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Irreversible Oxidation of the Exosphere and Acceleration of the Biosphere Across the Archean-Paleoproterozoic Transition

Presenter: Jay Kaufman
When: April 25, 2011 11AM PDT

Around two and half billion years ago a harmonic convergence of tectonic, volcanic, oceanographic, atmospheric, and biological events resulted in the irreversible oxidation of Earth’s thin crust and surface environments. Lithological and geochemical evidence of this terrestrial metamorphosis – which stimulated global environmental, climatic, and biological innovations – is preserved in sedimentary archives sampled in outcrop and deep time drill cores from ancient continental fragments scattered about the globe. Recent time-series investigations of geochemical change in the shallow Archean and Paleoproterozoic oceans predict stepwise growth in atmospheric oxygen and ozone, the planetary sunscreen, and in seawater nitrate and sulfate, which sustain key microbial ecosystems. In this evolutionary seminar we will explore the possible sources and sinks of oxygen on the early Earth and the effect of its geologically sudden rise (coined by Dick Holland as the Great Oxidation Event or GOE) on weathering, climate, and the onset of a modern-style carbon cycle.

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