Breaking New Research on Evolution of Oxygen Supports Jupiter Conception of Earth
November 1, 2012 in Science
October 24, 2012
Evolution of Oxygen — Long-Standing Theory Challenged
“A team led by geochemists at the University of California, Riverside challenges the so-called Great Oxidation Event 2.4 billion years ago, and the simple notion of an up-only trend for early oxygen and provides the first compelling direct evidence for a major drop in oxygen after the first rise. The Great Oxidation was critical for the origin and evolution of the first forms of eukaryotic life. The second big step in the up-only hypothesis occurred almost two billion years later, coinciding with the first appearances and earliest diversification of animals.
“Our group is among a subset of scientists who imagine that oxygen, once it began to accumulate in the ocean-atmosphere system, may have ultimately risen to very high levels about 2.3-2.2 billion years ago, perhaps even to concentrations close to what we see today,” said Timothy Lyons, a professor of biogeochemistry and the principal investigator of the project. “But unlike the posited irreversible rise favored by many, our new data point convincingly to an equally impressive, and still not well understood, fall in oxygen about 200 million years later.”
This drop in oxygen may have ushered in more than a billion years that were marked by a return to low-oxygen concentrations at Earth’s surface, including the likelihood of an oxygen-free deep ocean. “It is this condition that may have set the environmental stage and ultimately the clock for the advance of eukaryotic organisms and eventually animals,” he said. Study results appear online this week in the Proceedings of the National Academy of Sciences.
“The time window between 2.3 and 2.1 billion years ago is famous for the largest and longest-lived positive carbon isotope excursion in Earth history,” said Noah Planavsky, currently a postdoctoral fellow at Caltech, and first author of the research paper. He explained that carbon isotopes are fractionated during photosynthesis. When organic matter is buried, oxygen is released and rises in the biosphere. The burial of organic matter is tracked by the positive or heavy isotopic composition of carbon in the ocean.”
The drop after the first major rise in oxygen levels [2.3-2.1 billion years ago] is evident of Titan’s transition to Triton.
4.5 billion years ago
Jupiter’s Great Red Spot