The Thermal Conductivity of Lower Mantle Minerals

地幔矿物的导热性影响着广泛的地球基本过程。它控制着从地核到地幔的热量传递。这反过来又决定了地核的冷却、内核的年龄和地球磁场的产生。热导率决定了俯冲板块俯冲到下地幔时升温的速度。这就影响了它们对地震波的可见性，更重要的是，它们对板块驱动力和地幔对流的贡献有多大。传导和对流之间的平衡决定了地幔中热上升流的大小和稳定性，并暗示了地幔柱和其他大型火成岩事件。然而，尽管热导率在控制许多地球过程中的重要性，地幔矿物的热导率知之甚少。MgSiO3钙矿是地球上最丰富的矿物相，但只有一组实验测量其电导率。这些是在室温（10兆帕）和最高温度340 K下制成的。地幔的压力和温度达到136gpa和4000k，因此需要进行巨大的外推。此外，仅在纯MgSiO3钙钛矿上测量了电导率，而地幔钙钛矿含有Fe2+， Fe3+和Al3+。我们建议将从头算分子动力学模拟与新的实验技术相结合，为三种主要下地幔矿物提供一套全面准确的热导率。我们将在所有适当的压力和温度条件下以及适当的化学成分下进行实验。

The thermal conductivity of mantle minerals affects a wide range of fundamental Earth processes. It controls the heat transferred from the core to the mantle. This in turn determines the cooling of the core, the age of the inner core and the generation of the Earth's magnetic field. Thermal conductivity determines how quickly subducting slabs warm up as they are subducted into the lower mantle. This then affects how visible they are to seismic waves, and more importantly, how much they contribute to plate-driving forces and mantle convection in general. The balance between conduction and convection determines the size and stability of thermal upwellings in the mantle, with implications for plumes and other large igneous events. Yet, despite the importance of thermal conductivity in controlling many Earth processes, thermal conductivities of mantle minerals are very poorly known. MgSiO3 perovksite is the most abundant mineral phase on the Earth and yet there is only one set of experiments measuring its conductivity. These were made at room pressure (10 MPa) and a maximum temperature of 340 K. The pressures and temperatures of the mantle reach 136 GPa and 4000 K, and so a huge extrapolation is required. Moreover, the conductivity was only measured on the pure MgSiO3 perovksite, whereas mantle perovskites contain Fe2+, Fe3+ and Al3+. We propose to use a combination of ab initio molecular dynamics simulations with new experimental techniques to provide a comprehensive set of accurate thermal conductivites for the three main lower mantle minerals. We will do this for all appropriate pressure and temperature conditions and appropriate chemical compositions.