Unraveling The Big Melt in the Neoproterozoic

With my defense behind me, and my Ph.D. thesis submitted to graduate studies, I can start thinking about what lies ahead. I have finally had a normal weekend around home for the first time in months. I slept late, spent some time in the kitchen cooking good food, and spent most of the day packing what’s left of my belongings into boxes. It also means I have a bit of time to write a blog entry to share a preview of my next adventures.

My next stop in my scientific journey will be Boston. In less than a month’s time, I will begin a postdoctoral fellowship at Harvard University in the Johnston group (Earth History and Isotope Geobiology). This is a major departure from my Ph.D. research direction in the fossil fuel and energy world, but the common thread is the isotope systems used to investigate these problems. The main focus of my postdoc project will be to investigate the major changes in Earth`s atmosphere during deglaciation of the Neoproterozoic “Snowball Earth” events. Various hypotheses and models have been proposed to explain the greenhouse climate required to melt a Snowball Earth, but until recently there has not been a direct proxy to measure the amount of CO2 in the atmosphere, and thus constrain the modeling with empirical evidence. Dr. Huming Bao recently developed a laser fluorination system that can measure 17O values directly from sulfates in the rock record. A large negative 17O anomaly in atmospheric oxygen is associated with deglaciation of Snowball Earth, owing to the high concentration of CO2 (up to 35X present day), and low concentration of O2 (1/20th of present day) in the atmosphere during this time. This signal is recorded in the rock record via sulfates derived from oxidative weathering that are deposited either as anhydrite or barite. We will build one of these instruments this fall at Harvard and begin to measure the extensive rock samples that are in collection at Harvard that were collected by researchers there over the past twenty years (always properly archive your samples!). By measuring oxygen isotopes of sulfates in Neoproterozoic cap carbonates from around the world, we will start to determine the global extent and magnitude of the observed oxygen isotope anomaly, and thus the amount of CO2 in the atmosphere during deglaciation. This will ultimately provide constraints on the global climate system during one of the biggest climate shifts in Earth history. I’m also exceptionally excited about starting to work with Dave Johnston, who I met at the Goldschmidt conference in Montreal last year. We have very similar research interests, and we seem to collaborate well, having written a couple grants together remotely over the past year.

One of the best things about starting a pure research project is the removal of industry restrictions on what data can be published, versus what data are proprietary. This will also hopefully enable more frequent blog posts with new ideas about a time in Earth’s history that has fascinated me since my undergrad course in glacial sedimentology. Combining Neoproterozoic with a new and exciting isotope system is an ideal setup for me, and I look forward to sharing more discoveries in the near future.


ps – submission of my Ph.D. papers has begun, now that industry restrictions have been removed. Look out for these in the next couple months as they work their way through peer-review.