Collaborative Research: Rapid Magma Ascent Recorded in Volatile Diffusion Profiles

合作研究：挥发性扩散剖面记录的岩浆快速上升

• 批准号: 1524581
• 负责人: Erik Hauri
• 金额: $ 6.67万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524581&HistoricalAwards=false
• 关键词: Collaborative; Research; Rapid; Magma; Ascent

What makes some eruptions more explosive than others? This fundamental questions is still largely unanswered, even after a given eruption has occurred. Theories link eruptive vigor to the amount of gas and stiffness of the magma, but magmas that have similar stiffness and gas-forming species can still erupt in a wide range of styles, some highly explosive, some quiescent. This project explores another fundamental parameter ? the rate at which magma rises in the volcanic conduit prior to eruption. The magma ascent rate will affect eruptive volume and vigor and also how bubbles form, grow and coalesce. In general, slow magma rise leads to more efficient bubble separation and less explosive eruption. This project aims to test the control of magma rise speed by extracting timescale information from erupted crystals and glass for several eruptions that span a range of exlosive magnitudes. This project will take advantage of new developments in using the zonation of volatile species in glass and crystals to obtain diffusive timescales that reflect ascent on the order of minutes to days prior to eruption. Four different chronometers will be used: 1) multi-species volatile diffusion through melt embayments, 2) water loss through olivine from melt inclusions of different sizes, 3) water zonation in olivine and clinopyroxene, and 4) zonation inside melt inclusions. Data will be obtained that derive from different microbeam techniques (NanoSIMS, FTIR, electron probe, laser ablation ICPMS) that record chemical zonation at the resolution of 5-25 microns. The proposed targets are a pair of well-documented eruptions from each of three volcanoes: Etna (2001 and 3930BP), Cerro Negro (1992 and 1995) and Paricutin (1943 and 1948), which span the range in mass eruption rates that characterize the transition from strombolian to subplinian styles. The eruptions targeted are specifically designed to test ideas as to the relationship between ascent rate and eruption rate in hydrous mafic magmas, among the most common but least well understood eruptions. This project will support a Ph.D. student and two high school interns from the Manhattan Center for Science and Mathematics, a public high school comprised largely of minority students from lower socioeconomic groups.

是什么使得某些火山喷发比其他火山喷发更具爆炸性？即使在一次特定的火山喷发之后，这个基本问题仍然基本上没有得到解答。理论将喷发活力与岩浆的气体量和硬度联系起来，但具有相似硬度和气体形成物质的岩浆仍然可以以多种形式喷发，有些是高度爆炸性的，有些是静止的。该项目探索了另一个基本参数？喷发前火山管道中岩浆上升的速度。岩浆上升速率会影响喷发量和活力，以及气泡的形成、生长和合并方式。一般来说，缓慢的岩浆上升会导致更有效的气泡分离和更少的爆炸性喷发。该项目旨在通过从爆发的晶体和玻璃中提取跨越一系列爆炸震级的几次喷发的时间尺度信息来测试对岩浆上升速度的控制。 该项目将利用玻璃和晶体中挥发性物质分区的新进展，以获得反映喷发前几分钟到几天上升的扩散时间尺度。将使用四种不同的计时器：1）通过熔体海湾的多物种挥发性扩散，2）不同尺寸的熔体包裹体通过橄榄石的水损失，3）橄榄石和单斜辉石中的水分带​​，以及4）熔体包裹体内部的分带。数据来源于不同的微束技术（NanoSIMS、FTIR、电子探针、激光烧蚀ICPMS），以 5-25 微米的分辨率记录化学分区。拟议的目标是三座火山中每座火山的一对有据可查的喷发：埃特纳火山（2001 年和 3930 年）、塞罗内格罗火山（1992 年和 1995 年）和帕里库廷火山（1943 年和 1948 年），它们跨越了表征火山喷发的大规模喷发率范围。从斯特龙博风格到亚普林风格的过渡。目标喷发是专门设计的，目的是测试有关含水基性岩浆上升速率和喷发速率之间关系的想法，这是最常见但最不为人所知的喷发之一。该项目将支持博士学位。曼哈顿科学与数学中心的学生和两名高中实习生，这是一所公立高中，主要由来自较低社会经济群体的少数族裔学生组成。