Collaborative Research: The Onset of the Galapagos Plume as a Window Into the Deep Earth

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Large igneous provinces (LIPs) are the record of the most voluminous volcanic eruptions on Earth. These events were so large that they triggered environmental change leading to catastrophic mass extinctions and oceanic anoxic events. The magmas comprising LIPs are our only direct samples from the deep Earth, having ascended to the surface in deeply rooted upwellings known as mantle plumes. These samples from regions that have been isolated deep within the Earth for billions of years provide information that is crucial for gaining a better understanding the links between geochemical cycles operating on the interior and exterior of our planet. For example, the effect of crustal materials carried into the mantle by subduction (crustal recycling) on the long-term oxidation evolution of the mantle, the effect of volatiles such as water on the generation of LIP primary magmas, and the potential preservation of primordial domains in the lower mantle remain major unknowns in the understanding of the evolution of our planet. This team proposes to shed new light on these questions by studying ultramafic lavas from the west coast of Costa Rica (Tortugal) as well as the islands of Curacao and Gorgona, comprising three distinct localities remnants of Caribbean LIP that are related to the onset of the Galapagos Plume ~89 Ma.A fundamental question to be answered in this study is whether volatile species recently reported in komatiites and LIPs are the result of deep recycling processes or if they reflect primordial, volatile-rich domains within the deep Earth. In the proposed study, researchers provide a systematic approach to answering this question. They will determine the isotopic compositions of helium, osmium, and tungsten on the same samples on which they will perform melt inclusion and mineral studies to constrain volatile contents and oxidation state. These terranes are ideal for this study as they formed by high-degrees of partial melting (thereby resembling the composition of their source), record high crystallization temperatures, high mantle potential temperatures, and the samples rapidly quenched at submarine conditions potentially minimizing the effects of diffusive loss of hydrogen from the inclusions. The volatile budgets of magmas related to the onset of the Galapagos Plume will help quantify the budget of volatiles released at Earth's surface during LIP eruption events, further clarifying the effects of LIPs on mass extinctions. This project will support a graduate student at Cornell, as well as provide independent research opportunities to undergraduate students. Results from this project will be incorporated in outreach and teaching activities of the PIs. This proposed research will enhance collaborations among Cornell, Woods Hole Oceanographic Institution, and the University of Maryland.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.