M. & Thordarson, T. Reconstructing the deep CO2 degassing behaviour of large basaltic fissure eruptions. Earth Planet. Sci. Lett. 393, 120–131 (2014).

    Article  ADS  CAS  Google Scholar 

  30. Le Voyer, M., Kelley, K. A., Cottrell, E. & Hauri, E. H. Heterogeneity in mantle carbon content from CO2-undersaturated basalts. Nat. Commun. 8, 14062 (2017).

    Article  ADS  Google Scholar 

  31. Shishkina, T. A., Botcharnikov, R. E., Holtz, F., Almeev, R. R. & Portnyagin, M. V. Solubility of H2O- and CO2-bearing fluids in tholeiitic basalts at pressures up to 500MPa. Chem. Geol. 277, 115–125 (2010).

    Article  ADS  CAS  Google Scholar 

  32. Jenner, F. E. & O’Neill, H. S. C. Major and trace analysis of basaltic glasses by laser-ablation ICP-MS. Geochem. Geophys. Geosyst. 13, Q03003 (2012).

  33. Sobolev, A. V. & Shimizu, N. Ultra-depleted primary melt included in an olivine from the Mid-Atlantic Ridge. Nature 363, 151–154 (1993).

    Article  ADS  CAS  Google Scholar 

  34. Berry, A. J., Stewart, G. A., O’Neill, H. S. C., Mallmann, G. & Mosselmans, J. F. W. A re-assessment of the oxidation state of iron in MORB glasses. Earth Planet. Sci. Lett. 483, 114–123 (2018).

    Article  ADS  CAS  Google Scholar 

  35. Hartley, M. E., Bali, E., MacLennan, J., Neave, D. A. & Halldorsson, S. A. Melt inclusion constraints on volatile systematics and degassing history of the 2014–2015 Holuhraun eruption, Iceland. Contrib. Mineral. Petrol. 173, 10 (2018).

    Article  ADS  Google Scholar 

  36. Lehnert, K., Su, Y., Langmuir, C. H., Sarbas, B. & Nohl, U. A global geochemical database structure for rocks. Geochem. Geophys. Geosyst. 1, 1012 (2000).

  37. Lissenberg, C. J., MacLeod, C. J. & Bennett, E. N. Consequences of a crystal mush-dominated magma plumbing system: a mid-ocean ridge perspective. Phil. Trans. R. Soc. A (2018).

    Article  ADS  Google Scholar 

  38. Dixon, J. E. & Stolper, E. M. An experimental study of water and carbon dioxide solubilities in mid-ocean ridge basaltic liquids. Part II: applications to degassing. J. Petrol. 36, 1633–1646 (1995).

    CAS  Google Scholar 

  39. Ghiorso, M. S. & Gualda, G. A. R. An H2O–CO2 mixed fluid saturation model compatible with rhyolite-MELTS. Contrib. Mineral. Petrol. 169, 53 (2015).

    Article  ADS  Google Scholar 

  40. Newman, S. & Lowenstern, J. B. Volatile Calc: a silicate melt–H2O–CO2 solution model written in Visual Basic for Excel. Comput. Geosci. 28, 597–604 (2002).

    Article  ADS  CAS  Google Scholar 

  41. Shishkina, T. A. et al. Compositional and pressure effects on the solubility of H2O and CO2 in mafic melts. Chem. Geol. 388, 112–129 (2014).

    Article  ADS  CAS  Google Scholar 

  42. Saal, A. E., Hauri, E. H., Langmuir, C. H. & Perfit, M. R. Vapour undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth’s upper mantle. Nature 419, 451–455 (2002).

    Article  ADS  CAS  Google Scholar 

  43. Rosenthal, A., Hauri, E. H. & Hirschmann, M. M. Experimental determination of C, F, and H partitioning between mantle minerals and carbonated basalt, CO2/Ba and CO2/Nb systematics of partial melting, and the CO2 contents of basaltic source regions. Earth Planet. Sci. Lett. 412, 77–87 (2015).

    Article  ADS  CAS  Google Scholar 

  44. Workman, R. K. & Hart, S. R. Major and trace element composition of the depleted MORB mantle (DMM). Earth Planet. Sci. Lett. 231, 53–72 (2005).

    Article  ADS  CAS  Google Scholar 

  45. Jakobsson, M. et al. The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0. Geophys. Res. Lett. 39, 12609 (2012).

  46. Ryan, W. B. F. et al. Global multi-resolution topography synthesis. Geochem. Geophys. Geosyst. 10, Q03014 (2010).

    Article  Google Scholar 

Download references


We thank H. J. B. Dick for providing access to Gakkel Ridge samples, C-J. de Hoog for expert advice on SIMS analysis, D. Muir for assistance with the EDS analysis, and A. Oldroyd for help with sample preparation. We also thank Mark Behn for comments on the original manuscript. This research was supported by NERC grants NE/L002434/1 (to E.N.B.), NE/R001332/1 (to M.-A.M.) and NE/M000427/1 (to F.E.J) and IMF641/1017 (to C.J.L.) and by an AXA Professorship and Wolfson Merit Award (to K.V.C.).

Author information

Authors and Affiliations



E.N.B. and C.J.L. conceived the study. E.N.B. collected all data (except for the melt-inclusion trace-element data collected by F.E.J.). E.N.B. wrote the manuscript (under the supervision of C.J.L.). K.V.C., M.-A.A. and F.E.J. contributed to critical discussions and commented on the manuscript.

Corresponding authors

Correspondence to Emma N. Bennett or C. Johan Lissenberg.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Peer review information Nature thanks Mark D. Behn and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Extended data figures and tables

Extended Data Fig. 1 Sample locations along the Gakkel Ridge.

Green symbols show new plagioclase- and olivine-hosted melt-inclusion analysis; orange symbols show new plagioclase-hosted melt-inclusion data supplemented by olivine-hosted melt-inclusion data from ref. 3; purple and yellow symbols indicate data from ref. 2 and from ref. 3, respectively. AVR, axial volcanic ridge; SM, seamount; BR, basement ridge; DSF, deep seafloor. IBCAO bathymetric data are from ref. 45. The Global Multi-Resolution Topography (GMRT) synthesis46 base map underlies the IBCAO bathymetry. The map was made using GeoMapApp (

Extended Data Fig. 2 Textural complexity of olivine and plagioclase and melt-inclusion distribution.

Backscattered-electron images of plagioclase (ac) and olivine (df). Plagioclase can be unzoned (c) or show patchy zoning (a) or reverse and normal zoning (b); plagioclase shows both internal (a, b) and external (c) resorption. Olivine is present in poly- and mono-mineral glomerocrysts (d, e) and as individual skeletal crystals (f); reverse (d) and normal (e) zoning is present. Scale bars are all 100 μm. Dashed red and yellow lines in a, b and d show the locations of resorption. Numbers correspond to the analysed melt inclusions highlighted in Supplementary Table 2. O and P refer to host olivine and plagioclase crystals, respectively; in d, a melt inclusion has been analysed from olivine within a polymineralic glomerocryst or clot.

Extended Data Fig. 3 Relationship between melt-inclusion size and CO2 content.

Both plagioclase- and olivine-hosted melt inclusions show no relationship between melt inclusion size and CO2 content.

Source Data

Extended Data Fig. 4 Crystallization depths recorded by melt inclusions from individual samples.

Within each sample, plagioclase records greater crystallization depths than olivine. The three individual samples are from the 31° E basement ridge (HLY0102-D95-11 and HLY0102-D48-SGB) and 3° E seamount (HLY0102-D27-8).

Source Data

Extended Data Fig. 5 Textural relationship of high-pressure olivine-hosted melt inclusion.

a, Phase map showing the association of the high-pressure olivine-hosted melt inclusion (MI) with plagioclase. White lines delineate grain boundaries. Plagioclase exhibits complex zoning (such as oscillatory (OZ) and patchy zoning (PZ) in b and c). Plagioclase exhibits both internal and external resorption (IR and ER, respectively) in b and c. Large amoeboid melt inclusions (c) also suggest the occurrence of resorption. Plagioclase melt inclusions were microcrystalline and hence were not analysed for their volatile contents. Scale bars are 500 μm. For information relating to phase map acquisition, see ref. 37.

Extended Data Fig. 6 Calibration curves for CO2 and H2O analysis.

Calibration curves are shown for H2O (a) and CO2 (b). The different coloured lines in each panel indicate different analytical sessions.

Source Data

Extended Data Fig. 7 Plagioclase-hosted melt-inclusion PEC correction.

Plagioclase-hosted melt-inclusion compositions were empirically corrected for PEC (b). Host plagioclase compositions were added to the melt inclusions iteratively until the melt inclusions met the Al2O3 content (at a given Mg#) of the pseudo-liquid line of descent. The pseudo-liquid line of descent comprises two parts. First, a regression through Gakkel glass data36,37 (black line), and second, a line hand-picked to run along the top of the olivine-hosted melt inclusions2,3 and Gakkel glass data (red line) (a). A second PEC correction was undertaken using a different pseudo-liquid line of descent (green line) (c) that resulted in lower corrections. A comparison of pressures calculated following each of these PEC corrections shows that there is negligible difference between pressures calculated from the resulting melt compositions (d). Gakkel glass data were downloaded from the PetDB36 database ( on 15 July 2016.

Source Data

Extended Data Fig. 8 Relationship between PEC correction and crystallization depths.

There is no relationship between the magnitude of PEC correction and crystallization depth.

Source Data

Extended Data Fig. 9 Comparison between VolatileCalc and MagmaSat H2O-CO2 models.

The majority of melt inclusions have SiO2 > 49 wt%, hence VolatileCalc pressures were calculated using a default SiO2 value (49 wt%; orange points). Where SiO2 < 49 wt%, specific VolatileCalc pressures were calculated (blue points); blue points correspond to orange points with no outline calculated with the default SiO2 content. VolatileCalc pressures are lower when the specific SiO2 (not the default 49 wt% SiO2) content of the melt inclusion is used.

Source Data

Supplementary information

Supplementary Tables

This excel file contains Supplementary Tables 1-5 which include information about SIMs, EDS and LA-ICP-MS analysis and raw and corrected melt inclusion compositions

Source data

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Bennett, E.N., Jenner, F.E., Millet, MA. et al. Deep roots for mid-ocean-ridge volcanoes revealed by plagioclase-hosted melt inclusions. Nature 572, 235–239 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing