Magma Rheology, Transport, and Eruption: Field, Experiments and Models

岩浆流变学、输送和喷发：现场、实验和模型

• 批准号: RGPIN-2018-03841
• 负责人: Russell, James
• 金额: $ 4.44万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=663935
• 关键词: Magma; Rheology; Transport; Eruption; Field

This research program comprises 3 distinct but complementary themes in volcanology.******A) A Model for Silicate Melt Viscosity: Redux***Viscosity is the most important physical property governing transport and eruption of magma. In 2008, we published the "GRD model" for predicting the viscosity of natural hydrous silicate melts. Although widely accepted as the best model available, due to the increasing diversity of scientists using the model a new 2nd generation model is overdue. The new model will: i) be more accurate (relative to the experimental database), ii) span a wider range of melt compositions (e.g., kimberlite), iii) account for higher pressures, iv) add the volatile CO2, and v) allow for iron as both species Fe3+ and Fe2+. Most importantly, the model will be based on the Adams-Gibbs theory for cooperative relaxation of melts, which connects transport (viscosity) and thermodynamic properties (entropy, heat capacity). The resulting model will capture virtually all silicate melts found on Earth and other planets, and have a stronger theoretical basis allowing for prediction of other thermochemical properties.******B) Rheological behaviour of lava domes: Experiments & models***Magma rheology is key to understanding and predicting the styles and intensities of volcanic eruption. The Rock Mechanics of Volcanic Systems is a new, dynamic, and highly competitive area of research; it lies at the interface between the fields of rock mechanics and experimental volcanology. The goal of this experimentation is to establish the rheological properties of volcanic materials at the elevated conditions attending volcanic eruption. The resulting datasets are used to build constitutive equations that predict the flow of natural magmas as a function of stress, strain-rate, temperature, and crystal content. The constitutive relationships are key to more sophisticated and accurate modelling of volcanic eruptions. ******C) Particle Attrition in Fluidized Volcanic Systems***During ascent and eruption, magmas commonly become high velocity, gas-rich, particle-laden suspensions. These environments support “attrition” - that is, vigorous, sustained particle-particle interactions causing grain size reduction and reshaping of the suspended cargo. The shapes and surface properties of crystals and rock fragments in natural volcanic deposits directly inform on the conditions attending magma transport and eruption, including, flow regime (laminar vs. turbulent), ascent velocity, and residence time. We will use experiments to study attrition in gas and fluid jets at conditions comparable to volcanic systems. The experiments elucidate the mechanisms and rates of attrition as a function of particle density, energy, and time. Our goal is to create a paradigm for using the properties of the "milled” (i.e. attrited) lithics and crystals in volcanic deposits to infer transport and eruption conditions.

该研究计划包括3个不同但完整的火山学主题。**** a）硅酸盐熔体粘度的模型：redux ****粘度是管理岩浆运输和喷发的最重要的物理特性。 2008年，我们发表了“ GRD模型”，用于预测天然含水硅熔体的粘度。尽管被广泛接受为最佳模型，但由于使用该模型的科学家的多样性越来越多，新的第二代模型过期了。新模型将：i）更准确（相对于实验数据库），ii）跨越更大范围的熔体组成（例如，金伯利特），iii）考虑到更高的压力，iv）添加挥发性二氧化碳和v）允许铁作为Fe3+和Fe2+的铁作为铁。最重要的是，该模型将基于与融化的合作放松的Adams-Gibbs理论，该理论连接运输（粘度）和热力学特性（熵，所得模型将捕获地球和其他行星上几乎所有的硅胶熔体，并且具有更强的理论基础，并具有更强的理论基础。模型****岩浆流变学是理解和预测火山喷发的风格和强度的关键。火山系统的岩石力学是一个新的，动态且竞争激烈的研究领域。它位于岩石机械和实验火山学场之间的界面。该实验的目的是在火山喷发的升高条件下建立火山材料的流变特性。所得数据集用于构建构成方程，以预测自然岩浆的流动，这是应力，应变率，温度和晶体含量的函数。构成关系是火山喷发更复杂和准确建模的关键。 ***** c）流化的火山系统中的颗粒损耗****在上升和喷发过程中，岩浆通常会变成高速，富含气体的颗粒，含粒子的悬浮液。这些环境支持“损耗” - 即剧烈的，持续的颗粒粒子相互作用，从而导致谷物尺寸减少并重塑悬浮的货物。天然火山沉积物中晶体和岩石碎片的形状和表面特性直接告知参加岩浆传输和喷发的条件，包括流动状态（层流与湍流），上升速度和停留时间。我们将使用实验在与火山系统相当的条件下研究气体和流体喷气机的尝试。该实验阐明了尝试的机制和速率，这是粒子密度，能量和时间的函数。我们的目标是创建一个范式，用于使用火山沉积中的“铣削”（即归因于晶体）的特性来推断运输和喷发条件。