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

S？？地球上地壳内岩浆形成和储存的过程对理解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，这使得岩浆很容易被流动和喷发。其他火山的部分数据集表明，这些情况普遍存在，但这一点仍有待检验。这个新项目将解决以下问题：岩浆总体上是否受到与胡德山类似的存储条件的影响，以及对火山下岩浆存储过程的基本控制是什么。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室计算机模型相结合，以探索岩浆添加、热损失和岩浆成分变化之间的相互作用。除了对火山学和地球化学学的贡献外，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(关键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害，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。该项目将通过为一名博士后研究人员和三名研究生(每个机构一名)提供支持，帮助培训下一代STEM劳动力。俄亥俄州立大学和加州大学的本科生也将参与这项研究。这个项目将把观测数据与选定的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？S地壳，这些条件的主要控制因素是什么？该项目将以我们对胡德山的研究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度优先的具体问题：1)浅层储集层体积的作用是什么？在1到10千米的喷发量上，岩浆储存条件是如何变化的？2)作文的作用是什么？英安质系统和流纹岩系统的岩浆储存热历史有区别吗？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，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中。这些结果将提供对岩浆储存物理条件的关键的、基于观察的了解，这反过来又将提供对岩浆储存过程的更好的了解。最终，我们将建立一个框架，在其中理解晶体记录的各个方面，例如矿物热压计的解释、结构信息和矿物分带捕获的时间尺度。这个项目的结果将在火成岩岩石学/地球化学领域产生广泛的影响，因为它为岩浆储集层内运行的过程提供了一个概念框架？至关重要的是，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.