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.

该奖项的全部或部分资金来源于《2021 年美国救援计划法案》（公法 117-2）。橄榄岩是地球上地幔通过水-岩石相互作用而发生蚀变的主要成分，在全球范围内发挥着重要作用。该项目将使用阿曼的萨迈伊蛇绿岩，这是该地区最大的一块橄榄岩。地球表面作为研究低温（25-60oC）橄榄岩蚀变过程的现场实验室，蛇绿岩内地下水中的自然环境示踪剂将用于提供低温蚀变的最大时间尺度以及氢气的来源和供应率。这些结果最终将有助于计算低温橄榄岩蚀变率和蛇绿岩系统的流体流量，从而为利用蛇绿岩进行地质二氧化碳储存以应对气候变化提供信息他们还将深入了解在这种极端超碱性环境以及地球上其他低温橄榄岩蚀变地点以及火星等其他地方可用于维持生命的化学能量。该项目将在教育和培训方面带来变革。该项目将由两所主要本科院校的地球科学家组成：萨克拉门托加州州立大学（一所为少数族裔服务的机构）和纽约巴纳德学院（一所女子学院），该项目将通过教师指导的学生项目和基于课程的方式支持学生的研究经验。本科生研究CURE 课堂模块将公开共享，供全国其他水文地质/地球化学教师使用。该项目还将支持地下水示范池的开发，以说明环境示踪剂的使用以及次生矿物沉淀的影响。该项目的目的是在 Samail 蛇绿岩的超碱性（pH 11-12）地下水中使用一套环境示踪剂来确定低温的最大时间尺度。作为国际大陆科学钻探计划阿曼地下水年龄的一部分，将使用最近安装在萨迈伊蛇绿岩地幔橄榄岩中的钻孔和采样设备来收集橄榄岩蚀变以及氢气的来源和供应率。对于该项目，年龄分布将通过环境示踪剂 3H、14C、稳定惰性气体、39Ar 和/或来确定。 81Kr.这些年龄将为低温橄榄岩蚀变的时间尺度设定上限，并有助于确定导致这种蚀变的水-岩石相互作用是否发生在水力传导的近地表中，或者是否存在更深和/或更古老的贡献。其他示踪剂（溶解的 He 和 H2、3He/4He 比率以及 H2 中的 δ2H）将用于区分超碱性地下水中几个先前提出的 H2 来源：低浓度本地生产最后，结合地下水年龄和测得的 H2 浓度，可以量化含水层中 H2 的最低积累率。然后，该氢气积累率可用于支持该独特生态系统中化学合成微生物生命的能力的生物能计算。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。