Current Research

General geochemistry, radiogenic and stable isotope geochemistry, volcanology. Interests include applying isotopes to address conventional and novel topics in the earth sciences and related fields. Current research targets evaluating the processes generating super-volcanic eruptions and how highly explosive magmas form and accumulate prior to such events. Volcanoes of interest include Valles caldera in New Mexico and Baitoushan volcano in North Korea/China. Additional interests include evaluating the age and sources of ore deposits in Idaho, evaluating basaltic magma systems in the western US and at the Endeavour Segment of the Juan de Fuca Ridge. Work also includes evaluating the sources of waters and salmon in the Pacific Northwest and California. Research incorporates and develops new techniques using Thermal Ionization Mass Spectrometry (TIMS), Multi-collector Inductively Coupled Mass Spectrometry (MC-ICPMS), and Laser Sampling and Single Crystal analyses.

Alkalic Volcanism at Baitoushan Volcano


Baitoushan is a poorly studied intraplate volcano located in the Changbaishan volcanic field on the border between China and North Koreo. Recent activity within the last 2000 years has consisted of large eruptions comparable to the historically famous eruptions of Tambora (1815) and Krakatau (1883). Current research includes in situ titanium in quartz analyses compared with quartz melt inclusions, and isotopic analyses of the same melt inclusions, which will allow correlation between crystal residence time, magmatic temperature, magma sources, and other magmatic processes.


Evaluating Young Volcanism at Baitoushan Volcano: Insights From Single Mineral Crystal Sr and Pb Isotope Analyses (Rodgers et al., 2008)

Evaluating the Timing of Volcanism at Baitoushan Volcano (North Korea/China) in the Context of Open-system Effects: Insights from Sr, Nd, and Pb Isotopes at the Single Grain Scale (2007)

Dating Mid Ocean Ridge Basalts at the Endeavour Segment, Juan de Fuca Ridge

Bathymetry (GeoMapApp) and sample locations at Endeavour

Endeavour is an intermediate mid ocean spreading ridge located off the west coast of Washington state. The locations of samples collected during a Ridge 2000 dive in 2005 will allow for the assesment of the timing of magmatism using U-series disequilibria because of the short-lived isotopes in the Uranium and Thorium decay chain. Over long time scales, mid ocean ridges spread symmetrically, which is observed in the orientations of magnetic minerals within the erupted basalts. Using U-series disequilibria, an assesment of the degree of symmetry on short time scales will be conducted.


Frequently Shifting Magma Sources at Endeavour Segment, Juan de Fuca Ridge (2007)

Basalt Geochemistry of the Endeavour Segment, Juan de Fuca Ridge (2006)

Endeavour basalt geology and petrology (2005)

Evaluating the timing of magmatism at Valles Caldera

Picture of Ridondo Peak, the largest resurgent dome within Valles Caldera


How much warning before a supereruption? Studies of Ti-zoned quartz in the Bandelier Tuff (2008)

Petrologic evidence for thermal rejuvenation of crystal mush in the Bandelier Tuff (2006)

Sr and Pb in High-silica Rhyolites: Lessons From the Bandelier Tuff (2004)


Pb isotope variations among Bandelier Tuff feldspars: No evidence for a long-lived silicic magma chamber (2003)

Sr isotope disequilibrium during differentiation of the Bandelier Tuff: Constraints on the crystallization of a large rhyolitic magma chamber (1999)