Collaborative Research: Understanding the Dynamics of Magmatic Processes in the Crust: A Case Study of Volcán Quizapu, Chile

合作研究：了解地壳中岩浆过程的动力学：以智利 Quizapu 火山为例

• 批准号: 0711551
• 负责人: George Bergantz
• 金额: $ 23.07万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711551&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Dynamics; Magmatic

The processes controlling the evolution of magmas (molten rock) in the Earth's crust are important as they control the behavior of volcanoes, and so condition the atmosphere and biosphere. Understanding the timescales and range of process that can produce a specific type of eruption or composition has been difficult, as magma reservoirs are not directly observable. Hence it is necessary to infer their behavior by studying natural examples that are the products of volcanic eruptions. But this information appears only as distinct ''snapshots,'' and so difficult to understand as the result of a continuous process, or set of linked processes. This project will provide a more complete picture of these processes by combining a forensic approach using field and lab data from a particular eruption, with computer models of magma processes that can link the snapshots into a continuous ''movie'' of what happens in the subsurface. Geologists will then better understand how any characteristic snapshot arises, and how to better infer unseen process that shape the upper portion of Earth.The approach to be used is to obtain U-series disequilibria data in conjunction with trace-element diffusion to identify the time scales of particular events in the magma reservoirs. The investigators will also measure major- and trace-element profiles across mineral grains to identify chemical signatures of magmatic processes. When combined, these data can provide a schedule of events that have happened in the magma reservoir. The overarching goal is to identify and distinguish the fundamental classes of physical processes that produce the chemical and textural diversity in crystals measured in the erupted products. In this study, they will be able to address part of this larger question by examining to what extent the chemical zonation in crystals requires open-system processes as opposed to simply gathering crystals from different regions of a closed-system magma reservoir. In order to do that, they will conduct an integrated numerical and geochemical study to (1) develop numerical models that track the response of active (smart) crystals to chemical and physical changes in their magmatic environment, and (2) compare the resulting synthetic crystal data to measurements of crystals in a natural example at Volcn Quizapu in Chile. Combining these two approaches allows for specific predictions to be made that can be independently tested by looking at the progressive changes in the chemistry of the magmatic products erupted from the deeper reservoirs.

控制地壳中岩浆（熔融岩石）演化的过程很重要，因为它们控制着火山的行为，从而影响着大气和生物圈。由于无法直接观察到岩浆库，因此很难理解能够产生特定类型喷发或成分的过程的时间尺度和范围。因此，有必要通过研究火山爆发产物的自然例子来推断它们的行为。但是这些信息只是作为不同的“快照”出现，因此很难理解为一个连续过程或一组链接过程的结果。该项目将通过使用特定喷发的现场和实验室数据的法医方法与岩浆过程的计算机模型相结合，提供这些过程的更完整的图片，这些模型可以将快照链接到地下发生的连续“电影”中。地质学家将更好地了解任何特征快照是如何产生的，以及如何更好地推断塑造地球上部的看不见的过程。所使用的方法是获得U系列不平衡数据，结合微量元素扩散，以确定岩浆库中特定事件的时间尺度。研究人员还将测量矿物颗粒的主要和微量元素剖面，以确定岩浆过程的化学特征。当这些数据结合在一起时，可以提供岩浆库中发生的事件的时间表。总体目标是确定和区分产生喷发产品中测量的晶体中的化学和质地多样性的物理过程的基本类别。在这项研究中，他们将能够通过研究晶体中的化学环带在多大程度上需要开放系统过程来解决这个更大问题的一部分，而不是简单地从封闭系统岩浆库的不同区域收集晶体。为了做到这一点，他们将进行综合的数值和地球化学研究，以（1）开发数值模型，跟踪活性（智能）晶体对岩浆环境中化学和物理变化的响应，以及（2）将所得的合成晶体数据与智利Volcn Quizapu自然实例中的晶体测量进行比较。结合这两种方法可以做出具体的预测，通过观察从更深的储层喷发的岩浆产物的化学性质的渐进变化，可以独立地进行测试。