Shock Wave Studies of Liquids in Earth's Core and Mantle

该奖项将为加州理工学院冲击波实验室提供持续的支持，使其能够在与地球最深处相匹配的条件下测量硅酸盐和金属液体的物理特性。这些信息对于解释下地幔和地核的组成、温度、热流和随时间的演化方面的地球物理观测至关重要。它还允许关于早期熔融地球的推测性想法（即，原始岩浆海洋）发展成详细的理论。冲击压缩是唯一可以在这种极端条件下同时测量液体密度、压力、温度、能量和声速的实验方法。 作为这项研究的一部分，该团队将进行实验开发，以实现比以前更高的初始预热温度，从而能够直接研究与原始岩浆海洋和下地幔岩石学最相关的高熔点液体成分。实验和科学议程包括：1）建立在冲击温度测量技术的进步，以观察冲击硅酸盐液体的温度，限制它们在下地幔压力下的热容，从而完成我们在压力-温度-密度-能量空间中描述它们的状态方程的能力; 2）进一步开发新方法，以实现更高的初始预处理率，加热温度比以前可能的，使研究状态方程的超镁铁液体成分最相关的早期岩浆海洋和下地幔岩石学;以及3）开始测量液态铁合金沿着实际外芯温度分布的声速和密度，以使外芯中观察到的声速随深度的明确梯度成为对外芯成分的新的和关键的约束。

This award will provide continued support for the Caltech shock wave laboratory to enable the measurement of physical properties of silicate and metallic liquids under conditions matching those in the deepest parts of the Earth. This information is critical to interpreting geophysical observations of the lower mantle and core in terms of composition, temperature, heat flow, and evolution over time. It also allows speculative ideas about an early molten earth (i.e., primordial magma ocean) to be developed into detailed theories. Shock compression is the only experimental method that can simultaneously measure density, pressure, temperature, energy, and sound speed of liquids at such extreme conditions. As part of this study, the team will undertake experimental developments to achieve much higher initial pre-heating temperatures than were previously possible, enabling the direct study of high-melting point liquid compositions most relevant to the primordial magma ocean and lower mantle petrology. The experimental and science agenda includes: 1) building on advances in shock temperature measurement techniques to look at temperatures of shocked silicate liquids, constraining their heat capacity at lower mantle pressures and thereby completing our ability to describe their equation of state in pressure-temperature-density-energy space; 2) furthering the development of new methods to achieve much higher initial pre-heating temperatures than were previously possible to enable the study of the equation of state of ultramafic liquid compositions most relevant to the early magma ocean and lower mantle petrology; and 3) initiating measurements of the sound speeds and densities of liquid iron alloys along actual outer core temperature profiles in order to make the well-defined observed gradient in sound speed with depth in the outer core a new and critical constraint on outer core composition.