Iron partitioning in pyrolitic lower mantle |
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| Authors: | Ryosuke Sinmyo Kei Hirose |
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| Institution: | 1. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, Japan
2. Bayerisches Geoinstitut, Universit?t Bayreuth, 95440, Bayreuth, Germany
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| Abstract: | The partitioning of iron between Mg-rich perovskite (Pv) and ferropericlase (Fp) was investigated for a pyrolitic bulk composition over a wide range of simulated lower-mantle pressures and temperatures from 28 to 114 GPa and from 1,900 to 2,300 K, in a laser-heated diamond anvil cell (DAC). The recovered DAC samples are chemically homogeneous, indicating a relatively small temperature gradient during laser heating. The chemical compositions of coexisting Pv, Fp, and Ca-rich perovskite (CaPv) were determined by energy-dispersive X-ray spectroscopy (EDS) using an EDS instrument attached to a transmission electron microscope. Our results demonstrate that at pressures above 90 GPa, Pv becomes more Fe-rich with increasing pressure, which is likely due to the effects of high-spin to low-spin crossover of Fe3+ in Pv. We highlight that such a change in Fe–Mg partitioning between Pv and Fp should have a strong influence on the physical properties of the deep lower mantle. |
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