UW-Madison: Fossil fuel formation: Key to atmosphere’s oxygen?

CONTACT: Jon Husson, (610) 389-0893

MADISON – For the development of animals, nothing – with the exception of DNA – may be more important than oxygen in the atmosphere.

Oxygen enables the chemical reactions that animals use to get energy from stored carbohydrates – from food. So it may be no coincidence that animals appeared and evolved during the “Cambrian explosion,” which coincided with a spike in atmospheric oxygen roughly 500 million years ago.

It was during the Cambrian explosion that most of the current animal designs appeared.

In green plants, photosynthesis separates carbon dioxide into molecular oxygen (which is released to the atmosphere), and carbon (which is stored in carbohydrates).

But photosynthesis had already been around for at least 2.5 billion years. So what accounted for the sudden spike in oxygen during the Cambrian?

A study now online in the February issue of Earth and Planetary Science Letters links the rise in oxygen to a rapid increase in the burial of sediment containing large amounts of carbon-rich organic matter. The key, says study co-author Shanan Peters, a professor of geoscience at the University of Wisconsin-Madison, is to recognize that sediment storage blocks the oxidation of carbon.

Without burial, this oxidation reaction causes dead plant material on Earth’s surface to burn. That causes the carbon it contains, which originated in the atmosphere, to bond with oxygen to form carbon dioxide. And for oxygen to build up in our atmosphere, plant organic matter must be protected from oxidation.

And that’s exactly what happens when organic matter – the raw material of coal, oil and natural gas – is buried through geologic processes.

To make this case, Peters and his postdoctoral fellow Jon Husson mined a unique data set called Macrostrat, an accumulation of geologic information on North America whose construction Peters has masterminded for 10 years.

READ MORE AT http://news.wisc.edu/fossil-fuel-formation-key-to-atmospheres-oxygen/