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Partitioning of sulfur and sulfur isotopes between fluids and melts - a key for understanding and monitoring of magmatic degassing

硫和硫同位素在流体和熔体之间的分配——理解和监测岩浆脱气的关键

基本信息

批准号：
164914959
负责人：
Professor Dr. Harald Behrens
金额：
--
依托单位：
Institut für Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/164914959?language=en
关键词：
Partitioning sulfur isotopes between fluids

项目摘要

Understanding of degassing of magmas is central to monitoring and forecasting of volcanic eruptions. Sulfur is a major volatile released from magmas after decompression and the improved understanding of sulfur isotope geochemistry is vital to volcanic hazard mitigation, because sulfur partitions strongly into the vapor in oxidized melt-vapor systems. The determi2 nation of the sulfur isotope geochemistry in gases from arc magmas is extremely useful to constrain sulfur fluxes in the crust and the underlying mantle wedge. However, this requires a good knowledge (1) of the sulfur isotope-characterization of primitive melts, (2) of the behavior of sulfur during decompression of magmas as well as during magma-fluid interactions and (3) of the distribution of sulfur isotopes between phases (minerals, melts, fluids). In the proposed research we want to investigate experimentally the distribution of sulfur and of sulfur isotopes between liquids and fluids both under near-equilibrium conditions (long term experiments) and under kinetic control (rapid decompression, rapid cooling). Base compositions for this pioneering study will be in the compositional range from dacite to andesitic basalt which have relevance for arc volcanism and can dissolve sufficient sulfur for reliable quantitative analyses. The experimental products will be analyzed with various analytical techniques including SIMS and Laser Ablation-ICPMS. One aim of the project will be to improve these techniques for measurement of sulfur isotopes at low sulfur concentrations in glasses. The experimental results will be used to interpret glass inclusion data which will be mainly obtained by our cooperation partner Charles Mandeville (American Museum of Natural History (AMNH), New York). Combination of the data will be used to develop degassing scenarios for selected volcanoes.

了解岩浆的脱气作用是监测和预测火山喷发的核心。硫是减压后从岩浆中释放出来的一种主要挥发性物质，提高对硫同位素地球化学的理解对于减轻火山灾害至关重要，因为硫在氧化的熔体-蒸汽系统中强烈地分配到蒸汽中。弧岩气中硫同位素地球化学的测定对限制地壳和下伏地幔楔体中的硫通量是非常有用的。然而，这需要很好地了解(1)原始熔体的硫同位素特征，(2)在岩浆减压和岩浆-流体相互作用期间硫的行为，以及(3)硫同位素在相间(矿物、熔体、流体)之间的分布。在拟议的研究中，我们希望通过实验研究在接近平衡的条件下(长期实验)和在动力学控制(快速减压、快速冷却)下，硫和硫同位素在液体和液体之间的分布。这项开创性研究的基础成分将在英安岩到安山质玄武岩的成分范围内，这些成分与弧火山作用有关，可以溶解足够的硫，以便进行可靠的定量分析。实验产物将用包括SIMS和激光烧蚀-ICPMS在内的各种分析技术进行分析。该项目的目标之一将是改进这些在玻璃中低硫浓度下测量硫同位素的技术。实验结果将用于解释玻璃夹杂数据，这些数据将主要由我们的合作伙伴查尔斯·曼德维尔(美国自然历史博物馆，纽约)获得。这些数据的组合将被用来制定选定火山的脱气情景。