My research centers on development and application of noble gas geochemistry techniques to a diverse range of terrestrial and solar system questions. Specific focus areas include geochronology and thermochronometry using the (U-Th)/He system, surface exposure dating with cosmogenic isotopes, evolution of Earth’s mantle and atmosphere from analysis of volatiles in rocks, and identification of major … Continued
My research program focuses on understanding the large-scale physical and chemical behavior of the Earth and other planets through experimental study of geological materials under extreme conditions of pressure and temperature. Our group uses both static and dynamic compression experiments to explore crystal structures, phase relations, kinetics, and mechanical properties of materials at conditions that … Continued
My group’s research is most noteworthy for its exploration of the isotopic structures of molecules, which record the mechanisms, conditions, and substrates of molecular synthesis or history of reaction for virtually any compound, and can serve as highly specific forensic ‘fingerprints’. Our contributions include invention of enabling technologies, study of fundamental chemical principles governing molecular … Continued
The Earth is unique among the terrestrial planets in the Solar System in having a fluid envelope that fosters life. The key behind Earth’s habitable climate over geologic time is well-tuned cycles of volatiles and fluids (e.g. water, carbon dioxide, nitrogen, and sulfur) between the interior and the exosphere. In the modern Earth, sinking of … Continued
My research group studies the origin of the solar system, the formation of planets, and the early evolution of Earth by measuring the isotopic composition of rocks that witnessed those epochs. Among our most notable achievements, (1) we dated the formation of Mars and showed that it was a stranded planetary embryo; (2) we established … Continued
I study the structure and dynamics of planets, with a particular focus on the generation of magnetic fields by planets. I am currently a co-investigator on NASA’s Juno mission, a polar orbiter around Jupiter, where I am most closely involved in measurements of the planet’s magnetic and gravitational fields. In very recent work, my research … Continued
The coupling of atmospheric chemistry and climate on Earth and other planets on time scales from months to billions of years is studied through aircraft, balloon, and ground-based observations, computer simulations, and laboratory experiments. Of particular interest are studies of photochemical isotope effects. These studies range from crossed beam laboratory experiments to stratospheric observations. Photochemistry … Continued
Our group has investigated all aspects of water-rock-biota interaction throughout the critical zone – the entire zone extending from the top of vegetation to groundwater. We have developed models for soil formation on rocks of different composition under different conditions. Our work also includes studies of the impacts of human activities such as shale-gas development … Continued
Our research focuses on deciphering and understanding biogeochemical processes through elucidation of the molecular and isotopic characteristics of molecular biomarkers in organisms, sediments, rocks and petroleum. We are examining spatial, temporal and stratigraphic variations in biogeochemical records to elucidate: (i) Controls on carbon cycling, especially factors reflecting fluctuations in ocean productivity and biota, (ii) Evidence … Continued
Modeling of the carbon cycle in the ocean and its sediments, and its impact on global climate. Topics include CaCO3 that will neutralize fossil fuel CO2, and methane hydrate that may release carbon to the ocean, eventually.