[meteorite-list] Deep within the Earth's rocky mantle lies oceans' worth of water locked up in a type of mineral called ringwoodite, new research shows

From: Shawn Alan <shawnalan_at_meteoritecentral.com>
Date: Tue, 17 Jun 2014 13:26:01 -0700
Message-ID: <20140617132601.e8713c95af9984a493c5db01816d4c10.d79632e790.wbe_at_email22.secureserver.net>

Hello Listers,

Tenham meteorite, the first Australian meteorite fall has some good new
in the science world :)

Enjoy.


Shawn Alan
IMCA 1633
ebay store http://www.ebay.com/sch/imca1633nyc/m.html
Website http://meteoritefalls.com


Found! Hidden Ocean Locked Up Deep in Earth's Mantle

A water-rich mineral

Ringwoodite is a rare type of mineral that forms from olivine under very
high pressures and temperatures, such as those present in the mantle's
transition zone. Laboratory studies have shown that the mineral can
contain water, which isn't present as liquid, ice or vapor; instead, it
is trapped in the ringwoodite's molecular structure as hydroxide ions
(bonded oxygen and hydrogen atoms).

In March, another research group discovered an unusual diamond from the
mantle that encased hydrous ringwoodite. Though the find suggested the
transition zone could contain a lot of water, it was the first and only
ringwoodite specimen from the mantle scientists have ever analyzed (all
other samples were produced in the lab or found in meteorites), and may
not be representative of other mantle ringwoodite.

"Right now, we're one-for-one, because that ringwoodite had some H2O in
it, but we didn't know if it was normal," Schmandt told Live Science. So
Schmandt and geophysicist Steven Jacobsen of Northwestern University in
Illinois set out to observationally test if other mantle ringwoodite
also contains water.

The researchers knew the crystal structure of ringwoodite allows the
transition zone to hold water, but that structure changes if the
material moves across the boundary to the lower mantle (due to
increasing pressures and temperatures). Because the structure of
minerals in the lower mantle can't trap water the way ringwoodite can,
Schmandt and Jacobsen reasoned the rocks would melt as they flowed from
the transition zone to the lower mantle. "Melting is just a mechanism of
getting rid of the water," Schmandt said.

To test this hypothesis, Jacobsen and his colleagues conducted lab
experiments to simulate what would happen to transition zone ringwoodite
as it travels deeper into the Earth. They synthesized hydrous
ringwoodite and recreated the temperatures and pressures it would
experience in the transition zone by heating it with lasers and
compressing it between hard, anvil-like diamonds.

for more on this go to this link
http://news.msn.com/science-technology/found-hidden-ocean-locked-up-deep-in-earths-mantle?ocid=ansnews11
Received on Tue 17 Jun 2014 04:26:01 PM PDT