CAREER: The Evolution of Super-Hydrous Magmas in the Earth's Crust

Petrology and geochemistry are cornerstones of geology and the study of Earth systems and processes. Experimental studies have often been the necessary component for advances in understanding plate tectonics and subduction zones in particular. This proposal describes an integrated research and teaching program with foundations in experimental petrology, thermodynamics, and volcanology, to advance the understanding of how volcanoes work, how water affects the evolution of volcanoes and their behavior, while providing new hands-on teaching tools to generate excitement for future petrologists currently at the graduate, undergraduate or high school level.

In particular, this proposal will study the eruptive products from the most explosively active volcano in the world. The research proposed here is an experimental and geochemical study primarily designed to use amphibole chemistry to quantify pre-eruptive water contents in super-hydrous arc magmas at deep crustal and upper mantle conditions. This study consists of 3 broad research tasks that will form the foundation of a new paradigm for understanding volatile flux and recycling in the Earth, and an education plan that will develop new ways of bringing technology and teaching petrology together in the classroom.

This project will undertake four interrelated tasks aimed at studying the pre-eruption dynamics of magma storage and evolution in the most magmatically productive volcanic area of the world and focuses specifically on geochemistry related to super-hydrous magmas. Experiments are to be executed with the broad goal of bridging the gap in our knowledge about magmatic water contents between the termination of hydrous flux melting, and the trapping of melt inclusions and crystallization of plagioclase in the shallow crust.

Experimental studies will explore the geochemical evolution of hydrous magmas and make the first quantitative measurements on hydrogen, fluorine, and chlorine partitioning in amphibole at lower crustal conditions. Measuring the H contents in amphiboles will provide immense geologic value only if we can account for the intensive and extensive variables that control the geochemical partitioning between melt and crystal, and the dehydrogenation of amphibole.

Amphibole synthesis experiments at controlled P, T, XH2O and fO2 will be conducted. Results will be incorporated into databases such as LEPR and be available to incorporate into important community thermodynamic models such as MELTS and its successor ENKI. Currently, amphibole is the only major phase not included in these modeling algorithms, highlighting the importance of general experimental studies on this mineral.

There is a paucity of hydrous experiments at lower crustal pressures in the literature and these experiments will help to fill that gap. This study will be expanding our current knowledge of the stability of amphibole, an important phase in Earth's crust, but one without a low-pressure stability field so it has often gone under-appreciated in its role in producing geochemical trends at arcs.Through the CAREER program, the PI will develop new teaching and outreach tools that will improve the way ternary phase diagrams are taught in petrology classes, as well as produce 3D models of volcanoes that can be used for virtual field trips and volcanology outreach.

The objectives of this effort are to: 1. Create hands-on methods for teaching petrology and volcanology to undergraduate students, to improve understanding and retention. 2. Create pathways to generate excitement in these subjects among undergraduates by making the new visualizations available for distribution to other undergraduate institutions.

To achieve these goals a plan will be implemented that includes software development, curriculumdevelopment, and distribution of 3D renderings to the AR app platform.

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.