Collaborative Research: The History of Degassing and Differentiation of the Bishop Tuff Rhyolitic Magma

合作研究：主教凝灰岩流纹质岩浆的脱气和分异历史

• 批准号: 9714187
• 负责人: John Christensen
• 金额: $ 7.2万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 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 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9714187&HistoricalAwards=false
• 关键词: Collaborative; Research; History; Degassing; Differentiation

9714187 Christensen This study aims to document the physical and chemical evolution of a large body of silica-rich magma (Bishop Tuff) that erupted about 0.76 million years ago in east-central California. New field work provides a stratigraphical framework that permits evaluation of space-time relations between differentiation, ascent, crystallization and eruption of the magma. The collaborators will analyze submillimeter-sized glass and hourglass inclusions (eruptively quenched melt) in volcanic phenocrysts for major, minor, and trace elements in addition to volatile species H2O and CO2 and isotopes of argon, strontium and neodymium. They will also analyze feldspar crystals paying particular attention to trace element and isotopic zonations so as to associate age of crystallization with pressure of crystallization, melt and magma composition as well as time and sequence of eruption. A main goal is to test the idea that argon and CO2 correlate as a result of degassing and reveal interaction of magma with meteoric water that contained dissolved air. Undergraduate students and young scientists will participate in the project and gain experience in research and collaboration. The results will constrain concepts regarding how such large bodies of silicic magma form, develop density and composition gradients, and erupt. The results will have significant implications for the role of silicic magmatism in the degassing and evolution of continental crust.

9714187克里斯滕森（Christensen）这项研究旨在记录大约776万年前在加利福尼亚州东部的大约776亿年前爆发的大量二氧化硅岩浆（Bishop Tuff）的物理和化学演化。新的现场工作提供了一个地层框架，可以评估岩浆的分化，上升，结晶和喷发之间的时空关系。 合作者将在火山表晶中分析亚毫米尺寸的玻璃和沙漏夹杂物（爆发的熔融熔体），用于主要，次要物种H2O和CO2，以及氩，畸形和新近偏二氮的挥发性物种H2O和CO2以及同位素。他们还将分析Feldspar晶体，特别注意痕量元件和同位素分区，以使结晶的年龄与结晶，熔体和岩浆组成的压力以及喷发的时间和序列相关联。一个主要目标是测试氩和二氧化碳因脱气而与含有溶解空气的陨水相互作用而相关的想法。 本科生和年轻科学家将参加该项目，并获得研究和协作的经验。结果将限制有关如此大的硅质岩浆形式，密度和组成梯度以及爆发的概念。 结果将对硅质岩浆作用在大陆壳的脱气和演变中的作用具有重要意义。