Collaborative Research: NSF GEO-NERC: The Cracking of a Craton: Understanding Volatile Release during Continental Breakup

合作研究：NSF GEO-NERC：克拉通的破裂：了解大陆破裂期间的挥发物释放

• 批准号: 2319898
• 负责人: Tobias Fischer
• 金额: $ 32.08万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-12-01 至 2026-11-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2319898&HistoricalAwards=false
• 关键词: Collaborative; Research; NSF; GEO; NERC

This is a project that is jointly funded by the National Science Foundation's Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own country.Cratons are the oldest and most stable parts of the Earth’s continents. During continental break-up or rifting events, these stable crustal areas split apart and eventually give way to magma rising from Earth’s deep interior and the formation of new crust. Volatile elements such as helium, nitrogen and carbon dioxide play an important role during all aspects of plate tectonics. Major volatiles are transported from the Earth’s surface into Earth’s interior during subduction and may accumulate below and within the stable cratons due to radiogenic production and upwelling from the mantle below. The mechanisms and time-scales of this accumulation remain poorly understood, yet are significant because these processes form reservoirs of economically valuable gases such as helium and hydrogen, and geologically important gases such as carbon dioxide. When cratons eventually break apart, these gases are released to the atmosphere and have potentially significant climatic impacts on geological time scales. The objective of this work is to determine the geological processes that control volatile production in the craton, their migration through the crust and release at the surface. The investigated field site is the area surrounding the Tanzania Craton, a type example of a stable craton surrounded by the East African Rift, and a location of intense magmatism and extensional tectonics. This particular geologic setting is ideally suited to investigate the formation processes of cratonic volatiles and their potential release mechanism due to magnetism and rifting. During the course of the project two Tanzanian students will get their Ph.D. education and experience at the Woods Hole/MIT graduate program and the University of New Mexico. The students will be trained in field and laboratory techniques, data interpretation and application of these techniques for understanding the processes of reservoir formation of these economically valuable gases. This project is a comprehensive study of the volatile gases that are being emitted from gas and water seeps along the flanks of the Tanzanian craton - a region where the stable continental craton is actively being “cracked” by rifting and simultaneously heated by plume-induced volcanism. The overall aims are to understand: 1) the mechanisms by which gases have been produced and stored in stable cratons over 109-year timescales, and 2) how they are liberated and transported to the surface during cratonic breakup. The study primarily focuses on helium (He) and nitrogen (N2) and their isotopic characteristics, which are the main constituents of cratonic gas accumulation, but we will measure all other noble gases (Ne, Ar, Kr, Xe) and their isotopes, CO2, CH4 (as well as their isotopes) and H2 in seeps. The PIs will use field- and lab-generated gas chemistry results to form an integrated model of gas formation and transport along the flanks of the Tanzania craton. Volatile fluxes will be calculated to understand the extent of gas release when a cratonic region is disrupted by rifting and volcanism. Determining how cratonic gases are released to the crust and eventually to the atmosphere is important for understanding volatile movements on large spatial and temporal scales. By constraining how volatiles are accumulated and released during steady-state rifting and magmatic conditions, the PIs will characterize cratonic volatile inventories and fluxes. This information will be of interest to the broader Earth science community, and provide valuable context to researchers studying the potential climatic effects when gases are abruptly released from the stable craton to the atmosphere as well as the formation of economically valuable gas reservoirs of helium and hydrogen. Two Tanzanian students will be jointly supervised by the PI’s of the award and trained in field and laboratory techniques at their respective institutions. There will be opportunity for the students to obtain in depth training in noble gas geochemistry, gas geochemistry and stable isotopes, as well as modeling approaches to understand the processes of formation of these economically valuable gas reservoirs.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.

该项目由美国国家科学基金会地球科学理事会 (NSF/GEO) 和英国国家环境研究委员会 (NERC) 通过 NSF/GEO-NERC 牵头机构协议本协议共同资助。允许美国/英国联合提案提交，并由其研究人员拥有最大预算比例的机构进行同行评审。在成功联合确定资助后，每个机构将资助其预算比例和与其相关的研究人员。自己的克拉通是地球大陆最古老、最稳定的部分，在大陆分裂或裂谷事件中，这些稳定的地壳区域分裂，最终让位于从地球内部深处升起的岩浆，并形成新的地壳。例如氦、氮和二氧化碳在板块构造的各个方面发挥着重要作用。主要挥发物在俯冲过程中从地球表面输送到地球内部，并可能在稳定层下方和内部积聚。由于放射成因产生和地幔上升流而形成的克拉通对这种积累的机制和时间尺度仍然知之甚少，但意义重大，因为这些过程形成了具有经济价值的气体（例如氦和氢）以及具有地质意义的气体（例如碳）。当克拉通最终分裂时，这些气体会释放到大气中，并对地质时间尺度产生潜在的重大气候影响。这项工作的目的是确定控制克拉通挥发物产生的地质过程。克拉通，它们穿过地壳迁移并在地表释放。所调查的现场地点是坦桑尼亚克拉通周围的区域，这是被东非裂谷包围的稳定克拉通的典型例子，也是一个强烈的岩浆活动和伸展构造的位置。特殊的地质环境非常适合研究克拉通挥发物的形成过程及其由于磁性和裂谷而产生的潜在释放机制。在该项目期间，两名坦桑尼亚学生将在该项目中获得博士学位并获得经验。伍兹霍尔/麻省理工学院研究生项目和新墨西哥大学的学生将接受现场和实验室技术、数据解释和这些技术的应用方面的培训，以了解这些具有经济价值的气体的储层形成过程。坦桑尼亚克拉通两侧的气体和水渗漏所释放出的挥发性气体，在该地区，稳定的大陆克拉通正在因裂谷而活跃地“破裂”，同时又受到羽流引发的火山活动的加热。目的是了解：1）109年时间尺度内稳定克拉通产生和储存气体的机制，以及2）它们在克拉通破裂过程中如何释放并输送到地表）以及氮气（N2）及其含量。同位素特征，这是克拉通天然气聚集的主要成分，但我们将测量所有其他稀有气体（Ne、Ar、Kr、Xe）及其渗透物中的同位素、CO2、CH4（及其同位素）和 H2 PI 将利用现场和实验室生成的气体化学结果来形成沿着坦桑尼亚克拉通侧翼的气体形成和传输的综合模型。目的是了解当克拉通地区受到裂谷和火山活动破坏时计算出的气体释放程度，确定克拉通气体如何释放到地壳并最终释放到大气中。通过限制稳态裂谷和岩浆条件下挥发物的积累和释放方式，PI 将描述克拉通挥发物的库存和通量，这一信息对于更广泛的地球来说非常重要。科学界，并为研究人员研究气体从稳定克拉通突然释放到大气中时的潜在气候影响以及具有经济价值的氦和氢气藏的形成提供了宝贵的背景。两名坦桑尼亚学生将参与其中。由该奖项的 PI 共同监督，并在各自机构接受现场和实验室技术培训。学生将有机会获得稀有气体地球化学、气体地球化学和稳定同位素以及建模方法方面的深入培训。这些具有经济价值的气藏的形成过程。该奖项反映了 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。