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

墨西哥雷维拉吉多群岛的板内岩浆活动地球上大多数火山活动发生在像瀑布这样的弧线上，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内火山作用，这两个过程都无法解释。该项目将探索其中一个地方--雷维拉吉多群岛、活动火山岛和水下火山--火山活动的原因。该地区的火山活动没有活动板块边界，也没有证据表明其下方有深根，这为检验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一次考察航行，以研究海底并测量洋壳的性质。潜水器将观察水下火山系统，并采集熔岩样本。邮轮上熔岩的化学成分和水面上火山的现有样本将与地球物理测量一起使用，以解释为什么该地区是火山活跃的。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热柱有关，但在另一些情况下，岩浆活动的根源要少得多。这项提议将解决两种明显的板内火山作用的起源和关系，表现在一个废弃的大洋中脊扩张中心和一个薄弱的热点，两者都存在于墨西哥的雷维拉吉多群岛。一艘研究邮轮将收集地球物理数据和新的海底潜在年轻区域熔岩样本。当与现有样本的新数据相结合时，这些限制将为检验区域火山活动的起源和演化特征的几个关键假说提供一个框架。这项工作将检验失败的扩张中心、化学或热地幔不均质性、岩石圈-软流圈边界的持续熔融层以及岩石圈结构驱动的上升流作为驱动该古板块边界持续岩浆活动的潜在解释的潜在作用。这项工作将进一步测试在大洋板块内背景下，结晶驱动和同化驱动的过程在产生大量过碱性硅质岩浆中的作用。将分析喷发熔岩的主要/微量/挥发性元素和同位素地球化学，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。这种对熔岩成分/年龄的地球化学约束以及对岩石圈结构和历史的地球物理约束的组合，将能够评估导致大洋板内环境中岩浆活动和演化的关键过程，以便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，并通过使用基金会的智力优势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.