High Pressure-Temperature Equations of State, Oxygen Fugacity, and Earth's Core

高压-温度状态方程、氧逸度和地核

• 批准号: 0635722
• 负责人: Andrew Campbell
• 金额: --
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2010-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635722&HistoricalAwards=false
• 关键词: Pressure; Temperature; Equations; State; Oxygen

The properties of materials at high pressure and temperature are essential for understanding the Earth's deep interior. This project is extending our understanding of the equations of state (pressure - volume - temperature relationships) of several geophysically important materials, through in situ measurement of unit cell volumes under high pressure, high temperature conditions (up to 100 GPa and 2500 K). Simultaneous pressure - volume - temperature measurements of a metal and its coexisting oxide provide a more precise measure of their relative equations of state than measurements of each phase separately. Synchrotron x-ray diffraction is used to measure volumes of both phases, and high pressures and temperatures are generated using a laser heated diamond anvil cell. Complementary studies using a multi-anvil press are also underway; these strengthen the data set in the lower pressure range ( 25 GPa). The experimental methodologies for both sets of experiments was successfully demonstrated in earlier investigations, but had not been broadly applied. Metals and oxides are being studied primarily, including iron-iron oxide, nickel-nickel oxide, and rhenium-rhenium oxide. There are several applications of these data to studies of the Earth's interior. One is the improved extension of oxygen fugacity buffers to high pressures, by integration of precise, experimentally determined relative volumes of coexisting metal-oxide phases. These results allow one to better quantify the oxygen potential at high pressures, which is needed to understand, for example, core-mantle interaction and elemental partitioning in the mantle. Furthermore, the oxygen fugacity conditions of many high pressure geochemical studies are either controlled by, or referenced to, these metal-oxide buffers. Precise comparison of experimental results that are based on different buffers requires knowledge of the relative shifts of those buffers with increasing pressure. Finally, these studies facilitate direct comparison of experimentally determined densities of candidate core constituents with the observed, seismologically constrained density profiles of the core. More data have been needed here to improve precision and reduce extrapolations, especially at high temperature. The information gained from this project will benefit our understanding of the chemical evolution of the planet and the formation of the core.

高压和温度下材料的特性对于理解地球深内部是至关重要的。该项目通过原位测量高压，高温条件（高达100 GPA和2500 K）的原位测量来扩展我们对几种地球物理材料的状态方程（压力 - 体积 - 温度关系）的理解。同时压力 - 金属及其共存的氧化物的温度测量值比单独的每个相的测量更精确地测量其状态的相对方程。同步加速器X射线衍射用于测量这两个相的体积，并使用激光加热的钻石砧池产生高压力和温度。使用多媒体出版社的互补研究也正在进行中；这些加强了较低压力范围（25 GPA）的数据集。两组实验的实验方法在较早的研究中已成功证明，但并未广泛应用。主要研究金属和氧化物，包括铁铁氧化铁，氧化镍镍和氧化鼻。这些数据有几种应用于地球内部的研究。一种是通过整合共存金属氧化物相的精确，实验确定的相对体积，改善了氧赋形性缓冲液向高压的扩展。这些结果使人们可以更好地量化高压下的氧气电位，这需要理解，例如核心掩盖相互作用和地幔中的元素分配。此外，许多高压地球化学研究的氧气散发条件要么由这些金属氧化物缓冲液控制或参考。基于不同缓冲液的实验结果的精确比较需要了解这些缓冲区随着压力增加的相对移位的知识。最后，这些研究有助于直接比较候选核心成分的实验确定的密度与观察到的核心密度密度谱。这里需要更多数据来提高精度并减少外推，尤其是在高温下。从该项目中获得的信息将使我们对地球的化学演变和核心形成的理解有利。