Collaborative Research: Reconstructing the geometry of magmatic plumbing systems using fluid inclusions

合作研究：利用流体包裹体重建岩浆管道系统的几何形状

• 批准号: 2217221
• 负责人: Hector Lamadrid
• 金额: $ 17.94万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2217221&HistoricalAwards=false
• 关键词: Collaborative; Research; Reconstructing; geometry; magmatic

Constraining the depth at which magma feeding volcanic eruptions is stored in the crust is critical both for volcano monitoring agencies to interpret unrest signals during volcanic crises, and for our understanding of the formation of energy-critical metal deposits and the evolution of the Earth’s crust. However, popular techniques using earthquakes and ground deformation to obtain storage depths cannot be used at many potentially hazardous volcanoes which show little activity at present, or have limited monitoring networks. More widely applicable methods which measure the chemistry of erupted crystals are associated with large uncertainty. This team will investigate a powerful but under-used approach in volcanology, by measuring the densities of pockets of gas-rich fluids trapped within growing crystals, known as fluid inclusions (FI). This method has the potential to be significantly more precise and accurate, placing very tight constraints on where magma is stored in the crust. After investigating the strengths and weaknesses of depths from FIs using eruptions from Hawai’i and Canary Islands as a case study (where storage depths have been determined by other methods), magma storage depths will be investigated in a series of explosive eruptions that occurred several centuries ago at both locations where future eruptions of this type present a significant hazard. A rapid response simulation will be carried out in collaboration with Hawaiian Volcano Observatory (HVO) to determine just how quickly estimates of magma storage depths can be obtained during the next large eruptive crisis, and how this information can be used to inform decision making to mitigate societal risk. This proposal will foster close collaborations between three PIs with complimentary scientific expertise at different career levels, and support several students and a postdoc in a multi-tiered mentoring structure spanning three institutions. The team will develop and distribute synthetic and natural fluid inclusions to be used as calibration standards, and a workshop will promote collaboration and synergy between different research groups using Raman spectroscopy.This award will capitalize on recent advances in the spectral and spatial resolution of confocal Raman spectroscopy, allowing highly precise and accurate measurements of the densities of CO2-rich fluids trapped within fluid inclusions down to ~ 1 µm in size. The simple physical relationship between the density and pressure of a CO2-rich fluid means that distributions of FI densities can be converted into magma storage pressures with very small errors (~5-10%), and then magma storage depths using known crustal density profiles. First, detailed comparisons of depths obtained from FIs will be compared to published work investigating melt inclusion saturation pressures in samples from Kīlauea Volcano, Hawai’i, and Timanfaya, Canary Islands. This will permit assessment of sources of uncertainty affecting FI barometry such as decrepitation (when the inclusion explodes) using high-resolution electron backscatter diffraction (HR-EBSD), and the presence of additional volatile species (e.g., S, Cl, H) using synthetic FIs equilibrated with different fluid compositions. After determining the strengths and weaknesses of fluid inclusion barometry, new constraints will be placed on changes in magmatic plumbing during explosive to effusive transitions at Kīlauea Volcano (a significant societal hazard), evolution from shield to post-shield in the Galápagos, and from unknown samples during an eruption simulation in collaboration with HVO. Synthetic FIs with different concentrations of CO2 will be synthesized and characterized with an experimentally calibrated Raman system to distribute to laboratories around the world to use as standard reference materials for calibration of Raman Spectrometers. This will eliminate systematic offsets between densities determined in different laboratories.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.

限制供给火山喷发的岩浆在地壳中的储存深度对于火山监测机构在火山危机期间解释动荡信号，以及对于我们理解能源关键金属矿床的形成和地壳的演化都是至关重要的。然而，使用地震和地面变形来获取储存深度的流行技术不能用于许多具有潜在危险的火山，这些火山目前显示出很少的活动，或者监测网络有限。更广泛应用的测量喷发晶体化学成分的方法与较大的不确定度有关。这个团队将研究火山学中一种强大但未得到充分利用的方法，通过测量捕获在不断生长的晶体中的富气流体的密度，即所谓的流体包裹体(FI)。这种方法有可能大大提高精确度和精确度，对地壳中岩浆的储存位置施加非常严格的限制。在使用夏威夷和加那利群岛的喷发作为案例研究(这些地区的储存深度已经通过其他方法确定)之后，将在几个世纪前在这两个地点发生的一系列爆炸性喷发中调查岩浆储存深度，这两个地点未来的这类喷发将构成重大危险。将与夏威夷火山观测站合作进行快速反应模拟，以确定在下一次大规模喷发危机期间，估计岩浆储存深度的速度有多快，以及如何利用这些信息为决策提供信息，以减轻社会风险。这项提议将促进三个在不同职业水平上具有互补科学专业知识的私人投资机构之间的密切合作，并在横跨三个机构的多层次指导结构中支持几名学生和一名博士后。该团队将开发和分发人造和天然流体包裹体作为校准标准，并将举办一个研讨会，促进使用拉曼光谱的不同研究小组之间的合作和协同。该奖项将利用共焦拉曼光谱在光谱和空间分辨率方面的最新进展，允许高精度和准确地测量捕获在流体包裹体中的富二氧化碳流体的密度，尺寸可达~1微米。富含CO2流体的密度和压力之间的简单物理关系意味着，FI密度的分布可以非常小的误差(~5-10%)转换成岩浆存储压力，然后利用已知的地壳密度剖面转换成岩浆存储深度。首先，从FIS获得的深度的详细比较将与研究夏威夷Kī劳埃亚火山和加那利群岛蒂曼法亚样品中熔体包裹体饱和压力的公开工作进行比较。这将允许使用高分辨率电子背散射衍射(HR-EBSD)来评估影响重力测量的不确定度来源，例如爆裂(当夹杂物爆炸时)，以及使用与不同流体成分相平衡的合成FIS来评估其他挥发性物质(例如S、氯、H)的存在。在确定了流体包裹体压力测量的优势和劣势之后，将对Kī劳埃亚火山(一项重大社会危害)从爆炸到喷涌过渡过程中岩浆管道的变化、加拉帕戈斯从屏蔽到屏蔽后的演化以及与美国地质调查局合作进行喷发模拟期间未知样品的变化施加新的限制。具有不同二氧化碳浓度的合成FI将被合成，并使用经实验校准的拉曼系统进行表征，以分发到世界各地的实验室，用作校准拉曼光谱仪的标准参考材料。这将消除不同实验室测定的密度之间的系统性偏差。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。