RUI: The Evolution of the Galapagos Hotspot

世界上许多火山岛链，如夏威夷或Galápagos，都是地幔柱的表面表现，地幔柱是地球上最重要但最不为人所知的构造现象之一。主流理论认为，地幔柱起源于地幔深部，将物质从地核-地幔边界运送到地表，距离近3000公里。因此，海洋岛屿火山喷发出的熔岩化学成分的变化可能提供了从如此深处取样的唯一方法，并在此过程中确定地球上这些否则无法进入的部分的成分和结构。该项目的主要目标是对3个最古老的Galápagos岛屿进行实地和地球化学研究，以调查与海洋岛屿有关的持久问题：1)提供Galápagos羽流的物质的性质是什么，这反过来将提供有关地球深部成分的信息；2)羽流的成分如何随时间变化；3) Galápagos火山在远离地幔柱中心的过程中是如何演化的？后一个问题涉及海洋岛屿火山的生命周期，与全世界海洋群岛正在进行的养护和保存工作特别有关。这些问题将分两个阶段加以解决。首先，实地研究将在三个最古老、特征最不明确的岛屿，圣克鲁斯岛、圣克里斯托瓦尔岛和Española岛进行，这些岛屿加起来记录了近300万年的羽流历史。放射性成因同位素、主微量元素和Ar-Ar分析将用于了解化学演化。第二阶段的重点是通过对群岛上精选的熔岩进行高分辨率铅同位素分析，确定Galápagos地幔储层的组成。总之，这些努力将允许评估在Galápagos观测到的复杂地球化学变化的相互竞争的假设，并深入了解地幔柱的起源和性质。这个项目最重要的目标之一是让本科生成为研究团队不可或缺的一员。他们还将参加一个关于地幔动力学的研讨会，该研讨会将用于开发一个由该领域专家介绍的数字存储库，该存储库将被存档并在线提供。厄瓜多尔学生将参加实地考察，并在高露洁度过一个夏天，在那里他们还将接受分析地球化学技术的培训。最后，学生们将参加在高露洁建立的外展计划，与来自纽约州北部的K-12学生一起进行动手科学活动，并在高露洁可视化实验室开发最先进的火山演化演示。

Many of the world's volcanic island chains, such as Hawaii or the Galápagos, are the surface manifestation of mantle plumes, one of the most important but least well understood tectonic phenomena on Earth. The dominant theory is that mantle plumes originate in the deep mantle, transporting material from the core-mantle boundary to the surface, a distance of nearly 3000 km. As such, variations in the chemical composition of lavas erupted at ocean island volcanoes may provide the only way to sample material from such great depths and, in the process, to determine the composition and structure of these otherwise inaccessible parts of the planet. The primary goal of this project is to carry out a field and geochemical study of the 3 oldest Galápagos Islands to investigate persistent questions related to ocean islands: 1) what is the nature of the material supplying the Galápagos plume, which in turn will provide information about the composition of the deep Earth; 2) how does the plume's composition vary with time; and 3) how do Galápagos volcanoes evolve as they are carried away from the plume's center? The latter question, which addresses the life cycle of ocean island volcanoes, is particularly relevant to ongoing conservation and preservation efforts at oceanic archipelagos worldwide.These questions will be addressed in two stages. First, field studies will be carried out on the 3 oldest, most poorly characterized islands, Santa Cruz, San Cristobal, and Española, which together record almost 3 million years of the plume's history. Radiogenic isotopes, major and trace element, and Ar-Ar analyses will be applied to understand the chemical evolution. The second phase is a focused effort to define the compositions of Galápagos mantle reservoirs by applying high-resolution lead isotopic analyses to a selection of lavas from across the archipelago. Taken together, these efforts will permit evaluation of competing hypotheses for the complex geochemical variation observed in the Galápagos and insight into the origins and nature of mantle plumes. One of the most important goals of this project is the engagement of undergraduates as integral members of the research team. They will also participate in a seminar on mantle dynamics, which will be used to develop a digital repository of presentations by experts in the field that will be archived and made available online. Ecuadorian students will participate in fieldwork and spend a summer at Colgate, where they will also be trained in analytical geochemistry techniques. Finally, students will participate in an established outreach program at Colgate, working with K-12 students from across upstate NY performing hands-on science activities and developing a state-of-the-art presentation on volcanic evolution at the Colgate Visualization Lab.