When was the great oxidation event

And in a study published recently in the journal Nature Geoscience, a research team led by scientists at Arizona State University has provided compelling evidence for significant ocean oxygenation before the GOE , on a larger scale and to greater depths than previously recognized. For this study, the team targeted a set of 2. McRae Shale. Read the full press release. Notice: This is an archived and unmaintained page. For current information, please browse astrobiology.

You are here: Home » Articles. If the glaciation came first, it is possible that it was because nutrients that were derived from rocks ground up by glaciers were washed into the oceans by rivers and floodwaters when the ice sheets melted. Once in the ocean these nutrients could have stimulated a cyanobacterial bloom thereby increasing oxygen production.

Conversely, oxygenation of the atmosphere during the GOE would have destabilised methane, a greenhouse gas that is thought to have been present in greater concentrations in the early atmosphere.

A rapid drop in methane levels would have caused a collapse of the greenhouse effect, therefore triggering a sudden and severe cooling of the climate. These sedimentary rocks were deposited in shallow seawater between 2. We analysed the sulphur they contained using a new state-of-the-art technique developed at the University of St Andrews in Scotland, and our results are now published in the journal PNAS.

The relative amounts of each of these sulphur isotopes is usually predictable. However, in rocks more than 2. Therefore we can use the point at which sulphur with this sort of unpredictable isotope ratios vanishes from ancient rocks to pinpoint the GOE.

We found evidence in the older Russian rocks we looked at, but in the younger rocks it was absent. This is strong evidence that the GOE happened in a million-year interval between 2. This is earlier than previous estimates of the GOE, but we argue that it is consistent with sulphur isotope records from South Africa, North America and Australia. Importantly, given the age constraints on the snowball Earth deposit, we can now say the GOE preceded the most severe of the glacial episodes.

We conclude, as others have argued , that it is likely that rising atmospheric oxygen concentrations lowered methane levels and weakened the greenhouse effect thereby pushing the planet into a period of major glaciation.

So, why does this matter?