Research
Koma Kulshan (Mt. Baker), WA
The goal of this research is to address fundamental questions in volcano science related to how and when volcanoes erupt through a geochemical and mineralogical study of lavas erupted from Koma Kulshan (Mt. Baker) in northern Washington State, and is a collaboration with Prof. Sue DeBari at WWU and Asst. Prof. Hannah Shamloo at CWU. The study is an integrated approach combining proven petrologic techniques (i.e., mineral chemistry and textures and thermobarometry) with methodologies that are breaking new ground (i.e., machine learning, diffusion chronometry, and reconstructed volatiles in melt inclusions). The resultant data will be used to reconstruct the architecture of magma storage in arc crust and quantify the timing of magma storage and ascent prior to eruption–key factors required for eruption event trees and hazard mitigation plans implemented by the Cascades Volcano Observatory. Kulshan lavas provide a unique sample set ideal for this study as previous work has identified distinct crystal clots and co-crystallizing assemblages that represent different parts of a transcrustal system tapped upon eruption over 10s of thousands of years. This work provides the opportunity to test how transcrustal magmatic systems evolve through time and improves our understanding of arc volcanoes globally.
Augustine Volcano, AK
Augustine Volcano is one of the most frequently active and highest hazard threat volcanoes in the US. Through a recently funded NSF grant, my colleagues, Alison Koleszar (Colgate University) and Matt Loewen (AVO), and I, our research group aims to explore the connections between subsurface and eruptive processes at intermediate arc volcanoes in the Aleutians. This project is titled, “Testing the controls on eruption size and style at intermediate arc volcanoes: Evidence from the Holocene record at Augustine Volcano.” WWU graduate students Sloane Kennedy and Mahina Robbins both completed MS theses in Summer 2023 focusing their thesis research on petrologic and geochemical investigations of Tephra B (~400 ybp) and Tephra M (~800 ybp), respectively. Graduate student Saisha Brody continues this research focused on the volatile contents and storage depths of magmas involved in the eruption of Tephra C (~1100 ypb).
Ocean island basalts
A major goal of most of my research is utilizing the geochemistry of basalts to understanding volatile cycling and the origin of heterogeneity in the deep mantle. To do this, I primarily use the volatile and B-isotope composition of olivine-hosted melt inclusions (measured by ion microprobe techniques) in basaltic magmas erupted at ocean islands around the globe. This work began during my postdoc as part of a NERC consortium titled ‘Mantle volatiles: processes, reservoirs, and fluxes.’
Cinder Cone, Lassen National Park, California
Cinder cones are the most abundant volcanic landform on earth. In the Lassen area alone, over 500 monogenetic cinder cones and small shield volcanoes have erupted in the last 12 Ma, representing the largest percentage of total erupted volume in the southern Cascades. Despite the abundance of monogenetic volcanoes in the Cascades and consequently, their likelihood to pose volcanic hazards in the northwestern United States, these types of volcanoes are vastly understudied, especially when compared to more evolved and longer-lived stratovolcanoes.
Much of my research has focused around cinder cone volcanoes - I have studied their storage and eruptive processes, have exploited their mafic magmas to study mantle processes, and worked with a number of Middlebury College students to study their eruptive behavior. As a continuation of my work, my colleague, Dr. Megan Newcombe (University of Maryland) and I have received NSF funding for our proposed work titled, “How variable is magma decompression rate during a single eruption?” This funded project will allow us to explore the connections between ascent rate and explosivity of mafic arc magmas through a case study of the eruption of Cinder Cone. At present, WWU undergraduate students Amanda Florea and Shae Fairchild are both focusing their independent research projects on determining magmatic ascent process and rates through bubble size distribution analyses.
Mafic magma storage and evolution
Much of my research with Middlebury College geology students focused on cinder cone magmatism in the southern Cascades – specifically, utilizing the major and trace element composition of olivine and pyroxene to determine pre-eruptive storage, evolution, and ascent timescales.
The combined thesis research of Sophie Leiter, who utilzied petrography, bulk geochemistry, and geobarometric techniques, and Andrew Hollyday, who collected core-rim trace element data (SEM and LA-ICP-MS) and performed trace element diffusion modeling, was recently published in the journal Contributions to Mineralogy and Petrology. Their work was combined to infer the magmatic evolution and storage depths of CPX-bearing cinder cone magmas, estimate ascent rates, and interrogate the potential for TE diffusion modelling in CPX.
Volatile recycling in the Cascade Arc
In subduction zones, the mantle is thought to be fluxed by fluids and/or melts derived from the downgoing plate, which lower the mantle solidus, producing melts that rise through the continental crust and form arc volcanoes. However, beneath the Cascade Arc subducts some of the youngest, and consequently warmest oceanic crust globally, raising questions about the role of slab dehydration and melting and melt production in the mantle wedge. To address this, I have focused much of my work on utilizing the compositions of olivine-hosted melt inclusions from primitive basalts in the Lassen Region (southermost active segment) of the Cascade Arc. By measuring the volatile (H2O, CO2, Cl, S, and F), major element, trace element, and stable isotopes (δD, δ11B, and δ18O) compositions of these melt inclusions, we hope to better understand the processes that govern how magma forms beneath the Cascades.