CAREER: Mass Transport and Fluid-Rock Reactions Driven by Multicomponent Aqueous Fluids

流体是在地壳中传输热量和物质的最有效的媒介。流体和流体-岩石反应对地壳岩石的成分、矿床的形成以及全球地球化学循环（如水（H2O）和碳的循环）具有很强的控制作用。这些过程发生在从地球表面的环境温度和压力到地球内部深处的极端温度和压力。因此，为了理解和预测这些过程如何运行，需要在广泛的条件下详细了解流体的物理和化学性质。所讨论的流体通常是H2O加上各种溶解的盐、矿物质和气体的复杂溶液。这项拟议的研究重点是开发方法，从分析数据中量化地质流体的成分，并预测地壳压力-温度条件下的流体密度和矿物溶解度。这些新的方法和数据将有助于开发新的研究方向，更好地了解从地球表面到地球内部深处的地质过程，以及地球的化学演变。这里开发的方法将有助于量化与热水流体形成矿物存款有关的过程，从而通过促进资源开发而造福社会。作为该项目的一部分，将开发用于数据分析的新计算机程序并将其与基于网络的培训模块链接，并将举办地球化学分析和数据解释的短期课程，这将有助于教育并促进科学进步。地质系统中流体介导的质量和能量转移的最新模型是基于稀释水或水-氯化钠等简单系统。这项拟议的研究将扩展这种建模复杂的流体成分，涉及一套额外的盐，离子和挥发性溶质。这里采用的方法涉及到结合地球化学分析（特别是矿物中的流体包裹体分析）与热力学建模获得的数据。流体的组成特性将根据Pitzer的形式主义使用离子活性关系进行评估。流体的体积性质将被描述为温度，压力和组成（包括复杂的盐水）的函数，使用偏摩尔体积和混合的过量体积的组合方法。矿物在流体中的溶解度将根据新的密度依赖溶解度模型进行量化，目标是复杂的盐水以及地质蒸汽。这些新方法将更好地近似地质流体，因此对流体驱动过程的未来地球化学建模产生积极影响。预计这些方法也将对涉及高温水性流体的化学工程和工艺设计产生积极影响。

Fluids are the most efficient agents for transporting heat and material in Earth's crust. Fluids and fluid-rock reactions exert strong controls on the compositions of crustal rocks, formation of mineral deposits, and global geochemical cycles such as those of water (H2O) and carbon. These processes occur from ambient temperatures and pressures at Earth's surface to extreme temperatures and pressures in Earth's deep interior. Therefore, to understand and predict how these processes operate, detailed knowledge of the physical and chemical properties of fluids are needed over wide range of conditions. The fluids in question are commonly complex solutions of H2O plus various dissolved salts, minerals and gases. This proposed research focuses on developing methods to quantify the compositions of geologic fluids from analytical data, and to predict the fluid densities and mineral solubilities over crustal pressure-temperature conditions. These new methods and data will contribute to develop new research directions and to better understand geologic processes from Earth's surface to its deep interior, as well as Earth's chemical evolution. The methods developed here will help quantify processes related to mineral deposit formation by hot aqueous fluids, thus benefiting society by contributing to resource development. As part of this project, new computer programs for data analysis will be developed and linked to web-based training modules, and short courses in geochemical analysis and data interpretation will be run, which will both contribute to education and promote scientific progress.Most recent models for fluid-mediated mass and energy transfer in geologic systems are based on simple systems such as dilute H2O or H2O-NaCl. This proposed research will extend such modeling to complex fluid compositions involving a suite of additional salts, ions and volatile solutes. The approach adopted here involves combining data obtainable from geochemical analyses (particularly, analyses of fluid inclusions in minerals) with thermodynamic modeling. Compositional properties of fluids will be assessed using ion-activity relations according to Pitzer's formalism. The volumetric properties of fluids will be described as functions of temperature, pressure and composition (including complex brines) using a combined approach of partial-molar volumes and excess volumes of mixing. The solubilities of minerals in fluids will be quantified according to a new density-dependent solubility model, targeting complex brines as well as geologic vapors. These new methods will better approximate geologic fluids and therefore have a positive impact on future geochemical modeling of fluid-driven processes. These methods are also projected to have a positive impact on chemical engineering and process design involving high-temperature aqueous fluids.