Collaborative Research: Structure and properties of geofluids and their impact on fluid migration in subduction zones

合作研究：俯冲带地流体的结构和性质及其对流体运移的影响

• 批准号: 2246803
• 负责人: Yanbin Wang
• 金额: $ 38.98万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2246803&HistoricalAwards=false
• 关键词: Collaborative; Research; Structure; properties; geofluids

Magmatism plays a vital role in transporting matter and energy from the Earth’s deep interior to the surface. While some eruptions are explosive, others erupt without major explosive behavior, leading to different natural hazards for each eruptive style. These distinct eruption styles are controlled by the fundamental physical properties of magma, particularly viscosity, and density. The viscosity of magma is highly dependent on the atomic-scale structure of the magma, influenced by magma composition, temperature, pressure, and the presence of dissolved gasses such as water vapor. In this study, the researchers aim to obtain fundamental physical constraints on the structure and viscosity of magma at conditions relevant to the Earth’s interior. We will combine the experimentally derived physical properties of magma and fluids with numerical simulations to predict how magmas migrate from the Earth’s subducting plates. It is the migration of this material that ultimately leads to eruptions at the surface, but the complex role of viscosity in magma transport makes it difficult to trace material from its source in the interior to the surface. The project will provide training for the next generation of Earth Scientists at various stages of their career, including high school, undergraduate, and graduate students, as well as post-doctoral scholars. Although extensive research has been done to constrain the elastic and transport properties of fluids and melts at conditions relevant to the Earth’s interior, the combined effects of pressure, temperature, and dissolved water remain poorly constrained at the conditions of the upper mantle where these melts are produced. This research will couple lab- and synchrotron-based experimental data to pressures up to 20 GPa with first-principles molecular dynamics (FPMD) simulations, with the objective to determine the local melt structure, and fluid and melt viscosity to high pressures and temperatures. This work will quantify the structure and properties of aqueous fluids with dissolved albite, in addition to albite and basaltic melts with and without water. The results will provide insight into how pressure, temperature, and composition affect the structure and viscosity of polymerized aluminosilicate melts at mid-mantle depths and illuminate the causes of observed pressure anomalies on viscosity. The resulting viscosities will be integrated into two-phase flow models in the slab-arc system and the upwelling region above the mantle transition zone to assess the pathways of melt migrations through state-of-the-art geodynamical models. These models will assess how the pattern of fluid migration changes with slab age and subduction rate, slab thermal structure, and the distribution and volume of fluid sources in the subducting slab. The resulting work will assess the impact of fluid volumes due to melting and whether melting alone is sufficient to focus melts into a narrow region beneath volcanic regions.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.

岩浆作用在将物质和能量从地球内部深处输送到地表方面发挥着至关重要的作用，而有些喷发是爆炸性的，而另一些喷发则没有重大的爆炸行为，从而导致每种喷发类型产生不同的自然灾害。岩浆的基本物理特性，特别是粘度和密度 岩浆的粘度高度依赖于岩浆的原子级结构，受岩浆成分、温度、压力和溶解物的存在的影响。在这项研究中，研究人员的目标是获得与地球内部相关的条件下岩浆结构和粘度的基本物理约束，我们将通过数值模拟结合实验得出的岩浆和流体的物理特性来进行预测。岩浆如何从地球俯冲板块迁移，正是这种物质的迁移最终导致地表喷发，但粘度在岩浆输送中的复杂作用使得很难追踪物质的来源。该项目将为处于职业生涯各个阶段的下一代地球科学家提供培训，包括高中生、本科生和研究生，以及博士后学者。在与地球内部相关的条件下，流体和熔体的弹性和传输特性，压力、温度和溶解水的综合影响在产生这些熔体的上地幔条件下仍然受到很少的限制。和基于同步加速器的实验数据通过第一原理分子动力学 (FPMD) 模拟，可承受高达 20 GPa 的压力，目的是确定高压和高温下的局部熔体结构以及流体和熔体粘度。这项工作将量化水性流体的结构和特性。溶解的钠长石，以及有水和无水的钠长石和玄武岩熔体。结果将深入了解压力、温度和成分如何影响聚合铝硅酸盐的结构和粘度。地幔中部深度的熔体，并阐明观察到的粘度压力异常的原因，由此产生的粘度将被整合到板弧系统和地幔过渡带上方的上升流区域的两相流模型中，以评估熔体的路径。这些模型将通过最先进的地球动力学模型评估流体迁移模式如何随板片年龄和俯冲速率、板片热结构以及俯冲板片中流体源的分布和体积而变化。由此产生的工作将评估融化引起的流体量的影响，以及仅融化是否足以将熔体集中到火山区域下方的狭窄区域。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持以及更广泛的影响审查标准。