Variation of thermal conductivity and heat flux at the Earth's core mantle boundary
Variation of thermal conductivity and heat flux at the Earth's core mantle boundary
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DOI：
10.1016/j.epsl.2014.01.009
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发表时间：
2014-03-15
影响因子：
5.3
通讯作者：
Dobson, David P.
中科院分区：
文献类型：
--
作者：
Ammann, Michael W.;Walker, Andrew M.;Dobson, David P.
主导地球内部动力学的两个对流系统在岩石地幔和金属液态地核之间的边界相遇。驱动板块构造和地球动力的过程之间的能量传递受最下层地幔（D”）的热传导控制。我们使用原子尺度模拟来确定D ‘’条件下MgSiO3钙钛矿和后钙钛矿的热导率，并探索这两种对流系统如何相互作用。我们发现，钙钛矿后的导热系数（约为12 W/mK）比相同条件下的钙钛矿后的导热系数（约为8.5 W/mK）大50%，且具有各向异性，a轴的导热系数比c轴的导热系数高40%。这增强了进入D ‘’冷区（后钙钛矿稳定）的高热通量，加强了地核和地幔对流之间的反馈。与岩石圈的情况类似，地幔对流有可能引起变形，从而改变地幔从下面加热的方式。我们通过将我们的原子尺度结果与D ‘’结构模型相结合来验证这一点，并建议各向异性热导率可能有助于在地幔柱漫长的生命周期中稳定其根部。(C) 2014 Elsevier B.V.版权所有
The two convective systems that dominate Earth's internal dynamics meet at the boundary between the rocky mantle and metallic liquid core. Energy transfer between processes driving plate tectonics and the geodynamo is controlled by thermal conduction in the lowermost mantle (D ''). We use atomic scale simulations to determine the thermal conductivity of MgSiO3 perovskite and post-perovskite under D '' conditions and probe how these two convective systems interact. We show that the thermal conductivity of post-perovskite (similar to 12 W/mK) is 50% larger than that of perovskite under the same conditions (similar to 8.5 W/mK) and is anisotropic, with conductivity along the a-axis being 40% higher than conductivity along the c-axis. This enhances the high heat flux into cold regions of D '' where post-perovskite is stable, strengthening the feedback between convection in the core and mantle. Reminiscent of the situation in the lithosphere, there is potential for deformation induced texturing associated with mantle convection to modify how the mantle is heated from below. We test this by coupling our atomic scale results to models of texture in D '' and suggest that anisotropic thermal conductivity may help to stabilise the roots of mantle plumes over their protracted lifetime. (C) 2014 Elsevier B.V. All rights reserved.