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: 0711354
• 负责人: Kari Cooper
• 金额: $ 6.53万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard 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=0711354&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.

控制地壳岩浆（熔融岩石）演化的过程很重要，因为它们控制着火山的活动，从而控制着大气和生物圈。由于无法直接观测到岩浆储层，因此很难理解能够产生特定类型喷发或成分的时间尺度和过程范围。因此，有必要通过研究作为火山爆发产物的自然例子来推断它们的行为。但是，这些信息只以不同的“快照”形式出现，因此很难理解为连续过程或一组关联过程的结果。该项目将结合现场和实验室数据的法医方法，结合岩浆过程的计算机模型，将这些快照连接到地下发生的连续“电影”中，从而提供这些过程的更完整的画面。这样，地质学家就能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。所采用的方法是获得u系列不平衡数据，并结合微量元素扩散，以确定岩浆储层中特定事件的时间尺度。研究人员还将测量矿物颗粒中的主要元素和微量元素剖面，以确定岩浆过程的化学特征。将这些数据结合起来，就可以提供岩浆储层中发生的事件的时间表。总体目标是识别和区分在喷发产物中测量的晶体中产生化学和结构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分带在多大程度上需要开放系统过程，而不是简单地从封闭系统岩浆储层的不同区域收集晶体，来解决这个更大问题的一部分。为了做到这一点，他们将进行一项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；(2)将合成晶体数据与智利奎兹卡普火山自然例子中的晶体测量结果进行比较。结合这两种方法，可以做出具体的预测，这些预测可以通过观察从更深的储层喷发出来的岩浆产物的化学成分的逐渐变化来独立验证。