Collaborative Research: Assessment of Sulfur Recycling in Arc Magmatism through Secondary Ion Mass Spectrometry Study of Sulfur Isotopes in Experimental and Natural Mafic Glasses

智力上的优点。这项建议要求提供资金，用于基于含S气体、硅酸盐熔体和浓缩S相(硫酸盐和硫化物)之间的同位素分馏进行全球硫循环的合作实验和分析研究。来自三个机构的科学家参与其中(美国自然历史博物馆(C.Mandeille，Pi)、伍兹霍尔海洋研究所(N.Shimizu，Pi)和罗德岛大学(K.Kelley，Pi)。拟议的研究包括两个不同的方面。首先，将进行实验室实验，以确定S同位素在共存相间的分馏机理和大小随压力、温度、硅酸盐熔体的化学成分、氧逸度以及S在硅酸盐熔体和气相中的形态而变化。S的同位素分析将在伍兹霍尔海洋研究所使用IMS1280离子微探头二次离子质谱仪(SIMS)技术进行。这种用于硫同位素测量的新技术现在可以应用于熔融包裹体(10‘S微米)尺度的硅酸盐玻璃，从而可以分析捕获的岩浆包裹体中的硫同位素，评估火山脱气作用，并评估弧状岩浆中硫的最终来源。在第二阶段，将测定以橄榄石、斜方辉石和单斜辉石为主的玻璃包裹体捕获的天然原始岩浆的S同位素组成；通过罗德岛的激光烧蚀电感耦合等离子体质谱分析，将在同一玻璃上测定互补的挥发性、亲石性和高场强微量元素丰度。将对印度尼西亚加龙岗、意大利埃特纳和阿拉斯加奥古斯丁火山样品进行研究，以研究源地幔的S同位素组成，水和氧逸度对硅酸盐熔体与S相之间S同位素分馏的影响，以及脱气过程对硅酸盐熔体S同位素组成的影响。总之，这些研究路径有望建立S同位素地球化学的常规测量，作为跨越俯冲带的化学通量的强大示踪剂，并用于评估地球主要储集层(地幔、岩石圈(包括地壳)和水圈-大气耦合)之间的硫循环。更广泛的影响。了解挥发性脱气是监测和预测火山喷发的核心。还有。加强对硫同位素地球化学的了解对减轻火山灾害至关重要。私人投资机构将把科学成果纳入各自机构的教育和推广计划。皮凯利是一名职业生涯早期的女科学家，由罗德岛大学的NSF资助的高级项目支持，该项目旨在培养女性科学家的职业生涯。她将为夏季本科生海洋学研究奖学金(SURFO)学生(大学)提供建议。罗德岛州海洋研究生院的NSF资助的REU项目)在该项目的保护下。皮曼德维尔将在这个项目的第二年和第三年为美国自然历史博物馆REU的两名学生提供建议。PI将作为讲师参加AMNH的城市科学教学培训更新(TRUST)计划，该计划为大纽约市高中地球科学教师提供专业发展机会。AMNH将在项目的每一年举行一次信托会议。

Intellectual merit. This proposal requests funding for acollaborative experimental and analytical study of global recycling of sulfur based on the isotopic fractionation between S-bearing gases, silicate melt, and condensed S phases (sulfate and sulfide). Scientists from three institutions are involved (American Museum of Natural History (C. Mandeville, lead PI), Woods Hole Oceanographic Institution (N. Shimizu, PI), and University of Rhode Island (K. Kelley, PI). The proposed research comprises two separate aspects. First, laboratory experiments will be carried out to determine mechanisms and magnitudes of S isotopic fractionations between coexisting phases as a function of pressure, temperature, chemical composition of silicate melt, fugacity of oxygen, and speciation of S in silicate melt and gas phase. S isotopic analysis will be made using secondary ion mass spectrometry (SIMS) techniques with the IMS 1280 ion microprobe at Woods Hole Oceanographic Institution. This new SIMS technique for sulfur isotopic measurements can now be applied to silicate glasses at the melt inclusion (10's of microns) scale thus allowing analysis of sulfur isotopes in trapped magma inclusions, evaluation of volcanic degassing, and assessment of the ultimate source of sulfur in arc magmas. In a second phase, S isotopic compositions will be determined for natural primitive magmas trapped as glass inclusions hosted by olivine, orthopyroxene and clinopyroxene; complementary volatile, lithophile and high field strength trace element abundances will be determined on the same glasses via laser ablation ICP-MS analysis at Rhode Island. This will be carried out for samples from Galunggung (Indonesia), Etna (Italy), and Augustine (Alaska), volcanoes so as to investigate S isotopic compositions of source mantle, effects of water and oxygen fugacity on S isotopic fractionation between silicate melt and S-bearing phases, and effects of degassing processes on S isotopic composition of silicate melts. Together, these research paths are expected to establish routine measurement of S isotope geochemistry as a powerful tracer for chemical fluxes across subduction zones and for assessment of sulfur recycling among Earth's major reservoirs (mantle, lithosphere (including crust), and coupled hydrosphere-atmosphere). Broader Impacts. Understanding of volatile degassing is central to monitoring and forecasting volcanic eruptions. Also. improved understanding of sulfur isotope geochemistry is vital to volcanic hazard mitigation. The PIs will incorporate the scientific results into educational and outreach programs at their respective institutions. PI Kelley is an early-career female scientist, supported by the University of Rhode Island's NSF-funded ADVANCE program, which is aimed at nurturing the careers of female scientists. She will advise a Summer Undergraduate Research Fellowship in Oceanography (SURFO) student (Univ. of Rhode Island, Graduate School of Oceanography's NSF-funded REU program) under the umbrella of this project. PI Mandeville will advise two American Museum of Natural History REU students in years 2 and 3 of this project. The PI will participate as a lecturer in the Training Renewal for Urban Science Teaching (TRUST) program at AMNH which provides professional development opportunities for greater New York City high school Earth science teachers. A TRUST session will be administered by AMNH in each year of the project.