Earth History
I have a longstanding interest in Earth's biologic and environmental history that began when I collected fossils in North Carolina as a kid. Professionally, this interest has manifested itself as research on the early Cambrian with Adam Maloof (Princeton University) and my ongoing research efforts on the Deccan Traps and the end-Cretaceous extinction. I also routinely produce high-precision U-Pb zircon dates for volcanic ash beds from key stratigraphic intervals to help other researchers calibrate rates of extinction, evolution, and environmental change.
Miocene ash beds in lacustrine sedimentary rock near Clarkia, Idaho. Dating tuffs such as these using high-precision U-Pb geochronology remains the gold standard in generating stratigraphic age models.
Geochemical Change in the Early Cambrian Ocean
I had the opportunity to work with a large geochemical dataset from early Cambrian carbonates with Adam Maloof (Princeton University) as an undergraduate. This research focused on the variability of carbonate-hosted, redox-sensitive trace elements during a key interval of time between 541-517 Ma. This period marks the beginning of the great evolutionary radiation known as the Cambrian Explosion. Our data showed a long-term decrease in carbonate-hosted U and V during this time that we attributed to increasing levels of dissolved oxygen in the global ocean (Maloof et al., 2010).
Graph showing the evolution of the carbon isotope, U, and V composition of carbonates in Morocco during the early Cambrian from Maloof et al. (2010). Both U and V are normalized and corrected for silicic sedimentary input using Th content and the post-Archean average shale composition. We interpreted these negative trends to represent increasing levels of dissolved oxygen in Earth's ocean during this time.