Stability and Structure of MgSiO3 Perovskite to 2300-Kilometer Depth in Earth's Mantle
Stability and Structure of MgSiO3 Perovskite to 2300-Kilometer Depth in Earth's Mantle
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地幔2300公里深处MgSiO3钙钛矿的稳定性和结构
DOI：
10.1126/science.1061235
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发表时间：
2001
期刊：
影响因子：
56.9
通讯作者：
G. Shen
中科院分区：
文献类型：
--
作者：
S. Shim;T. Duffy;G. Shen
在地球下地幔的中部（约1700公里深度）和底部附近，地震学上观察到了无法解释的特征，这些特征可能对地球的动力学和演化产生重要影响。(Mg（Fe）SiO_3钙钛矿被认为是地幔深部的主要矿物，但其稳定性和结构的实验结果并不一致。在这里，我们报告了在接近地幔地热的条件（50至106吉帕斯卡，1600至2400开尔文）下，使用三种不同的起始材料（（Mg0.9Fe0.1）SiO顽火辉石、MgSiO 3玻璃）对（Mg，Fe）SiO 3钙钛矿进行的原位X射线衍射观察。和MgO+SiO2混合物。我们的研究结果证实了（Mg，Fe）SiO 3钙钛矿在地幔中至少2300公里深处的稳定性。然而，高于83吉帕斯卡和1700开尔文（1900公里深度）的衍射图案目前不能排除从Pbnm钙钛矿到空间群为P21/m，Pmmn或P42/nmc的三种其他可能的钙钛矿结构之一的可能转变。
Unexplained features have been observed seismically near the middle (∼1700-kilometer depth) and bottom of the Earth's lower mantle, and these could have important implications for the dynamics and evolution of the planet. (Mg,Fe)SiO3 perovskite is expected to be the dominant mineral in the deep mantle, but experimental results are discrepant regarding its stability and structure. Here we report in situ x-ray diffraction observations of (Mg,Fe)SiO3perovskite at conditions (50 to 106 gigapascals, 1600 to 2400 kelvin) close to a mantle geotherm from three different starting materials, (Mg0.9Fe0.1)SiO enstatite, MgSiO3glass, and an MgO+SiO2 mixture. Our results confirm the stability of (Mg,Fe)SiO3 perovskite to at least 2300-kilometer depth in the mantle. However, diffraction patterns above 83 gigapascals and 1700 kelvin (1900-kilometer depth) cannot presently rule out a possible transformation from Pbnm perovskite to one of three other possible perovskite structures with space groupP21/m, Pmmn, orP42/nmc.