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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751008
• 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、火山喷发的时间和强度以及矿床的形成。它们在月球形成大碰撞后的地球演化过程中发挥了重要作用，在大型火成岩省爆发期间，它们被注入大气，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，但其他挥发物也通常以百万分之百到千万分之百的浓度存在。虽然我们对水在岩浆系统中的作用了解最多，但一些涉及水的基本过程仍然未知。我们仍然不完全了解岩浆中水的溶解和气泡生长的机制和速率。水对结晶动力学和硅酸盐熔体与矿物（其中一些是微量元素和关键矿石金属的重要储集层）之间的平衡的影响知之甚少。人们对少量岩浆挥发物的影响了解得更少，这些挥发物不仅影响岩浆过程，而且当脱气进入大气时，会严重影响地球表面的环境。由于它们在熔体中的低溶解度，少量挥发物在流体相的析出中起着基本作用，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，特别是关键金属（如Li、Be、B、Co、稀土元素等）的形成中起着至关重要的作用。重要的是，我们对岩浆系统中这些微量挥发物的行为知之甚少，无法定量模拟它们的运输和储存。该研究项目将研究平衡和不平衡过程，包括主要和次要挥发物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析出形成气泡，开发新的方法来估计古代岩浆中的挥发物和脱气到大气中，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。该研究项目以实验、建模和与在该领域工作的同事合作为中心，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。