Very low sound velocities in iron-rich (Mg,Fe)O: Implications for the core-mantle boundary region

摘要: The sound velocities of (Mg_(.16)Fe_(.84))O have been measured to 121 GPa at ambient temperature using nuclear resonant inelastic x-ray scattering. effect electronic environment the iron sites on were tracked in situ synchrotron Mossbauer spectroscopy. We found be much lower than those other presumed mantle phases similar conditions, most notably very high pressures. Conservative estimates and dilution aggregate show that only a small amount iron-rich (Mg,Fe)O can greatly reduce average velocity an assemblage. propose source ultra-low zones. Other properties this phase, such as enhanced density dynamic stability, strongly support presence localized patches above core-mantle boundary.