Collaborative Research: The Behavior of Sulfur During Magma Mixing and Implications for Magma Degassing and Ore Formation

合作研究：岩浆混合过程中硫的行为及其对岩浆脱气和成矿的影响

• 批准号: 1250239
• 负责人: Adam Simon
• 金额: $ 21.47万
• 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: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1250239&HistoricalAwards=false
• 关键词: Collaborative; Research; Behavior; Sulfur; During

The proposed experimental study will elucidate the effect(s) of magma mixing on the mobility of sulfur and sulfur-affine elements. In particular, this study investigates the interaction of sulfur-rich magmas coming from the mantle that mix with more evolved magmas that are typically stored for extended times in magma chambers below the volcanic edifice and have relatively low sulfur concentrations. Understanding the behavior of sulfur during such mixing should significantly improve our ability to forecast volcanic behavior. In the atmosphere, volcanic-released sulfur (often during magma mixing) modulates climate and leads to acid rain in humid volcanic regions. Furthermore, sulfur mobility during magma mixing is thought to facilitate metal transport from silicate melt to magmatic aqueous fluids that are responsible for the evolution of societally important magmatic-hydrothermal ore deposits. A quantitative understanding of how sulfur is mobilized and how it facilitates mass transport during magma mixing of andesite and dacite magma remains unexplored experimentally. As magmas hybridize during diffusive re-equilibration, sulfur-bearing phase stability is investigated as a function of time and oxidation state. Given differential diffusivities of different components in diffusion-couple experiments, diffusive gradients lead to transient local environments, in which sulfides and/or sulfates may in one spot be precipitated while in another area they may be dissolved. This drives complex mass transfer between the mafic and felsic magma. Reduced and oxidized conditions will allow the team to assess the role of sulfur oxidation state on these processes.

拟议的实验研究将阐明岩浆混合对硫和硫酸含量元素的迁移率的影响。特别是，这项研究研究了来自地幔富含硫的岩浆的相互作用，这些岩浆与更具进化的岩浆混合在一起，通常在火山建筑以下的岩浆腔室中存储，并且硫浓度相对较低。了解这种混合过程中硫的行为应显着提高我们预测火山行为的能力。在大气中，火山释放的硫（通常在岩浆混合期间）调节气候，并导致潮湿的火山区域酸雨。此外，岩浆混合过程中的硫迁移率被认为促进了从硅酸盐融化到岩浆水性液体的金属转运，这些液体负责社会上重要的岩浆岩浆 - 水热矿石的演变。对安山岩和麦岩浆岩浆混合过程中如何促进硫的方式的定量理解，它如何促进质量转运。随着岩浆在扩散重新校准期间杂交时，研究了含硫相稳定性，作为时间和氧化态的函数。鉴于扩散群实验中不同成分的差异扩散率，扩散梯度导致瞬时局部环境，其中硫化物和/或硫酸盐可能会在一个位置沉淀，而在另一个区域可能会溶解它们。这驱动了镁铁质和长英质岩浆之间的复杂传质。减少和氧化的条件将使团队能够评估硫氧化状态在这些过程中的作用。