Water Diffusion in Dacitic Melt and Glass, and Explosive Volcanic Eruptions

英安石熔体和玻璃中的水扩散以及火山喷发

• 批准号: 0228752
• 负责人: Youxue Zhang
• 金额: $ 30万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0228752&HistoricalAwards=false
• 关键词: Water; Diffusion; Dacitic; Melt; Glass

ZhangEAR-0228752Gas-driven volcanic eruptions are a major natural hazard. These eruptions are powered by the exsolution of H2O and other volatiles from magma. The process is complex, and understanding it requires quantification and modeling of a number of variables and processes, especially the diffusion of water. After many years of work, most of the fundamental data for high-silica rhyolite--a magma with 77 wt% silica--has been experimentally determined. However, there is a critical need for experimental studies of dacitic magmas, containing around 65 wt% silica and common to explosive eruptions such as the 1980 eruption of Mount St. Helens, the 1991 eruption of Mount Pinatubo, and the 1991 eruption of Mount Unzen. Under this grant, water diffusion in dacitic melt and glass will be investigated using dehydration and diffusion couple experiments over a wide range of temperature, pressure, and H2O contents. Experiments will be performed in one-atmosphere furnaces, rapid-quench cold-seal pressure vessels, internally-heated pressure vessels, and a piston-cylinder apparatus. Hydrous species concentrations will be analyzed by Fourier Transform Infrared Spectroscopy, and diffusion profiles modeled using a nonlinear diffusion equation. The results will be used to model bubble growth and magma fragmentation in dacite.

张EAR-0228752气体驱动的火山喷发是一种主要的自然灾害。这些喷发是由岩浆中的水和其他挥发物的溶出提供动力的。这个过程很复杂，理解它需要对许多变量和过程进行量化和建模，特别是水的扩散。经过多年的工作，高硅流纹岩（一种含有 77 wt% 二氧化硅的岩浆）的大部分基本数据已通过实验确定。然而，迫切需要对英安岩岩浆进行实验研究，英安岩岩浆含有约 65 wt% 的二氧化硅，常见于爆炸性喷发，例如 1980 年圣海伦斯火山喷发、1991 年皮纳图博火山喷发和 1991 年云仙火山喷发。在此资助下，将通过脱水和扩散耦合实验在较宽的温度、压力和水含量范围内研究英安岩熔体和玻璃中的水扩散。实验将在单气氛炉、快淬冷封压力容器、内热式压力容器和活塞缸装置中进行。含水物质浓度将通过傅里叶变换红外光谱分析，并使用非线性扩散方程建模扩散剖面。结果将用于模拟英安岩中的气泡生长和岩浆破碎。