Skip to main content

Thank you for visiting nature.com. 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.

Evidence for a Fe3+-rich pyrolitic lower mantle from (Al,Fe)-bearing bridgmanite elasticity data

An Author Correction to this article was published on 16 May 2018

This article has been updated

Abstract

The chemical composition of Earth’s lower mantle can be constrained by combining seismological observations with mineral physics elasticity measurements1,2,3. However, the lack of laboratory data for Earth’s most abundant mineral, (Mg,Fe,Al)(Al,Fe,Si)O3 bridgmanite (also known as silicate perovskite), has hampered any conclusive result. Here we report single-crystal elasticity data on (Al,Fe)-bearing bridgmanite (Mg0.9Fe0.1Si0.9Al0.1)O3 measured using high-pressure Brillouin spectroscopy and X-ray diffraction. Our measurements show that the elastic behaviour of (Al,Fe)-bearing bridgmanite is markedly different from the behaviour of the MgSiO3 endmember2,4. We use our data to model seismic wave velocities in the top portion of the lower mantle, assuming a pyrolitic5 mantle composition and accounting for depth-dependent changes in iron partitioning between bridgmanite and ferropericlase6,7. We find excellent agreement between our mineral physics predictions and the seismic Preliminary Reference Earth Model8 down to at least 1,200 kilometres depth, indicating chemical homogeneity of the upper and shallow lower mantle. A high Fe3+/Fe2+ ratio of about two in shallow-lower-mantle bridgmanite is required to match seismic data, implying the presence of metallic iron in an isochemical mantle. Our calculated velocities are in increasingly poor agreement with those of the lower mantle at depths greater than 1,200 kilometres, indicating either a change in bridgmanite cation ordering or a decrease in the ferric iron content of the lower mantle.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Experimental setup and results.
Figure 2: Pressure dependence of the average acoustic velocities of (Al,Fe)-bearing bridgmanite (red circles).
Figure 3: Mineral-physics-based seismic models.
Figure 4: Deviation of modelled seismic velocities from PREM with depth.

Change history

  • 16 May 2018

    In this Letter, some of the elastic constants reported in Extended Data Table 1 and the values of the elastic constants at room pressure cited in the manuscript on page 544 were incorrect, as a result of an error in the script used to generate the numbers. These errors have been corrected online.

References

  1. 1

    Cammarano, F., Marquardt, H., Speziale, S. & Tackley, P. J. Role of iron-spin transition in ferropericlase on seismic interpretation: a broad thermochemical transition in the mid mantle? Geophys. Res. Lett. 37, L03308 (2010)

    Article  ADS  CAS  Google Scholar 

  2. 2

    Murakami, M., Ohishi, Y., Hirao, N. & Hirose, K. A perovskitic lower mantle inferred from high-pressure, high-temperature sound velocity data. Nature 485, 90–94 (2012)

    Article  ADS  CAS  Google Scholar 

  3. 3

    Cobden, L. et al. Thermochemical interpretation of 1-D seismic data for the lower mantle: the significance of nonadiabatic thermal gradients and compositional heterogeneity. J. Geophys. Res. 114, B11309 (2009)

    Article  ADS  CAS  Google Scholar 

  4. 4

    Chantel, J., Frost, D. J., McCammon, C. A., Jing, Z. & Wang, Y. Acoustic velocities of pure and iron-bearing magnesium silicate perovskite measured to 25 GPa and 1200 K. Geophys. Res. Lett. 39, L19307 (2012)

    Article  ADS  CAS  Google Scholar 

  5. 5

    Ringwood, A. E. A model for the upper mantle. J. Geophys. Res. 67, 857–867 (1962)

    Article  ADS  Google Scholar 

  6. 6

    Nakajima, Y., Frost, D. J. & Rubie, D. C. Ferrous iron partitioning between magnesium silicate perovskite and ferropericlase and the composition of perovskite in the Earth’s lower mantle. J. Geophys. Res. 117, B08201 (2012)

    ADS  Google Scholar 

  7. 7

    Irifune, T. et al. Iron partitioning and density changes of pyrolite in Earth’s lower mantle. Science 327, 193–195 (2010)

    Article  ADS  CAS  Google Scholar 

  8. 8

    Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Phys. Earth Planet. Inter. 25, 297–356 (1981)

    Article  ADS  Google Scholar 

  9. 9

    McCammon, C. Perovskite as a possible sink for ferric iron in the lower mantle. Nature 387, 694–696 (1997)

    Article  ADS  CAS  Google Scholar 

  10. 10

    Wang, X., Tsuchiya, T. & Hase, A. Computational support for a pyrolitic lower mantle containing ferric iron. Nat. Geosci. 8, 556–559 (2015)

    Article  ADS  CAS  Google Scholar 

  11. 11

    Zhang, S., Cottaar, S., Liu, T., Stackhouse, S. & Militzer, B. High-pressure, temperature elasticity of Fe- and Al-bearing MgSiO3: implications for the Earth’s lower mantle. Earth Planet. Sci. Lett. 434, 264–273 (2016)

    Article  ADS  CAS  Google Scholar 

  12. 12

    Marquardt, H. & Marquardt, K. Focused Ion Beam preparation and characterization of single-crystal samples for high-pressure experiments in the diamond-anvil cell. Am. Mineral. 97, 299–304 (2012)

    Article  ADS  CAS  Google Scholar 

  13. 13

    Sinogeikin, S. V., Zhang, J. & Bass, J. D. Elasticity of single crystal and polycrystalline MgSiO3 perovskite by Brillouin spectroscopy. Geophys. Res. Lett. 31, L06620 (2004)

    Article  ADS  CAS  Google Scholar 

  14. 14

    Li, L. et al. Elasticity of (Mg, Fe)(Si, Al)O3-perovskite at high pressure. Earth Planet. Sci. Lett. 240, 529–536 (2005)

    Article  ADS  CAS  Google Scholar 

  15. 15

    Yeganeh-Haeri, A. Synthesis and re-investigation of the elastic properties of single-crystal magnesium silicate perovskite. Phys. Earth Planet. Inter. 87, 111–121 (1994)

    Article  ADS  CAS  Google Scholar 

  16. 16

    Li, B. & Zhang, J. Pressure and temperature dependence of elastic wave velocity of MgSiO3 perovskite and the composition of the lower mantle. Phys. Earth Planet. Inter. 151, 143–154 (2005)

    Article  ADS  CAS  Google Scholar 

  17. 17

    Boffa Ballaran, T. et al. Effect of chemistry on the compressibility of silicate perovskite in the lower mantle. Earth Planet. Sci. Lett. 333–334, 181–190 (2012)

    Article  ADS  CAS  Google Scholar 

  18. 18

    Shukla, G., Cococcioni, M. & Wentzcovitch, R. M. Thermoelasticity of Fe3+- and Al-bearing bridgmanite: effects of iron spin crossover. Geophys. Res. Lett. 43, 5661–5670 (2016)

    Article  ADS  CAS  Google Scholar 

  19. 19

    Jackson, J. M., Zhang, J., Shu, J., Sinogeikin, S. V. & Bass, J. D. High-pressure sound velocities and elasticity of aluminous MgSiO3 perovskite to 45 GPa: implications for lateral heterogeneity in Earth’s lower mantle. Geophys. Res. Lett. 32, L21305 (2005)

    Article  ADS  CAS  Google Scholar 

  20. 20

    Murakami, M., Sinogeikin, S. V., Hellwig, H., Bass, J. D. & Li, J. Sound velocity of MgSiO3 perovskite to Mbar pressure. Earth Planet. Sci. Lett. 256, 47–54 (2007)

    Article  ADS  CAS  Google Scholar 

  21. 21

    Lin, J.-F., Speziale, S., Mao, Z. & Marquardt, H. Effects of the electronic spin transitions of iron in lower-mantle minerals: implications to deep-mantle geophysics and geochemistry. Rev. Geophys. 51, 244–275 (2013)

    Article  ADS  Google Scholar 

  22. 22

    Frost, D. J. et al. Experimental evidence for the existence of iron-rich metal in the Earth’s lower mantle. Nature 428, 409–412 (2004)

    Article  ADS  CAS  Google Scholar 

  23. 23

    Sinmyo, R., Hirose, K., Muto, S., Ohishi, Y. & Yasuhara, A. The valence state and partitioning of iron in the Earth’s lowermost mantle. J. Geophys. Res. 116, B07205 (2011)

    Article  ADS  CAS  Google Scholar 

  24. 24

    Fukao, Y. & Obayashi, M. Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity. J. Geophys. Res. 118, 2013JB010466 (2013)

    Article  Google Scholar 

  25. 25

    Tackley, P. J. Mantle convection and plate tectonics: toward an integrated physical and chemical theory. Science 288, 2002–2007 (2000)

    Article  ADS  CAS  Google Scholar 

  26. 26

    Walter, M. J. et al. Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions. Science 334, 54–57 (2011)

    Article  ADS  CAS  Google Scholar 

  27. 27

    Jackson, I. Elasticity, composition and temperature of the Earth’s lower mantle: a reappraisal. Geophys. J. Int. 134, 291–311 (1998)

    Article  ADS  Google Scholar 

  28. 28

    Smith, E. M. et al. Large gem diamonds from metallic liquid in Earth’s deep mantle. Science 354, 1403–1405 (2016)

    Article  ADS  CAS  Google Scholar 

  29. 29

    Marquardt, H., Speziale, S., Reichmann, H. J., Frost, D. J. & Schilling, F. R. Single-crystal elasticity of (Mg0.9Fe0.1)O to 81 GPa. Earth Planet. Sci. Lett. 287, 345–352 (2009)

    Article  ADS  CAS  Google Scholar 

  30. 30

    Zhang, Z., Stixrude, L. & Brodholt, J. Elastic properties of MgSiO3-perovskite under lower mantle conditions and the composition of the deep Earth. Earth Planet. Sci. Lett. 379, 1–12 (2013)

    Article  ADS  CAS  Google Scholar 

  31. 31

    Catalli, K. et al. Effects of the Fe3+ spin transition on the properties of aluminous perovskite—new insights for lower-mantle seismic heterogeneities. Earth Planet. Sci. Lett. 310, 293–302 (2011)

    Article  ADS  CAS  Google Scholar 

  32. 32

    Xu, Y. & McCammon, C. Evidence for ionic conductivity in lower mantle (Mg,Fe)(Si,Al)O3 perovskite. J. Geophys. Res. 107, 2251 (2002)

    ADS  Google Scholar 

  33. 33

    Rudolph, M. L., Lekic´, V. & Lithgow-Bertelloni, C. Viscosity jump in Earth’s mid-mantle. Science 350, 1349–1352 (2015)

    Article  ADS  CAS  Google Scholar 

  34. 34

    Marquardt, H., Speziale, S., Koch-Müller, M., Marquardt, K. & Capitani, G. C. Structural insights and elasticity of single-crystal antigorite from high-pressure Raman and Brillouin spectroscopy measured in the (010) plane. Am. Mineral. 100, 1932–1939 (2015)

    Article  ADS  Google Scholar 

  35. 35

    Schulze, K., Buchen, J., Marquardt, K. & Marquardt, H. Multi-sample loading technique for comparative physical property measurements in the diamond-anvil cell. High Press. Res. (in the press)

  36. 36

    Kantor, I. et al. BX90: A new diamond anvil cell design for X-ray diffraction and optical measurements. Rev. Sci. Instrum. 83, 125102 (2012)

    Article  ADS  CAS  Google Scholar 

  37. 37

    Kurnosov, A. et al. A novel gas-loading system for mechanically closing of various types of diamond anvil cells. Rev. Sci. Instrum. 79, 045110 (2008)

    Article  ADS  CAS  Google Scholar 

  38. 38

    Whitfield, C. H., Brody, E. M. & Bassett, W. A. Elastic moduli of NaCl by Brillouin scattering at high pressure in a diamond anvil cell. Rev. Sci. Instrum. 47, 942–947 (1976)

    Article  ADS  CAS  Google Scholar 

  39. 39

    Sinogeikin, S. V. & Bass, J. D. Single-crystal elasticity of pyrope and MgO to 20 GPa by Brillouin scattering in the diamond cell. Phys. Earth Planet. Inter. 120, 43–62 (2000)

    Article  ADS  CAS  Google Scholar 

  40. 40

    Speziale, S., Marquardt, H. & Duffy, T. S. in Spectroscopic Methods in Mineralogy and Materials Science, Vol. 78, 543–603 (Mineral Society of America, 2014)

    CAS  Google Scholar 

  41. 41

    Trots, D. et al. Elasticity and equation of state of Li2B4O7 . Phys. Chem. Miner. 38, 561–567 (2011)

    Article  ADS  CAS  Google Scholar 

  42. 42

    Angel, R. & Finger, L. W. SINGLE: a program to control single-crystal diffractometers. J. Appl. Cryst. 44, 247–251 (2011)

    Article  CAS  Google Scholar 

  43. 43

    Pamato, M. G. et al. Single-crystal elasticity of majoritic garnets: stagnant slabs and thermal anomalies at the base of the transition zone. Earth Planet. Sci. Lett. 451, 114–124 (2016)

    Article  ADS  CAS  Google Scholar 

  44. 44

    Stixrude, L. & Lithgow-Bertelloni, C. Thermodynamics of mantle minerals – I. Physical properties. Geophys. J. Int. 162, 610–632 (2005)

    Article  ADS  Google Scholar 

  45. 45

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

    Article  ADS  CAS  Google Scholar 

  46. 46

    Stixrude, L. & Lithgow-Bertelloni, C. Thermodynamics of mantle minerals – II. Phase equilibria. Geophys. J. Int. 184, 1180–1213 (2011)

    Article  ADS  CAS  Google Scholar 

  47. 47

    Canil, D. & O’Neill, H. S. C. Distribution of ferric iron in some upper-mantle assemblages. J. Petrol. 37, 609–635 (1996)

    Article  ADS  CAS  Google Scholar 

  48. 48

    Brown, J. M. & Shankland, T. J. Thermodynamic parameters in the Earth as determined from seismic profiles. Geophys. J. R. Astron. Soc. 66, 579–596 (1981)

    Article  ADS  MATH  Google Scholar 

  49. 49

    Lin, J. F. et al. Sound velocities of hot dense iron; Birch’s law revisited. Science 308, 1892–1894 (2005)

    Article  ADS  CAS  Google Scholar 

  50. 50

    Tange, Y., Takahashi, E., Nishihara, Y., Funakoshi, K.-i. & Sata, N. Phase relations in the system MgO-FeO-SiO2 to 50 GPa and 2000°C: an application of experimental techniques using multianvil apparatus with sintered diamond anvils. J. Geophys. Res. 114, B02214 (2009)

    ADS  Google Scholar 

  51. 51

    Wolf, A. S., Jackson, J. M., Dera, P. & Prakapenka, V. B. The thermal equation of state of (Mg, Fe)SiO3 bridgmanite (perovskite) and implications for lower mantle structures. J. Geophys. Res. 120, 7460–7489 (2015)

    Article  ADS  CAS  Google Scholar 

  52. 52

    Speziale, S., Zha, C. S., Duffy, T. S., Hemley, R. J. & Mao, H. K. Quasi-hydrostatic compression of magnesium oxide to 52 GPa; implication for the pressure-volume-temperature equation of state. J. Geophys. Res. B 106, 515–528 (2001)

    Article  ADS  CAS  Google Scholar 

  53. 53

    Fischer, R. A. et al. Equation of state and phase diagram of FeO. Earth Planet. Sci. Lett. 304, 496–502 (2011)

    Article  ADS  CAS  Google Scholar 

  54. 54

    Xu, W., Lithgow-Bertelloni, C., Stixrude, L. & Ritsema, J. The effect of bulk composition and temperature on mantle seismic structure. Earth Planet. Sci. Lett. 275, 70–79 (2008)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

This research was supported through the projects ‘GeoMaX’ funded under the Emmy-Noether Program of the German Science Foundation (MA4534/3-1) and the ERC advanced grant number 227893 ‘DEEP’ funded through the EU 7th Framework Programme. The FEI Scios FIB machine at BGI Bayreuth is supported by grant INST 91/315-1 FUGG. H.M. acknowledges support from the Bavarian Academy of Sciences. We thank J. Buchen for assistance in creating Fig. 1c, H. Schulze for sample polishing and K. Marquardt for help with the FIB device.

Author information

Affiliations

Authors

Contributions

A.K., H.M., D.F. and T.B.B. designed the research. L.Z. synthesized the bridgmanite sample. A.K. performed the experiments and analysed the Brillouin data. T.B.B. performed the XRD analysis. D.F. and H.M. discussed the content of the paper and performed the modelling. H.M. wrote the paper draft. All authors commented on the manuscript.

Corresponding author

Correspondence to H. Marquardt.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Reviewer Information Nature thanks I. Jackson and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Extended data figures and tables

Extended Data Figure 1 Effect of FeAlO3 incorporation on the room pressure elastic moduli of MgSiO3 bridgmanite.

The red circles represent data based on this study on (Al,Fe)-bearing bridgmanite and earlier Brillouin scattering work on single-crystal MgSiO3 bridgmanite13. The blue and green symbols refer to computational studies14,18.

Extended Data Figure 2 Densities (red curve) as a function of depth calculated from our model.

The dashed line corresponds to PREM.

Extended Data Figure 3 Modelled sound wave velocities for (Mg0.9Fe0.1Si0.9Al0.1)O3 (red curves) along with the experimental data from this study.

Extended Data Figure 4 Modelled sound wave velocities.

For (Mg0.9Fe0.1)O (red curves) along with experimental data29. The data below 35 GPa have been employed to constrain the physical properties of the FeO and MgO components in the model as the effects of the iron spin transition are not captured by the model. At the temperature conditions of Earth’s mantle, the effects of the iron spin crossover will be shifted to depths beyond those modelled in this study21 and are, therefore, irrelevant to the present contribution.

Extended Data Figure 5 Fe-partitioning coefficient KD(app) from our model in comparison to previous experimental data measured on a pyrolitic mantle composition.

The thermodynamic model not only matches available elasticity data for bridgmanite and ferropericlase (Extended Data Figs 3, 4) but also reproduces changes in Fe–Mg partitioning between these phases with depth in both Al-free and Al-bearing systems.

Extended Data Figure 6 Secondary electron image of polished single crystals of bridgmanite.

Crystals have been cut to half-circles by a focused ion beam12,34.

Extended Data Figure 7 Standard deviation as a function of the signal-to-noise ratio in Brillouin spectra.

Extended Data Table 1 Summary of high-pressure elastic constants derived for (Mg0.9Fe0.1Si0.9Al0.1)O3
Extended Data Table 2 Summary of ambient pressure elastic constants reported for MgSiO3 and (Fe,Al)-bearing MgSiO3 from both experimental and theoretical work
Extended Data Table 3 Summary of parameters used for the model calculations

PowerPoint slides

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kurnosov, A., Marquardt, H., Frost, D. et al. Evidence for a Fe3+-rich pyrolitic lower mantle from (Al,Fe)-bearing bridgmanite elasticity data. Nature 543, 543–546 (2017). https://doi.org/10.1038/nature21390

Download citation

Further reading

Comments

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.

Search

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