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.

是什么使某些爆发比其他爆发更具爆炸性？即使发生了给定的喷发，这个基本问题仍然在很大程度上尚未得到答复。理论将爆发活力与岩浆的气体和刚度联系起来，但是具有相似刚度和气体形成物种的岩浆仍然可以在多种样式中爆发，有些高度爆炸性，有些静态。该项目探讨了另一个基本参数？喷发前火山导管中岩浆上升的速度。岩浆上升速度将影响喷发的体积和活力，以及气泡形成，生长和聚结。通常，缓慢的岩浆升高会导致更有效的气泡分离和爆炸性较小。该项目的目的是通过从爆发的晶体和玻璃中提取跨越一系列异常大小的几次爆发的时间尺度信息来测试岩浆上升速度的控制。 该项目将利用新的发展，利用玻璃和晶体中挥发性物种的分区来获得散射的时间表，这些时间表反映在喷发前几分钟到几天。将使用四个不同的计时仪：1）多种物种通过熔体胚胎的挥发性扩散，2）从不同尺寸的熔体夹杂物中通过橄榄石流失的水分流失，3）3）橄榄石和临床中的水分区，以及4）熔体内包含物的分区。将获得数据，该数据源自不同的微束技术（Nanosims，FTIR，Electron探针，激光烧蚀ICPMS），它们以5-25微米的分辨率记录化学分区。所提出的目标是来自三个火山中每一个的一对有据可查的爆发：ETNA（2001和3930bp），Cerro Negro（1992和1995）和Paricutin（1943和1948），它们的范围跨越了从斯特朗博利亚到亚倍倍倍膨胀型的质量爆发率。针对性的爆发是专门设计的，用于测试含水镁铁质岩浆的上升速率和喷发率之间的关系，这是最常见但最不理解的喷发。该项目将支持博士学位。来自曼哈顿科学与数学中心的学生和两名高中实习生，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。