Discovery challenges timeline of oxygen on Earth

Two multinational teams of scientists, including four researchers from Arizona State University, are reporting that traces of oxygen appeared in Earth’s atmosphere 50 to 100 million years before the “Great Oxidation Event.” This event happened between 2.3 and 2.4 billion years ago when most geoscientists think atmospheric oxygen rose sharply from very low levels. The amount of oxygen before that time is uncertain and controversial.

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<p><a href="http://www.physorg.com/news110122626.html">Discovery challenges timeline of oxygen on Earth</a></p> <p>Two multinational teams of scientists, including four researchers from Arizona State University, are reporting that traces of oxygen appeared in Earth’s atmosphere 50 to 100 million years before the “Great Oxidation Event.” This event happened between 2.3 and 2.4 billion years ago when most geoscientists think atmospheric oxygen rose sharply from very low levels. The amount of oxygen before that time is uncertain and controversial.</p>