Collaborative Research: Hydrous melting of a lithologically-heterogeneous mantle: A combined experimental and computational approach

About This Grant

The Earth’s mantle melts as it rises beneath mid-ocean ridges and hotspot volcanoes. This process generates ocean crust and is responsible for most of the volcanic eruptions on Earth. The presence of even small amounts of water in the mantle is known to have large effects on the amount of magma produced. Likewise, small changes in chemical composition of the mantle rocks will also change the amount of magma produced. This project will be the first to study both of these factors together. The project involves both laboratory experiments that replicate the conditions in the mantle and computational models that predict melting. Two graduate students will conduct each aspect of the project, respectively, but also will be cross-trained under the guidance of principle investigators. Several first-year undergraduates will also be involved in the research, leveraging an existing program at the University of Utah. The anticipated outcome of this research will be the first models that accurately predict the combined effect of water and composition variations on mantle melting. The project will also support making video tutorials to help with the adoption of the software developed in this project. The presence of even small amounts of water and other volatiles can significantly alter the way that mantle rocks melt and how much magma is produced to form new crust and create volcanoes. Understanding the mantle melting processes from the composition of basalts produced is a very difficult problem, so laboratory experiments and computational modeling provide the best ways to address these questions. This project integrates high pressure-high temperature laboratory experiments and geochemical numerical models to investigate the impacts of variable water content on melting of a realistic mantle composition containing both peridotites and pyroxenites as they coexist in a decompressing, rising mantle plume. The project will develop the first model parameterization that can accurately predict the effects of water on melting a lithologically realistic mantle containing pyroxenites, and make publicly available open-source software to enable other researchers to run these models. The central hypothesis is that increasing both the abundance of pyroxenite and the concentration of water in the decompressing mantle will generate measurably deeper melting than either factor alone. Experimental data generated during the project will add significantly to the public Library of Experimental Phase Relations and the EarthChem national data repository. This project will enable two graduate students to continue their studies and will provide first-hand research experiences for freshmen students at University of Utah. 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.