Scientists at the University of Western Ontario, working with U.S. and British colleagues, said their findings resolve a long-standing puzzle in martian science and yield a much clearer picture of the Red Planet's evolution that can now be compared to that of habitable Earth.
Writing in the journal Nature, the team said an example from the Royal Ontario Museum's Martian meteorite collection began as part of a 200 million-year-old lava flow on Mars and contains an chemical signature indicating a hidden layer deep beneath the surface that is almost as old as the solar system.
Crystals that grew while the meteorite was launched from Mars toward Earth allowed the scientists to narrow down the timing to less than 20 million years ago, they said, while also identifying possible launch locations on the flanks of the super volcanoes at the martian equator.
The researchers used an electron beam to study the composition of the meteorites.
Western University earth sciences Professor Desmond Moser estimates there are roughly 60 Mars rocks dislodged by meteorite impacts that are now on Earth and available for study, in addition to hundreds of meteorites from other cosmic sources.
"Basically, the inner solar system is our oyster," he said. "We have hundreds of meteorites that we can apply this technique to, including asteroids from beyond Mars to samples from the moon."