The high conductivity of iron and thermal evolution of the Earth's core
The high conductivity of iron and thermal evolution of the Earth's core
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DOI：
10.1016/j.pepi.2013.07.010
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发表时间：
2013-11-01
影响因子：
2.3
通讯作者：
Hernlund, John W.
中科院分区：
文献类型：
--
作者：
Gomi, Hitoshi;Ohta, Kenji;Hernlund, John W.
我们测量了铁和铁硅合金的电阻率至100gpa。还计算了铁的电阻率对岩心压力的影响。结合考虑岩心金属饱和电阻率的第一个地球物理模型，结果表明，最外层岩心的热导率大于90 W/m/K。这些数值明显高于传统的估计，这意味着在地球早期，快速的长期地核冷却，一个小于1ga的内核，以及普遍存在的最下层地幔融化。随着深度增强的电导率抑制了深核中的对流，使得其中心可能在内核结晶开始之前已经稳定分层。可能需要超过10太瓦的现有热流来解释所观察到的发电机特性。(C) 2013 Elsevier B.V.版权所有
We measured the electrical resistivity of iron and iron-silicon alloy to 100 GPa. The resistivity of iron was also calculated to core pressures. Combined with the first geophysical model accounting for saturation resistivity of core metal, the present results show that the thermal conductivity of the outermost core is greater than 90 W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1 Ga, and ubiquitous melting of the lowermost mantle during the early Earth. An enhanced conductivity with depth suppresses convection in the deep core, such that its center may have been stably stratified prior to the onset of inner core crystallization. A present heat flow in excess of 10 TW is likely required to explain the observed dynamo characteristics. (C) 2013 Elsevier B.V. All rights reserved.