Collaborative Research: A natural laboratory approach to studying copper and volatiles in a volcanic system

Copper is essential to modern technology and infrastructure, and much of the world's copper ore formed from magmas in volcanic arcs. Most deposits mined today formed in the shallow crust, but the story of each deposit begins much deeper in Earth’s crust. This project will study how copper behaves in arc magma using samples from volcanoes in the Cascades. This project will reveal how those deep processes set the stage for the formation of copper deposits. The results will improve understanding of how metals move through active volcanoes, how ore deposits form, and how Earth's crust has evolved. The project will also strengthen the U.S. STEM workforce by training students in advanced analytical and laboratory techniques. In addition, the team will build a virtual field trip of the study area so the public can learn more about Cascades volcanoes. The behavior of copper, particularly during early mafic differentiation, is notoriously difficult to constrain using typical approaches such as experimental petrology or field studies at arc-front stratovolcanoes. This project will examine short-lived mafic volcanoes in the Indian Heaven Volcanic Field (Central Cascade arc) as a natural laboratory. This ‘natural laboratory’ approach allows precise characterization of how copper behaves during crystallization and degassing in magmas, with a variety of parental compositions and storage conditions. Olivine-hosted melt inclusions from six mafic volcanoes will be collected and analyzed to generate a data set that will allow the simultaneous study of the behavior of silicate melt, sulfide, and magmatic vapor. To ensure accurate characterization of the storage pressure, sulfur and copper contents of melts at each volcano, experiments will be used to overcome complications caused by vapor bubbles inside the melt inclusions. In parallel, a suite of untreated, naturally glassy melt inclusions that provide major element, H2O and redox information will be analyzed. These analyses will be used to develop an open-source framework to model the behavior of both volatile elements and copper during crystallization and degassing. This project includes the development of a Virtual Field Trip of Indian Heaven Volcanic Field featuring interviews with researchers and an accompanying teacher’s guide. 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.