title: Disproportionation of (Mg,Fe)SiO₃ perovskite in Earth's deep lower mantle.
abstract: The mineralogical constitution of the Earth's mantle dictates the geophysical and geochemical properties of this region. Previous models of a perovskite-dominant lower mantle have been built on the assumption that the entire lower mantle down to the top of the D″ layer contains ferromagnesian silicate [(Mg,Fe)SiO3] with nominally 10 mole percent Fe. On the basis of experiments in laser-heated diamond anvil cells, at pressures of 95 to 101 gigapascals and temperatures of 2200 to 2400 kelvin, we found that such perovskite is unstable; it loses its Fe and disproportionates to a nearly Fe-free MgSiO3 perovskite phase and an Fe-rich phase with a hexagonal structure. This observation has implications for enigmatic seismic features beyond ~2000 kilometers depth and suggests that the lower mantle may contain previously unidentified major phases.
authors.affiliation: Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China. Geophysical Laboratory, Carnegie Institution of Washington (CIW), Washington, DC 20015, USA. zhangli@hpstar.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, CIW, Argonne, IL 60439, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Meng
authors.affiliation: Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China. High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, CIW, Argonne, IL 60439, USA.
authors.forename: Wenge
authors.initials: W
authors.lastname: Yang
authors.affiliation: Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China. High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, CIW, Argonne, IL 60439, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA. Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Mao
authors.affiliation: Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA.
authors.forename: Qiao-Shi
authors.initials: QS
authors.lastname: Zeng
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 USA.
authors.forename: Jong Seok
authors.initials: JS
authors.lastname: Jeong
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wagner
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 USA.
authors.forename: K Andre
authors.initials: KA
authors.lastname: Mkhoyan
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Ruqing
authors.initials: R
authors.lastname: Xu
authors.affiliation: Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China. Geophysical Laboratory, Carnegie Institution of Washington (CIW), Washington, DC 20015, USA.
authors.forename: Ho-kwang
authors.initials: HK
authors.lastname: Mao