Collaborative Research: NSF-SNSF: Crystal-melt dynamics in crustal magma reservoirs

When magmas remain underground, without erupting, those systems are called plutons. Part of what determines whether those magmas will erupt from plutons is how closely integrated the melt and the crystals are (also called how “mushy” the system is). This collaborative US-Swiss team will integrate field data, laboratory experiments, and computational numerical analysis to develop a model for understanding the physics of plutons and how crystals and melt interact within them. This project supports a team in the US, and a team in Switzerland. The field work, led by the Swiss part of this team, will occur in Adamello, Italy; Spirit Mountain, USA; and the Famatinian arc, Argentina). The Swiss team will look at the geochemistry and microtextures of the rock, and compare them with the experiments and numerical models created by the US team. Developing models to examine how melt and crystals separate in mushes is critical for understanding what leads to volcanic eruptions. The international collaborative nature of this work will provide unique training for the graduate students and postdoctoral scholars involved. Undergraduate Research Experience programs at Brown and MIT will engage even more students in the project. This collaborative U.S.-Swiss project is supported by the U.S. National Science Foundation (NSF) and the Swiss National Science Foundation (SNSF), where NSF funds the U.S. investigator and SNSF funds the partners in Switzerland. While developments in geochemistry, geochronology and petrology over the past decades have highlighted the importance of mushy magma reservoirs as a fundamental element of crustal magmatic distilleries, our understanding of the physics underpinning the evolution of these systems lags behind. The challenges with these multiphase systems are in part caused by their complexity and the wide range of temporal and spatial scales involved and in part because bridging laboratory experiments, modeling and field sample analyses across scales is difficult and requires a complex multidisciplinary effort. This project supports a multidisciplinary approach, combining new laboratory experiments, granular mechanics models and field samples analyses. Their objectives are twofold: (1) the development of a unified framework for melt-crystal separation in magmas from dilute suspension to crystal mushes tested and validated against experiments and crystal-scale simulations and (2) the application of this new model to field examples complemented with geochemical and petrographical analyses to link processes with their expression in the rock record and define textural signatures associated with each process. This US-Switzerland collaboration is designed to address these challenges and bring a new light on the multiphase dynamics of magmas undergoing phase separation. The models developed here will contribute to granular mechanics and multiphase fluid dynamics within and beyond Earth Sciences and provide a new perspective on the dynamics of magma reservoirs in general. 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.