Collaborative Research: Origin and Evolution of Intraplate Magmatism at the Revillagigedo Archipelago, Mexico

地球上的大多数火山活动都发生在像喀斯喀特山脉这样的弧形地带，或者发生在像夏威夷这样的热点地区的板块内。最近的研究揭示了另一类板块内火山活动，这两种过程都无法解释。这个项目将探索这些地方之一的火山活动的原因，Revillagigedo群岛，活火山岛和水下火山。该地区的火山活动没有活跃的板块边界，也没有证据表明其下方有一个深根，这为测试这种火山活动发生的原因提供了一个理想的地点。我们将对这些岛屿进行考察航行，以研究海底和测量海洋地壳的性质。潜水器将观察水下火山系统并收集熔岩样本。游轮上熔岩的化学成分和现有的水上火山样本将与地球物理测量相结合，以解释为什么这个地区火山活跃。地球上的板块内火山活动有多种形式。在某些情况下，它显然与深根地幔柱有关，但在其他情况下，岩浆活动的根源就不那么受限制了。该提案将解决两种明显的板内火山活动的起源和关系，表现在一个废弃的洋中脊扩张中心和一个弱热点，都存在于墨西哥的Revillagigedo群岛。一项研究巡航将收集地球物理数据和新的海底样本，这些样本可能是年轻的区域熔岩。当与现有样本的新数据相结合时，这些限制将为测试关于区域火山活动起源和演化特征的几个关键假设提供一个框架。这项工作将测试失败扩张中心的潜在作用，化学或热地幔非均质性，岩石圈-软流圈边界的持续熔融层，以及由岩石圈结构驱动的上升流，作为驱动该化石板块边界持续岩浆活动的潜在解释。这项工作将进一步测试结晶与同化驱动的过程在海洋板内环境中产生大量过碱性硅质岩浆的作用。分析喷发熔岩的主要/痕量/挥发性元素和同位素地球化学，以确定火山作用的年龄，识别地幔源特征，模拟地幔温度和岩浆液体下降线，并评估可能改变岩浆成分的同化或结晶过程。地球物理数据和建模将有助于建立当地岩石圈结构和年龄的模型。结合地球化学对熔岩组成/年龄的限制和地球物理对岩石圈结构和历史的限制，可以评估海洋板块内岩浆活动和演化的关键过程，并与其他板块内海洋岛屿和海底山进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Intraplate Magmatism at the Revillagigedo Archipelago, Mexico Most volcanic activity on Earth takes place at arcs like the Cascades or within plates at hotspots, such as Hawaii. Recent work reveals another class of within-plate volcanism that can’t be explained by either of these processes. This project will explore the causes of volcanic activity in one of these places, the Revillagigedo archipelago, active volcanic islands and underwater volcanoes. The volcanism in the area, with no active plate boundary and no evidence of a deep root beneath it, provides an ideal location to test ideas about why this kind of volcanism occurs. We will conduct a research voyage to these islands to study the seafloor and measure properties of the ocean crust. Submersible dives will observe the underwater volcanic systems and collect samples of lava. The chemical composition of lava from the cruise and existing samples from the above-water volcanoes will be used with the geophysical measurements to develop an explanation for why this area is volcanically active. Intraplate volcanism on Earth takes many forms. In some cases, it is clearly related to a deep-rooted mantle plume, but in others, the root of magmatism is much less constrained. This proposal will address the origins and relationships between two apparent styles of intraplate volcanism, expressed at an abandoned mid-ocean ridge spreading center and a weak hotspot, both present in the Revillagigedo archipelago, Mexico. A research cruise will collect geophysical data and new submarine samples of potentially young regional lavas. When integrated with new data for existing samples, these constraints will provide a framework for testing several key hypotheses for the origins and evolved character of the regional volcanism. This work will test the potential roles of a failed spreading center, a chemical or thermal mantle heterogeneity, a persistent melt layer at the lithosphere-asthenosphere boundary, and upwelling driven by lithospheric structure as potential explanations for driving continued magmatism at this fossil plate boundary. This work will further test between roles of crystallization- vs. assimilation-driven processes in producing voluminous peralkaline, silicic magmas in an oceanic intraplate setting. Major/trace/volatile element and isotopic geochemistry of erupted lavas will be analyzed in order to determine ages of volcanism, fingerprint the mantle source characteristics, model mantle temperature and magmatic liquid lines of descent, and evaluate assimilation or crystallization processes that may modify magmatic compositions. Geophysical data and modeling will aid in development of a model of local lithospheric structure and age. This combination of geochemical constraints on lava compositions/ages and geophysical constraints on lithospheric structure and history will enable assessment of the critical processes responsible for magmatic activity and evolution in an oceanic intraplate setting, for comparison with other intraplate oceanic islands and seamounts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.