Collaborative Research: Measurement of Copper Speciation in Basaltic Glasses using X-ray Absorption Spectroscopy, a New Window on Metal Solubility and Transport in Magmatic Systems

合作研究：使用 X 射线吸收光谱测量玄武岩玻璃中的铜形态，这是岩浆系统中金属溶解度和传输的新窗口

• 批准号: 1834959
• 负责人: Paul Wallace
• 金额: $ 8.14万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1834959&HistoricalAwards=false
• 关键词: Collaborative; Research; Measurement; Copper; Speciation

The solubility of metals such as copper (Cu) in silicate melts can be strongly influenced by natural properties of the magma such as pressure, temperature, and melt composition. Understanding how such things control metal solubility, particularly for Cu, is important for a number of reasons. It helps researchers understand potential driving mechanisms for core formation in terrestrial planets, or the conditions that lead to the formation of economically important metallogenic ore deposits. It's also key to understanding how volcanic degassing may impact metal emissions to the atmosphere. This study proposes to use synchrotron-based X-ray absorption fine structure (XAFS) spectroscopy of natural and synthetic magmatic glasses with the goal of providing the first direct, experimental constraints on the speciation of Cu in terrestrial melts. XAFS is currently the only methodology available for directly measuring Cu speciation in magmatic glasses at natural concentrations with high spatial resolution. In addition to the scientific goal of constraining which Cu species exist in melts, this work will broaden the participation of minority students in geoscience, and train students in state-of-the-art experimental and analytical techniques.This will be achieved through three overlapping projects. Project 1 will include copper speciation measurements of synthetic basaltic glasses that are produced at controlled sulfur and oxygen conditions. This suite of synthetic glasses will have both oxygen and sulfur fugacity carefully controlled and will then be analyzed for changes in Cu speciation using XAFS. Project 2 includes Cu speciation measurements of natural glasses sampled from volcanic systems. This project targets natural samples from a sulfide-dominated system with H2O-poor melts (using samples collected from the Kilauea summit vent between 2008 and present), samples from a sulfide-dominated system with higher-H2O melts (from a basaltic cinder cone in the southern Cascade Range), and from sulfate dominated volcanics from both the southern Cascades Range and the Colima Graben in western Mexico. Project 3 will focus on developing advanced, synchrotron-based spectroscopic techniques for Cu K-edge XAFS of magmatic glasses, which will be applied to samples available from Projects 1 and 2, with a focus on developing High Energy-Resolution Fluorescence Detected XAFS (HERFD-XAFS) techniques for the analysis of Cu in geologic materials and magmatic glasses specifically. Such new HERFD-XAFS techniques hold the promise of providing superior spectroscopic sensitivity and resolution compared to conventional XAFS methods for uniquely constraining the copper ligands are present in these samples. These proposed measurements will be the first application of these methods to magmatic glasses and will establish a new database of spectroscopic measurements that will be available to the petrology community. Together, this suite of studies will significantly contribute to our understanding of metal solubility and transport in magmatic systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

硅酸盐熔体中金属（CU）等金属的溶解度可能会受到岩浆的自然特性，例如压力，温度和熔体组成。由于多种原因，了解这些东西如何控制金属溶解度，尤其是对于CU，这很重要。它可以帮助研究人员了解陆地行星中核心形成的潜在驾驶机制，或者导致形成经济重要的金属矿石沉积物的条件。这也是了解火山脱水如何影响金属排放到大气的关键。这项研究建议使用基于同步加速器的X射线吸收细胞（XAFS）天然和合成岩浆玻璃的光谱，目的是提供有关陆生融化中CU形成的第一个直接实验性约束。 XAFS目前是唯一用于直接在具有高空间分辨率的天然浓度下直接测量岩浆玻璃中CU形成的方法。除了限制哪种铜物种存在于融化中的科学目标外，这项工作还将扩大少数群体学生参与地球科学的参与，并培训学生从事最先进的实验和分析技术。这将通过三个重叠的项目实现。项目1将包括在受控硫和氧气条件下生产的合成盆底玻璃的铜值测量。这套合成玻璃套件将仔细控制氧气和硫磺卵石，然后使用XAFS分析CU形成的变化。项目2包括对从火山系统采样的天然眼镜的CU形成测量。该项目针对以硫化物为主的系统的天然样品，并带有H2O罚款融化（使用2008年至今之间从基拉韦亚峰顶通风口收集的样品），来自硫化物主导的系统的样品，具有较高的h2O熔体（从南部级联的colfate山脉范围内的较高的基底煤层锥体和从硫酸盐范围内占用了较高的基础煤层锥，以及从硫酸盐范围内占用的山脉和cascade山脉的范围。项目3将着重于开发用于基于同步的岩浆眼镜的高级，基于同步的光谱技术，该技术将应用于项目1和2中可获得的样品，重点是开发高能荧光检测到的XAFS（HERFD-XAFS）技术，用于分析地质材料中Cu的CU分析cu in Geologologic ander Magmatics Magses and Magsecepection。与常规的XAFS方法相比，这种新的HERFD-XAF技术具有提供优质光谱敏感性和分辨率的希望，这些方法在这些样品中存在于唯一地限制铜配体的唯一限制。这些提出的测量将是这些方法在岩浆眼镜上的首次应用，并将建立一个新的光谱测量数据库，该数据库将可供质质学界使用。这套研究将共同​​有助于我们对岩浆系统中的金属溶解度和运输的理解。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。

项目成果

Direct measurements of copper speciation in basaltic glasses: understanding the relative roles of sulfur and oxygen in copper complexation in melts

• DOI: 10.1016/j.gca.2019.09.029
• 发表时间: 2019-12-15
• 期刊: GEOCHIMICA ET COSMOCHIMICA ACTA
• 影响因子: 5
• 作者: Lanzirotti, Antonio;Lee, Lopaka;Wallace, Paul J.
• 通讯作者: Wallace, Paul J.