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Nadja Drabon (Harvard University)
"The Effect of the Giant 3.26 Gyr Meteorite impact on the Earth’s Early Surface Environment and Life"
Large meteorite impacts strongly affected the habitability of the early Earth. The rocks of the Archean Eon record at least 16 major impact events with bolides larger than 10 km in diameter. These impacts likely had severe consequences for the surface conditions of early Earth. I will present on the analysis of sedimentary rocks across the 3.26 Ga S2 impact event (37-58 km bolide) to evaluate its environmental effects and consequences for early life. The results reveal that the impact caused a giant tsunami, evaporation of the uppermost layer of the ocean, and an increase in iron by mixing Fe 2+ -rich deep with Fe 2+ -poor shallow waters. Although meteorite impacts are usually seen as destructive and the S2 impact certainly had disastrous short-term consequences, it may have had some medium-term benefits for the early biosphere. The mixing of Fe 2+ to the upper water column potentially provided electron donors to the photic zone. In addition, the post-impact hothouse environment may have led to increased erosion and weathering, injecting nutrients like phosphorus into the oceans. Overall, meteorite impacts may have had transient benefits for early life on Earth.