My research focuses on how terrestrial planets, including planet Earth, works. My group investigates the feedback and linkages between processes operating within planetary interiors and processes operating on the surface over a range of timescales. The program is interdisciplinary, collaborative and addresses fundamental questions in the Earth and planetary sciences through the application of modeling techniques and novel geochemical measurements, primarily noble gases.
ORIGIN OF VOLATILES
The different noble gases in planetary mantles and atmospheres provide constraints on the delivery and incorporation of volatiles into growing planets. My group has found evidence for magma oceans and atmospheric loss during Earth’s accretion. We are finding exciting new evidence for delivery of chondritic volatiles to both Earth and Mars during the very earliest stages of planet formation, as well as in the later stages of planet formation. We are currently investigating early mantle degassing rates, the distribution of noble gases between the core, mantle and atmosphere during accretion, and the origin of the atmospheres on Earth, Venus and Mars. Check out some papers on the origin of volatiles and early Earth.
SOLID EARTH CHEMISTRY
Noble gases provide a unique insight into the evolution of Earth’s mantle. Ocean island basalts (OIBs), such as those erupted at Hawaii, have relatively high 3He/4He ratios compared to mid-ocean ridge basalts (MORBs); therefore, it has been suggested that OIBs are derived from an undegassed, primordial mantle reservoir. My group has focused on understanding the origin of these different mantle chemical reservoirs and their relationship to Earth’s formation and recycling from the surface and atmosphere. We have found geochemical evidence for the formation of chemical reservoirs during Earth’s accretion and their persistence in the modern day mantle. These observations form the basis of quantifying mantle mixing timescales, rates of crustal-mantle exchange and the time history of volatile outgassing and ingassing rates. Check out some papers on the evolution of Earth’s interior.
EARTH’S SURFACE INTERIOR INTERACTIONS
Feedbacks between Earth’s interior and its surface through the exchange of volatiles on geologically long timescales have played an important role in keeping Earth habitable. We are producing records of the long-term interior-surface volatile exchange rates to better understand these feedbacks. More recently feedbacks on significantly shorter timescales have been recognized. For example, sea-level changes associated with Pleistocene glacial cycles have been hypothesized to modulate melt production and hydrothermal activity at ocean ridges, yet little is known about fluctuations in hydrothermal circulation on timescales longer than a few millennia. We are finding that rapid sea-level changes influence hydrothermal output on mid-ocean ridges, which in turn can influence ocean chemistry. Thus, feedbacks between climate variability and volcanic processes may play out on millennial timescales as well. Check out some papers on Earth’s surface interior interactions.
NOBLE GAS ISOTOPES
My group has made new advances in multicollector noble gas mass spectrometry, particularly for the heavy noble gases. We are also developing new techniques for more efficient cryogenic separation of heavy noble gases and sample collection techniques that minimize air contamination. These technical developments open the door to addressing a range of science questions involving volatiles and volatile evolution on planets.
