Phase Relations Between Silicate Melts and Crustal Brines

拟议研究的最终目标是了解地壳盐水对地球深部地壳和上地幔熔融过程和物质输送的作用。提出的实验将提高目前的理解俯冲带的岩浆过程和测量的贡献，盐水流体的稳定性花岗岩形成的熔体在地壳浅部环境。拟议的研究将促进对与地球深部水文循环有关的质量和热量转移的理解，在这种循环中，水在俯冲带被带入地幔，在火山处被释放回地表。了解类地行星内部C-O-H挥发物的引入、运输和储存与可居住性的性质、生命的起源以及有利于生命的外部证据有着深刻的联系。硅酸盐熔体的结构表征及其玻璃形成能力与材料和玻璃科学直接相关。实验数据将通过实验相位关系图书馆和该机构网络基础设施内的数据存储库向公众提供。一系列讲座和实验室演示/图尔斯将交付给乔治梅森大学（GMU）的本科生/研究生，GMU的一些本科生将在为期10周的暑期实习计划中参与该项目，在研究机构（CIW）和公立国家资助的大学（GMU）之间建立强有力的伙伴关系挥发分在硅酸盐熔体和含水流体中的溶解度和溶解机制控制着地幔通量，并影响着共存相的性质，如扩散率、电导率和粘度。这对沿着洋中脊、陆壳浅部和俯冲带发育的岩浆系统之间的物理化学不均一性产生了深刻的影响。然而，很少有人知道的硅酸盐熔体流体相关系，特别是富含溶解碱金属，碱土金属和卤素离子的盐水流体。该建议旨在探索溶解盐、流体pH和熔体过碱度对硅酸盐熔体和地壳卤水之间相关系的影响，以更好地理解熔体聚合和共存相中的C-O-H溶解度。该项目将限制熔体-流体关系，不仅作为压力/温度的函数，而且还作为共存相的相对丰度和成分变化的函数。在一系列水热金刚石对顶砧实验中，将采用拉曼振动/红外光谱法对与富含电解质的水溶液共存的硅酸盐熔体的结构、挥发性成分和性质进行原位和实时调查。实验将揭示CO2溶解度，网络改性阳离子和熔融聚合程度之间的相互作用。原位研究将补充散装CO2溶解度测量淬火的玻璃在高温和高压下的熔体流体平衡。这项工作的核心是非原位和原位实验方案沿着实时化学和光谱分析的创新整合。在这项研究中，使用超纯合成金刚石砧将大大提高监测原位熔体-流体相互作用的分析方法的有效性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The ultimate objective of the proposed study is to understand the role of saline crustal fluids on melting processes and material transport in Earth's deeper crust and upper mantle. Experiments proposed will enhance the current understanding of magmatic processes in subduction zones and gauge the contribution of saline fluids on the stability of granitic-forming melts at shallow crustal environments. The proposed study will promote understanding on the mass and heat transfer associated with the deep Earth's hydrological cycle, wherein water is carried into the mantle at subduction zones and released back to the surface at volcanoes. Understanding the introduction, transport, and storage of C-O-H volatiles in the interiors of terrestrial-like planets is profoundly linked to the nature of habitability, the origin of life, and the external evidence of conditions favorable for life. Structural characterization of silicate melts and their glass-forming abilities are directly relevant to materials and glass science. Experimental data will be made available to the public through the Library of Experimental Phase Relations, and a data repository hosted within the institution's web infrastructure. A series of lectures and lab demonstrations/tours will be delivered to George Mason University (GMU) undergraduate/graduate students, and some undergraduate students from GMU will participate in the project during a 10-week summer internship program, creating a strong partnership between a research-institution (CIW) and a public state-funded University (GMU).The solubility and solution mechanisms of volatiles in silicate melts and aqueous fluids governs mantle fluxes, and affects the properties of coexisting phases such as diffusivity, electrical conductivity and viscosity. This has a profound effect on the physical and chemical heterogeneities between the magmatic systems developed along mid-ocean ridges, shallow continental crust and subduction zones. Very little is known, however, about the silicate melt-fluid phase relations, especially for saline fluids enriched in dissolved alkalis, alkaline earths, and halogen ions. This proposal aims to explore the effect of dissolved salts, fluid pH and melt peralkalinity on the phase relations between silicate melts and crustal brines to better understand melt polymerization and C-O-H solubility in the coexisting phases. This project will constrain the melt-fluid relationships as function not only of pressure/temperature but also of relative abundances and compositional variability of the coexisting phases. In a series of hydrothermal diamond anvil cell experiments, Raman vibrational/Infrared spectroscopy will be employed for the in-situ and real-time investigation of the structure, volatile composition and properties of silicate melts coexisting with electrolyte-enriched aqueous solutions. Experiments will reveal the interplay between CO2 solubility, network-modifying cations and extent of melt polymerization. The in-situ studies will be complimented by bulk CO2 solubility measurements in glasses quenched from melt-fluid equilibria at high temperatures and pressures. At the core of this effort is an innovative integration of ex-situ and in-situ experimental protocols along with real-time chemical and spectroscopic analysis. In this study, use of ultrapure synthetic diamond anvils will increase tremendously the effectiveness of analytical methods that monitor in-situ melt-fluid interactions.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.