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: 1834939
• 负责人: Elisabet Head
• 金额: $ 9.43万
• 依托单位: Northeastern Illinois University
• 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 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1834939&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.

金属(如铜)在硅酸盐熔体中的溶解度会受到岩浆自然性质的强烈影响，如压力、温度和熔体组成。了解这些物质如何控制金属的溶解度，特别是对铜来说，是很重要的，原因有很多。它帮助研究人员了解类地行星核心形成的潜在驱动机制，或导致经济上重要的成矿矿床形成的条件。这也是理解火山脱气可能如何影响金属排放到大气中的关键。这项研究建议使用天然和合成岩浆玻璃的同步加速器X射线吸收精细结构(XAFS)光谱，目的是提供第一个直接的实验约束，以确定陆地熔体中铜的形态。XAFS是目前可用于以高空间分辨率在自然浓度下直接测量岩浆玻璃中铜形态的唯一方法。除了限制熔体中存在哪些铜的科学目标外，这项工作还将扩大少数民族学生对地球科学的参与，并培训学生使用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将包括在受控的硫和氧条件下生产的合成玄武岩玻璃的铜形态测量。这套合成玻璃将仔细控制氧逸度和硫逸度，然后将使用XAFS分析铜形态的变化。项目2包括从火山系统取样的天然玻璃的铜形态测量。该项目的目标是来自以硫化物为主、贫水熔体的系统的自然样本(使用从2008年至今从基拉韦厄山顶喷口采集的样本)、来自以硫化物为主、具有较高H2O熔体的系统的样本(来自南部喀斯喀特山脉的玄武岩灰渣锥)，以及来自南部喀斯喀兹山脉和墨西哥西部科利马格拉本的以硫酸盐为主的火山岩的样本。项目3将侧重于开发基于同步加速器的岩浆玻璃铜K边XAFS光谱技术，该技术将应用于项目1和项目2提供的样品，重点是开发专门用于分析地质材料和岩浆玻璃中铜的高能量分辨率荧光检测XAFS技术。与传统的XAFS方法相比，这种新的HERFD-XAFS技术有望提供更高的光谱灵敏度和分辨率，以唯一地限制这些样品中存在的铜配体。这些拟议的测量将首次将这些方法应用于岩浆玻璃，并将建立一个新的光谱测量数据库，供岩石界使用。总而言之，这套研究将大大有助于我们了解金属在岩浆系统中的溶解和迁移。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.