My research is focused on understanding the feedbacks and linkages between processes operating within the deep Earth and processes operating on the Earths surface. The inert nature of the noble gases make them unique geochemical tracers for studying a variety of processes including the accretionary history of extraterrestrial material to Earth, formation of the terrestrial atmosphere, low temperature thermochronometry, exposure age dating, geochemical evolution of the Earth's mantle, and magma degassing. more

The Harvard Noble Gas Laboratory is capable of measuring all the noble gases, from He to Xe. The lab has pioneered multicollector measurements of Ne and Xe. more

Deep mantle neon and xenon
New measurements from the Iceland plume demonstrate that the mantle sources for mid-ocean ridge basalts (MORBs) and plumes formed within the first 100 Myr and have experienced limited mixing over Earth history. Xe isotopes indicate that the volatile content of the plume source is distinct from the upper mantle.

How much water goes back into the mantle?
We found that the sea level record provides one of the best long term constraints on water cycling between the solid Earth and the surface. Our estimates for the mantle return water flux are much lower than previously suggested.

Mantle paradoxes
Learn about our solutions to the helium paradox and the argon paradox.

Currently I am working on the heat-helium imbalance in mantle and characterizing the heavy noble gas composition of more deep mantle sources.

Corals as dust archives
The progressive drying of the Sahel region in Africa from 1960s to early 1990s has had devastating social, economic, and environmental consequences. Using a novel helium-based proxy method, we have constructed a high-resolution 300-year record of dust emission from the Sahel that reveal the natural modes of variability in dust and correlations with sea surface temperatures.

Antarctic ice sheet history
We reported the first ice-elevation history from the interior of the West Antarctic Ice Sheet (WAIS), placing limits on the WAIS contribution to sea level changes during the last interglacial period. New cosmogenic nuclide data indicate fast erosion rates or recent ice cover in the Dry Valleys, calling into question the conventional wisdom about the pristine nature of the Dry Valleys.

Quantifying land surface evolution
My group demonstrated that the frequency distribution of cosmogenic nuclides in river sediments can be utilized to map out the spatial variability of erosion rates within a basin and to qunatitatively constrain the exact form of the erosion law. Current work is focused on understanding the link between climate and erosion rates on the Hawaiian island of Kauai.

Right: A dust plume from W. Africa passing over the Cape Verde Islands