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

在过去的14 Ma中，阿蒂特兰火山中心产生了三个阶段的火山产物（阿蒂特兰I 14-11 Ma，阿蒂特兰II 10-8 Ma，阿蒂特兰III 1 Ma至今），包括层火山，圆顶和大，小体积的熔结凝灰岩，其中三个导致了破火山口的形成。这些破火山口的路径反映了危地马拉弧前火山活动中几乎无处不在的模式，即活动轨迹随着时间的推移向南/西南方向移动。该项目将研究阿蒂特兰中心火山产物的地球化学和岩石学，并提出一个概念模型，解释岩浆成因的性质及其相互作用，因为岩浆混合以前曾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，因为它们随着时间的推移而演变。阿蒂特兰是一个特别重要的研究地点，因为相对而言，人们对供给火山的岩浆管道系统知之甚少，特别是对前第四纪火山活动。它也代表了一个罕见的位置，伸展和挤压构造体制相互重叠。将采用的方法包括从各种喷发中收集样品，用扫描电镜、电磁功率放大器和LA-ICP-MS进行点和剖面分析，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主要元素和微量元素及放射性同位素分析。然后将这些数据输入各种模型，包括各种温压计和相平衡模型，如MELTS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