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

SGER：协调 U 系列主要阶段和附属阶段的年龄

• 批准号: 0649295
• 负责人: Kari Cooper
• 金额: $ 3.56万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-11-01 至 2007-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0649295&HistoricalAwards=false
• 关键词: SGER; Reconciling; series; Ages; Major

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.

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和这些过程的时间尺度。该奖项将探索一种新的方法来解开为什么使用不同矿物相（辅助相与主要相）的U系列同位素组成获得的晶体年龄往往会产生不一致的年龄。 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，在俄勒冈州瀑布的南姐妹火山的流纹岩穹丘和新西兰的塔拉威拉火山杂岩的流纹岩穹丘样品中，锆石的原位238 U-230 Th年龄和主相和锆石的整体分离的226 Ra-230 Th和238 U-230 Th年龄）。这一年的探索性研究将使他们能够解决主相和副相结晶之间的时间关系的核心问题，同时为进一步的工作奠定基础。 这一勘探项目的结果可能对该领域产生直接和重大的影响，因为它们将为解释越来越多的锆石和主要阶段的年龄数据提供更强有力的背景;了解主相和副相记录相同岩浆事件的程度是至关重要的，以便从对不同系统的研究中概括岩浆系统的工作方式。迄今为止进行的。