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High-pressure Sound Velocity of Perovskite-Enstatite and Possible Composition of Earths Lower Mantle |
| GONG Zi-zheng1,2;XIE Hong-sen1;LIU Yong-gang1;HUO Hui2;JING Fu-qian2;GUO Jie1;XU Ji-an1,3 |
| 1Material Laboratory of the Earths Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002
2Laboratory for Shock Waves and Detonation Physics Research, Southwest Institute of Fluid Physics, Chengdu 610003
I3nstitute of Geosciences, Academia Sinica, Taipei 11529
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| Cite this article: |
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GONG Zi-zheng, XIE Hong-sen, LIU Yong-gang et al 1999 Chin. Phys. Lett. 16 695-697 |
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Abstract The compressional sound velocity vp for enstitate of polycrystalline specimens was measured at pressures from 40 to 140 GPa by using the optical analyzer techniques under shock loading. The dependence of vp (in units of km/s) on Hugoniot pressure p (in units of GPa) can be described by: vp = 3.079 - 0.691 lnp + 0.0941n2p. The vp satisfies Birch's law: vp = 6.213 + 1.212 ρ, where ρ is corresponding density, indicating that enstatite is stable throughout the conditions of the lower mantle. Here P wave velocity is 0.5% lower and S wave velocity is 2% higher than those of preliminary reference earth model, respectively. It is concluded that the lower mantle is mainly composed of perovskite-(Mg1-x,Fex)SiO3 and only small amount of (Mg1-x,Fex)O is allowed in it.
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| Keywords:
91.35.Lj
62.50.+p
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Published: 01 September 1999
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