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A group of researchers at the University of Calgary, Canada, has discovered one of the contributory factors behind the great mass extinction of the late Permian period, that caused the extinction of 95% of marine species and 70% of those on land. This event left the way clear for the subsequent world domination by the dinosaurs.
It was already believed that this frightening extinction, about 250 million years ago, could have been connected with volcanic eruptions on an unprecedented scale, but it wasn't known that this initiated another catastrophe for life on Earth; the burning of huge coal deposits. These were present in the region of Pangaea (the single super-continent present in that era) now located in an area of Siberia known as the Siberian Traps, covering an area of 2 million km2 (equivalent to half of Europe).
At the end of the Permian era these produced the largest volcanic eruption for which these exists scientific evidence.
As if the gas and dust emitted into the atmosphere by the eruption, and the fires caused by lava flows weren't enough, the combustion of coal deposits released enormous quantities of ash, carbon dioxide and methane, with serious repercussions for both the thermal equilibrium of the planet and the carbon cycle. This had a devastating effect on marine life, already threatened by oxygen levels that had long been decreasing.
Unmistakable traces of coal ash have recently been found by Steve Grasby, Benoit Beauchamp and Hamed Sanei in sedimentary rocks (allowing the epoch of the eruption to be determined) in the high Canadian Arctic, particularly in those of Buchanan Lake, Axel Heiberg Island (photo above).
The presence of that particular type of ash supports the idea of an intense period of volcanic activity, simply because it is difficult to imagine any other cause for such a massive combustion of coal. The results of the discovery made by the Calgary team have been published in Nature Geoscience.
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