In situ monitoring of reaction progress during serpentinization of oceanic lithosphere using synthetic fluid inclusions

使用合成流体包裹体原位监测海洋岩石圈蛇纹石化过程中的反应进程

• 批准号: 1459433
• 负责人: Robert Bodnar
• 金额: $ 31.62万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1459433&HistoricalAwards=false
• 关键词: situ; monitoring; reaction; progress; during

Few techniques exist where visual observations and compositional measurements can be made of mineral reactions inside natural host minerals in real-time. This research by two investigators at Virginia Tech, one of whom is early career, explores an exciting and potentially transformative new experimental method by which synthetic fluid inclusions, filled with fluids of seawater-like composition, are grown in the laboratory and then held at temperatures and pressures at which important geological mineral reactions occur. In these reactions, secondary minerals precipitate inside the inclusion due to the reaction between the fluid and host mineral. This research targets serpentinization of the ocean crust, which involves the formation of serpentine, a hydrous mineral, and other secondary phases from anhydrous magnesium-rich silicate minerals (olivine, pyroxene,and garnet) that are the primary constituents of seafloor lavas. Serpentinization of ocean crust releases H2O into the mantle which can trigger melting and arc volcanism. It is also linked to the generation of abiotic organic compounds due to the release of hydrogen during mineral reaction. These organic molecules can form the base of the food chain for microbes living in in the ocean crust. Broader impacts of the work include (1) developing new experimental methods and demonstrating their utility, (2) developing the Raman spectroscopic identification of hydrous minerals associated with serpentinization reactions, (3) support of an early career female scientist and a minority graduate student; and (4) creation of podcasts on science in Spanish to inform and excite Hispanic audiences about science and the proposed research. This experimental program will react fluids in minerals at ~280 degrees C for a number of weeks and monitor the dissolution and precipitation reactions that take place in the fluid inclusions as a function of time, temperature, fluid composition, and host mineral composition using a variety of state-ot-the-art analytical techniques that include: microthermometry, Raman spectroscopy, laser ablation inductively coupled plasma mass spectrometry, micro-FTIR (Fourier Transform Infrared) spectroscopy, and FIB-SEM (focused ion beam scanning electron microscopy). An additional research goal is to develop Raman spectroscopy as a tool for the identification of phases associated with serpentinization, including the identification of chrysotile, lizardite, antigorite, and magnetite, as well as the protolith phases undergoing reaction. Results of the experiments will be compared with predictions from thermodynamic models. Successful development of this experimental technique and demonstation of its applicabilty has the potential to impact other fields of science such as pharmachology and materials science where the ability to observe chemical reactions and their rates of reaction in host crystals in real-time may lead to breakthroughs in understanding.

很少有技术可以对天然宿主矿物内部的矿物反应进行实时视觉观察和成分测量。 弗吉尼亚理工大学的两名研究人员（其中一名处于职业生涯早期）进行的这项研究探索了一种令人兴奋且具有潜在变革性的新实验方法，通过该方法，在实验室中生长充满类似海水成分的流体的合成流体包裹体，然后在一定温度下保存以及发生重要地质矿物反应的压力。在这些反应中，由于流体和基质矿物之间的反应，次生矿物在包裹体内部沉淀。这项研究的目标是海洋地壳的蛇纹石化，其中涉及从无水富镁硅酸盐矿物（橄榄石、辉石和石榴石）形成蛇纹石（一种含水矿物）和其他次生相，这些硅酸盐矿物是海底熔岩的主要成分。 海洋地壳的蛇纹石化作用将H2O释放到地幔中，从而引发熔融和弧火山活动。它还与矿物反应过程中释放氢而产生非生物有机化合物有关。这些有机分子可以形成生活在海洋地壳中的微生物食物链的基础。这项工作的更广泛影响包括（1）开发新的实验方法并展示其实用性，（2）开发与蛇纹石化反应相关的含水矿物的拉曼光谱鉴定，（3）支持一名早期职业女性科学家和一名少数族裔研究生； (4) 创建西班牙语科学播客，向西班牙裔观众介绍科学和拟议的研究，并激发他们的兴趣。该实验计划将在约 280 摄氏度的温度下使矿物中的流体反应数周，并使用各种方法监测流体包裹体中发生的溶解和沉淀反应，作为时间、温度、流体成分和基质矿物成分的函数。先进的分析技术，包括：显微测温、拉曼光谱、激光烧蚀电感耦合等离子体质谱、显微 FTIR（傅里叶变换红外）光谱和 FIB-SEM（聚焦离子束扫描）电子显微镜）。另一个研究目标是开发拉曼光谱作为识别与蛇纹石化相关的相的工具，包括识别温石棉、蜥蜴石、叶蛇纹石和磁铁矿，以及进行反应的原石相。实验结果将与热力学模型的预测进行比较。 这种实验技术的成功开发及其适用性的证明有可能影响其他科学领域，例如药理学和材料科学，其中实时观察化学反应及其在宿主晶体中的反应速率的能力可能会带来突破理解。