RUI: Collaborative Research: Constraining peridotite alteration timescales with environmental tracers (3H, 39Ar, 14C and 81Kr)

RUI：合作研究：用环境示踪剂（3H、39Ar、14C 和 81Kr）约束橄榄岩蚀变时间尺度

• 批准号: 2127532
• 负责人: Amelia Vankeuren
• 金额: $ 14.66万
• 依托单位: University Enterprises, Incorporated
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2127532&HistoricalAwards=false
• 关键词: RUI; Collaborative; Research; Constraining; peridotite

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Peridotite is the main constituent of the Earth's upper mantle. Peridotite alteration through water-rock interaction plays an important role in the global carbon budget and produces hydrogen gas (H2) that can support lifeforms fueled by chemical energy. This project will use the Samail ophiolite in Oman, the largest chunk of peridotite rock at the Earth’s surface, as a field laboratory to investigate the process of low temperature (25-60oC) peridotite alteration. Natural environmental tracers in groundwater within the ophiolite will be used to provide a maximum timescale for low temperature alteration and the source and supply rate of H2. These results will eventually help to calculate the rate of low temperature peridotite alteration and fluid flow through the ophiolite system and thus inform the use of ophiolites for geological carbon dioxide storage to combat climate change. They will also provide insight into the amount of chemical energy available to support life in this extreme hyperalkaline environment and in other locations of low temperature peridotite alteration on Earth and potentially elsewhere, like Mars. This project will be transformative in the education and training of geoscientists at two primarily undergraduate institutions: California State University, Sacramento, a minority-serving institution, and Barnard College in New York City, a women's college. The project will support student research experiences through both faculty-mentored student projects and course-based undergraduate research experiences (CUREs). CURE classroom modules will be publicly shared for use by other hydrogeology/geochemistry instructors throughout the nation. The project will also support the development of groundwater demonstration tanks to illustrate the use of environmental tracers and the impact that precipitation of secondary minerals can have on groundwater flow. The aim of this project is to use a suite of environmental tracers in the hyperalkaline (pH 11-12) groundwater of the Samail ophiolite to determine the maximum timescale of low temperature peridotite alteration and the source and supply rate of H2 gas. Groundwater samples will be collected using boreholes and sampling equipment recently installed in the mantle peridotite of the Samail ophiolite as part of the International Continental Scientific Drilling Program's Oman Drilling Project. Groundwater ages are currently unknown and estimates span several orders of magnitude. For this project, age distributions will be determined with environmental tracers 3H, 14C, stable noble gases, 39Ar and/or 81Kr. These ages will place upper bounds on the timescale of low temperature peridotite alteration and help determine if the water-rock interaction causing this alteration is taking place in the hydraulically conductive near-surface or if there are deeper, and/or older contributions. Other tracers (dissolved He and H2, 3He/4He ratios, and δ2H in H2) will be used to distinguish between several previously proposed sources of H2 in hyperalkaline groundwater: local production by low temperature water-rock interaction, transport from deeper sources, or release through weathering of fluid inclusions formed by peridotite alteration at higher temperature. Finally, the combination of groundwater ages and measured H2 concentrations will be used to quantify a minimum H2 accumulation rate in the aquifer. This H2 accumulation rate can then be used in bioenergetic calculations of the capacity to support chemosynthetic microbial life in this unique ecosystem.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.

该奖项是根据2021年《美国救援计划法》的全部或部分资助的（公共法117-2）。腹膜石是地球上层地幔的主要组成部分。通过水摇滚相互作用改变橄榄岩在全球碳预算中起着重要作用，并产生氢气（H2），可以支持化学能源为生命形式提供生命形式。该项目将使用阿曼的Samail Ophiolite，这是地球表面最大的橄榄岩岩石部分，作为野外实验室，以研究低温（25-60oc）橄榄岩改变的过程。蛇绿岩内地下水中的自然环境示踪剂将用于为低温改变以及H2的来源和供应速率提供最大的时间尺度。这些结果最终将有助于计算低温橄榄岩改变和流动流经蛇纤维系统的速率，从而告知使用蛇纤维用于地质二氧化碳储存以应对气候变化的使用。他们还将洞悉可用的化学能量，以在这种极端的超烷丁环境中以及在地球上低温橄榄石改变的其他位置以及在其他地方（如火星）的其他位置进行洞察力。该项目将在两个小学本科机构的地球科学家的教育和培训方面具有变革性：加利福尼亚州立大学，萨克拉曼多，少数民族服务机构和纽约市的巴纳德学院，一所女子学院。该项目将通过以教师为生的学生项目和基于课程的本科研究经验（Cures）来支持学生的研究经验。治疗课堂模块将被全国其他水文地质/地球化学讲师公开共享。该项目还将支持地下水示范池的发展，以说明环境示踪剂的使用以及次级矿物质的降水对地下水流的影响。该项目的目的是在Samail Ophiolite的Hyperalkaline（pH 11-12）地下水中使用一套环境示踪剂，以确定低温橄榄石改变的最大时间表以及H2气体的源和供应速率。作为国际大陆科学钻探计划的阿曼钻探项目的一部分，将使用最近安装在Samail Ophiolite的地幔橄榄石中的钻孔和采样设备收集地下水样品。目前，地下水年龄尚不清楚，估计范围跨越了几个数量级。对于该项目，年龄分布将由环境示踪剂3H，14C，稳定的贵重气体，39AR和/或81kr确定。这些年龄将在低温橄榄石变化的时间尺度上放置上限，并有助于确定是否会发生水圈相互作用，是否发生了其他示踪剂（溶解He和H2，3He/4he/4He的比率，H2中的Δ2H），以及在H2中使用Δ2H），将使用较低的局部生产量的较低温度延伸或替代品，以区分较低温度的生产量：在较高温度下橄榄岩改变形成的流体夹杂物的风化。最后，地下水年龄和测得的H2浓度的组合将用于量化含水层中的最低H2累积速率。然后，该H2积累速率可以用于在这个独特的生态系统中支持化学合成微生物寿命的能力的生物能计算。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响标准来评估通过评估来获得支持的。