Disproportionation of (Mg,Fe)SiO3 perovskite in Earth's deep lower mantle

Li Zhang, Yue Meng, Wenge Yang, Lin Wang, Wendy L. Mao, Qiao Shi Zeng, Jong Seok Jeong, Andrew J. Wagner, K. Andre Mkhoyan, Wenjun Liu, Ruqing Xu, Ho Kwang Mao

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)877-882
Number of pages6
JournalScience
Volume344
Issue number6186
DOIs
StatePublished - 2014

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