Numerical Modeling of Reaction-Enhanced Fluid Flow and Isotopic Exchange in Contact Aureoles

流体流动是与变质作用一起发生在火成岩侵入体接触光晕中的最重要的过程。流体流动驱动变质反应，诱导热量平流和质量输运。大量的野外、化学、矿物学和流体包裹体数据表明，岩浆-热液系统非常复杂，空间多变，并且随着热条件的变化而随时间演变。然而，在接触变质事件中，这些过程的时间演化往往难以从岩石学和地球化学中破译。数值计算机技术提供了检测接触光晕随时间演变的二维和三维方面的手段。本研究的目的是在数值上考察岩浆驱动的热液系统中，变质反应产生挥发物时岩石固有的瞬态渗透率变化如何影响流体通量、演化流体的组成以及岩石和流体之间的化学交换。研究结果对解释古岩浆-热液系统流体流动的矿物学、微量元素和稳定同位素特征具有指导意义。在更广泛的背景下，这项研究将增强我们对深部岩浆驱动的热液系统（包括火山和地热系统）和成矿过程的长期行为的理解。这些热液系统在地壳的质量再分配及其化学演化中发挥了关键作用，并负责集中可以经济地勘探的金属。该项目将培养一名精通复杂过程计算建模的研究生。在与社区的接触方面，将雇用一名本科生来帮助制作软件指南，该指南可以稍后分发给感兴趣的团体。

Along with metamorphism, fluid flow is the most important process that occurs in contact aureoles of igneous intrusions. Fluid flow drives metamorphic reactions and induces advective heat and mass transport. There is a very large body of field, chemical, mineralogic, and fluid inclusion data that demonstrate that magmatic-hydrothermal systems are very complex, spatially variable, and compositionally evolve through time as thermal conditions change. However, the temporal evolution of these processes during a contact metamorphic event is often difficult to decipher from petrology and geochemistry. Numerical computer techniques provide means to examine two and three-dimensional aspects of contact aureole evolution with time. The goal of this research is to numerically examine how transient permeability changes that are inherent to rocks in which metamorphic reactions produce volatiles, influence fluid fluxes, compositions of evolving fluids, and chemical exchange between rocks and fluids in magma-driven hydrothermal system. The results will serve as a guide for interpreting mineralogic, trace element and stable isotope signatures of fluid flow in fossil magmatic-hydrothermal systems. In a broader context, this study will enhance our understanding of the long-term behavior of deep, magma-driven hydrothermal systems, including volcanic and geothermal systems, and ore-generating processes. These hydrothermal systems have played a key role in mass redistribution in the Earth's crust and its chemical evolution and are responsible for concentrating metals that can be explored economically. This project will train a graduate student that will be proficient in computational modeling of complex processes. In terms of outreach to the community, an undergraduate student will be hired to help in production of a guide to the software that could be later distributed to interested parties.