Physics of the Earth and Planetary Interiors 148 (2005) 353–359 Temperature dependence of the elastic moduli of ringwoodite Norihito Mayama a , Isao Suzuki a,∗ , Toshiaki Saito a , Ichiro Ohno b , Tomoo Katsura c , Akira Yoneda c a Department of Earth Sciences, Faculty of Science, Okayama University, Okayama, Okayama-ken 700-8530, Japan b Department of Earth Sciences, Ehime University, Matsuyama, Ehime-ken 790-8577, Japan c Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori-ken 682-0193, Japan Received 15 April 2004; received in revised form 7 September 2004; accepted 14 September 2004 Abstract The elastic moduli of polycrystalline ringwoodite, (Mg 0.91 Fe 0.09 ) 2 SiO 4 , were measured up to 470 K by means of the resonant sphere technique. The adiabatic bulk (K S ) and shear (µ) moduli were found to be 185.1(2) and 118.22(6) GPa at room temperature, and the average slopes of dK S /dT and dµ/dT in the temperature range of the study were determined to be -0.0193(9) and -0.0148(3)GPa/K, respectively. Using these results, we estimate seismic wave velocity jumps for a pure olivine mantle model at 520 km depth. We find that the jump for the S-wave velocity is about 1.5 times larger than that for the P-wave velocity at this depth. This suggests that velocity jumps at the 520 km discontinuity are easier to detect using S-waves than P-waves. © 2004 Elsevier B.V. All rights reserved. Keywords: Ringwoodite; High temperature; Elastic moduli; 520 km discontinuity 1. Introduction The 410, 520 and 660 km seismic discontinuities in the Earth’s mantle are attributed to successive trans- formations from olivine to wadsleyite, wadsleyite to ringwoodite and then break down to a mixture of mag- nesiowustite and (Mg,Fe)SiO 3 -perovskite (Ringwood, 1975; Liu, 1976; Ito, 1977). Therefore, the elastic prop- erties of these phases provide information about the ∗ Corresponding author. Tel.: +81 86 251 7886; fax: +81 86 251 7895. E-mail address: isuzuki@cc.okayama-u.ac.jp (I. Suzuki). structure and composition at these depths. The temper- ature dependences of the elastic moduli for olivine and periclase have been measured up to 1800 K by means of the resonant method (Isaak et al., 1989a, 1989b; Isaak, 1992). Recently, the high-pressure phases have also become measurable by the resonant method because we have been able to synthesize pore free samples a few millimeters in size. The tem- perature dependences of elastic moduli for wads- leyite and MgSiO 3 -perovskite have been reported (Katsura et al., 2001; Mayama et al., 2004; Aizawa et al., 2004). Furthermore, the properties of ringwood- ite were measured by means of Brilliouin spectroscopy 0031-9201/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.pepi.2004.09.007