Collaborative Research: Sulfur Isotope Systematics and Oxygen Fugacity Evolution in the 1257 Samalas Magma Reservoir, Indonesia

合作研究：印度尼西亚 1257 Samalas 岩浆库的硫同位素系统学和氧逸度演化

• 批准号: 1820185
• 负责人: Marc-Antoine Longpre
• 金额: $ 15.32万
• 依托单位: CUNY Queens College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-15 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1820185&HistoricalAwards=false
• 关键词: Collaborative; Research; Sulfur; Isotope; Systematics

Sulfur is the third most abundant volatile element in volcanic systems following water and CO2. Release of sulfur to the atmosphere during volcanic eruptions can perturb climate on a global scale and cause acid rain, resulting in significant environmental impact. The eruption of Mt. Samalas on Lombok Island, Indonesia, in 1257 generated the largest volcanic sulfur emission event of the last 2000 years. This event is coincident with a multi-year global cooling event around the beginning of the "Little Ice Age." The central research question of this project is: how did this volcano build up so much eruptible sulfur? The scientist participants will test hypotheses of sulfur enrichment mechanisms by probing deep into sulfur's properties and behavior within sulfides, apatites, and volcanic glasses (rapidly cooled melts) from pumice samples from this eruption. The project will utilize the most advanced analytical techniques to investigate sulfur chemistry, many of which were developed recently by participants on the research team. This project will yield new insights into the capability of magmatic systems beneath volcanoes to accumulate reservoirs of eruptible sulfur large enough to create significant global environmental impacts. This work will support several early-career researchers, and will engage a diverse group of undergraduate students to participate at City University of New York (CUNY) and the American Museum of Natural History (AMNH). The project exploits the complex geochemical behavior of sulfur to track its movement from the liquid phase (silicate melt) into solid (mineral) and gas phases in magmatic systems. Sulfur is a polyvalent element that can change its valence state from S2- to S6+ over a narrow redox range relevant for terrestrial magmatic systems. This makes sulfur an excellent tracer for changes in magma redox conditions that may have played a critical role in the transport, enrichment, and release of sulfur during the 1257 Mt. Samalas eruption. The involved magmatic processes (e.g., degassing) should lead to predictable fractionations of sulfur isotopes in glasses and minerals, which will further constrain the dynamics of sulfur build-up at Samalas. The valence states of sulfur in minerals and glasses will be determined via X-ray absorption near-edge structure (XANES) spectroscopy, whereas sulfur isotope ratios will be measured by secondary ionization mass spectrometry (SIMS). This dovetailing of redox and isotope studies is a powerful new approach to addressing sulfur-related science questions. This project will serve as a blueprint for future studies of other volcanic systems and will have implications for magmatic sulfide ore-forming processes and crustal magma evolution of interest to the broader Earth science community.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.

硫是水和二氧化碳之后火山系统中第三大的挥发性元件。火山喷发期间，向大气释放到大气中会在全球范围内扰动气候，并导致酸雨，从而产生重大的环境影响。 1257年，印度尼西亚伦波克岛（Lombok Island）的萨马拉斯山（Mt. Samalas）在1257年爆发是过去2000年最大的火山硫排放事件。这项活动与“小冰河时代”开始时与全球多年的全球冷却活动相吻合。该项目的中心研究问题是：这座火山如何建立如此多的硫磺硫？科学家参与者将通过深入硫化物，磷灰岩和火山玻璃（快速冷却的融化）中的硫化物的性质和行为来检验硫富集机制的假设。该项目将利用最先进的分析技术来研究硫化学，其中许多是由研究小组的参与者最近开发的。该项目将产生对火山下岩浆系统能力的新见解，积累了足够大的硫化硫的储层，以产生重大的全球环境影响。这项工作将支持几位早期的研究人员，并将吸引一群多样化的本科生参加纽约市城市大学（CUNY）和美国自然历史博物馆（AMNH）。该项目利用了硫的复杂地球化学行为，以跟踪其从液相（硅酸盐熔体）转移到岩浆系统中的固体（矿物）和气相的运动。硫是一种多价元素，可以在与陆生岩浆系统相关的狭窄氧化还原范围内将其价状态从S2-+更改为S6+。这使硫成为改变岩浆氧化还原条件变化的绝佳示踪剂，这可能在1257吨萨马拉斯山爆发期间在运输，富集和释放中起关键作用。涉及的岩浆过程（例如，脱气）应导致玻璃和矿物质中硫同位素的可预测分馏，这将进一步限制萨马拉斯硫的硫磺堆积的动力学。矿物质和玻璃中硫的价态将通过X射线吸收近边结构（XANES）光谱法确定，而硫同位素比率将通过次级电离质谱法（SIMS）来测量。这种对氧化还原和同位素研究的互补性是解决与硫相关的科学问题的有力新方法。该项目将成为对其他火山系统的未来研究的蓝图，并将对岩浆硫化物矿石形成的过程以及对广阔地球科学社区的兴趣演变的进化。这一奖项反映了NSF的法定任务，并通过使用基金会的知识优点和广泛的影响来评估NSF的法定任务，并被认为是值得的支持。