Modeling Magmatic Crystallization and Melting Behavior with Synthetic Water-Salt Fluid Inclusions

通过本项目，开发了一种利用人工合成的H20-KCl流体包裹体来直观模拟岩石学高年级学生岩浆结晶和熔融行为的技术。这项技术为学生提供了一种互动的、可视化的学习体验，让他们了解永远无法直接观察到的地质过程。使用已知成分的合成H2O-KCl流体包裹体和加热和冷却阶段，学生们进行一项练习，他们观察和控制：(1)共晶熔化（冰和钾盐在-10.7℃下），(2)冰或钾盐的液态结晶和熔化，以及(3)冰或钾盐的最终熔化温度。利用这些数据，学生们构建自己的H2O-KCl系统中富水部分的相图，然后探索以下问题：(1)共晶和液相温度与体组成之间的关系；(2)相律在不同温度下的应用。该技术的主要优点是，所有类似于岩浆系统的重要相变（即，共晶和液相行为，结晶和熔融结构）都可以由学生直观地观察和控制。因此，相图上的每一个空间、线和点都将与学生直接相关，并导致对相图的更有意义的解释及其在火成岩中的应用。

Through this project, a technique of using synthetic H20-KCl fluid inclusions is developed to visually simulate magmatic crystallization and melting behavior for students enrolled in an upper-division petrology course. The technique offers students an interactive, visual learning experience of a geologic process that can never be directly observed. Using synthetic H2O-KCl fluid inclusions of known composition and a heating and cooling stage, students conduct an exercise in which they observe and control: (1) eutectic melting (of ice and sylvite at -10.7 C), (2) liquidus crystallization and melting of ice or sylvite, and (3) final ice or sylvite melting temperatures. Using these data, students construct their own phase diagram of the water-rich portion of the H2O-KCl system and will then explore questions on the (1) the relationship between eutectic and liquidus temperatures and bulk composition and (2) applications of the phase rule at various temperatures. The main advantage of this technique is that all of the important phase changes analogous to magmatic systems (i.e., eutectic and liquidus behavior, crystallization and melting textures) can be visually observed and controlled by the student. Consequently, every space, line and point on a phase diagram will have direct relevance to the student and result in a more meaningful interpretation of phase diagrams and their application to igneous rocks.