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ABSTRACT NEARLY 60 years ago, Bernal1 proposed that a polymorphic phase transformation in olivine might be responsible for the seismic velocity discontinuity near 410 km depth in the mantle.

Phase equilibria experiments2,3 have since shown that the olivine (α) to wadsleyite (β) transition in (Mg,Fe)2SiO4 occurs at the appropriate pressure (13.8 GPa) under mantle conditions.

Comparison of laboratory measurements of the acoustic velocity contrast in the α–β system to the magnitude of the seismically observed discontinuity at 410 km provides a way to constrain the

olivine content of the mantle at this depth. Here we report measurements of the full set of elastic moduli of single-crystal forsterite (α-Mg2SiO4) at pressures between 3 and 16 GPa, using

Brillouin scattering in a diamond anvil cell. At 13.8 GPa, the aggregate compressional-and shear-wave velocities of α-Mg2SiO4 are 2.7 ± 0.7% lower than predicted from earlier low-pressure

data4,5. From our data, and assuming a homogeneous mantle composition, the seismic velocity contrast at 410 km depth can be satisfied only by a mantle containing less than ~40% olivine. This

is well below the olivine abundance assumed in peridotite-based upper-mantle models. Access through your institution Buy or subscribe This is a preview of subscription content, access via

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* Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS THE INFLUENCE OF Δ-(AL,FE)OOH ON SEISMIC HETEROGENEITIES IN

EARTH’S LOWER MANTLE Article Open access 08 June 2021 VARIATION IN BRIDGMANITE GRAIN SIZE ACCOUNTS FOR THE MID-MANTLE VISCOSITY JUMP Article Open access 05 July 2023 PERICLASE DEFORMS MORE

SLOWLY THAN BRIDGMANITE UNDER MANTLE CONDITIONS Article Open access 11 January 2023 REFERENCES * Bernal, J. D. _The Observatory_ 59, 268 (1936). Google Scholar  * Ringwood, A. E.

_Composition and Petrology of the Earth's Mantle_ (McGraw-Hill, New York, 1975). Google Scholar  * Akaogi, M., Ito, E. & Navrotsky, A. _J. geophys. Res._ 94, 15671–15685 (1989).

Article  ADS  Google Scholar  * Kumazawa, M. & Anderson, O. L. _J. geophys. Res._ 74, 5961–5972 (1969). Article  ADS  CAS  Google Scholar  * Graham, E. K. & Barsch, G. R. _J.

geophys. Res._ 74, 5949–5959 (1969). Article  ADS  CAS  Google Scholar  * Nolet, G., Grand, S. P. & Kennett, B. L. N. _J. geophys. Res._ 99, 23753–23766 (1994). Article  ADS  Google

Scholar  * Gwanmesia, G. D., Rigden, S., Jackson, I. & Liebermann, R. C. _Science_ 250, 794–797 (1990). Article  ADS  CAS  Google Scholar  * Weidner, D. J. _Geophys. Res. Lett._ 12,

417–420 (1985). Article  ADS  CAS  Google Scholar  * Bina, C. R. & Wood, B. J. _Nature_ 324, 449–451 (1986). Article  ADS  Google Scholar  * Duffy, T. S. & Anderson, D. L. _J.

geophys. Res._ 94, 1895–1912 (1989). Article  ADS  CAS  Google Scholar  * Ita, J. & Stixrude, L. _J. geophys. Res._ 97, 6849–6866 (1992). Article  ADS  CAS  Google Scholar  * Isaak, D.

G., Anderson, O. L. & Goto, T. _J. geophys. Res._ 94, 5895–5906 (1989). Article  ADS  CAS  Google Scholar  * Webb, S. L. _Phys. Chem. Miner._ 16, 684–692 (1989). Article  ADS  CAS 

Google Scholar  * Isaak, D. G. _J. geophys. Res._ 97, 1871–1885 (1992). Article  ADS  CAS  Google Scholar  * Yoneda, A. & Morioka, M. in _High-Pressure Research: Applications to Earth

and Planetary Sciences_ (eds Syono. Y. & Manghnani, M. H.) 207–214 (Terra Scientific, Tokyo, 1992). Google Scholar  * Fei, Y. _et al._ _J. geophys. Res._ 97, 4489–4495 (1992). Article 

ADS  CAS  Google Scholar  * Zaug, J. M., Abramson, E. H., Brown, J. M. & Slutsky, L. J. _Science_ 260, 1487–1490 (1993). Article  ADS  CAS  Google Scholar  * Meng, Y. _et al._ _J.

geophys. Res._ 98, 22199–22208 (1993). Article  ADS  CAS  Google Scholar  * Mao, H. K. & Bell, P. M. _Yb. Carnegie Instn Wash._ 79, 409–411 (1980). Google Scholar  * Mao, H. K., Xu, J.

& Bell, P. M. _J. geophys. Res._ 91, 4673–4676 (1986). Article  ADS  CAS  Google Scholar  * Downs, R. T., Zha, C. S., Duffy, T. S. & Finger, L. W. _Am. Miner._ (in the press). * Zha,

C. S., Duffy, T. S., Mao, H. K. & Hemley, R. J. _Phys. Rev._ B48, 9246–9255 (1993). Article  CAS  Google Scholar  * Every, A. G. _Phys. Rev._ B22, 1746–1760 (1980). Article  ADS 

MathSciNet  CAS  Google Scholar  * Watt, J. P., Davies, G. F. & O'Connell, R. J. _Rev. Geophys. Space Phys._ 14, 541–563 (1976). Article  ADS  CAS  Google Scholar  * Davies, G. F.

& Dziewonski, A. M. _Phys. Earth planet. Inter._ 10, 336–343 (1975). Article  ADS  CAS  Google Scholar  * Sawamoto, H., Weidner, D. J., Sasaki, S. & Kumazawa, M. _Science_ 224,

749–751 (1984). Article  ADS  CAS  Google Scholar  * Grand, S. P. & Helmberger, D. V. _Geophys. J. R. astr. Soc._ 76, 399–438 (1984). Article  ADS  Google Scholar  * Walck, M. C.

_Geophys. J. R. astr. Soc_ 76, 697–723 (1984). Article  ADS  Google Scholar  * Mechie, J. _et al._ _Earth planet. Inter._ 79, 269–286 (1993). Article  ADS  Google Scholar  * Sumino, Y. &

Anderson, O. L. in _Handbook of Physical Properties of Rocks_ Vol. III (ed. Carmichael, R. S.) 39–137 (CRC, Boca Raton, FL. 1989). Google Scholar  * Akaogi, M. & Akimoto, S. _Phys.

Earth planet. Inter._ 19, 31–51 (1979). Article  ADS  CAS  Google Scholar  Download references AUTHOR INFORMATION Author notes * Thomas S. Duffy Present address: Consortium for Advanced

Radiation Sources, The University of Chicago, 5640 South Ellis, Chicago, Illinois, 60637, USA AUTHORS AND AFFILIATIONS * Geophysical Laboratory and Center for High-Pressure Research,

Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC, 20015, USA Thomas S. Duffy, Chang-sheng Zha, Robert T. Downs, Ho-kwang Mao & Russell J. Hemley Authors *

Thomas S. Duffy View author publications You can also search for this author inPubMed Google Scholar * Chang-sheng Zha View author publications You can also search for this author inPubMed 

Google Scholar * Robert T. Downs View author publications You can also search for this author inPubMed Google Scholar * Ho-kwang Mao View author publications You can also search for this

author inPubMed Google Scholar * Russell J. Hemley View author publications You can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT

THIS ARTICLE CITE THIS ARTICLE Duffy, T., Zha, Cs., Downs, R. _et al._ Elasticity of forsterite to 16 GPa and the composition of the upper mantle. _Nature_ 378, 170–173 (1995).

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