Investigating shifts in magma genesis at the Atitlan volcanic centre, Guatemala

在过去的14 Ma期间，阿提特兰火山中心在三个阶段(阿提特兰一期14-11 Ma，阿提特兰二期，10-8 Ma，阿蒂兰三期1 Ma至今)产生了一系列火山产物，包括层状火山、穹隆和大小体积的火山沸石，其中三个阶段形成了火山口。这些火山口的轨迹反映了危地马拉弧前火山活动几乎无处不在的模式，即活动地点随着时间的推移向南/西南方向移动。该项目将研究阿提特兰中心火山产物的地球化学和岩石学，并产生一个概念性模型，解释岩浆成因的性质及其相互作用，因为岩浆混合以前被认为是这里的一个重要过程。它还将研究岩浆生成过程的变化，因为它们是随着时间的推移而演变的。阿提特兰是一个特别重要的研究地点，因为人们对火山的岩浆管道系统知之甚少，特别是前第四纪的火山活动。它也代表了伸展和挤压构造制度相互重叠的罕见位置。这可以通过产生具有减压和熔融特征的混合岩浆来体现出来。将使用的方法包括从各种喷发中收集样本，用扫描电子显微镜、电子探针和LA-ICPMS进行斑点和剖面分析，以及分别在ActLab、开放大学和NERC同位素地球科学实验室进行全岩专业、微量元素和放射性成因同位素分析。然后，这些将输入到各种模型中，包括各种温度气压计和相平衡模型，如熔体和EC-RA XFC

Over the past 14 Ma, the Atitlan volcanic centre has been producing a range of volcanic productsover three phases (Atitlan I 14-11 Ma, Atitlan II, 10-8 Ma, Atitlan III 1 Ma to present), includingstratovolcanoes, domes, and large and small volume ignimbrites, three of which have resulted inthe formation of calderas. The path of these calderas mirror a pattern which is near ubiquitous inGuatemalan arc-front volcanism, whereby the locus of activity shifts south/southwestwards overtime. This project will look into the geochemistry and petrology of the volcanic products of theAtitlan centre and produce a conceptual model that will explain the nature of the genesis of themagmas and their interactions with one another, as magma mixing has previously been identifiedas an important process here. It will also examine the change in magma generation processesas they have evolved over time. Atitlan is an especially important site to study, as relativelylittle is known about the magma plumbing system feeding the volcanoes, especially for the pre-Quaternary volcanism. It also represents a rare location where extensional and compressionaltectonic regimes overlie one another. This could manifest itself by producing hybrid magmaswith both decompression and flux melting signatures.The methods that will be used include collection of samples from the various eruptions, spotand profile analyses by SEM, EMPA and LA-ICP-MS as well as whole rock major and traceelement and radiogenic isotope analyses at Actlab, the Open University and the NERC IsotopeGeoscience Laboratories respectively. These will then feed into a variety of models includingvarious thermobarometers and phase equilibria models such as MELTS and EC-RA xFC