Research within the group focuses generally on metal isotope systematics in laboratory and natural systems. We conduct research utilizing a range of metal isotopes, including (but not limited to) Ca, Mg, Sr, Li, Cu, and Fe. Our primary objective is to understand how to interpret the past using a range of geochemical proxies with greater precision and accuracy. We are also interested in seeking new applications of stable metal isotopes to solved applied problems of relevance to society.

Prospective students: read about my advising philosophy and expectations for students.

To these ends, we conduct both laboratory experiments and studies of natural systems, the results of which are interpreted using simple modeling approaches (and more complex ab initio and reactive transport approaches where needed). The research in the group relies on a combination of all of these approaches, again to improve our understanding of how natural systems function.

Generally speaking, we are interested in:

Developing and evaluating isotopic proxies for elemental cycling in the geologic past.

Characterizing the global geochemical cycles of metals such as Ca, Mg, Li, Cu, and Fe (amongst others).

Some recent research in these areas include:

1. Interpretation of isotopic measurements
2. Proxy fidelity (e.g., alteration due to diagenesis)
   • Solid-fluid exchange over both million-year and short time scales (carbonates and goethite)
   • Effects of mineral precipitation/transformation on isotopic composition of minerals (carbonates, sulfates, and sulfides)
   • Physical and chemical indicators of diagenetic exchange at small spatial scales (nano-SIMS, SEM, etc)
3. Expression of isotopic biosignatures
   • The effect of organic molecules and microbial systems on mineral isotopic signatures
4. Application of isotopic and geochemical tools to studies of past climate perturbations (such as the PETM, OAEs, impacts, etc)
5. Constraints on geochemical cycles
   • Measured the elemental geochemistry, mineralogy, and Ca isotopic composition of surface sediments in arid environments
   • Extended point measurements of surface geochemistry to larger spatial scales using satellite-based hyperspectral data
   • Elucidate controls on dust production in arid systems, and the consequent effects on the mineralogy and chemistry of dust
   • Fe isotopic composition of sub-glacial streams on the Greenland Ice Sheet
   • The role of clay authigenesis in the global Li cycle

I also have a long-term interest in advancing analytical techniques, enhancing both accuracy and precision of isotopic analyses. This is required with some non-traditional isotope systems, such as Ca, because the observed variability in nature is small. My group works primarily with MC-ICP-MS (multiple collector inductively coupled plasma) and TIMS (thermal ionization) mass spectrometry. I also have strong interests in coupling these bulk measurements to small scale imaging and semi-quantified analyses (e.g., by SEM, nano-SIMS, and TEM).