Collaborative Research: Dynamics of caldera-scale rhyolitic magma systems

该项目的目标是对形成大型流纹岩岩浆系统并将其推向动荡和潜在喷发状态的动态过程建立新的理解。智利南部安第斯山脉拉古纳德尔莫勒火山场(LDM)的天然实验室为研究目前正在进行的岩浆迁移、储集层生长和地壳变形的系统动力学提供了一个极好的机会。该项目将：(1)查明目前动乱的原因，包括：(A)测量目前在大熔岩下的一个或多个岩浆体的大小、深度和熔融比例；(B)估计这些参数如何随时间演变，以及(C)评估当前形变和更长期的~20000年的隆起是否反映了系统对玄武岩的补充；(2)将岩石学和地质年代学数据结合起来，以跟踪和模拟过去约100,000年来的结晶、冷却、岩浆混合和加热事件，并确定过去25,000年来流纹质熔岩的喷发是共享一个共同的浅层熔体来源，还是有更广泛的起源于地壳深处；以及(3)创建耦合的数值模型，将观测与各种时间尺度上的多相岩浆-地壳系统的物理和化学联系起来。由于地球最终将经历另一次形成火山口的流纹岩喷发，因此需要收集全面的信息并创建模型，真实地解释导致这些破坏性事件的动力学。迎接这一挑战需要了解：(1)推动这些系统组装和增长的缓慢地质过程、岩浆条件和结构变化，以及(2)复杂的多相系统在长(几年到几千年)和短(天到几个月)人类时间尺度上的动力学。目前还缺乏对这些过程之间的耦合的确切把握，因为它们在时间和空间上的规模都在许多数量级上。这个项目提供了一个独特的机会来研究这样一个系统的动力学，而岩浆迁移、储集层增长和惊人的地壳变形目前正在进行中。通过观察和新的建模方法探索这一前沿将产生对系统动力学的前所未有的洞察。

The objective of this project is to build a new understanding of the dynamic processes that create large rhyolitic magma systems and drive them into states of unrest and potential eruption. The natural laboratory at the Laguna del Maule volcanic field (LdM) in the Southern Andes of Chile presents a remarkable opportunity to investigate system dynamics while magma migration, reservoir growth, and crustal deformation are currently underway. This project will: (1) Ascertain the cause of the ongoing episode of unrest, including: (a) gauging the dimensions, depth, and melt fraction of the magma body or bodies currently beneath LdM; (b) estimating how these parameters evolve with time, and (c) assessing whether both current deformation, and longer term, ~20,000 year, uplift, reflects replenishment of the system with basalt; (2) Integrate petrologic and geochronologic data to track and model crystallization, cooling, magma mixing and heating events over the past ~100,000 years, and to determine whether the eruptive flare-up of rhyolitic lavas during the last 25,000 years shares a common, shallow source of melt or has more diffuse origins deeper in the crust; and (3) Create coupled numerical models that will link the observations to the physics and chemistry of the multi-phase magma-crust system over a variety of timescales. Since Earth will eventually experience another caldera-forming rhyolitic eruption, there is a need to gather comprehensive information and create models that realistically account for the dynamics that lead to these destructive events. Meeting this challenge will require understanding: (1) the slow geologic processes, magmatic conditions, and structural changes that propel assembly and growth of these systems, and (2) the dynamics of a complex multiphase system on both long (years to millennia), and short (days to months) human time scales. A firm grasp on the coupling among these processes is currently lacking because they operate on scales ranging over many orders of magnitude temporally and spatially. This project affords a unique opportunity to investigate the dynamics of such a system while magma migration, reservoir growth, and astonishing crustal deformation are currently underway. Exploring this frontier through both observations and novel modeling approaches will yield unprecedented insight into system dynamics.