EAGER: Investigating the possibility of low temperature (<700 C) melt in silicic igneous systems

EAGER：调查低温的可能性（

• 批准号: 1919714
• 负责人: Craig Lundstrom
• 金额: $ 8.47万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1919714&HistoricalAwards=false
• 关键词: EAGER; Investigating; possibility; low; temperature

The questions of how Earth's crust was made by silicic magmas, and how large volcanoes like Yellowstone erupt, have perplexed geologists for centuries. This project will include collecting new geochemical data from observed volcanic rocks and performing laboratory experiments aimed at assessing the controversial hypothesis that magmas at temperatures of 500 to 550 degrees C play a role in making and erupting silicic melts. The project has potential to make transformative change on views of how silicic magma systems operate with potential impacts including how the continental crust forms, why silicic magmas erupt, and how ore deposits form. This project will train a graduate student, and develop a new device for thermal gradients in a cold seal system that will benefit other experimental petrologists. This exploratory project builds upon the recent finding that hydrous peralkaline melts can coexist with quartz + feldspar at temperatures below the nominal igneous solidus (700 degrees C). Three tasks aimed at assessing the possibility that this low temperature melt exists and plays a role in eruption of silicic magmas are proposed: 1) Assess the role of decompression of low temperature melt in equilibrium with quartz and feldspar by releasing pressure from 1 kb to 0.3 kb and comparing to know phase equilibria; 2) Develop a thermal gradient apparatus using cold seal vessels at 1 kb pressure; 3) Compare the intra mineral isotope ratios of U, Fe and Si from mineral separates of the Fish Canyon Tuff to assess if connections between the making of granites and silicic volcanic rocks can be discerned.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地壳是如何由岩浆形成的，以及像黄石公园这样的大火山是如何喷发的，这些问题困扰了地质学家几个世纪。该项目将包括从观测到的火山岩中收集新的地球化学数据，并进行实验室实验，以评估一个有争议的假设，即温度为500至550摄氏度的岩浆在形成和喷发火山熔岩中发挥作用。该项目有可能对岩浆系统如何运作的观点产生革命性的变化，包括大陆地壳如何形成，岩浆为什么爆发以及矿床如何形成。该项目将培养一名研究生，并开发一种新的冷密封系统中的热梯度装置，这将有利于其他实验岩石学家。这一探索性项目建立在最近的发现基础上，即含水过碱性熔体可以在低于标称火成岩固相线（700摄氏度）的温度下与石英+长石共存。本文提出了三项旨在评估这种低温熔体存在并在岩浆喷发中起作用的任务：1）通过从1千巴到0.3千巴的压力释放并与已知的相平衡进行比较，评估与石英和长石平衡的低温熔体的减压作用：2）研制一种使用冷密封容器的1kb压力下的热梯度装置; 3）比较鱼峡谷凝灰岩矿物分离物中铀、铁和硅的矿物内同位素比率，以评估花岗岩和火山岩的形成之间是否存在联系。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

项目成果

δ56Fe of magnetite as a tool for tracking mush-to-magma processes

δ56Fe 磁铁矿作为追踪糊状岩浆过程的工具

• 发表时间: 2022
• 期刊: VM Goldschmidt 2022
• 作者: Karoline M Bruckel;Craig Lundstrom
• 通讯作者: Craig Lundstrom