Collaborative Research: Volatile Loss During Magma Ascent and Cooling

合作研究：岩浆上升和冷却过程中的挥发性损失

• 批准号: 0948478
• 负责人: Erik Hauri
• 金额: $ 5.84万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948478&HistoricalAwards=false
• 关键词: Collaborative; Research; Volatile; Loss; During

A critical parameter governing the style and vigor of volcanic eruptions is the rate at which magma ascends and degases from the storage region to the surface. The magma ascent rate, in turn, controls the time available for loss of volatile species from the magma, melts and crystals. This project aims to assess directly the volatile loss from magmas over timescales of minutes to months, as measured in volcanic crystals and glass, and from this provide estimates of magma ascent rates critical to a quantitative understanding eruptive processes. The focus here is on explosive, basaltic to basaltic andesite eruptions, for which very little is yet known about the magma ascent and degassing processes leading to eruption. The approach is motivated by new developments in analytical techniques that enable measurement of volatile species (including water and carbon dioxide) at fine spatial resolution. Three different kinds of measurements will interrogate volcanic systems at different timescales: 1) volatile concentration profiles in melt embayments within crystals (by nanoSIMS ionmicroprobe), which may reflect diffusive re-equilibration with the exterior, degassing magma over the timescale of minutes (water) to hours (sulfur). 2) water contents within nominally anhydrous phenocrysts, which may preserve diffusive exchange over the timescale of hours (olivine) to months (clinopyroxene). 3) volatile contents in olivine-hosted melt inclusions, which may reflect timescales and processes intermediate between those that affect melt embayments and crystals, above. Well-studied Central American volcanoes (Cerro Negro, Irazu, Arenal) will enable comparisons of volatile loss and ascent rates for different eruptive styles. The project has implications for the understanding of volcanic hazards associated with explosive volcanism, will support the training and development of two graduate students, and provide lecture and seminar material for a course at Columbia University (Frontiers of Science) that engages 500 freshmen each year.

控制火山喷发的风格和活力的关键参数是岩浆从存储区域到表面上升和de度的速度。岩浆上升速率反过来控制了从岩浆，融化和晶体中丧失挥发性物种的时间。该项目旨在直接评估在火山晶体和玻璃中测量的时间表，直接在数分钟到几个月的时间标准中造成的挥发性损失，从此可以估计岩浆上升速率对定量理解的爆发过程至关重要。 这里的重点是爆炸性的玄武岩到玄武岩安山岩爆发，对于导致喷发的岩浆上升和脱气过程知之甚少。 该方法是由分析技术的新发展激发的，这些发展能够以精细的空间分辨率测量挥发性物种（包括水和二氧化碳）。三种不同类型的测量将在不同的时间尺度上审问火山系统：1）晶体内熔体胚胎中挥发性浓度曲线（由Nanosims Ionmicrobobe），这可能反映出可以反映出扩散的重新平衡与外部，分钟数分钟（水）的脱水岩浆（水）到小时（硫）。 2）名义上无水表晶中的水含量，可以在小时时间（橄榄石）到几个月（Clinopyroxene）中保留扩散的交换。 3）橄榄石托管熔体夹杂物中的挥发性含量，这可能反映了上面影响熔体胚胎和晶体的时间表和过程。经过深入研究的中美洲火山（塞罗·黑德，伊拉祖，阿雷纳尔）将使不同喷发风格的挥发性损失和上升率进行比较。 该项目对理解与爆炸性火山主义相关的火山危害有影响，将支持两名研究生的培训和开发，并为哥伦比亚大学（科学前沿）的课程提供讲座和研讨会材料，该课程每年参与500名新生。