[meteorite-list] Meteorites 'Cause Volcanic Eruptions'

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 10 Sep 2008 10:46:29 -0700 (PDT)
Message-ID: <200809101746.KAA10126_at_zagami.jpl.nasa.gov>

http://www.inthenews.co.uk/news/healthandscience/science/meteorites-cause-volcanic-eruptions-$1239971.htm

Meteorites 'cause volcanic eruptions'
In The New (United Kingdom)
September 10, 2008

Violent volcanic eruptions witnessed from the dawn of time to the
present day could all have been prompted by meteorite strikes billions
of years ago.

Geologists are presenting new evidence that contradicts the belief the
gas that causes volcanoes to erupt - 'light' helium - came to Earth via
its gravitational pull.

Volcanic eruptions occur when the gas, which arrived when the world was
in a molten state and is trapped in the deep Earth, melts.

But University of Manchester scientists say that the 'fingerprint' left
by the 3He isotope does not match solar nebula but instead meteorites.

"We have shown that the neon gas fingerprint expected for the captured
solar nebula model is not matched," Professor Chris Ballentine said.

"Instead we have found a meteorite signature, which suggests the massive
early atmosphere is not trapped by gravitational attraction as
originally thought but a result of meteorites spewing out gas on impact."

Prof Ballentine and his team also identified a second signature,
obtained via studying CO2 gas from the Colorado Plateau, which is
identical to seawater.

"The only explanation for this is that seawater trapped in ocean crust
is being driven back down into the deep Earth in a tectonic process
called subduction," he explained.

Previous thinking had stated that water at these depths would be
impossible due to it melting during the subduction process.

"This process has the potential to fundamentally change how scientists
think Earth has behaved over time. Even a little bit of water added to
rock in the deep earth makes it more plastic and allows movement of
tectonic plates sitting on top to be quicker," Prof Ballentine added.

"The source and fate of atmospheres and water on planets is central to
understanding the origin of life and the conditions that lead to our own
planet looking as it does today. Our work provides evidence that changes
our big picture understanding of how planetary systems acquire their
volatile elements.
Received on Wed 10 Sep 2008 01:46:29 PM PDT