Permian Extinction: Volcanic Gas

["Richard W. Travsky" <rtravsky@uwyo.edu>]

http://www.imperial.ac.uk/P7101.htm

The world's largest mass extinction was probably caused by poisonous 
volcanic gas, according to research published today.

The research, published in the journal Geology, reveals vital clues about 
the mass extinction at the end of the Permian period, 250 million years 
ago, when mammal-like reptiles known as synapsids roamed the earth.
[...]
However, analysis of a unique set of molecules found in rocks taken from 
the Dolomites in Italy has enabled scientists to build up a picture of 
what actually happened. The molecules are the remains of polysaccharides, 
large sugar-based structures common in plants and soil, and they tell the 
story of the extinction.

The molecules date from the same time as a major volcanic eruption that 
caused the greatest ever outpouring of basalt lava over vast swathes of 
land in present day Siberia.

The researchers believe that the volcanic gases from the eruption, which 
would have depleted earth's protective ozone layer and acidified the land 
and sea, killed rooted vegetation. This meant that soil was no longer 
retained and it washed into the surrounding oceans.

The chemistry of the rocks reveals that although the sugar molecules were 
found in marine sediments, they derived from land, supporting the theory 
that massive soil erosion caused them to end up in the sea.

Soil materials in the oceans would have blocked out light and soaked up 
oxygen. Analysis of rock chemistry suggests that after the soil crisis on 
land, the marine ecosystem succumbed to the stresses of environmental 
change and oceanic life faltered, completing a global catastrophe.