[meteorite-list] Western-led 'International Beam Team' Solves Martian Meteorite Age Puzzle
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 25 Jul 2013 15:22:48 -0700 (PDT)
Western-led 'international beam team' solves Martian meteorite age puzzle
July 24, 2013
By directing energy beams at tiny crystals found in a Martian meteorite,
a Western University-led team of geologists has proved that the most common
group of meteorites from Mars is almost 4 billion years younger than many
scientists had believed ? resolving a long-standing puzzle in Martian
science and painting a much clearer picture of the Red Planet's evolution
that can now be compared to that of habitable Earth.
In a paper published today in the journal Nature, lead author Desmond
Moser, an Earth Sciences professor from Western's Faculty of Science,
Kim Tait, Curator, Mineralogy, Royal Ontario Museum, and a team of Canadian,
U.S., and British collaborators show that a representative meteorite from
the Royal Ontario Museum (ROM)'s growing Martian meteorite collection,
started as a 200 million-year-old lava flow on Mars, and contains an ancient
chemical signature indicating a hidden layer deep beneath the surface
that is almost as old as the solar system.
The team, comprised of scientists from ROM, the University of Wyoming,
UCLA, and the University of Portsmouth, also discovered crystals that
grew while the meteorite was launched from Mars towards Earth, allowing
them to narrow down the timing to less than 20 million years ago while
also identifying possible launch locations on the flanks of the supervolcanoes
at the Martian equator.
More details can be found in their paper titled, "Solving the Martian
meteorite age conundrum using micro-baddeleyite and launch-generated zircon."
Moser and his group at Western's Zircon & Accessory Phase Laboratory (ZAPLab),
one of the few electron nanobeam dating facilities in the world, determined
the growth history of crystals on a polished surface of the meteorite.
The researchers combined a long-established dating method (measuring radioactive
uranium/lead isotopes) with a recently developed gently-destructive, mineral
grain-scale technique at UCLA that liberates atoms from the crystal surface
using a focused beam of oxygen ions.
Moser estimates that there are roughly 60 Mars rocks dislodged by meteorite
impacts that are now on Earth and available for study, and that his group's
approach can be used on these and a much wider range of heavenly bodies.
"Basically, the inner solar system is our oyster. We have hundreds of
meteorites that we can apply this technique to, including asteroids from
beyond Mars to samples from the Moon," says Moser, who credits the generosity
of the collectors that identify this material and make it available for
MEDIA CONTACT: Jeff Renaud, Senior Media Relations Officer, 519-661-2111,
ext. 85165, jrenaud9 at uwo.ca, _at_jeffrenaud99
Photo of the NWA 5298 meteorite
Received on Thu 25 Jul 2013 06:22:48 PM PDT