Melts, fluids, crystals: equilibrium and disequilibrium processes in magmatic systems

熔体、流体、晶体：岩浆系统中的平衡和不平衡过程

• 批准号: RGPIN-2020-04715
• 负责人: Baker, Don
• 金额: $ 3.72万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740140
• 关键词: Melts; fluids; crystals; equilibrium; disequilibrium

Volatiles (H2O, CO2, S, F, Cl, Br, etc.) play a vital role in magmatic systems. Their concentrations affect phase equilibria, the timing and intensity of volcanic eruptions, and the formation of ore deposits. They played a major role in the evolution of the Earth following the Moon-forming giant impact, and their injection into the atmosphere during eruptions of large igneous provinces has been linked to major extinction events in Earth's history. The dominant volatile in magmatic systems is H2O, however the other volatiles are also commonly present at concentrations of 100's to 1000's of ppm. Although we know most about the effects of water in magmatic systems, some fundamental processes involving water remain unknown. We still do not understand completely the mechanisms and rates of water exsolution and bubble growth in magmas. The influence water exerts on the kinetics of crystallization and the equilibria between silicate melts and minerals, some of which are important reservoirs of trace elements and critical ore metals, is little understood. Even less is known about the effects of minor magmatic volatiles, which not only influence magmatic processes, but when degassed into the atmosphere severely impact Earth's surficial environment. Because of their low solubilities in melts, minor volatiles play a fundamental role in the exsolution of a fluid phase, possibly initiating volcanic eruptions. Additionally, at least two of these minor volatile elements, Cl and S, play a crucial role in the formation of ore deposits, particularly of critical metals (e.g., Li, Be, B, Co, rare earth elements, etc.). Importantly, we do not know enough about the behaviour of these minor volatiles in magmatic systems to quantitatively model their transport and storage. This research program will investigate equilibrium and disequilibrium processes involving major and minor volatiles and their interactions with crystals and melts in magmatic systems on Earth and other planetary bodies in the solar system. We will investigate their exsolution from the melt to form bubbles, develop new ways to estimate volatiles in ancient magmas and degassed into the atmosphere, and improve our understanding of the ability of volatiles to transport Cl, S and ore metals at conditions similar to those in crustal magmatic systems and following the Moon-forming impact. This research program is centered around experiments, modeling, and collaboration with colleagues working in the field applying the experimental results to natural samples. Because the research program will quantitatively measure storage and transport of critical metals, the results of the program will not only improve our understanding of the degassing of magmatic systems, but also will be used to model ore metal transport that can be applied to our search for critical mineral resources in Canada.

挥发物（H2O、CO2、S、F、Cl、Br等）在岩浆系统中起着至关重要的作用它们的浓度影响相平衡、火山爆发的时间和强度以及矿床的形成。它们在形成月球的巨大撞击之后的地球演化中发挥了重要作用，并且它们在大火成岩省爆发期间注入大气层与地球历史上的重大灭绝事件有关。岩浆系统中的主要挥发物是H2O，然而其他挥发物也通常以100至1000 ppm的浓度存在。虽然我们对水在岩浆系统中的作用了解最多，但涉及水的一些基本过程仍然未知。岩浆中水的出溶和气泡的生长机制和速率至今尚未完全弄清楚。水对结晶动力学和硅酸盐熔体和矿物之间的平衡的影响，其中一些是微量元素和关键矿石金属的重要水库，是知之甚少。对微量岩浆挥发物的影响所知更少，这些挥发物不仅影响岩浆过程，而且在脱气进入大气层时严重影响地球的表面环境。由于它们在熔体中的溶解度低，微量挥发物在流体相的出溶中起着重要作用，可能引发火山爆发。此外，这些微量挥发性元素中至少有两种，Cl和S，在矿床的形成中起着至关重要的作用，特别是关键金属（例如，Li、Be、B、Co、稀土元素等）。重要的是，我们对这些次要挥发物在岩浆系统中的行为了解不够，无法定量模拟它们的运输和储存。该研究计划将研究涉及主要和次要挥发物的平衡和不平衡过程及其与地球和太阳系其他行星体岩浆系统中晶体和熔体的相互作用。我们将研究它们从熔体中出溶形成气泡，开发新的方法来估计古老岩浆中的挥发物并脱气到大气中，并提高我们对挥发物在类似于地壳岩浆系统和月球形成影响的条件下运输Cl，S和矿石金属的能力的理解。该研究计划围绕实验，建模以及与在该领域工作的同事合作，将实验结果应用于自然样本。由于该研究计划将定量测量关键金属的储存和运输，该计划的结果不仅将提高我们对岩浆系统脱气的理解，而且还将用于模拟矿石金属运输，可应用于我们在加拿大寻找关键矿产资源。