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 Christensen这项研究旨在记录大约76万年前在加州中东部爆发的富含二氧化硅的岩浆（主教凝灰岩）的物理和化学演化。新的野外工作提供了一个地层学框架，允许评价岩浆的分异、上升、结晶和喷发之间的时空关系。 合作者将分析火山斑晶中的亚毫米大小的玻璃和沙漏状内含物（喷发淬火熔体），以获得主要，次要和微量元素，以及挥发性物质H2O和CO2以及氩，锶和钕的同位素。他们还将分析长石晶体，特别注意微量元素和同位素分带，以便将结晶年龄与结晶压力，熔体和岩浆成分以及喷发时间和顺序联系起来。一个主要的目标是测试的想法，氩和CO2相关的结果脱气和揭示岩浆与大气水的相互作用，含有溶解的空气。 本科生和年轻科学家将参与该项目，并获得研究和合作经验。这些结果将限制关于如此大的岩浆体如何形成、发展密度和成分梯度以及喷发的概念。 研究结果对探讨岩浆活动在陆壳脱气和演化中的作用具有重要意义。