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

地球上大多数的火山活动都发生在像瀑布这样的弧形地带，或者发生在热点地区的板块内部，比如夏威夷。最近的研究揭示了另一类板内火山活动，这两种过程都无法解释。该项目将探索这些地方之一的火山活动的原因，即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深根，这为测试为什么会发生这种火山活动提供了一个理想的位置。我们将对这些岛屿进行研究航行，研究海底并测量海洋地壳的特性。潜水将观察水下火山系统并收集熔岩样本。考察所得熔岩的化学成分和水上火山的现有样本将与地球物理测量结果一起用于解释该地区火山活动的原因。地球上的板内火山活动有多种形式。在某些情况下，它显然与根深蒂固的地幔柱有关，但在其他情况下，岩浆活动的根源则不那么受限制。该提案将讨论两种明显的板内火山活动风格之间的起源和关系，这两种火山活动在墨西哥Revillagigedo群岛的一个废弃的洋中脊扩张中心和一个弱热点中表达。一次研究巡航将收集地球物理数据和潜在年轻区域熔岩的新海底样本。当与现有样本的新数据相结合时，这些限制将为测试区域火山作用的起源和演变特征的几个关键假设提供一个框架。这项工作将测试潜在的作用失败的扩展中心，化学或热地幔的不均匀性，在岩石圈软流圈边界的持久性熔融层，和岩石圈结构驱动的上涌驱动持续岩浆活动在这个化石板块边界的潜在解释。这项工作将进一步测试在海洋板内环境中产生大量过碱性岩浆的结晶与同化驱动过程之间的作用。将对喷发熔岩的主要/微量/挥发性元素和同位素地球化学进行分析，以确定火山活动的年龄，确定地幔来源特征，模拟地幔温度和岩浆液体下降线，并评价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。这种对熔岩成分/年龄的地球化学约束和对岩石圈结构和历史的地球物理约束的结合，将有助于评估大洋板内环境中负责岩浆活动和演化的关键过程，与其他板内海洋岛屿和海山进行比较。该奖项反映了NSF的法定使命，并通过利用基金会的智力价值和更广泛的影响审查标准。

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.