Temperature dependence of elastic moduli of β‐(Mg, Fe) 2 SiO 4

The elastic moduli of polycrystalline wadsleyite, β‐(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 165.72(6) and 105.43(2) GPa at room temperature. The average slopes ( dK S / dT and d μ/ dT ) in the range were determined to be −0.0175(3) and −0.0159(1) GPa/K. We estimated that the P ‐, S ‐wave velocity and density jumps for the α‐ to β‐phase transformation at the 410‐km depth condition were 9.5, 11.2 and 5.4%, respectively. These results suggest that the olivine component at the depth should be 52 and 42 volume % for P ‐ and S ‐waves.