High‐Pressure Single‐Crystal Elasticity and Thermal Equation of State of Omphacite and Their Implications for the Seismic Properties of Eclogite in the Earth's Interior
High‐Pressure Single‐Crystal Elasticity and Thermal Equation of State of Omphacite and Their Implications for the Seismic Properties of Eclogite in the Earth's Interior
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DOI：
10.1029/2018jb016964
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
M. Hao;Jin S. Zhang;C. Pierotti;Z. Ren;D. Zhang
中科院分区：
文献类型：
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作者：
M. Hao;Jin S. Zhang;C. Pierotti;Z. Ren;D. Zhang
绿辉石是榴辉岩的主要矿物相，是板块向地球内部俯冲的主要驱动力。我们使用布里渊光谱首次在环境温度下测量了绿辉石在高达18 GPa的高压下的单晶弹性模量。速度-压力数据与三阶有限应变状态方程的最小二乘拟合得出KS 0 ′ = 4.5（3），G 0 ′ = 1.6（1），ρ0 = 3.34（1）g/cm 3，KS 0 = 123（3）GPa，G 0 = 74（2）GPa。此外，同步加速器单晶X射线衍射数据已收集到高达18 GPa和700 K。对霍兰德-鲍威尔热-压状态方程的拟合得到KT 0 ′ = 4.6（5）和α0 = 2.7（8）× 10−5 K−1。根据所获得的绿辉石的热弹性参数，模拟了榴辉岩的各向异性地震速度，并与200 ~ 500 km范围内的地幔岩进行了比较。榴辉岩和地幔岩在地震性质方面的最大对比在~310和410 km之间观察到。
Omphacite is a major mineral phase of eclogite, which provides the main driving force for the slab subduction into the Earth's interior. We have measured the single‐crystal elastic moduli of omphacite at high pressures for the first time up to 18 GPa at ambient temperature using Brillouin spectroscopy. A least squares fit of the velocity‐pressure data to the third‐order finite strain equation of state yields KS0′ = 4.5 (3), G0′ = 1.6 (1) with ρ0 = 3.34 (1) g/cm3, KS0 = 123 (3) GPa, and G0 = 74 (2) GPa. In addition, the synchrotron single‐crystal X‐ray diffraction data have been collected up to 18 GPa and 700 K. The fitting to Holland‐Powell thermal‐pressure equation of state yields KT0′ = 4.6 (5) and α0 = 2.7 (8) × 10−5 K−1. Based on the obtained thermoelastic parameters of omphacite, the anisotropic seismic velocities of eclogite are modeled and compared with pyrolite between 200 and 500 km. The largest contrast between the eclogite and pyrolite in terms of seismic properties is observed between ~310 and 410 km.