[meteorite-list] World's Largest Mass Extinction Probably Caused by Poisonous Volcanic Gas

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Dec 2 15:55:54 2005
Message-ID: <200512022054.jB2KsKf20527_at_zagami.jpl.nasa.gov>

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

No safe ground for life to stand on during world's largest mass extinction
Imperial College London News Release

For immediate release
1 December 2005

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.

Many scientists had previously thought that an asteroid hitting the
earth or a deep-sea methane release had caused the extinction, which
obliterated more than two-thirds of reptile and amphibian families.

The researchers believe that the volcanic gases from the eruption killed
rooted vegetation

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.

Dr Mark Sephton from Imperial College London's Department of Earth Sciences
and Engineering and lead author of the research, said: "The cause of the
end Permian extinction has been highly controversial. We show that the
terrestrial ecosystem was the first to suffer. The continent-wide nature
of the event implies that it was caused by something in the atmosphere.
The unique chemical data indicates that something fast and catastrophic
happened on land."

Prof Henk Visscher of Utrecht University, also part of the research
team, commented: "Similar to the 'Dead Zone' nowadays spreading in the
Gulf of Mexico, the soil crisis could have caused a worldwide expanse of
uninhabitable low-oxygen conditions in shallow marine waters. So what
began on land ended in the sea. It seems there was no place to hide at
this time of great dying."

Dr Sephton believes that lessons can be learned in the present day from
the damage caused by the end Permian extinction: "Land degradation is a
worsening global problem thanks to human activity and soil erosion has
caused the loss of a third of arable land over the last forty years. 35%
of the Earth's land is now soil-free. Identifying the nature of the end
Permian soil crisis may help us understand what is in store for us in
the years ahead," he said.

The research was carried out by an international team of scientists from
the United Kingdom, the Netherlands and the United States.

-ends-

For further information please contact:

Laura Gallagher
Press Officer
Communications Division
Tel: +44 (0)20 7594 6702
Mobile: +44 (0)7803 886 248
E-mail: l.gallagher_at_imperial.ac.uk

Notes to editors:

1. "Catastrophic soil erosion during the end-Permian biotic crisis"
Geology: Vol. 33, No. 12, pp. 941944.

Mark A. Sephton(1) Cindy V. Looy(2) Henk Brinkhuis(3) Paul B. Wignall(4)
Jan W. de Leeuw(5) Henk Visscher(6)

(1)Impacts and Astromaterials Research Centre, Department of Earth
Science and Engineering, South Kensington Campus, Imperial College
London, London SW7 2AZ, UK

(2)Smithsonian Institution, P.O. Box 37012, National Museum of Natural
History, Department of Paleobiology, MRC-121, Washington, D.C.
20013-7012, USA

(3)Department of Palaeoecology, Laboratory of Palaeobotany and
Palynology, Utrecht University, Budapestlaan 4, 3584 CD, Utrecht,
Netherlands

(4)School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK

(5)Department of Marine Biogeochemistry and Toxicology, Royal
Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg,
Texel, Netherlands

(6)Department of Palaeoecology, Laboratory of Palaeobotany and
Palynology, Utrecht University, Budapestlaan 4, 3584 CD, Utrecht,
Netherlands

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Website: www.imperial.ac.uk
Received on Fri 02 Dec 2005 03:54:20 PM PST