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: $ 8.89万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751310
• 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: ReduxViscosity 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 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 SystemsDuring 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.

这项研究计划包括三个截然不同但相辅相成的火山学主题。a)硅酸盐熔体粘度模型：还原粘度是控制岩浆迁移和喷发的最重要的物理性质。2008年，我们发表了预测天然含水硅酸盐熔体粘度的“GRD模型”。虽然被广泛认为是最好的模型，但由于使用该模型的科学家越来越多样化，新的第二代模型早就应该出现了。新的模型将：i)更准确(相对于实验数据库)，ii)覆盖更大范围的熔体成分(例如，金伯利岩)，iii)考虑更高的压力，iv)添加挥发性二氧化碳，v)考虑Fe3+和Fe2+两种物种的铁。最重要的是，该模型将基于熔体协同松弛的Adams-Gibbs理论，该理论将传输(粘度)和热力学性质(熵、热容)联系起来。由此产生的模型将捕捉到几乎所有在地球和其他行星上发现的硅酸盐熔体，并具有更强的理论基础，从而能够预测其他热化学性质。b)熔岩穹顶的流变行为：实验它位于岩石力学领域和实验火山学之间的交界处。这项实验的目的是确定火山物质在火山喷发过程中的升高条件下的流变性。得到的数据集被用来建立本构方程，该方程预测作为应力、应变率、温度和晶体含量的函数的天然岩浆的流动。本构关系是更复杂、更准确地模拟火山喷发的关键。C)流态化火山系统中的颗粒磨损在上升和喷发过程中，岩浆通常会变成高速、富含气体、充满颗粒的悬浮体。这些环境支持“磨损”--即强烈、持续的颗粒-颗粒相互作用，导致悬浮货物的颗粒尺寸减小和形状重塑。天然火山沉积物中晶体和岩石碎屑的形状和表面性质直接影响岩浆运移和喷发的条件，包括流动状态(层流和湍流)、上升速度和停留时间。我们将使用实验来研究气体和流体射流在与火山系统相当的条件下的磨损。这些实验阐明了磨损率与颗粒密度、能量和时间的函数关系。我们的目标是创造一种范例，利用火山沉积物中“磨碎”(即磨蚀)的岩屑和晶体的性质来推断运输和喷发条件。