Thermal effects of pyroxenites on mantle melting below mid-ocean ridges


After travelling in Earth’s interior for up to billions of years, recycled material once injected at subduction zones can reach a subridge melting region as pyroxenite dispersed in the host peridotitic mantle. Here we study genetically related crustal basalts and mantle peridotites sampled along an uplifted lithospheric section created at a segment of the Mid-Atlantic Ridge through a time interval of 26 million years. The arrival of low-solidus material into the melting region forces the elemental and isotopic imprint of the residual peridotites and of the basalts to diverge with time. We show that a pyroxenite-bearing source entering the subridge melting region induces undercooling of the host peridotitic mantle, due to subtraction of latent heat by melting of the low-T-solidus pyroxenite. Mantle undercooling, in turn, lowers the thermal boundary layer, leading to a deeper cessation of melting. A consequence is to decrease the total amount of extracted melt, and hence the magmatic crustal thickness. The degree of melting undergone by a homogeneous peridotitic mantle is higher than the degree of melting of the same peridotite but veined by pyroxenites. This effect, thermodynamically predicted for a marble-cake-type peridotite–pyroxenite mixed source, implies incomplete homogenization of recycled material in the convective mantle.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Temporal variations of Nd isotopes and degree of melting along the VLS.
Fig. 2: Interpretative sketch of the upwelling mantle column below the VLS.
Fig. 3: Melt-PX24 numerical experiments for adiabatic melting of a two-component mantle source with lherzolite plus SD pyroxenite (M7-1629).
Fig. 4: Variation of the degree of melting estimated from mantle peridotite and associated basalts along the SWIR and the MAR from the Equator to the Azores hotspot region.
Fig. 5: The difference in the degree of melting estimated from genetically related basalts and peridotites (ΔF) versus the Nd isotopic composition of basalt.


  1. 1.

    Bonatti, E. et al. Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere. Nature 423, 499–505 (2003).

    Article  Google Scholar 

  2. 2.

    Brunelli, D., Seyler, M., Cipriani, A., Ottolini, L. & Bonatti, E. Discontinuous melt extraction and weak refertilization of mantle peridotites at the Vema lithospheric section (Mid-Atlantic Ridge). J. Petrol. 47, 745–771 (2006).

    Article  Google Scholar 

  3. 3.

    Bonatti, E. et al. Flexural uplift of a lithospheric slab near the Vema transform (central Atlantic): timing and mechanisms. Earth Planet. Sci. Lett. 240, 642–655 (2005).

    Article  Google Scholar 

  4. 4.

    Cipriani, A., Bonatti, E., Brunelli, D. & Ligi, M. 26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: the Vema lithospheric Section revisited. Earth Planet. Sci. Lett. 285, 87–95 (2009).

    Article  Google Scholar 

  5. 5.

    Cipriani, A., Brueckner, H. K., Bonatti, E. & Brunelli, D. Oceanic crust generated by elusive parents: Sr and Nd isotopes in basalt-peridotite pairs from the Mid-Atlantic Ridge. Geology 32, 657–660 (2004).

    Article  Google Scholar 

  6. 6.

    Cipriani, A. et al. A 19 to 17 Ma amagmatic extension event at the Mid-Atlantic Ridge: ultramafic mylonites from the Vema lithospheric section. Geochem. Geophys. Geosyst. 10, Q10011 (2009).

    Article  Google Scholar 

  7. 7.

    Plank, T. & Langmuir, C. H. Effects of the melting regime on the composition of the oceanic crust. J. Geophys. Res. 97, 19749–19770 (1992).

    Article  Google Scholar 

  8. 8.

    Klein, E. M. & Langmuir, C. H. Global correlations of ocean ridge basalt chemistry with axial depth and crustal thickness. J. Geophys. Res. 92, 8089 (1987).

    Article  Google Scholar 

  9. 9.

    Dick, H. J. B. & Bullen, T. Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contrib. Mineral. Petrol. 86, 54–76 (1984).

    Article  Google Scholar 

  10. 10.

    Michael, P. J. & Bonatti, E. Peridotite composition from the North Atlantic: regional and tectonic variations and implications for partial melting. Earth Planet. Sci. Lett. 73, 91–104 (1985).

    Article  Google Scholar 

  11. 11.

    Katz, R. F. & Weatherley, S. M. Consequences of mantle heterogeneity for melt extraction at mid-ocean ridges. Earth Planet. Sci. Lett. 335–336, 226–237 (2012).

    Article  Google Scholar 

  12. 12.

    Weatherley, S. M. & Katz, R. F. Melting and channelized magmatic flow in chemically heterogeneous, upwelling mantle. Geochem. Geophys. Geosyst. 13, Q0AC18 (2012).

    Article  Google Scholar 

  13. 13.

    Katz, R. F. & Rudge, J. F. The energetics of melting fertile heterogeneities within the depleted mantle. Geochem. Geophys. Geosyst. 12, Q0AC16 (2011).

    Article  Google Scholar 

  14. 14.

    Phipps Morgan, J. Thermodynamics of pressure release melting of a veined plum pudding mantle. Geochem. Geophys. Geosyst. 2, 1001 (2001).

    Article  Google Scholar 

  15. 15.

    Sleep, N. H. Tapping of magmas from ubiquitous mantle heterogeneities: an alternative to mantle plumes? J. Geophys. Res. 89, 10029–10041 (1984).

    Article  Google Scholar 

  16. 16.

    Ito, G. & Mahoney, J. J. Flow and melting of a heterogeneous mantle: 1. Method and importance to the geochemistry of ocean island and mid-ocean ridge basalts. Earth Planet. Sci. Lett. 230, 29–46 (2005).

    Article  Google Scholar 

  17. 17.

    Shorttle, O. Geochemical variability in MORB controlled by concurrent mixing and crystallisation. Earth Planet. Sci. Lett. 424, 1–14 (2015).

    Article  Google Scholar 

  18. 18.

    Rudge, J. F., Maclennan, J. & Stracke, A. The geochemical consequences of mixing melts from a heterogeneous mantle. Geochim. Cosmochim. Acta 114, 112–143 (2013).

    Article  Google Scholar 

  19. 19.

    Warren, J. M. Global variations in abyssal peridotite compositions. Lithos 248–251, 193–219 (2016).

    Article  Google Scholar 

  20. 20.

    Bown, J. W. & White, R. S. Variation with spreading rate of oceanic crustal thickness and geochemistry. Earth Planet. Sci. Lett. 121, 435–449 (1994).

    Article  Google Scholar 

  21. 21.

    Cande, S. C., LaBrecque, J. L. & Haxby, W. F. Plate kinematics of the South Atlantic: Chron C34 to present. J. Geophys. Res. Solid Earth 93, 13479–13492 (1988).

    Article  Google Scholar 

  22. 22.

    Cande, S. C. & Kent, D. V. Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic. J. Geophys. Res. Solid Earth 100, 6093–6095 (1995).

    Article  Google Scholar 

  23. 23.

    Langmuir, C. H., Klein, E. M. & Plank, T. in Mantle Flow and Melt Generation at Mid-Ocean Ridges (ed. Morgan, J. P.) 183–280 (American Geophysical Union, Washington DC, 1992).

  24. 24.

    Lambart, S., Baker, M. B. & Stolper, E. M. The role of pyroxenite in basalt genesis: Melt-PX, a melting parameterization for mantle pyroxenites between 0.9 and 5 GPa. J. Geophys. Res. Solid Earth 121, 5708–5735 (2016).

    Article  Google Scholar 

  25. 25.

    Shorttle, O. & Maclennan, J. Compositional trends of Icelandic basalts: implications for short-length scale lithological heterogeneity in mantle plumes. Geochem. Geophys. Geosyst. 12, Q11008 (2011).

    Article  Google Scholar 

  26. 26.

    Ligi, M., Cuffaro, M., Chierici, F. & Calafato, A. Three-dimensional passive mantle flow beneath mid-ocean ridges: an analytical approach. Geophys. J. Int. 175, 783–805 (2008).

    Article  Google Scholar 

  27. 27.

    Mckenzie, D. & Bickle, M. J. The volume and composition of melt generated by extension of the lithosphere. J. Petrol. 29, 625–679 (1988).

    Article  Google Scholar 

  28. 28.

    Shen, Y. & Forsyth, D. W. Geochemical constraints on initial and final depths of melting beneath mid-ocean ridges. J. Geophys. Res. 100, 2211–2237 (1995).

    Article  Google Scholar 

  29. 29.

    Lambart, S., Laporte, D. & Schiano, P. Markers of the pyroxenite contribution in the major-element compositions of oceanic basalts: review of the experimental constraints. Lithos 160–161, 14–36 (2013).

    Article  Google Scholar 

  30. 30.

    Stracke, A., Bourdon, B. & McKenzie, D. Melt extraction in the Earth’s mantle: constraints from U–Th–Pa–-Ra studies in oceanic basalts. Earth Planet. Sci. Lett. 244, 97–112 (2006).

    Article  Google Scholar 

  31. 31.

    Stracke, A., & Bourdon, B. The importance of melt extraction for tracing mantle heterogeneity. Geochim. Cosmochim. Acta 73, 218–238 (2009).

    Article  Google Scholar 

  32. 32.

    Rubin, K. H., Sinton, J. M., Maclennan, J. & Hellebrand, E. Magmatic filtering of mantle compositions at mid-ocean-ridge volcanoes. Nat. Geosci. 2, 321–328 (2009).

    Article  Google Scholar 

  33. 33.

    Lambart, S., Laporte, D. & Schiano, P. An experimental study of pyroxenite partial melts at 1 and 1.5 GPa: implications for the major-element composition of Mid-Ocean Ridge Basalts. Earth Planet. Sci. Lett. 288, 335–347 (2009).

    Article  Google Scholar 

  34. 34.

    Lambart, S., Laporte, D., Provost, A. & Schiano, P. Fate of pyroxenite-derived melts in the peridotitic mantle: thermodynamic and experimental constraints. J. Petrol. 53, 451–476 (2012).

    Article  Google Scholar 

  35. 35.

    Helffrich, G. R. & Wood, B. J. The Earth’s mantle. Nature 412, 501–507 (2001).

    Article  Google Scholar 

  36. 36.

    Graham, D. W., Blichert-Toft, J., Russo, C. J., Rubin, K. H. & Albarede, F. Cryptic striations in the upper mantle revealed by hafnium isotopes in southeast Indian ridge basalts. Nature 440, 199–202 (2006).

    Article  Google Scholar 

  37. 37.

    Liu, B. & Liang, Y. The prevalence of kilometer-scale heterogeneity in the source region of MORB upper mantle. Sci. Adv. 3, e1701872 (2017).

    Article  Google Scholar 

  38. 38.

    Hoernle, K. et al. On- and off-axis chemical heterogeneities along the South Atlantic Mid-Ocean-Ridge (5-11°S): shallow or deep recycling of ocean crust and/or intraplate volcanism? Earth Planet. Sci. Lett. 306, 86–97 (2011).

    Article  Google Scholar 

  39. 39.

    Paulick, H., Münker, C. & Schuth, S. The influence of small-scale mantle heterogeneities on Mid-Ocean Ridge volcanism: evidence from the southern Mid-Atlantic Ridge (7°30′S to 11°30′S) and Ascension Island. Earth Planet. Sci. Lett. 296, 299–310 (2010).

    Article  Google Scholar 

  40. 40.

    Liang, Y. Simple models for dynamic melting in an upwelling heterogeneous mantle column: analytical solutions. Geochim. Cosmochim. Acta 72, 3804–3821 (2008).

    Article  Google Scholar 

  41. 41.

    Borghini, G. et al. Meter-scale Nd isotopic heterogeneity in pyroxenite-bearing Ligurian peridotites encompasses global-scale upper mantle variability. Geology 41, 1055–1058 (2013).

    Article  Google Scholar 

  42. 42.

    Borghini, G. et al. Pyroxenite layers in the Northern Apennines’ upper mantle (Italy)-generation by pyroxenite melting and melt infiltration. J. Petrol. 57, 625–653 (2016).

    Article  Google Scholar 

  43. 43.

    Gale, A., Langmuir, C. H. & Dalton, C. A. The global systematics of ocean ridge basalts and their origin. J. Petrol. 55, 1051–1082 (2014).

    Article  Google Scholar 

  44. 44.

    Seyler, M. & Brunelli, D. Sodium chromium covariation in residual clinopyroxenes from abyssal peridotites sampled in the 43°–46°E region of the Southwest Indian Ridge. Lithos 302–303, 142–157 (2018).

    Article  Google Scholar 

  45. 45.

    Cipriani, A., Bonatti, E. & Carlson, R. W. Nonchondritic 142Nd in suboceanic mantle peridotites. Geochem. Geophys. Geosyst. 12, Q03006 (2011).

    Article  Google Scholar 

  46. 46.

    Todt, W., Cliff, R., Hanser, A. & Hofmann, A. W. Evaluation of a 202Pb–205Pb double spike for high-precision lead isotope analysis. Geophys. Monogr. Ser. 95, 429–437 (1996).

    Google Scholar 

  47. 47.

    Meyzen, C. M. et al. New insights into the origin and distribution of the DUPAL isotope anomaly in the Indian Ocean mantle from MORB of the Southwest Indian Ridge. Geochem. Geophys. Geosyst. 6, Q11K11 (2005).

    Article  Google Scholar 

  48. 48.

    Meyzen, C. M., Toplis, M. J., Humler, E., Ludden, J. N. & Mevel, C. A discontinuity in mantle composition beneath the southwest Indian ridge. Nature 421, 731–733 (2003).

    Article  Google Scholar 

  49. 49.

    Cannat, M., Rommevaux-Jestin, C., Sauter, D., Deplus, C. & Mendel, V. Formation of the axial relief at the very slow spreading Southwest Indian Ridge (49° to 69°E). J. Geophys. Res. 104, 22825–22843 (1999).

    Article  Google Scholar 

  50. 50.

    Seyler, M., Brunelli, D., Toplis, M. J. & Mével, C. Multiscale chemical heterogeneities beneath the eastern Southwest Indian Ridge (52°E–68°E): Trace element compositions of along-axis dredged peridotites.Geochem. Geophys. Geosyst. 12, Q0AC15 (2012).

    Google Scholar 

  51. 51.

    Paquet, M., Cannat, M., Brunelli, D., Hamelin, C. & Humler, E. Effect of melt/mantle interactions on MORB chemistry at the easternmost Southwest Indian Ridge (61°–67°E). Geochem. Geophys. Geosyst. 17, 4605–4640 (2016).

    Article  Google Scholar 

  52. 52.

    Brunelli, D., Paganelli, E. & Seyler, M. Percolation of enriched melts during incremental open-system melting in the spinel field: a REE approach to abyssal peridotites from the Southwest Indian Ridge. Geochim. Cosmochim. Acta 127, 190–203 (2014).

    Article  Google Scholar 

  53. 53.

    Cannat, M. & Seyler, M. Transform tectonics, metamorphic plagioclase and amphibolitization in ultramafic rocks of the Vema transform fault (Atlantic Ocean). Earth Planet. Sci. Lett. 133, 283–298 (1995).

    Article  Google Scholar 

  54. 54.

    Spiegelman, M. & Kenyon, P. The requirements for chemical disequilibrium during magma migration. Earth Planet. Sci. Lett. 109, 611–620 (1992).

    Article  Google Scholar 

  55. 55.

    Spiegelman, M. & Elliott, T. Consequences of melt transport for uranium series disequilibrium in young lavas. Earth Planet. Sci. Lett. 118, 1–20 (1993).

    Article  Google Scholar 

  56. 56.

    Lundstrom, C. C., Gill, J., Williams, Q. & Perfit, M. R. Mantle melting and basalt extraction by equilibrium porous flow. Science 270, 1958–1961 (1995).

    Article  Google Scholar 

Download references


This work has been supported by Italian-PRIN prot. 2015C5LN35 and by the US National Science Foundation under grant no. OCE-05-51288. We are also grateful for the support of the Deep Energy community of the Carbon Observatory funded by the Alfred P. Sloan Foundation. We thank C. Langmuir, H. Dick, J. Warren and M. Seyler for stimulating insightful discussions and critical reading of an early version of the work. We are grateful to M. Ligi for his support on geophysics and S. Lambart for helping on Melt-PX. We also thank S. Lambart and A. Stracke for their constructive reviews that greatly improved the manuscript. This is Lamont-Doherty contribution number 8205.

Author information




D.B. performed the modelling. A.C. analysed the samples. D.B. and A.C. processed the geochemical data and jointly wrote the paper. E.B. provided the opportunity and support for sea expeditions and work. All of the authors discussed the results and the interpretations.

Corresponding authors

Correspondence to Daniele Brunelli or Anna Cipriani.

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.

Supplementary information

Supplementary Information

Supplementary information

Supplementary Data Set

Supplementary Tables

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Brunelli, D., Cipriani, A. & Bonatti, E. Thermal effects of pyroxenites on mantle melting below mid-ocean ridges. Nature Geosci 11, 520–525 (2018).

Download citation

Further reading