Dynamics of crystal mush: Insight from 2D and 3D analysis of drill cores from Kilauea Iki lava lake, Hawaii

水晶糊的动力学：夏威夷基拉韦厄艾基熔岩湖岩心 2D 和 3D 分析的见解

• 批准号: 2310195
• 负责人: Katharine Cashman
• 金额: $ 66.98万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310195&HistoricalAwards=false
• 关键词: Dynamics; crystal; mush; Insight; 2D

Drilling hot lava sounds like science fiction, but it is not only a suggested source of clean energy but was actually done multiple times between 1960 and 1988. Then scientists at the Hawaiian Volcano Observatory probed a lava lake that formed during an eruption in 1959. The goal was to ‘watch’ the lake cool and solidify by collecting drill core samples. Early drill cores sampled only the upper crust of the lake, which comprised both fully crystalline rock and crystal ‘mush’ comprising crystals with up to 45% melt (quenched to glass by water during coring). Later cores were drilled through the entire lake, sampling both upper and lower solid crust as well as interior mush. Chemical analysis of the resulting drill cores showed that during solidification, melt, bubbles and crystals were moving around within the lava lake. Knowing what processes control those movements could improve our understanding of how, when and why melt, bubbles and crystals are rearranged in magmatic systems under volcanoes. It may also reveal how the movement of bubbles and crystals prepare for and trigger volcanic eruptions. The team will use x-ray scanning technology to get 3D images of the cores that will show the spatial distribution of glass plus crystals plus bubbles as a function of position in the lake and time since 1959. Individual core images can be used to model properties - such as melt percentage, connectivity and permeability - that control melt movement. Tracking these processes through space and time will not only provide an unprecedented look into a volcano but also aid future drilling efforts. For a century, conceptual models of (1) melt evolution in magmatic systems and (2) formation of eruptible (melt-rich) magma bodies were framed around the concept of large, long-lived, melt-dominated magma chambers. However, both geophysical imaging and petrologic analysis of magmatic systems suggest that they dominated by crystal ʻmushʻ that contains lenses of melt. Reconciliation of these two perspectives is key to improving our understanding of the magma systems that feed volcanic eruptions and requires improved understanding of the physical processes that control, and the chemical consequences of, redistribution of melt, crystals and volatiles within mush-dominated systems. This project will address this problem using µCT scans of a suite of cores obtained by drilling into the solidifying Kilauea Iki lava lake, Hawaii. 18 cores collected between 1960 and 1988 include samples with up to 45% melt (now glass), track the initial growth of a cooling crust and later transected both the upper and lower crust as well as intervening crystal mush. Petrologic studies of the cores have documented complex and diverse movements of melt, crystals and bubbles within the lake. New 3D data will be used to map the physical properties of crystal mush in space and time. Additional 2D analysis will examine the chemical consequences of melt and crystal distribution and, specifically, look for evidence of reactive flow associated with different types of melt channels. Accompanying 2D analog experiments and modeling will track particle-particle interactions when gas is fluxed through suspensions of viscous liquid + photoelastic solid particles. The results of the combined work will improve understanding of lava lake (and sill) solidification and aid interpretation of geophysical signals from partially molten systems. The idea of drilling into volcanoes also captures the public imagination and has practical applications to the development of “clean” hydrothermal energy. The researchers will develop these themes in a virtual exhibit for the Smithsonian Institution on the topic of Drilling Hot Lava.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

钻探热熔岩听起来像科幻小说，但这不仅是一种清洁能源的建议来源，而且在 1960 年至 1988 年间实际上已经进行过多次。随后，夏威夷火山观测站的科学家探测了 1959 年喷发期间形成的熔岩湖。目标是通过收集钻芯样本来“观察”熔岩湖冷却和凝固。早期的钻探仅对湖的上层地壳进行取样，其中包括完全结晶的岩石和晶体“糊状物”，其中晶体的熔体含量高达 45%（在取芯过程中被水淬火成玻璃）。后来在整个湖中钻取了岩心，对上层和下层固体地壳以及内部糊状物进行了采样。对所得钻芯的化学分析表明，在凝固、熔化过程中，气泡和晶体在熔岩湖内移动。了解控制这些运动的过程可以提高我们对火山下岩浆系统中融化、气泡和晶体如何、何时以及为何重新排列的理解。它还可能揭示气泡和晶体的运动如何准备和引发火山喷发。该团队将使用 X 射线扫描技术来获取岩心的 3D 图像，该图像将显示自 1959 年以来玻璃、晶体和气泡的空间分布，作为湖中位置和时间的函数。单个岩心图像可用于对控制熔体运动的属性进行建模，例如熔体百分比、连通性和渗透性。通过空间和时间追踪这些过程不仅可以对火山进行前所未有的观察，而且有助于未来的钻探工作。一个世纪以来，（1）岩浆系统中的熔体演化和（2）可喷发（富含熔体）岩浆体的形成的概念模型都是围绕大型、寿命长、以熔体为主的岩浆室的概念构建的。然而，岩浆系统的地球物理成像和岩石学分析表明，它们以含有熔融透镜体的晶体“糊状物”为主。协调这两种观点是提高我们对火山喷发的岩浆系统的理解的关键，并且需要更好地理解控制熔体、晶体和挥发物在糊状主导系统中重新分布的物理过程及其化学后果。该项目将通过对一组岩心进行 µCT 扫描来解决这个问题，这些岩心是钻入夏威夷凝固的基拉韦厄艾基熔岩湖而获得的。 1960 年至 1988 年间收集的 18 个岩心包括熔化率高达 45% 的样本（现在是玻璃），追踪冷却地壳的初始生长，随后横切上地壳和下地壳以及中间的水晶糊。对岩心的岩石学研究记录了湖内熔体、晶体和气泡复杂多样的运动。新的 3D 数据将用于绘制水晶糊在空间和时间上的物理特性。额外的二维分析将检查熔体和晶体分布的化学后果，特别是寻找与不同类型熔体通道相关的反应流的证据。伴随的 2D 模拟实验和建模将跟踪当气体流经粘性液体 + 光弹性固体颗粒的悬浮液时颗粒与颗粒之间的相互作用。联合工作的结果将提高对熔岩湖（和岩台）凝固的理解，并帮助解释部分熔融系统的地球物理信号。钻火山的想法也激发了公众的想象力，并在开发“清洁”热液能源方面具有实际应用。研究人员将在史密森学会以钻探热熔岩为主题的虚拟展览中开发这些主题。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。