RESEARCH INTERESTS I combine geochemical techniques and thermodynamic principles with physical and field-based observations in order to better understand complex geologic processes. I am interested in a wide range of topics, but I have been particularly interested in the effects of temperature, pressure and chemical composition on phase changes and the resulting physical consequences; an interest that has led me directly into solution geochemistry, both aqueous and igneous. My PhD project at the University of Oregon focuses on magmatic processes occurring in the Cascades including: - melt generation - melt transport, mixing & storage - crystallization & crustal assimilation histories - convergent margin element cycling - volcanic explosivity & degassing I find it amazing at how fundamentally analogous this research is to seemingly unrelated processes as: - water-aquifer interactions and equilibration - exsolution of vapor/dissolved gases in thermal and nonthermal geysers - solution gas exsolution from crude oil and formation of liquid gasoline from 'wet gas' - CO2 sequestration UNIVERSITY OF OREGON Volcanic explosivity is driven by degassing of volatiles (e.g. H2O, CO2) as magma experiences decompression during ascent to the surface, a process similar to uncorking a bottle of champagne. Most of the dissolved volatiles are ultimately derived from the dehydration of oceanic crust as one tectonic plate is subducted beneath another. During degassing, magma undergoes partial crystallization and developing crystals may trap small amounts of parent liquid within their structure as melt inclusions. Certain crystals (particularly olivine) are ideal vessels for preserving volatile-rich melts (these melt inclusions rapidly quench to glass upon eruption). The Cascades have historically been viewed as a dry, and therefore weak volcanic arc in terms of volumetric output, eruption frequency, and explosivity. My preliminary data, however, suggest a relatively large range in water contents (H2O = most abundant volatile in volcanic systems) of up to ~4 % by weight – concentrations similar to those found in other, more active arcs around the world. My study focuses on pre-eruptive (i.e. initial) volatile contents trapped within olivine-hosted glass inclusions from eruptions of the abundant cinder cones (and lava flows) located throughout the Central Oregon and Northern California High Cascades. One objective of my study is to construct a >100 km geochemical transect across the volcanic arc (west to east) to characterize the range in initial volatile contents and better understand the spatial relationships associated with depth to the subducting plate. These eruptions are smaller, more frequent, and historically have been under-studied compared to their larger, catastrophic cousins (e.g. St. Helens, Pinatubo). The youngest cinder cone eruptions in the area occurred 1300 years before present (~700 AD). Recent activity, however, to the west of South Sister (the bulge) demonstrates that volcanic processes continue to operate beneath the Cascades. Although generally not life-threatening, smaller cinder cone eruptions can continue to expel ash and effuse lava for up to a decade (cf. Parícutin); disrupting air traffic, igniting forest fires, and destroying road networks and property. My research can be separated into deep- (mantle-melting) and shallow-level (ascent and degassing) processes and I am investigating how these systems are related by integrating geochemical and physical volcanological techniques. Two separate but interrelated aspects of my study are: 1) investigating the role of volatiles and their recycling efficiencies in a hot and dry subduction zone environment and 2) understanding the relationships between magmatic volatile contents and eruptive activity. This is the first study of the Cascades directly relating all major volatile contents (H2O, CO2, S, and Cl) with major and trace element chemistry and mineralogy to constrain conditions of magma formation and evolution (a topic of considerable interest to the academic geological community) and may even be applicable to future hazard assessments in the region. UNIVERSITY OF MINNESOTA My M.S. work was a 238U-230Th disequilibrium study of subduction-related basalt and basaltic andesite lavas originating from cinder cones in SE Guatemala. U-Th isotopes provide constraints on the timing (< 350 ka) and relative importance of mantle upwelling and decompression melting (230Th-excesses) compared with fluid addition during dehydration of the subducting slab (238U-excesses). The majority of the analyzed samples were in or very close to isotopic equilibrium, displaying both 238U- and 230Th-excesses, suggesting: 1) Both fluid-flux and decompression melting play important, competing roles in the production of SE Guatemalan magmas; 2) significant assimilation of geochemically similar, older crust may have limited observable U-Th disequilibria; or 3) analyzed lavas were older than expected. Unfortunately, poor age constraints and several > 350 ka whole-rock Ar-Ar dates did not permit more thorough interpretations to be made. UNION COLLEGE My undergraduate thesis (focused on sampling and analyzing surface and ground waters around Saratoga Springs, NY in order to better understand the origins of the cold, carbonated saline springs. The project included analyzing water samples by ICP-MS and Ion Chromatograph with subsequent modeling of mixing and mineral-water equilibration between fresh meteoric and saline end-members.