Collaborative research: Assessing changes in the state of a magma storage system over caldera-forming eruption cycles, a case study at Taupo Volcanic Zone, New Zealand

最大的火山喷发是罕见的事件，但可以代表一场全球灾难。较小规模的喷发仍可能产生重大(数十亿美元)的经济影响，并可能影响大量人的生活和生计，即使是在远离喷发的地方(例如，2010年冰岛相对较小的喷发)。该项目的重点是新西兰陶波火山带(TVZ)，作为一个大型和非常活跃的火山系统的案例研究，并将侧重于更好地了解地表以下岩浆体在大喷发之前、期间和之后的温度和流动性如何变化。这项研究将有助于我们理解产生如此大规模喷发的火山(例如美国的黄石火山系统)，并将为解释这些和其他活火山的实时危险监测提供关键的背景。此外，该项目将包括一名K-12教师的研究经验，以及将广泛传播的基于标准的新物理、化学和数学课程的开发。这一雄心勃勃的项目将更全面地了解支配硅质岩浆系统行为的过程，特别是那些导致大型火山口形成喷发的过程。这将通过将年龄数据与技术开发区喷发岩浆的结晶部分(斜长石和锆石)和液体部分(熔融包裹体)的成分数据结合起来的详细研究来实现。这些数据将为使用两条主要研究路线的新方法提供基础：1)通过将U系列测量得到的斜长石晶体群体的绝对年龄与微量元素扩散模型相结合来限制晶体在给定温度下的最大停留时间，从而限制喷发前岩浆储存的热历史；以及2)通过原位测量原生矿物和副矿物以及熔体包裹体(锆石中的18O，锆石中的Hf；斜长石和熔融包裹体中的铅同位素)，这将提供岩浆系统在储集层内跨时间和空间混合程度的量度，以及地幔和地壳来源对储集层贡献的变化。这种方法的独特优势在于，它将允许同时描述这些硅质储集层的热、成分和物理演化。因此，这项研究的结果将与其他硅质火山系统广泛相关，并将是在提高我们解释火山监测数据的能力方面向前迈出的重要一步。大型硅质系统是全球火山活动的终端成员，通过将这项研究的结果与其他正在进行的项目的结果联系起来，将开发更一般的控制火山下岩浆储存热条件的模型。

The largest volcanic eruptions are rare events but can represent a global catastrophe. Smaller eruptions may still have significant (billions of dollars) economic impacts and may affect the lives and livelihoods of large numbers of people, even in places distant from the erupting volcano (e.g., the relatively small eruption in Iceland in 2010). This project focuses on the Taupo Volcanic Zone (TVZ) in New Zealand as a case study of a large and very active volcanic system, and will focus on developing a better understanding of how the temperature and mobility of a magma body below the surface changes before, during, and after a major eruption. This study will contribute to our understanding of the volcanoes that produce such large eruptions (for example, Yellowstone volcanic system in the US), and will provide critical context for interpretation of real-time hazard monitoring at these and other active volcanoes. In addition, the project will include research experience for a K-12 teacher and development of new standard-based physics, chemistry and mathematics curriculum that will be disseminated broadly.This ambitious project will develop a more complete understanding of the processes that govern the behavior of silicic magmatic systems, and, in particular, those that lead to the development of large, caldera-forming eruptions. This will be accomplished by a detailed study coupling age data with compositional data for both crystalline (plagioclase and zircon) and liquid (melt inclusions) parts of the erupted magma at the TVZ. These data will provide the foundation for a novel approach using two primary lines of investigation: 1) Constraints on the thermal history of pre-eruptive magma storage by coupling absolute ages for plagioclase crystal populations derived from U-series measurements with trace element diffusion models to constrain the maximum residence time of crystals at a given temperature; and 2) Quantification of the compositional heterogeneity of crystals and melt components, through in-situ measurements of trace-element and isotopic compositions in primary and accessory minerals and in melt inclusions (δ18O in zircon, εHf in zircon; Pb isotopes in plagioclase and melt inclusions), which will provide a measure of the degree to which the magma system is mixed across time and space within the reservoir as well as variations in the contributions of mantle and crustal sources to this reservoir. The unique strength of this approach is that it will allow simultaneous characterization of the thermal, compositional, and physical evolution of these silicic reservoirs. Therefore, the results of this study will be broadly relevant to other silicic volcanic systems and will represent an important step forward in improving our ability to interpret volcano monitoring data. Large silicic systems represent an end-member for volcanic activity globally, and more general models of the controls on the thermal conditions of magma storage beneath volcanoes will be developed by linking the results of this study with those from other ongoing projects.