Ancient sediments preserved on Earth contain our most accessible record of the evolution and proliferation of life on a habitable planet. These sediments also hold insights into how the physical and chemical properties of Earth's surface have transformed over geologic time to the hospitable environment we inhabit today. The microbial ecosystems that dominated the first ~2 billion years of life on Earth leave little to no tell-tale physical imprints on the rock record, leaving astrobiologists focused on early Earth history to rely on chemical fingerprints, such as stable isotope ratios, to understand the coevolution of the geosphere with the biosphere over geologic time.
In this talk I will discuss ongoing research efforts utilizing stable isotope records to understand feedbacks between microbial ecosystems and Earth surface chemistry on the run-up to the Great Oxidation Event, which occurred between 2.45 and 2.32 billion years ago. In particular, carbon and sulfur isotope systematics in drill cores through Neoarchean (~2.65 to 2.5 billion-years-old) sediments from South Africa and Western Australia show evidence for a reduced atmosphere that was periodically rich in methane, producing a hydrocarbon haze similar to that on Saturn's moon Titan. We are exploring the biogeochemical drivers for and consequences of this unusual atmosphere on the early Earth.
Tea and coffee will be available after the seminar.
The astrobiology seminar series
The astrobiology seminar series is run by the UK Centre for Astrobiology based in the School of Physics & Astronomy. Astrobiology is a multi-disciplinary subject and the seminar series actively encourages attendance by undergraduates, postgraduates and academic staff from other departments.
For further information or proposals for speakers contact casey.bryce [at] ed.ac.uk (Casey Bryce) or d.martin [at] ed.ac.uk (Derek Martin).