SGER: Reconciling U-series Ages of Major and Accessory Phases

了解地壳岩浆系统的动力学需要了解导致化学变化的过程类型以及这些过程的时间尺度。该奖项将探索一种新的方法来解释为什么使用不同矿物相（副相与主相）的u系列同位素组成获得的晶体年龄倾向于产生不同的年龄。作为研究计划的一部分，研究人员将测量一套全面的u系列晶体年龄（即锆石的原位238u -230岁年龄，以及主要相和锆石的整体分离的226ra -230岁和238u -230岁年龄），这些样品来自俄勒冈瀑布南姐妹火山的流纹岩圆顶和新西兰塔拉韦拉火山综合体的流纹岩圆顶。这一年的探索性研究将使他们能够解决主要相结晶和辅助相结晶时间关系的核心问题，同时为进一步的工作奠定基础。该勘探项目的结果可能会对该领域产生直接而重大的影响，因为它们将为解释锆石和主要阶段的年龄数据提供更强有力的背景；了解主要阶段和辅助阶段记录相同岩浆事件的程度是至关重要的，以便从迄今为止所进行的不同系统的研究中概括出岩浆系统是如何工作的。

Understanding the dynamics of crustal magma systems requires knowledge of the types of of processes that lead to chemical changes and the timescales of such processes. This award will explore a novel approach to unravel why crystal ages that are obtained using U-series isotopic compositions of different mineral phases (accessory versus major phases) tend to yield discrepant ages. As part of the research plan, the investigators will measure a comprehensive suite of U-series crystal ages (i.e., in situ 238U-230Th ages in zircon and 226Ra-230Th and 238U-230Th ages in bulk separates of both major phases and zircon) in samples from rhyodacite domes at South Sister Volcano, Oregon Cascades, and rhyolite domes of the Tarawera volcanic complex, New Zealand. This one year of exploratory research will allow them to address the core question of the temporal relationship between major and accessory phase crystallization, while simultaneously laying the foundation for further work. The results of this exploratory project could have immediate and significant impact on the field because they will provide a much stronger context for interpretation of the growing body of age data for zircon and major phases; understanding the extent to which major and accessory phases are recording the same magmatic events is critical in order to make generalizations about how magma systems work from the studies of disparate systems that have been conducted to date.