Collaborative Research: Bubble Trouble - Re-evaluating olivine melt inclusion barometry and trace-element geochemistry in the Cascades

合作研究：气泡麻烦 - 重新评估喀斯喀特橄榄石熔体包裹体气压和微量元素地球化学

• 批准号: 2342156
• 负责人: Penelope Wieser
• 金额: $ 29.32万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2342156&HistoricalAwards=false
• 关键词: Collaborative; Research; Bubble; Trouble; Re

Determining the depths at which molten rock (magma) is stored and processed in the crust is vital for interpretations of volcanic unrest in the lead up to eruptions and for understanding of the chemical evolution of the Earth’s continents. Despite their importance, the structure and operation of the regions which supply magma to the surface remain poorly understood. It is currently uncertain, for example, whether magma is distributed across “mush zones” spanning the entire crust or stored in distinct “magma chambers”. This project will re-evaluate magma storage depths and the origin of chemical variability in volcanic systems in the Cascades using an approach that makes use of small pockets of magma trapped within erupted crystals, termed melt inclusions. Crucially, the CO2 contents of small bubbles within these melt inclusions will be measured directly, in addition to the surrounding melt. This project will contribute to the scientific understanding of volcanism along the Cascade arc, which presents a significant hazard to society. It will also foster close collaborations and a multi-tiered, peer-to-peer mentoring structure between two early career PIs, two graduate students, and multiple undergraduate students. The grant will also support a mentoring program for scientists with disabilities and a virtual forum for academics with chronic illnesses and invisible disabilities to share their stories about adapting to fieldwork, conferences, and workshops.The volatile contents of olivine-hosted melt inclusions provide important constraints on the depths at which mafic magmas erupting in the Cascades were stored and staged prior to eruption. However, the vast majority (97%, N=410) of previously published olivine-hosted melt inclusion data from the Cascades did not measure CO2 in vapor bubble(s). Preliminary Raman analyses of N=339 Cascade vapor bubbles indicates that without these measurements, storage depths have been underestimated by factors of 2-5X. Measuring melt inclusion volatile contents while accounting for CO2 and carbonate in the vapor bubble (using in situ heating experiments) will better constrain magma storage depths in different regions of the Cascades and provide insights into any variations in storage depth along strike (perhaps due to melt H2O contents, crustal stress state, or magma flux rate). While whole-rock trace element analyses are commonly used to assess magmatic processes in both the crust and mantle, whole-rock samples are generally an amalgamation of materials assembled and modified over a great range of unknown depths. Trace element measurements from melt inclusions with known entrapment depths will better constrain assimilation and mixing processes affecting liquid compositions and can reveal where in the crust these processes occur. He isotope data from aliquots of olivine from the same samples will further constrain the extent to which crustal materials have contributed to the most mafic components. Together, these data will provide unique insights into the origins of enriched signatured of continental arc magmas. This study will also assess mantle melting conditions, the processes causing mafic magmas to stall in the crust, and other topics relevant for melt inclusion studies worldwide (e.g., identifying processes forming carbonate in vapor bubbles and testing bubble growth models). Graduate and undergraduate students will acquire skills in a wide variety of hands-on geochemical techniques, data interpretation, coding, and software development. Students will build networks by travelling to different laboratories, interacting with collaborators at academic and government institutions, and presenting their findings at professional conferences. The grant will also support the development and improvement of open-source software tools, helping the volcanological community move to data processing and modelling workflows which are findable, accessible, interoperable, and reusable (FAIR). The PIs will also co-ordinate a virtual forum with panelists and a Q&A to share the voices and experiences of individuals with invisible disabilities with a broader audience, with a focus on laboratory and field work.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.

确定熔岩（岩浆）在地壳中储存和加工的深度，对于解释导致火山爆发的火山动荡和理解地球大陆的化学演化至关重要。尽管它们很重要，但向地表提供岩浆的地区的结构和运作仍然知之甚少。例如，目前还不确定岩浆是分布在跨越整个地壳的“泥状带”上，还是储存在不同的“岩浆房”中。该项目将重新评估喀斯喀特火山系统的岩浆储存深度和化学变化的起源，使用的方法是利用被困在喷发晶体中的岩浆小袋，称为熔体包裹体。至关重要的是，除了周围的熔体外，这些熔体内含物中小气泡的二氧化碳含量将被直接测量。该项目将有助于科学地了解喀斯喀特弧沿线的火山活动，这对社会构成了重大危害。它还将促进两名早期职业导师、两名研究生和多名本科生之间的密切合作和多层次、点对点的指导结构。这笔拨款还将支持一项针对残疾科学家的指导计划，以及一个为患有慢性疾病和隐形残疾的学者提供的虚拟论坛，以分享他们适应实地工作、会议和讲习班的故事。含橄榄石的熔融包裹体的挥发性含量对喀斯喀特火山喷发的基性岩浆在喷发前的储存和分级深度提供了重要的限制。然而，绝大多数（97%，N=410）先前发表的来自Cascades的橄榄石为主的熔体包裹体数据没有测量蒸汽泡中的CO2。对N=339级联蒸汽气泡的初步拉曼分析表明，如果没有这些测量，储存深度被低估了2-5倍。测量熔体包裹体挥发性含量，同时考虑蒸汽泡中的二氧化碳和碳酸盐（使用原位加热实验），将更好地约束喀斯喀特不同区域的岩浆储存深度，并提供对沿走向储存深度的任何变化的见解（可能是由于熔体H2O含量、地应力状态或岩浆通量速率）。虽然整体岩石微量元素分析通常用于评估地壳和地幔的岩浆过程，但整体岩石样本通常是在未知深度的很大范围内组装和修改的材料的混合。从已知包裹体捕获深度的微量元素测量将更好地约束影响液体成分的同化和混合过程，并可以揭示这些过程在地壳中发生的位置。来自同一样品的橄榄石等分石的同位素数据将进一步限制地壳物质对大多数基性成分的贡献程度。总之，这些数据将为大陆弧岩浆的富集特征的起源提供独特的见解。这项研究还将评估地幔熔融条件，导致基性岩浆在地壳中停滞的过程，以及与全球熔体包裹体研究相关的其他主题（例如，识别蒸汽气泡中碳酸盐形成的过程和测试气泡生长模型）。研究生和本科生将获得各种各样的动手地球化学技术，数据解释，编码和软件开发技能。学生们将通过前往不同的实验室，与学术和政府机构的合作者互动，并在专业会议上展示他们的发现来建立网络。该赠款还将支持开发和改进开源软件工具，帮助火山学界转向可查找、可访问、可互操作和可重用（FAIR）的数据处理和建模工作流程。pi还将协调一个由小组成员组成的虚拟论坛和一个问答环节，以实验室和实地工作为重点，与更广泛的受众分享隐形残疾人士的声音和经历。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。