RIVERSIDE, Calif. Two teams of scientists, including three researchers from UC Riverside, report that traces of oxygen appeared in Earths atmosphere roughly 100 million years before the Great Oxidation Event 2.4 billion years ago. The Great Oxidation Event is when most geoscientists think atmospheric oxygen rose sharply from very low levels and set the stage for animal life that followed almost two billion years later.
Analyzing layers of sedimentary rock in a kilometer-long core sample they retrieved in 2004 from the Hamersley Basin in Western Australia, the researchers found evidence for the presence of a small but significant amount of oxygen 2.5 billion years ago in the oceans and likely also in Earths atmosphere.
Because the core was recovered from deep underground, it contains materials untouched by the atmosphere for billions of years. After retrieval, the scientists sliced the core longitudinally for analysis.
Study results appear in a pair of papers in tomorrows issue of Science.
The UCR contribution:
Geochemists Timothy Lyons, Steven Bates, and Clinton Scott of the UCR Department of Earth Sciences working with teams from Arizona State University and the universities of Maryland, Washington, and Alberta generated elemental and isotopic data that provide indirect, or proxy, evidence for the evolving atmosphere and its relationship to the early evolution of life.
This is the earliest convincing record for an ephemeral accumulation of oxygen in the biosphere before its irreversible rise beginning 2.4 billion years ago, said Lyons, a professor of biogeochemistry.
Scott, a graduate student working with Lyons, used metals in the ancient oceannow trapped in sedimentary rocksas proxies for the amount of oxygen in the early ocean and atmosphere. His doctoral research provided a baseline for t
|Contact: Iqbal Pittalwala|
University of California - Riverside