X-ray Emission Spectroscopy of Silicate Perovskite in the Earth's Lower Mantle

Jie Li¹*, Viktor Struzhkin¹, Ho-kwang Mao¹, Jinfu Shu¹, Yingwei Fei¹, Russell J. Hemley¹, Bjorn Mysen¹, Przemyslaw Dera¹, V. Prapapenka² and Guoyin Shen²

¹Carnegie Institution of Washington

²The University of Chicago

*Now at University of Illinois at Urbana Champaign

jackieli@uiuc.edu

APS-GSECARS

The lower mantle constitutes more than half of the Earth's interior by volume [Dziewonski and Anderson 1981], and is believed to consists predominantly of (Mg, Fe) (Si, Al)O₃ perovskite, with up to ~ 20%(Mg,Fe)O magnesiowüstite (also known as 'ferropericlase') [Ringwood 1975, Fei and Bertka 1999]. We present experimental evidence for an electronic spin-pairing transition of iron in the predominant lower mantle phase - silicate perovskite - at deep mantle pressures. Together with the recent observation of an electronic spin-pairing transition of iron in magnesiowüstite [Badro et al. 2003], our results show that most of iron in the deep mantle is in the low-spin state.