Collaborative Research: Thermodynamics of Magma Mixing

合作研究：岩浆混合热力学

• 批准号: 1551056
• 负责人: Frank Spera
• 金额: $ 25.2万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1551056&HistoricalAwards=false
• 关键词: Collaborative; Research; Thermodynamics; Magma; Mixing

Molten rock (magma) forms at tens to hundreds of kilometers below Earth's surface. These magmas can ascend, and each year on Earth, about 30 cubic kilometers erupts or stalls, much of it within a few thousand meters of the surface. Transport and storage of magma in the crust (uppermost layer of the solid Earth) is associated with the formation of many strategically- and economically-important mineral resources including gold, platinum, chromium, diamonds and other gemstones and represents a source of untapped green energy called geothermal heat. The research carried out in this study advances infrastructural knowledge of how magmas evolve chemically and thermally through interactions with crust and as they cool, mix, and eventually solidify. Because all magmas initially contain small amounts of dissolved water and carbon dioxide, as magma cools and crystallizes, it often becomes a bubbly mixture containing high-pressure fugitive gas that can produce explosive eruptions, thereby posing risks to humans, property and ecosystems. This research seeks to better understand these phenomena based on the latest results from condensed matter physics, fluid mechanics, and chemical thermodynamics, all in the context of complex system behavior.Magma emplaced in the crust is a classic example of a complex, open system where magmas and crustal host rock exchange material and energy. The thermochemical evolution of magma subject to this exchange is responsible for much of the compositional diversity observed on Earth. This research applies chemical thermodynamics to predict from first-principles the products of magma crystallization and to relate these products to the amount of geothermal energy that flows to the environment. Open system magmatic behavior that emphasizes the consequences of complete blending of two distinct magma batches (a process called magma mixing) is modeled using two mass and energy constrained computational tools: an exploratory model that utilizes simplified mixing thermodynamics and a more complex model, called the Magma Chamber Simulator, that employs state of the art thermodynamics. Simulations using these codes will generate a theoretical magma mixing taxonomy that will classify thermal and chemical characteristics of mixing end-members and products. This taxonomy will be tested by applying it to carefully chosen volcanic and plutonic rock suites that show clear evidence of magma mixing. Analysis of mixed magma products will define mass and thermal consequences of mixing that can be used to refine models of eruption, magma emplacement, and mass and energy exchange from deeper to shallower levels in Earth. Both computer codes will be enhanced to better capture the open-system characteristics identified by these studies, and public distribution of these computer resources to the earth and planetary sciences community will augment computational analysis of magma formation and evolution. The ultimate end product of this research will be enhanced understanding of the transport, storage, and eruption of molten rock, an integral part of the planetary plate tectonic recycling process.

熔岩（岩浆）在地球表面以下数十至数百公里处形成。这些岩浆可以上升，在地球上，每年大约有30立方公里的岩浆喷发或停滞，其中大部分都在距离地表几千米的范围内。岩浆在地壳（固体地球的最上层）中的运输和储存与许多具有战略和经济重要性的矿产资源（包括金、铂、铬、钻石和其他宝石）的形成有关，并且代表了称为地热的未开发的绿色能源的来源。在这项研究中进行的研究推进了岩浆如何通过与地壳的相互作用以及它们冷却，混合并最终固化的化学和热演化的基础知识。由于所有岩浆最初都含有少量的溶解水和二氧化碳，随着岩浆冷却和结晶，它往往会变成一种含有高压逃逸气体的气泡混合物，这种气体可能产生爆炸性喷发，从而对人类、财产和生态系统构成风险。本研究试图更好地理解这些现象的基础上，凝聚态物理学，流体力学和化学热力学的最新成果，所有在复杂的系统行为的背景下，岩浆侵位在地壳中是一个典型的例子，一个复杂的，开放的系统，岩浆和地壳寄主岩石交换物质和能量。岩浆的热化学演化受到这种交换是负责在地球上观察到的成分多样性。这项研究应用化学热力学从第一原理预测岩浆结晶的产物，并将这些产物与流向环境的地热能的量联系起来。开放系统的岩浆行为，强调两个不同的岩浆批次（一个过程称为岩浆混合）的完全混合的后果是使用两个质量和能量约束的计算工具建模：一个探索性的模型，利用简化的混合热力学和一个更复杂的模型，称为岩浆房模拟器，采用最先进的热力学。使用这些代码的模拟将产生一个理论上的岩浆混合分类，将混合端元和产品的热和化学特征进行分类。这种分类法将通过将其应用于精心挑选的火山岩和深成岩套来进行测试，这些套岩显示出岩浆混合的明确证据。对混合岩浆产物的分析将确定混合的质量和热后果，这些结果可用于改进喷发、岩浆就位以及地球中从深到浅的质量和能量交换的模型。这两种计算机代码将得到增强，以更好地捕捉这些研究所确定的开放系统特征，并将这些计算机资源公开分发给地球和行星科学界，这将增强岩浆形成和演化的计算分析。这项研究的最终结果将是提高对熔融岩石的运输，储存和喷发的理解，这是行星板块构造循环过程的一个组成部分。