Collaborative Research: Experimental Investigation of Magmatic Processes at Volcan Quizapu

沿着俯冲带(弧形)发生的火山喷发通常被解释为由新岩浆涌入其浅层储存系统所触发。该项目旨在通过测试喷发物质的结构和成分保持这一年代学的前提，来探索弧状岩浆在其所携带的“水晶货物”上的温度、压力、水分和成分的后期变化。实验样品和自然样品的比较将有助于揭示岩浆混合和喷发之间发生的岩浆室和过渡过程。智利安第斯火山历史上的两次喷发，一次是热液喷发，一次是爆炸性喷发，在以前的研究中已经被描述为岩石学和地球化学性质。有证据表明，这是一个以英安岩为主的岩浆系统，其中有单幕的、引发喷发的安山岩浆涌入。这些相互作用的相对简单使奇扎普成为一个理想的起点，可以进行有针对性的实验研究，解决与岩浆混合和上升/喷发有关的问题。研究的主要内容包括限制斜长石和角闪石对扰动的再吸收/去稳定化动力学，因为这些矿物保存了喷发前岩浆储存条件的证据。这项研究的目的是：(1)建立奇扎普英安岩和安山岩的喷发前环境条件；(2)通过一系列阶梯加热实验检验关键温度计和湿度计的响应时间；(3)探索筛状斜长石的形成条件；(4)通过高分辨率化学分析和扩散模拟，广泛考察晶体尺度对热力学扰动的响应。这些结果将对中等成分弧状岩浆之间的岩浆混合过程具有普遍意义，不仅因为再补充触发的奇扎普事件是典型的弧形火山，而且还因为研究重点所关注的晶体尺度过程(卤素对角闪石组成和稳定性的影响、加热时斜长石溶解动力学以及通过几种已提出的机制形成筛状结构)与广泛的岩浆环境密切相关。

Volcanic eruptions taking place along subduction zones (arcs) are commonly interpreted as triggered by the influx of new magma to their shallow storage systems. This project aims to explore the late-stage changes in temperature, pressure, water content, and composition of arc magmas on the "crystal cargo" they carry, by testing the premise that the textures and compositions of erupted materials preserve this chronology. Comparison of experimental and natural samples will shed light on magma chamber and transit processes occurring between magma mixing and eruption.Two historical eruptions of Volcan Quizapu (Chilean Andes), one effusive and one explosive, have been characterized petrologically and geochemically in prior studies. Evidence points to a magmatic system of predominantly dacite with single-episode, eruption-triggering influxes of andesitic magma. The relative simplicity of these interactions makes Quizapu an ideal starting point for a targeted experimental study addressing questions related to magma mixing and ascent/eruption. Key lines of inquiry include constraining resorption/de-stabilization kinetics of plagioclase and amphibole in response to perturbation, as these minerals preserve evidence of magma storage conditions prior to eruption. The goals of this investigation are to (1) establish pre-eruption environmental conditions of Quizapu dacite and andesite, (2) examine response times of key thermobarometers and hygrometers through a series of step-heating experiments, (3) explore the formation conditions of sieve-textured plagioclase, and (4) broadly examine crystal-scale responses to thermodynamic perturbations through high-resolution chemical analysis and diffusion modeling. The results will have general implications for magma mixing processes among intermediate-composition arc magmas, not only because the recharge-triggered Quizapu events are typical of arc volcanoes, but also because the crystal-scale processes on which the study focuses (the influence of halogens on amphibole composition and stability, plagioclase dissolution kinetics upon heating, and formation of sieve-texture via several proposed mechanisms) are germane to a broad spectrum of magmatic settings.