Thermal conductivity of MgO, MgSiO3 perovskite and post-perovskite in the Earth's deep mantle
Thermal conductivity of MgO, MgSiO3 perovskite and post-perovskite in the Earth's deep mantle
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DOI：
10.1016/j.epsl.2012.09.002
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发表时间：
2012-11-15
影响因子：
5.3
通讯作者：
Jahn, Sandro
中科院分区：
文献类型：
--
作者：
Haigis, Volker;Salanne, Mathieu;Jahn, Sandro
我们报告了在地球下地幔条件下钙钛矿和后钙钛矿结构中 MgO 和 MgSiO3 的晶格热导率，这是通过平衡分子动力学模拟获得的。利用先进的离子相互作用势，通过Green-Kubo方法计算了全电导率张量，发现MgSiO3后钙钛矿的电导率具有显着的各向异性。所有三相的热导率均被参数化为密度和温度的函数。假设无铁的下地幔成分的摩尔分数 x(MgSiO3) = 0.66 和 X-MgO = 0.34，则沿着模型地温线计算两相聚集体的电导率。研究发现，它随深度变化很大，从下地幔顶部的 9.5 W/(m·K) 上升到核幔边界上方热边界层顶部的 20.5 W/(m·K)。实验数据外推表明，在地幔深处条件下，实际数量的铁杂质的存在会使聚集体的导热率降低约 50%（Manthilake 等人，2011a）。根据这一结果和我们的热导率模型，我们估计含铁 MgO/MgSiO3 钙钛矿骨料穿过核幔边界的热通量为 10.8 TW，含铁 MgO/MgSiO3 后钙钛矿骨料为 10.6 TW。 (C) 2012 Elsevier B.V. 保留所有权利。
We report lattice thermal conductivities of MgO and MgSiO3 in the perovskite and post-perovskite structures at conditions of the Earth's lower mantle, obtained from equilibrium molecular dynamics simulations. Using an advanced ionic interaction potential, the full conductivity tensor was calculated by means of the Green-Kubo method, and the conductivity of MgSiO3 post-perovskite was found to be significantly anisotropic. The thermal conductivities of all three phases were parameterized as a function of density and temperature. Assuming a Fe-free lower-mantle composition with mole fractions x(MgSiO3) = 0.66 and X-MgO = 0.34, the conductivity of the two-phase aggregate was calculated along a model geotherm. It was found to vary considerably with depth, rising from 9.5 W/(m K) at the top of the lower mantle to 20.5 W/(m K) at the top of the thermal boundary layer above the core-mantle boundary. Extrapolation of experimental data suggests that at deep-mantle conditions, the presence of a realistic amount of iron impurities lowers the thermal conductivity of the aggregate by about 50% (Manthilake et al., 2011a). From this result and our thermal conductivity model, we estimate the heat flux across the core-mantle boundary to be 10.8 TW for a Fe-bearing MgO/MgSiO3 perovskite aggregate and 10.6 TW for a Fe-bearing MgO/MgSiO3 post-perovskite aggregate. (C) 2012 Elsevier B.V. All rights reserved.