17:15 〜 18:45
[SIT15-P11] Sound velocities of the hydrous iron-rich HH1-phase: implication for the lower mantle seismic heterogeneities
キーワード：Inelastic X-ray scattering, Hydrous phases, Lower mantle, Seismic anomalies
Water, which is heterogeneously distributed in the Earth’s interior, is one of the most important volatiles of our planet. Incorporation of water into a multicomponent system of the Earth's lower mantle can dramatically alter its phase relations 1,2. In particular, the formation of hydrous phases can lead to changes in the seismic velocities of the system. Thus, investigation of the sound velocities of lower mantle hydrous minerals offers important insight into lower mantle seismic anomalies. However, to date, there is a dearth of experimental data on the sound velocities of lower mantle hydrous phases.
HH1-phase (Fe12.76O18Hx, x~4.5) is an iron-rich hydrous hexagonal phase, which can be formed through reactions in basaltic or peridotitic compositions with water under the pressure and temperature conditions of the deep lower mantle 3. Laser-heated diamond anvil cell techniques were used to fabricate HH1-phase samples and then the composition was confirmed by diffraction. The sound velocity was measured using inelastic x-ray scattering at pressures between 64.7 and 79.6 GPa at BL43LXU at Spring-8 4. We thus investigate the changes in sound velocity of the major lower mantle mineral ferropericlase before and after its reaction with water. These findings not only fill a critical gap in the experimental data but also provide a better understanding of the lower mantle’s seismic anomalies and the role of water in the deep Earth processes.
References
1. Yuan, H. et al. Stability of Fe-bearing hydrous phases and element partitioning in the system MgO-Al2O3-Fe2O3-SiO2-H2O in Earth’s lowermost mantle. Earth Planet. Sci. Lett. 524, 115714 (2019).
2. Liu, L. et al. Formation of an Al-Rich Niccolite-Type Silica in Subducted Oceanic Crust: Implications for Water Transport to the Deep Lower Mantle. Geophys. Res. Lett. 49, (2022).
3. Liu, L. et al. Stability of a Mixed-Valence Hydrous Iron-Rich Oxide: Implications for Water Storage and Dynamics in the Deep Lower Mantle. J. Geophys. Res. Solid Earth 127, 1-11 (2022).
4. Baron, A. Q. R. The RIKEN Quantum NanoDynamics Beamline (BL43LXU): The Next Generation for Inelastic X-Ray Scattering. SPring-8 Inf. Newsl. 15, 14-19 (2010).
HH1-phase (Fe12.76O18Hx, x~4.5) is an iron-rich hydrous hexagonal phase, which can be formed through reactions in basaltic or peridotitic compositions with water under the pressure and temperature conditions of the deep lower mantle 3. Laser-heated diamond anvil cell techniques were used to fabricate HH1-phase samples and then the composition was confirmed by diffraction. The sound velocity was measured using inelastic x-ray scattering at pressures between 64.7 and 79.6 GPa at BL43LXU at Spring-8 4. We thus investigate the changes in sound velocity of the major lower mantle mineral ferropericlase before and after its reaction with water. These findings not only fill a critical gap in the experimental data but also provide a better understanding of the lower mantle’s seismic anomalies and the role of water in the deep Earth processes.
References
1. Yuan, H. et al. Stability of Fe-bearing hydrous phases and element partitioning in the system MgO-Al2O3-Fe2O3-SiO2-H2O in Earth’s lowermost mantle. Earth Planet. Sci. Lett. 524, 115714 (2019).
2. Liu, L. et al. Formation of an Al-Rich Niccolite-Type Silica in Subducted Oceanic Crust: Implications for Water Transport to the Deep Lower Mantle. Geophys. Res. Lett. 49, (2022).
3. Liu, L. et al. Stability of a Mixed-Valence Hydrous Iron-Rich Oxide: Implications for Water Storage and Dynamics in the Deep Lower Mantle. J. Geophys. Res. Solid Earth 127, 1-11 (2022).
4. Baron, A. Q. R. The RIKEN Quantum NanoDynamics Beamline (BL43LXU): The Next Generation for Inelastic X-Ray Scattering. SPring-8 Inf. Newsl. 15, 14-19 (2010).