Geophysics of Iron in the Earth's Core

通过分析穿过地球的地震波，我们可以观察到地球的内部结构，包括地球的核心，它是由富含铁的液态外部区域组成的，位于富含铁的固体内核之上。为了了解构成我们星球上最偏远地区的成分，我们建议在地球上存在的高压和高温下进行具有挑战性的实验室实验。并测量富铁物质的特性，这些特性在极端条件下会发生巨大变化。因此，本研究的主要目标是了解地核，地核在地球的演化、磁力、动力学过程和热演化中起着核心作用。在我们之前的支持下取得的进展的基础上，该项目采取了双管齐下的方法：在金刚石砧单元中使用静态高压技术来精确测定弹性特性，并通过强大的激光产生动态压缩，进行超高压-温度声速测量。对于静态高压实验，我们建议使用一套互补同步加速器x射线技术来确定铁的状态方程、总纵波和横波速度、速度各向异性和晶格优先取向以及弹性张量。对于动态实验，我们将与劳伦斯利弗莫尔国家实验室的冲击物理小组合作，使用Janus激光设备来确定铁和铁合金的纵波速度，特别是横波速度（使用横向位移干涉仪设置）。静态和动态结果的结合将为帮助理解和解释地核复杂的地震特征提供重要信息。预期的铁的高压-高温弹性数据将对参与地球深部研究的各种研究人员很有价值（例如，理论矿物物理学家可以改进他们的计算，地震学家可以解释他们的观察结果，地球动力学家可以限制他们的模型）。此外，这些技术进步将对地球科学以及基础科学和应用科学的其他实验工作者有用。

Analyzing the seismic waves that pass through our planet have provide observations of its internal structure including, the Earth's core which is composed of a liquid iron-rich outer region which lies above the solid, iron-rich inner core. In order to understand the constituents that make up this most remote region in our planet, we propose to conduct the challenging laboratory experiments at the high pressures and temperatures that exist in the Earth?s deep interior, and to measure of the properties of iron-rich materials which can be dramatically altered under the extreme conditions. The primary goal of the present research is thus to understand the Earth's core which plays a central role in the evolution, magnetism, dynamic processes, and thermal evolution of our planet. Building upon our progress resulting from our prior support, this project takes a two-pronged approach: using static high-pressure techniques in a diamond anvil cell for accurate determination of elastic properties and dynamic compression created by powerful lasers for ultrahigh pressure-temperature sound velocity measurements. For the static high-pressure experiments, we propose to determine the equation of state, aggregate compressional and shear wave velocities, velocity anisotropy and lattice preferred orientation, and elastic tensor of iron using a suite of complementary synchrotron x-ray techniques. For the dynamic experiments, we will collaborate with the Shock Physics Group at Lawrence Livermore National Laboratory and use the Janus laser facility to determine the compressional and especially the shear wave velocities (using a transverse displacement interferometer set-up) for iron and iron alloys. The combination of the static and dynamic results will provide important information for helping to understand and interpret the complex seismic signatures in the Earth's core. The anticipated, high pressure-temperature elasticity data for iron will be valuable to a wide variety of researchers involved in deep Earth studies (e.g. theoretical mineral physicists for improving their calculations, seismologists for interpretation of their observations, and geodynamicists for constraining their models). In addition, the technical advances will be useful to other experimentalists in the geosciences as well as fundamental and applied sciences.