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: 1250414
• 负责人: Philipp Ruprecht
• 金额: $ 17.38万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1250414&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亲和元素迁移率的影响。特别是，这项研究调查了来自地幔的富含硫的岩浆与更演化的岩浆的相互作用，这些岩浆通常在火山大厦下方的岩浆室中储存较长时间，并且硫浓度相对较低。了解硫在这种混合过程中的行为应该会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（通常在岩浆混合过程中）会调节气候并导致潮湿火山地区的酸雨。此外，岩浆混合过程中的硫流动性被认为促进了金属从硅酸盐熔体到岩浆含水流体的迁移，这导致了社会重要的岩浆热液矿床的演化。对硫如何流动以及如何促进安山岩和英安岩浆混合过程中的质量传输的定量理解尚未通过实验进行探索。当岩浆在扩散再平衡过程中混合时，研究了含硫相稳定性随时间和氧化态的变化。考虑到扩散偶实验中不同组分的扩散率不同，扩散梯度会导致瞬态局部环境，其中硫化物和/或硫酸盐可能在一个位置沉淀，而在另一区域可能溶解。这驱动了镁铁质和长英质岩浆之间复杂的质量传递。还原和氧化条件将使团队能够评估硫氧化态对这些过程的作用。

项目成果

The Survival of Mafic Magmatic Enclaves and the Timing of Magma Recharge

镁铁质岩浆包体的生存和岩浆补给的时间

• DOI: 10.1029/2020gl087186
• 发表时间: 2020-07
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Ruprecht, Philipp;Simon, Adam C.;Fiege, Adrian
• 通讯作者: Fiege, Adrian