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Lower Mantle Melting: Experiments and Thermodynamic Modeling in the System MgO-SiO2
Journal of Geophysical Research: Solid Earth ( IF 3.9 ) Pub Date : 2021-11-05 , DOI: 10.1029/2021jb022568 Jie Yao 1 , Daniel J. Frost 1 , Gerd Steinle‐Neumann 1
Journal of Geophysical Research: Solid Earth ( IF 3.9 ) Pub Date : 2021-11-05 , DOI: 10.1029/2021jb022568 Jie Yao 1 , Daniel J. Frost 1 , Gerd Steinle‐Neumann 1
Affiliation
Characterizing and modeling melting relations in the system MgO-SiO2 at lower mantle pressures rely on the location of the eutectic points for MgO-MgSiO3 and MgSiO3-SiO2. While at an uppermost lower mantle pressure there is general consensus on the eutectic composition in the former, large discrepancies exist for MgSiO3-SiO2 from experiments in the diamond anvil cell, ab-initio simulations and models built on them. In order to address this discrepancy, we have performed multi-anvil press experiments at GPa for Mg4Si6O16 and Mg3Si7O17 at temperatures of K and K. In the experiments at K, we observe the presence of partial melt. The recovered Mg4Si6O16 sample shows SiO2 stishovite as the liquidus phase, and electron microprobe analysis of the quenched melt determines as the eutectic composition. We fit a thermodynamic model to describe the melting relations in the MgO-SiO2 system, and extrapolate to core-mantle boundary pressure. At 136 GPa, we predict that the eutectic points have moved further away from enstatite composition, and solidus temperatures remain similar for MgO-MgSiO3 and MgSiO3-SiO2.
中文翻译:
下地幔熔化:MgO-SiO2 系统中的实验和热力学建模
在较低地幔压力下表征和模拟 MgO-SiO 2系统中的熔化关系依赖于 MgO-MgSiO 3和 MgSiO 3 -SiO 2共晶点的位置。虽然在最高的下地幔压力下,对于前者的共晶成分存在普遍共识,但金刚石砧座中的实验、从头算模拟和建立在其上的模型中的MgSiO 3 -SiO 2存在很大差异。为了解决这种差异,我们在GPa 条件下对 Mg 4 Si 6 O 16和 Mg 3 Si 7 O进行了多砧压机实验17在K 和K 的温度下。在K的实验中,我们观察到部分熔化的存在。回收的Mg 4 Si 6 O 16样品显示SiO 2 stishovite为液相,电子显微探针分析淬火熔体确定为共晶成分。我们拟合了一个热力学模型来描述 MgO-SiO 2系统中的熔化关系,并外推到核-幔边界压力。在 136 GPa 时,我们预测共晶点已远离顽火石组成,并且 MgO-MgSiO 3和 MgSiO 3 -SiO 2 的固相线温度保持相似.
更新日期:2021-11-30
中文翻译:
下地幔熔化:MgO-SiO2 系统中的实验和热力学建模
在较低地幔压力下表征和模拟 MgO-SiO 2系统中的熔化关系依赖于 MgO-MgSiO 3和 MgSiO 3 -SiO 2共晶点的位置。虽然在最高的下地幔压力下,对于前者的共晶成分存在普遍共识,但金刚石砧座中的实验、从头算模拟和建立在其上的模型中的MgSiO 3 -SiO 2存在很大差异。为了解决这种差异,我们在GPa 条件下对 Mg 4 Si 6 O 16和 Mg 3 Si 7 O进行了多砧压机实验17在K 和K 的温度下。在K的实验中,我们观察到部分熔化的存在。回收的Mg 4 Si 6 O 16样品显示SiO 2 stishovite为液相,电子显微探针分析淬火熔体确定为共晶成分。我们拟合了一个热力学模型来描述 MgO-SiO 2系统中的熔化关系,并外推到核-幔边界压力。在 136 GPa 时,我们预测共晶点已远离顽火石组成,并且 MgO-MgSiO 3和 MgSiO 3 -SiO 2 的固相线温度保持相似.