PROVIDENCE, R.I. [Brown University] Asteroid and comet impacts can cause widespread ecological havoc, killing off plants and animals on regional or even global scales. But new research from Brown University shows that impacts can also preserve the signatures of ancient life at the time of an impact.
A research team led by Brown geologist Pete Schultz has found fragments of leaves and preserved organic compounds lodged inside glass created by a several ancient impacts in Argentina. The material could provide a snapshot of environmental conditions at the time of those impacts. The find also suggests that impact glasses could be a good place to look for signs of ancient life on Mars.
The work is published in the latest issue of Geology Magazine.
The scorching heat produced by asteroid or comet impacts can melt tons of soil and rock, some of which forms glass as it cools. The soil of eastern Argentina, south of Buenos Aires, is rife with impact glass created by at least seven different impacts that occurred between 6,000 and 9 million years ago, according to Schultz. One of those impacts, dated to around 3 million years ago, coincides with the disappearance of 35 animal genera, as reported in the journal Science a few years back.
"We know these were major impacts because of how far the glass is distributed and how big the chunks are," Schultz said. "These glasses are present in different layers of sediment throughout an area about the size of Texas."
Within glass associated with two of those impacts one from 3 million years ago and one from 9 million years ago Schultz and his colleagues found exquisitely preserved plant matter. "These glasses preserve plant morphology from macro features all the way down to the micron scale," Schultz said. "It's really remarkable."
The glass samples contain centimeter-size leaf fragments, including intact structures like papillae, tiny bumps that line leaf surfa
|Contact: Mark Nickel|