We seek to place the evolution and large-scale effects of Earth's biosphere into a planetary context, with the aim of better understanding the emergence and maintenance of biosignatures on Earth and Earth-like worlds.
- Tracking oxygenic photosynthesis on the early Earth -
There is tantalizing evidence that organisms capable of producing oxygen gas (O2) evolved long before oxygen permanently accumulated in the atmosphere. If true, this observation can teach us critical lessons about the evolution of Earth's oxygen cycle and the emergence of atmospheric biosignatures on planets beyond our solar system. We are currently searching for evidence of this 'cryptic oxygenesis' in the rock record and trying to better understand its environmental impact.
- Understanding the emergence and maintenance of planetary biosignatures -
The chemistry of a planetary atmosphere is an exceptionally complex emergent phenomenon. For example, Earth's modern atmosphere — which bears striking evidence for a surface biosphere — has developed through the long-term interplay between solid Earth processes (heat flow, plate tectonics), couplings and feedbacks within surface environments (biospheric energy flux, climate stability), and atmospheric photochemistry. The chemical evolution of Earth's atmosphere thus provides a wealth of empirical and heuristic information that can be leveraged toward better understanding the emergence and maintenance of remotely detectable planetary biosignatures on Earth-like planets.
- Reconstructing the ecological context of the first complex life -
There is an intriguing correspondence between apparent changes in ocean-atmosphere oxidation state, catastrophic climate perturbation (the 'Snowball Earth' glacial episodes), and the emergence of Earth's first large, complex organisms. We seek to reconstruct this record through the application of conventional and novel trace element and stable isotope systems and the integration of these geochemical archives with both quantitative theoretical models and insights from the molecular/body fossil record.
- Developing new geochemical tools for tracking ocean-atmosphere redox chemistry -
The application of existing and emerging trace/major element and stable isotope systems to tracking the evolution of ocean-atmosphere chemistry demands parallel exploration of how these systems behave in modern and Recent environments. This work involves the construction and refinement of stable isotope mass balance models for the modern ocean, the exploration of how different geochemical proxy systems behave during early sediment burial diagenesis, and the examination of biogeochemical cycling in modern 'natural lab' environments.