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

点击翻译按钮获取中文摘要

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.