Research Interests  I am interested in the intertwined histories of Earth's climate, biota, and geology.  I utilize geochemical and ecological tools to help extract and interpret information from from the geological record.  Topics of interest include the Mio-Pliocene history of the East Asian Monsoons, the global expansion of tropical C4 grasses during the late Miocene, and carbonate diagenesis in the 'intermediate' temperature realm (ca. 50 - 400 C).

Lab Approach Our group is first and foremost engaged in the business of analytical geochemistry, specifically stable isotope ratio mass spectrometry (see lab website here).  We specialize in unique methodologies including clumped isotope paleothermometry and laser ablation microanalysis that allow scientific problems to be addressed in unprecedented detail.  We are a 'hands on' lab, with students, postdocs, and even PIs (gasp!) analyzing samples themselves and often fabricating equipment in order to conduct new analyses, streamline existing methodologies, and reduce 'downtime' when the normal equipment breaks down.  Automation is a lab speciality that allows us to maintain a high analytical throughput while freeing time for research and teaching.  Fieldwork is an important component of our research approach, and when possible we are involved in all aspects of study, starting at the outcrop, and continuing with laboratory measurements, data analysis, modeling, and finally talks and publications.

Clumped Isotopes  Many of our current efforts are focused on development of the carbonate clumped isotope thermometer.  Graduate student Greg Henkes is working on an empirical D47 vs T calibration in mollusks and brachiopods, and is collaborating with Ethan Grossman and Tom Yancey (TAMU) to use the method to study Carboniferous paleoclimate.  Former postdoc Marina Suarez used the method to study Miocene / Pliocene East Asian monsoons, and is now studying diagenetic clumped isotope signals in fossil bone apatite.  One of my main efforts since moving to Johns Hopkins focuses on lab experiments and theoretical understanding of solid-state reordering of C-O bonds in calcite.  These studies are geared towards understanding resetting of clumped isotope signals in deep burial environments, as related to temperatures of diagenetic processes in the upper few km of Earth's crust (see 2010 Goldschmidt poster here for the basic idea).