D/H isotope exchange between electrolyte-bearing C-O-H magmatic fluids: In-situ experiments involving vapors and brines

含电解质的 C-O-H 岩浆流体之间的 D/H 同位素交换：涉及蒸气和盐水的原位实验

基本信息

批准号：
1538671
负责人：
Dionysios Foustoukos
金额：
$ 15.98万
依托单位：
Carnegie Institution of Washington
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：
2015-10-01 至 2018-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1538671&HistoricalAwards=false
关键词：
isotope exchange between electrolyte bearing

项目摘要

The properties of H2O at high temperatures and pressures are important to know for both volcanic and magmatic processes, as well as for processes that impact the geothermal energy, nuclear waste, and chemical engineering industries. This research, using newly developed, novel laboratory techniques, such as hydrothermal diamond anvil cells coupled with Raman/Fourier Transform Infrared spectroscopy, will be used to make real time measurements of the solvation of gases and metals in light and heavy H2O at supercritical conditions. This project will bring new experimental techniques to bear to understand the systematics of hydrogen gas and methane dissolved in electrolyte-rich supercritical fluids by looking at the isotopes of hydrogen in the context of the evolution of geothermal fluids in the subsurface and the degassing of magmas in volcanoes. Data collected will be used to augment theoretical models of water cycling in Earth's interior. The experiments and their interpretation will also shed light on the mass and heat transfer associated with Earth's deep hydrological cycle as well as the interaction of geothermal fluids with the solid Earth, a process that contributes to the flux of carbon dioxide, methane, and other gases to the atmosphere. Broader impacts of the work include providing fundamental knowledge about H2O at high temperatures and pressures, which has implications for a broad array of fields in science and engineering, such as chemical engineering (e.g. toxic/radioactive waste remediation, nuclear power reactors), physical chemistry, geophysics, geochemistry, and energy-related research. In addition, a series of lectures and lab demonstrations will be created and presented to undergraduate and graduate students at the George Mason University in Virginia. Undergraduates will have an opportunity to be involved in the project through a 10-week internship program at the Carnegie Institute of Washington that will run during the summer both years that the award is active. Technical aspects of the research involve study of the exchange of deuterium and hydrogen isotopes between various hydrogen bearing volatiles (H2, CH4, H2O). The work will examine these volatiles in the context of understanding the thermal regime of volcanic settings and the source of magmatic fluids. For example, deuterium-depleted brines derived from seawater contribute to the hydrogen-isotope composition of Cl-rich melt inclusions in mid-ocean ridge basalt glasses. However, the composition of these brines is completely unconstrained, hindering efforts to trace the hydrogen-isotope composition of the mantle source of seafloor basalts. Furthermore, at present, there are no experimental data to describe the effect of degassing during magma ascent on the D/H exchange between H2(aq), CH4(aq) and H2O dissolved in Cl-rich, F-rich fluids, or aqueous fluids that contain common ions found in seawater (i.e., Na/K/Mg/Ca/Cl/F). In the latter case, the concentration and electrostatic properties of these ions on the structure of H2O and how they affect the solvation mechanism and solubility of H-D isotopologues of H2 and CH4 in supercritical H2O-D2O mixtures will be examined. Measurements will be made in-situ and in real-time by employing hydrothermal diamond-anvil cells and Raman/FTIR spectroscopy. Results will be complemented by the use of GC-TC/EA-Isotope Mass Ratio Spectrometry to determine bulk D/H ratios and isotope fractionations between species equilibrated at high-P/-T during experiments in solid-media high-pressure apparatus. The proposed study will compliment and support the new frontiers of H-D CH4 isotopologue geochemistry.

了解 H2O 在高温高压下的特性对于火山和岩浆过程以及影响地热能、核废料和化学工程行业的过程非常重要。这项研究采用新开发的新颖实验室技术，例如水热金刚石砧池与拉曼/傅立叶变换红外光谱相结合，将用于实时测量超临界条件下轻水和重水中气体和金属的溶剂化。该项目将采用新的实验技术，通过在地下地热流体演化和岩浆脱气的背景下观察氢的同位素，来了解富含电解质的超临界流体中溶解的氢气和甲烷的系统学。火山。收集到的数据将用于增强地球内部水循环的理论模型。这些实验及其解释还将揭示与地球深层水文循环相关的质量和热量传递，以及地热流体与固体地球的相互作用，这一过程有助于二氧化碳、甲烷和其他气体的通量到气氛。这项工作的更广泛影响包括提供有关高温高压下 H2O 的基础知识，这对科学和工程的广泛领域具有影响，例如化学工程（例如有毒/放射性废物修复、核电反应堆）、物理化学、地球物理学、地球化学和能源相关研究。此外，还将为弗吉尼亚州乔治梅森大学的本科生和研究生举办一系列讲座和实验室演示。本科生将有机会通过在华盛顿卡内基研究所为期 10 周的实习项目参与该项目，该项目将在该奖项有效的两年夏季进行。该研究的技术方面涉及研究各种含氢挥发物（H2、CH4、H2O）之间的氘和氢同位素交换。这项工作将在了解火山环境的热状况和岩浆流体来源的背景下研究这些挥发物。例如，源自海水的贫氘盐水有助于洋中脊玄武岩玻璃中富含 Cl 的熔体包裹体的氢同位素组成。然而，这些盐水的成分完全不受限制，阻碍了追踪海底玄武岩地幔源的氢同位素成分的努力。此外，目前还没有实验数据描述岩浆上升过程中的脱气对溶解在富Cl、富F流体或水相中的H2(aq)、CH4(aq)和H2O之间的D/H交换的影响。含有海水中常见离子（即 Na/K/Mg/Ca/Cl/F）的流体。在后一种情况下，将研究这些离子对 H2O 结构的浓度和静电性质，以及它们如何影响超临界 H2O-D2O 混合物中 H2 和 CH4 的 H-D 同位素体的溶剂化机制和溶解度。将利用热液金刚石砧池和拉曼/傅立叶变换红外光谱仪进行原位实时测量。结果将通过使用 GC-TC/EA-同位素质量比光谱法来补充，以确定在固体介质高压装置中的实验期间在高 P/-T 下平衡的物质之间的体积 D/H 比和同位素分馏。拟议的研究将补充和支持 H-D CH4 同位素地球化学的新领域。