Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth's D" layer

被引:743
作者
Oganov, AR
Ono, S
机构
[1] Swiss Fed Inst Technol, Dept Mat, Crystallog Lab, CH-8093 Zurich, Switzerland
[2] Japan Agcy Marine Earth Sci & Technol, Inst Frontier Res Earth Evolut, Yokosuka, Kanagawa 2370061, Japan
关键词
D O I
10.1038/nature02701
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The Earth's lower mantle is believed to be composed mainly of (Mg, Fe) SiO3 perovskite, with lesser amounts of (Mg,Fe)O and CaSiO3 (ref. 1). But it has not been possible to explain many unusual properties of the lowermost similar to150 km of the mantle (the D" layer) with this mineralogy. Here, using ab initio simulations and high-pressure experiments, we show that at pressures and temperatures of the D" layer, MgSiO3 transforms from perovskite into a layered CaIrO3-type post-perovskite phase. The elastic properties of the post-perovskite phase and its stability field explain several observed puzzling properties of the D" layer: its seismic anisotropy(2), the strongly undulating shear-wave discontinuity at its top(3-6) and possibly the anticorrelation between shear and bulk sound velocities(7,8).
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页码:445 / 448
页数:4
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