Residence Times of Silicic Magmas

硅质岩浆的停留时间

• 批准号: 9706519
• 负责人: Mary Reid
• 金额: $ 16.03万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9706519&HistoricalAwards=false
• 关键词: Residence; Times; Silicic; Magmas

9706519 Reid Large, highly explosive eruptions reflect the accumulation of magma at shallow crustal levels, which in turn, requires a heat input significantly in excess of output. The duration of magma accumulation and compositional modification is therefore a record of the thermal history of a volcano which, for voluminous rhyolitic magmas, may operate over timescales of tens of thousands to millions of years. To delimit the dynamics of magma accumulation, three new methods for dating the crystallization of minerals from rhyolitic magmas will be refined and employed. Two of these methods will utilize a high resolution ion microprobe which will enable individual zircon and allanite crystals to be dated and a detailed record of crystal growth to be obtained. The third method will determine the timing of quartz crystallization from age of the glass inclusions they contain. Major centers of rhyolitic volcanism, including Long Valley (California), Yellowstone (Wyoming), and Toba (Sumatra) calderas, will be investigated. The insights gathered from these studies will be used in conjunction with the temperature-dependence of crystallization to develop models for the thermal evolution of rhyolitic magmas associated with large-volume silicic systems.

9706519 Reid 大规模、高爆炸性喷发反映了岩浆在地壳浅层的积累，而这反过来又需要输入的热量大大超过输出。 因此，岩浆积累和成分改变的持续时间是火山热历史的记录，对于大量的流纹岩浆来说，火山的运行时间可能长达数万至数百万年。 为了界定岩浆堆积的动力学，将改进和采用三种新方法来测定流纹质岩浆中矿物结晶的年代。 其中两种方法将利用高分辨率离子微探针，对单个锆石和铝铜矿晶体进行测定，并获得晶体生长的详细记录。 第三种方法将根据石英中所含玻璃夹杂物的年龄来确定石英结晶的时间。将调查主要的流纹岩火山活动中心，包括长谷（加利福尼亚州）、黄石公园（怀俄明州）和多巴（苏门答腊岛）破火山口。从这些研究中收集到的见解将与结晶的温度依赖性结合起来，开发与大体积硅质系统相关的流纹质岩浆的热演化模型。