Effect of impurity on the elasticity of perovskite and postperovskite: Velocity contrast across the postperovskite transition in (Mg,Fe,Al)(Si,Al)O3
Effect of impurity on the elasticity of perovskite and postperovskite: Velocity contrast across the postperovskite transition in (Mg,Fe,Al)(Si,Al)O3
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DOI：
10.1029/2006gl025706
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发表时间：
2006-06
影响因子：
5.2
通讯作者：
T. Tsuchiya;J. Tsuchiya
中科院分区：
文献类型：
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作者：
T. Tsuchiya;J. Tsuchiya
我们计算的声速对比钙钛矿和钙钛矿后MgSiO 3，FeSiO 3和Al 2 O3化合物，使用平面波赝势方法的压力范围内的地球下地幔。在深地幔压力下，FeSiO 3和Al 2 O3 pv和ppv的剪切模量比Mg相小约20%，尽管体积模量相当，与以前的研究一致。在恒压下，由于Fe和Al含量变化到20 mol%，剪切速度到压缩速度、体积速度到剪切速度和密度到剪切速度的相对变化，我们发现RS/P为1.5 <$2.2，RΦ/S为0.1 <$0.4，Rρ/S为-1.0 <$-0.2。Fe和Al对ppv弹性的影响大于pv。因此，整个后钙钛矿相变的速度对比将随着Fe和Al含量的增加而减小。我们发现，正的速度变化几乎没有产生与MORB组成的pv。
We calculated the acoustic velocity contrasts between perovskite and postperovskite in MgSiO3, FeSiO3 and Al2O3 compounds, using the planewave pseudopotential method for a pressure range of the Earth's lower mantle. Both FeSiO3 and Al2O3 pv and ppv have about 20% smaller shear moduli than Mg‐phases at deep mantle pressures, though the bulk moduli are comparable, consistent with previous studies. For the relative variations of shear to compressional velocities, bulk to shear velocities and density to shear velocity at constant pressure due to variations in Fe and Al content up to 20 mol%, we find RS/P of 1.5∼2.2, RΦ/S of 0.1∼0.4 and Rρ/S of −1.0∼−0.2. Both Fe and Al influence elasticity of ppv more than that of pv. Therefore velocity contrasts across the postperovskite phase change would decrease with increasing Fe and Al content. We find that positive velocity variations are hardly produced in pv with the MORB composition.