Collaborative Research: Degassing-based constraints on the dynamics of submarine eruptions

合作研究：基于脱气的海底喷发动力学约束

• 批准号: 1333882
• 负责人: James Gardner
• 金额: $ 9.11万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1333882&HistoricalAwards=false
• 关键词: Collaborative; Research; Degassing; based; constraints

The dynamics (ascent rate, mass eruption rate, lava flow rate, etc.) of submarine eruptions, which account for roughly 70% of the Earth's annual volcanic activity, are essentially unknown. This research will develop a degassing-based "geospeedometer" (i.e., a method for determining how fast magma moves from its magma chamber to its final resting place on the sea floor). for mid-ocean ridge basalts that will allow quantification of eruption dynamics in Earth's largest volcanic system (i.e., the mid-ocean ridge spreading centers) and help to evaluate how those dynamics impact carbon fluxes from the vast mid-ocean ridge system. A combination of detailed microanalysis of textures and volatiles in lava samples from submarine volcanic lava flows and a unique set of laboratory experiments will be used to quantify the mechanisms and rates of degassing and vesiculation in mid-ocean ridge basalts. A "geospeedometer" will be developed on the basis of those results. This geospeedometer will allow us to understand and measure flow rates of mid-ocean ridge lavas, decompression rates of the eruptions feeding them, and how flow morphologies (sheet flow vs. pillow lava) reflect eruption rate. Analyses will be focused on samples from the well mapped and comprehensively sampled 2011 eruption of Axial Volcano on the Juan de Fuca Ridge off the northwest coast of the US and Canada. Samples from this eruption will be analyzed for degassing via volatile concentrations and vesicle-size distributions of samples collected along the Axial Volcano eruptive fissures and flow paths. A central challenge will be the linking of temerature, depressurization rate, and composition to volatile concentrations and vesicle populations. Thus, a series of laboratory decompression and cooling experiments using natural, CO2-supersaturated, mid-ocean ridge basalts will be undertaken to provide insights and input parameters for model calculations, leading to the quantification of results. the 2011 eruption of Axial Volcano will serve as the test case and be used to refine models of degassing and provide the vehicle for incorporating research reesults into broadly applicable models for submarine volcanic systems. The research will also help improve estimates of carbon flux by evaluating more rigorously and quantitatively the controls on seafloor basalt degassing of CO2. Broader impacts of the research include support of graduate and undergraduate students and engagement of the investigators with K-12 STEM teachers via already plannedteacher training workshops. Research will also be incorporated into courses taught by the investigators and data will be made freely available to the public through NSF-funded data management facilities.

海底喷发约占地球年度火山活动的 70%，其动态（上升速率、大规模喷发速率、熔岩流量等）基本上是未知的。这项研究将开发一种基于脱气的“地球速度计”（即一种确定岩浆从岩浆室移动到海底最终停留地的速度的方法）。 对于洋中脊玄武岩，这将有助于量化地球最大的火山系统（即洋中脊扩张中心）的喷发动态，并有助于评估这些动态如何影响广阔的洋中脊系统的碳通量。对海底火山熔岩流的熔岩样品中的质地和挥发物进行详细的微量分析以及一套独特的实验室实验相结合，将用于量化洋中脊玄武岩的脱气和发泡的机制和速率。将根据这些结果开发“地球速度计”。这种地球速度计将使我们能够了解和测量大洋中脊熔岩的流速、喷发的减压速率以及流动形态（片流与枕状熔岩）如何反映喷发速率。分析将重点关注美国和加拿大西北海岸胡安德富卡山脊轴心火山 2011 年喷发的详细绘图和全面采样的样本。此次喷发的样品将通过沿轴火山喷发裂缝和流动路径收集的样品的挥发性浓度和囊泡大小分布进行脱气分析。一个主要挑战是将温度、降压速率和成分与挥发性浓度和囊泡数量联系起来。因此，将利用天然的、二氧化碳过饱和的洋中脊玄武岩进行一系列实验室减压和冷却实验，为模型计算提供见解和输入参数，从而实现结果的量化。 2011年轴心火山喷发将作为测试案例，用于完善脱气模型，并为将研究结果纳入广泛适用的海底火山系统模型提供工具。 该研究还将通过更严格和定量地评估对海底玄武岩二氧化碳脱气的控制来帮助改进碳通量的估计。该研究的更广泛影响包括支持研究生和本科生，以及通过已计划的教师培训研讨会让研究人员与 K-12 STEM 教师进行接触。 研究还将纳入研究人员教授的课程中，数据将通过国家科学基金会资助的数据管理设施免费向公众提供。