Static Compression of CO2-bearing Silicate Liquids

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。这项研究的重点是二氧化碳在地球深处非常高的压力下溶解时如何与岩浆发生物理作用的问题。将被测量的主要物理性质是在广泛的压力和温度范围内含有不同量的二氧化碳的压缩岩浆的密度。最终目标是确定二氧化碳改变岩浆密度的程度，从而揭示含二氧化碳的岩浆相对于周围岩石变得浮力的程度。这些实验将极大地提高我们预测岩浆上升到地球表面并以熔岩形式喷发或形成向地球大气排放二氧化碳和其他气体的火山的条件的能力。实验数据还将为我们提供新的见解，了解二氧化碳等气体是如何被隔离在地球岩石深处的，以及早期地球在形成阶段有多少气体被脱气。这项工作采用了跨越地球上地幔熔化和岩浆产生的整个压力和温度条件的实验技术。该项目中的实验将允许在活塞-圆柱体和高达20 Gpa的多顶锤设备中使用沉浮方法来确定硅酸盐熔体中二氧化碳的部分摩尔体积，作为压力和熔体组成的函数。实验将揭示硅酸盐熔体的压力效应作为碱金属(K，Na)和碱土金属(Ca)阳离子浓度的函数的任何非理想性。这些实验还将提供有关不同合成环境对二氧化碳在硅酸盐熔体中的偏摩尔体积和二氧化碳溶解度的影响的信息。建议改进定量分析技术，使用傅里叶变换红外光谱(FTIR)、二次离子质谱仪(SIMS)和电子探针(EMP)来验证和表征实验运行产品中的二氧化碳总量。在为这个项目做准备时，该团队对碳化橄榄岩部分熔融进行了初步研究，以证明这些实验技术将有很高的成功可能性。该项目的结果将有助于为预测模型建立一个实验基础和新的数据库，这些模型用于计算任何给定的碳酸盐硅酸盐熔体成分的密度，这些成分可能是由行星地幔中的熔化产生的。高压下的新密度数据还将用于评估状态方程的预测能力，例如Birch-Murnaghan和Vinet方程，在计算高压和高温下挥发性含硅酸盐液体的密度时。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This research focuses on the problem of how carbon dioxide physically interacts with magma when dissolved under very high pressures in the Earth's deep interior. The main physical property that will be measured is the density of compressed magma with varying amounts of carbon dioxide under a wide range of pressure and temperatures. The ultimate goal is to determine the degree to which carbon dioxide alters the magma density, thus revealing how readily CO2-bearing magmas will become buoyant relative to surrounding rock. The experiments will greatly improve our ability to predict the conditions under which magmas rise to the Earth's surface and erupt as lavas or form volcanoes that emit carbon dioxide and other gases into Earth's atmosphere. The experimental data will also provide new insight into the way in which gases such as carbon dioxide were sequestered deep in the rocky part of our planet and how much was degassed from the early Earth during its formation stage. This effort employs experimental techniques that span the entire range of pressure and temperature conditions that exist for melting and magma production in the Earth's upper mantle.The experiments in this project will allow the determination of the partial molar volume of CO2 in silicate melts as a function of pressure and melt composition using the sink/float method in piston-cylinder and multi-anvil devices up to 20 GPa. The experiments will reveal any non-ideality in the pressure effect on silicate melt as a function of alkali metal (K, Na) and alkaline earth metal (Ca) cation concentration. The experiments will also be designed to provide information about effects of different synthesis environments on CO2 partial molar volume in silicate melt and CO2 solubility. It is proposed to refine quantitative analysis techniques to verify and characterize CO2-total in the experimental run products using Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry (SIMS), and the Electron Microprobe (EMP). In preparation for this project, the team carried out a pilot study on carbonated peridotite partial melt to demonstrate that these experimental techniques will have a high likelihood of success. The results from this project will help establish an experimental foundation and new database for predictive models used for calculating the density of any given carbonated silicate melt composition that could be produced by melting in planetary mantles. The new density data at high pressure will also be used to evaluate the predictive power of equations of state, such as the Birch-Murnaghan and Vinet equations, in calculating densities of volatile bearing silicate liquids at high pressure and temperatures.