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

地球内部岩浆的形成和储存过程？火山的上地壳是了解火山和火山灾害的根本重要性。两个PI先前由NSF支持的研究表明，在俄勒冈州的胡德山，岩浆在地下储存的总时间中只有一小部分（很可能不到1%）是在足够高的温度下度过的，这将使岩浆很容易被动员和喷发。其他火山的部分数据集表明，这些条件是普遍存在的，但这仍有待检验。这个新项目将解决的问题是，岩浆是否在一般情况下受到类似的存储条件，如在胡德山看到的，以及什么是火山下的岩浆存储过程的基本控制。该项目将通过对地表下生长的晶体进行地球化学测量来解决这些问题，并将提供有关岩浆储存时间和温度的信息。这些结果将与先进的岩浆房计算机模型相结合，以探索岩浆添加，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，这项工作还将对理解火山灾害产生影响。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）将有助于深入了解不同火山所代表的危险，并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，为培训下一代STEM劳动力做出贡献。在俄勒冈州立大学和UCD的本科生也将参加研究。该项目将结合选定的火山系统的观测数据与数值模拟，以解决更广泛的问题：？岩浆在地球上储存的热条件和物理条件是什么？的地壳，以及对这些条件的主要控制是什么？？该项目将建立在我们的结果胡德山和现有的部分数据集，通过探索两个高优先级的具体问题，涉及到岩浆系统的成熟：1）是什么作用的体积的浅储层？在1至10立方千米的喷发体积内，岩浆储存条件如何变化？（2）作文的作用是什么？英安质和流纹质系统中岩浆储存的热历史是否有差异？这个项目的结果将提供一些第一次观测数据的热历史的岩浆储存，和数值模拟将使我们能够把这些结果到一个概括的热力学框架。这些结果将提供一个关键的，基于观测的了解岩浆储存的物理条件，这反过来又将提供一个更好的了解岩浆库的过程。最终，我们将建立一个框架，以了解晶体记录的各个方面，如矿物温压，纹理信息的解释，并通过矿物环带捕获的时间尺度。这个项目的结果将有广泛的影响，在该领域的火成岩岩石学/地球化学提供了一个概念框架的过程中，岩浆水库？最重要的是，与不同过程相关的时间尺度。

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.