High-pressure experimental data on sound velocities of garnets are used for interpretation of seismological data related to the Earth’s upper mantle and the mantle transition zone. We have carried out a Nuclear Inelastic Scattering study of iron-silicate garnet with skiagite (77 mol%)–iron–majorite composition in a diamond anvil cell up to 56 GPa at room temperature. The determined sound velocities are considerably lower than sound velocities of a number of silicate garnet end-members, such as grossular, pyrope, Mg–majorite, andradite, and almandine. The obtained sound velocities have the following pressure dependencies: Vp [km/s] = 7.43(9) + 0.039(4) × P [GPa] and Vs [km/s] = 3.56(12) + 0.012(6) × P [GPa]. We estimated sound velocities of pure skiagite and khoharite, and conclude that the presence of the iron–majorite component in skiagite strongly decreases Vs. We analysed the influence of Fe3+ on sound velocities of garnet solid solution relevant to the mantle transition zone and consider that it may reduce sound velocities up to 1% relative to compositions with only Fe2+ in the cubic site.
Vasiukov, D., Ismailova, L., Kupenko, I., Cerantola, V., Sinmyo, R., Glazyrin, K., et al. (2018). Sound velocities of skiagite-iron-majorite solid solution to 56 GPa probed by nuclear inelastic scattering. PHYSICS AND CHEMISTRY OF MINERALS, 45(5), 397-404 [10.1007/s00269-017-0928-8].
Sound velocities of skiagite-iron-majorite solid solution to 56 GPa probed by nuclear inelastic scattering
Cerantola V;
2018
Abstract
High-pressure experimental data on sound velocities of garnets are used for interpretation of seismological data related to the Earth’s upper mantle and the mantle transition zone. We have carried out a Nuclear Inelastic Scattering study of iron-silicate garnet with skiagite (77 mol%)–iron–majorite composition in a diamond anvil cell up to 56 GPa at room temperature. The determined sound velocities are considerably lower than sound velocities of a number of silicate garnet end-members, such as grossular, pyrope, Mg–majorite, andradite, and almandine. The obtained sound velocities have the following pressure dependencies: Vp [km/s] = 7.43(9) + 0.039(4) × P [GPa] and Vs [km/s] = 3.56(12) + 0.012(6) × P [GPa]. We estimated sound velocities of pure skiagite and khoharite, and conclude that the presence of the iron–majorite component in skiagite strongly decreases Vs. We analysed the influence of Fe3+ on sound velocities of garnet solid solution relevant to the mantle transition zone and consider that it may reduce sound velocities up to 1% relative to compositions with only Fe2+ in the cubic site.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.