Collaborative Research: Thermodynamics of Magma Mixing

合作研究：岩浆混合热力学

• 批准号: 1551052
• 负责人: Wendy Bohrson
• 金额: $ 21.1万
• 依托单位: Central Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-15 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1551052&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)形成于地球表面以下数十至数百公里处。这些岩浆可以上升，每年在地球上大约有30立方公里的火山喷发或停止喷发，其中大部分在距离地表几千米的范围内。地壳(固体地球最上层)中岩浆的运输和储存与许多具有战略和经济意义的矿产资源的形成有关，包括金、铂、铬、钻石和其他宝石，是一种未开发的绿色能源，称为地热能。在这项研究中进行的研究促进了关于岩浆如何通过与地壳的相互作用以及当它们冷却、混合并最终凝固时以化学和热的方式演化的基础知识。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，它往往会变成含有高压逃逸气体的气泡混合物，可能会产生爆炸性喷发，从而对人类、财产和生态系统构成风险。这项研究基于凝聚态物理、流体力学和化学热力学的最新结果，试图更好地理解这些现象，所有这些都是在复杂系统行为的背景下。侵位在地壳中的岩浆是一个复杂的开放系统的经典例子，在这个系统中，岩浆和地壳主岩交换物质和能量。受这种交换影响的岩浆的热化学演化是地球上观察到的成分多样性的主要原因。这项研究应用化学热力学从第一性原理预测岩浆结晶的产物，并将这些产物与流入环境的地热能的量联系起来。开放系统岩浆行为强调两个不同岩浆批次完全混合的结果(称为岩浆混合过程)，使用两个质量和能量受限的计算工具来模拟：一个探索性模型利用简化的混合热力学，另一个更复杂的模型称为岩浆室模拟器，它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，该分类将对混合终端成员和产品的热和化学特征进行分类。这一分类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，这些岩石套显示出明显的岩浆混合证据。对混合岩浆产物的分析将确定混合的质量和热后果，可用于完善地球从深到浅的喷发、岩浆侵位和质量和能量交换模型。这两个计算机代码将得到改进，以更好地捕捉这些研究确定的开放系统特征，向地球和行星科学界公开分发这些计算机资源将增强对岩浆形成和演化的计算分析。这项研究的最终成果将是加深对熔岩的运输、储存和喷发的理解，熔岩是行星板块构造循环过程的组成部分。