Water Speciation and Viscosity of Hydrous Melts

水形态和含水熔体的粘度

• 批准号: 0125506
• 负责人: Youxue Zhang
• 金额: $ 29.68万
• 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: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125506&HistoricalAwards=false
• 关键词: Water; Speciation; Viscosity; Hydrous; Melts

ZhangEAR-0125506Viscosity of hydrous silicate melts plays a critical role in bubble growth, magma fragmentation and volcanic eruptions. This proposal requests funding to develop a new and long-term project for viscosity measurement using a novel technique developed over the years in my lab. It is based on the equivalence between glass transition temperature and the apparent equilibrium temperature of the hydrous species reaction in silicate melt. In order to obtain viscosity using this method, the equilibrium of the hydrous species reaction must also be characterized. Such data are important in their own right in understanding melt structure, water solubility and diffusion in magma, and D/H fractionation between water vapor and melt. In the three years of the grant period, we will concentrate on the following: a) speciation and viscosity at high pressures for hydrous rhyolitic melt up to 8 GPa; b) speciation equilibrium in hydrous dacitic melts and the viscosity of such melts to high dissolved H2O content (up to 8 wt% dissolved H2O); and c) development of more accurate viscosity models for hydrous rhyolitic and dacitic melts. The new viscosity model will be applied to re-evaluate previous results of bubble growth and magma fragmentation.

含水硅酸盐熔体的粘度在气泡生长、岩浆破碎和火山喷发中起着至关重要的作用。本提案要求资金开发一个新的和长期的项目，粘度测量使用新技术开发了多年来在我的实验室。它是基于硅酸盐熔体中水化物反应的玻璃化转变温度与表观平衡温度的等效性。为了用这种方法获得粘度，还必须对含水反应的平衡进行表征。这些数据对于了解岩浆的熔体结构、水在岩浆中的溶解度和扩散，以及水蒸气和熔体之间的D/H分馏等都具有重要意义。在三年的资助期内，我们将集中研究以下内容：a)高达8 GPa的含水流纹岩熔体在高压下的形态和粘度；b)含水酸性熔体的形态平衡以及这种熔体对高溶解H2O含量（高达溶解H2O的8wt %）的粘度；c)建立更精确的含水流纹岩和英白质熔体粘度模型。新的黏度模型将用于重新评价以前的气泡生长和岩浆破碎的结果。