Collaborative Research: Quantifying the Thermal History of Crustal Magma Storage Through Crystal Records and Numerical Modeling

地球内部岩浆形成和储存的过程？对认识火山和火山灾害具有重要意义。之前由nsf支持的两个pi的研究表明，在俄勒冈州的胡德山，只有一小部分（很可能不到1%）的岩浆储存在地下的总时间是在足够高的温度下度过的，这样岩浆就可以很容易地动员和喷发。其他火山的部分数据集表明，这些条件很普遍，但这还有待检验。这个新项目将解决这样的问题：岩浆是否普遍受制于与胡德山类似的储存条件，以及火山下岩浆储存过程的基本控制因素是什么。该项目将通过对地表下生长的晶体的地球化学测量来解决这些问题，并将提供有关岩浆储存持续时间和温度的信息。这些结果将与先进的岩浆房计算机模型相结合，探索岩浆添加、热损失和岩浆成分变化的相互作用。除了对火山学和地球化学科学的贡献外，这项工作还将对了解火山危害产生影响。特别是，不同岩浆体处于可喷发状态的时间百分比（以及，至关重要的是，控制这一时间百分比的过程）将提供对不同火山所代表的危险的深入了解，也将为解释地震成像或其他遥感应用的结果提供更好的背景。该项目将通过为每个机构的一名博士后研究员和三名研究生提供支持，为培养下一代STEM劳动力做出贡献。俄勒冈州立大学和UCD的本科生也将参与这项研究。该项目将把观测数据与选定火山系统的数值模拟结合起来，以解决更广泛的问题：？地球上岩浆储存的热和物理条件是什么？这些条件的主要控制因素是什么？该项目将以胡德山的结果和现有的部分数据集为基础，探索与岩浆系统成熟有关的两个高优先级的具体问题：1)浅层储层体积的作用是什么？岩浆储存条件在1至10立方公里的喷发体积上是如何变化的？2)作文的作用是什么？英安岩系和流纹岩系的岩浆储存热史是否有区别？该项目的结果将提供一些关于岩浆储存热历史的第一批观测数据，而数值模拟将使我们能够将这些结果纳入一个可推广的热力学框架。这些结果将为岩浆储存的物理条件提供一个关键的、基于观测的认识，这反过来将有助于更好地理解岩浆储层过程。最终，我们将建立一个框架，以了解晶体记录的各个方面，如矿物热压测量的解释，纹理信息和矿物分带捕获的时间尺度。该项目的结果将对火成岩岩石学/地球化学领域产生广泛的影响，为岩浆储层内的过程提供一个概念性框架。至关重要的是，时间尺度与不同的过程相关。

The processes involved in formation and storage of magma within the Earth?s upper crust are of fundamental importance to understanding volcanoes and volcanic hazards. Previous NSF-supported research by two of the PIs showed that at Mount Hood, Oregon, only a small fraction (most likely less than 1%) of the total time that magma is stored underground is spent at high enough temperatures that would allow magma to be easily mobilized and erupted. Partial data sets for other volcanoes suggest that these conditions are widespread, but this remains to be tested. This new project will address the questions of whether magmas in general are subject to similar storage conditions as those seen at Mount Hood, and what are the fundamental controls on the processes of magma storage underneath volcanoes. The project will address these questions using geochemical measurements of crystals that grew beneath the surface and will provide information on the duration and temperature of magma storage. These results will be combined with advanced computer models of magma chambers to explore the interplay of magma addition, heat loss and changes in magma composition. In addition to contributions to the science of volcanology and geochemistry, the work will have impacts in understanding volcanic hazards ? in particular, the percentage of time that different magma bodies spend in an eruptible state (and, critically, the processes that control that percentage of time) will provide insight into the hazard represented by different volcanoes and will also provide a better context to interpret the results of seismic imaging or other remote-sensing applications. This project will contribute to training the next-generation STEM workforce by providing support for a postdoctoral researcher and three graduate students, one at each institution. At OSU and at UCD undergraduates will also take part in the research.This project will integrate observational data with numerical modeling for selected volcanic systems, to address the broader question: ?What are the thermal and physical conditions of magma storage in the Earth?s crust, and what are the primary controls on those conditions?? This project will build on our results for Mount Hood and on existing partial data sets by exploring two high-priority specific questions that pertain to the maturation of magmatic systems: 1) What is the role of volume of the shallow reservoir? How do magma storage conditions vary over erupted volumes of 1 to 10 km3? and 2) What is the role of composition? Is there a difference between the thermal history of magma storage in dacitic and rhyolitic systems? The results of this project will provide some of the first observational data on the thermal histories of magma storage, and the numerical modeling will allow us to put these results into a generalizable thermodynamic framework. These results will provide a critical, observation-based understanding of the physical conditions of magma storage, which in turn will provide a better understanding of magma reservoir processes. Ultimately we will build a framework in which to understand various aspects of crystal records such as the interpretation of mineral thermobarometry, textural information, and time scales captured by mineral zonation. The results of this project will have broad implications within the field of igneous petrology/geochemistry by providing a conceptual framework for the processes that operate within magma reservoirs ? and crucially, the time scales relevant to the different processes.