Direct measurement of thermal conductivity in solid iron at planetary core conditions
Direct measurement of thermal conductivity in solid iron at planetary core conditions
复制标题
直接测量行星核心条件下固体铁的导热率
DOI：
10.1038/nature18009
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发表时间：
2016-06-02
期刊：
影响因子：
64.8
通讯作者：
Goncharov, Alexander F.
中科院分区：
文献类型：
--
作者：
Konopkova, Zuzana;McWilliams, R. Stewart;Goncharov, Alexander F.
在极端压力和温度下，热通过矿物和熔体的传导对行星的演化和动力学至关重要。在冷却的地核中，铁合金的导热系数定义了绝热热流，从而定义了可用于支持通过发电机作用产生地球磁场的热能和成分能(1-3)。描述地球核心的热传输的尝试一直是有问题的，高导热系数(4-7)的预测与传统的地球物理模型不一致，并且直接证据表明岩石记录中存在原始磁场(8-10)。为了解决这种差异，需要对堆芯热传输进行测量。在这里，我们介绍了使用动态激光加热的钻石砧腔(11，12)，在与水星大小到地球大小的行星的核心相关的压力和温度条件下，直接测量固体铁的热导率。我们的测量结果表明，地核的热导率接近先前估计的低端，即每开尔文每米18-44瓦。这一结果与古地磁测量(10)一致，表明地球的地球发电机自地球历史开始就一直存在，并允许有一个与发电机一样古老的坚固内核。
The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action(1-3). Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity(4-7) at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record(8-10). Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell(11,12). Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements(10) indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.