Mineral Dissolution in Silicate Melts

知识价值。本提案将研究硅酸盐熔体中的扩散晶体溶解。火成岩形成的关键过程之一。在岩浆通道、岩浆室或岩浆海洋中，夹带的捕虏体/异晶体和新结晶的矿物会下沉或上升，这取决于它们相对于熔体的密度。相对运动引起对流。在下降或上升时，每一个矿物颗粒都能在对流的存在下进行溶解。硅酸盐熔体中矿物的对流溶蚀速率尚未定量测定。最近的理论可以预测对流溶解速率；必要的输入参数包括系统条件（熔体和矿物成分以及温度和压力）、熔体和矿物密度、矿物的溶解度、主平衡决定成分的扩散系数和熔体的粘度。本项目旨在约束这些参数。粘度和密度可以从现有的模型估计。扩散率和溶解度可以从扩散溶解实验中得到。提出了以下新工作：(1)检验理论在岩浆系统中的适用性；（二）进行晶体扩散溶解实验，从中提取扩散系数和溶解度；（iii）将扩散晶体溶解实验的数据量化为温度和压力的函数；（iv）发展模型以预测自然界的扩散和对流晶体溶解速率，重点是某一矿物-熔体系统的对流溶解速率随温度和压力的变化。最终目标是开发一种工具来预测天然硅酸盐熔体中晶体的对流溶解速率，并应用于岩浆中异种晶体的消化或存活。更广泛的影响。该项目将支持研究生和本科生，博士后研究助理。国际合作者的参与将进一步促进美国和其他国家之间的科学网络。私家侦探经常将他的研究纳入不同层次的教学中。

Intellectual merit. This proposal will investigate diffusive crystal dissolution in silicate melts ? one of the key processes in igneous petrogenesis. In a magma conduit, chamber or ocean, entrained xenoliths/xenocrysts and newly crystallized minerals would sink or rise depending on their density relative to the melt. The relative motion induces convection. Upon descent or ascent, each mineral grain could undergo dissolution in the presence of convection. The convective dissolution rate of minerals in silicate melts has not been quantified before. Recent theory can predict convective dissolution rates; the necessary input parameters include the system conditions (melt and mineral compositions as well as temperature and pressure), melt and mineral density, the solubility of the mineral, diffusivity of the principal equilibrium-determining component, and viscosity of the melt. This project is designed to constrain these parameters. Viscosity and density can be estimated from available models. The diffusivity and solubility may be extracted from diffusive dissolution experiments. New work is proposed work as follows: (i) testing the theory for applicability in magmatic systems; (ii) conducting diffusive crystal dissolution experiments, from which diffusivity and solubility will be extracted; (iii) quantifying data from diffusive crystal dissolution experiments as a function of temperature and pressure; (iv) developing models to predict diffusive and convective crystal dissolution rates in nature, focusing on convective dissolution rates as a function of temperature and pressure for a given mineral-melt system. The ultimate goal is to develop a tool to predict convective dissolution rate of crystals in natural silicate melts, with application to digestion or survival of xenocrysts in magmas.Broader Impacts. The project will support graduate and undergraduate students, a post-doctoral research associate. Participation of an international collaborator will further scientific networking between the United States and other nations. The P.I. regularly incorporates his research into teaching at different levels.