Measuring geologic time is of fundamental importance to understanding the history of our Earth and solar system. The age constraints provided by geochronology are critical for determining the rates of many physical, chemical and biologic processes that shape our planet. My research focuses on the acquisition, improvement and application of geochronologic data. The U-Pb system is highly versatile, capable of providing extremely high-precision timing constraints on the formation and cooling history of rocks. My specific research projects are diverse, from linking global extinction events to large igneous province eruptions, to measuring the thermal and erosional history of Earth’s oldest continental crust.
EART 10 — Geologic Principles
EART 127 — Radiogenic Isotopes
EART 206 — Great Papers In The Earth Sciences
The answer to the question “when?” is one of the most compelling parts of any geologic story and a cornerstone to the complete, meaningful interpretation of any geological process or event. My research utilizes isotopic measurement of U and its daughter radionuclides to provide the answer to “when?” in diverse geologic and planetary systems. I apply U-Pb ID-TIMS analyses on accessory phases to answer thermochronologic questions: xenolithic rutiles record the long-term cooling history of the Superior Craton/Province of the Canadian shield, and phosphates from ordinary chondrites provide insight into the formation, cooling, and disruption history of the chondrite parent bodies and the first ~100 Myrs of the Solar System. I use U-Series measurements of glaciogenic sediments to infer the relative and absolute timing of comminution (i.e. wearing down) of sediments to inform the time constraints of glacial and climatic histories.
My research interests are focused on the improvement and application of the U-series and U-Pb isotopic systems as chronologic tools. Through the use of fieldwork, sample processing, U-series isotopic analyses, and numerical modeling, I am working to further develop a method to measure the timing of comminution (i.e. the reduction of particle size) of rocks in geologic systems. The ability to reliably date the timing of fine particle production will play a significant role in several Earth Science disciplines including glaciology, eolian and fluvial geomorphology, soil production, and fault dynamics. Currently, I am using comminution dating in several projects including: investigating the timing of glaciations in the Eastern Sierras, studying the frequency of earthquake activity on the San Andreas Fault, and examining the history of rock avalanches in the San Gabriel Mountains. Additionally, I am interested in the application of U-Pb thermochronology to accessory phases in ordinary chondrites to study the early accretion history of the solar system.