Evaluating Atmospheric Oxygen Levels During the Great Oxidation Event

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The establishment of an oxygen-rich atmosphere had a profound influence on the course of biological evolution, paving the way for the advent of eukaryotic cells and ultimately enabling the evolution of large animals, including humans. These conditions did not always exist: a substantial body of geologic evidence indicates that the atmosphere and oceans were free of oxygen during early part of Earth's history, prior to 2.4 billion years ago, but the subsequent history of the oxygenation is poorly resolved.This study addresses a key interval just after the first appearance of oxygen, from about 2.2 to 2.0 billion years ago, a time when tantalizing geologic evidence suggests that oxygen levels may have risen to levels that even exceeded modern levels before falling to lower levels that persisted for another billion and a half years before rising again to levels high enough to support the evolution of animals. Cores recently drilled in Fennoscandian rocks (with NSF funding) display features that appear to reflect extreme oxidation by groundwaters that permeated an ancient volcanic landscape. These cores will be scrutinized using a variety of microscopic and geochemical techniques to test the hypothesis that they were exposed to highly oxygen charged waters, themselves the consequence of an "overshoot" of atmospheric oxygen during the Great Oxidation Event.Participating in this project will be a Ph.D. student, an undergraduate working on a senior thesis, and a summer research intern participating in our ongoing program promoting earth sciences research to undergraduates from minority-serving institutions. This collaborative group will partner with their colleagues at the University of Wisconsin and in Europe in their exploration of the FAR-DEEP cores and the nature of environmental change in Earth's distant past.