期刊
SCIENCE
卷 344, 期 6186, 页码 877-882出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.1250274
关键词
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资金
- National Science Foundation (NSF) grants [EAR-0911492, EAR-1119504, EAR-1141929, EAR-1345112]
- U.S. Department of Energy-National Nuclear Security Administration (DOE-NNSA) [DE-NA0001974]
- DOE-Basic Energy Sciences (BES) [DE-FG02-99ER45775]
- NSF
- EFree, an Energy Frontier Research Center - DOE-BES [DE-SC0001057]
- NSF-Earth Sciences [EAR-1128799]
- DOE-GeoSciences [DE-FG02-94ER14466]
- DOE-BES [DE-AC02-06CH11357]
- Materials Research and Engineering Center program of the NSF [DMR-0819885]
- Directorate For Geosciences
- Division Of Earth Sciences [1345112, 1119504] Funding Source: National Science Foundation
- Division Of Earth Sciences
- Directorate For Geosciences [1141929] Funding Source: National Science Foundation
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 similar to 2000 kilometers depth and suggests that the lower mantle may contain previously unidentified major phases.
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