Impact Glass from Asteroids Stores Bio-Data for Millions of Years

First Posted: Apr 21, 2014 09:23 AM EDT
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Ancient impact glass from asteroids may tell us a little bit more about the history of our planet. This molten glass can encapsulated bits of plant life that reveal what Earth was like millions of years ago, and could allow scientists to gain further insight into how our planet formed.

Asteroid and comet impacts can cause widespread ecological havoc. Bombardment can kill off plants and animals at a staggering rate, and can also lead to mass extinctions. That's why studying these impacts is so important; it allows scientists to see how they might have affected the history of our planet.

In this case, the researchers examined large fields of impact glass in Argentina. There, they found fragments of leaves and preserved organic compounds lodged inside the glass. The material actually could help provide a snapshot of the environmental conditions that existed at the time of the impacts.

"We know these were major impacts because of how far the glass is distributed and how big the chunks are," said Pete Schultz, one of the researchers, in a news release. "These glasses are present in different layers of sediment throughout an area about the size of Texas."

When an asteroid or comet hits the Earth, it can melt tons of soil and rock. Some of this soil and rock actually forms glass as it cools, and then can trap organic material within it. Argentina in particular is home to impact glass created by at least seven different impacts that occurred between 6,000 and 9 million years ago. One of these impacts, which occurred about 3 million years ago, coincides with the disappearance of 35 animal genera.

So how were these organic samples preserved during the blast? The water in the exterior layers of the leaves found within the glass insulated the inside layers and allowed them to stay intact. While the outside layers "fried" quickly, the inside layers took longer to "cook" and thus were able to be preserved.

The findings have huge implications for Mars in particular. It indicates that asteroid and comet impact sites with glass could be perfect locations to search for evidence of past life.

"Impact glass may be where the 4 billion-year-old signs of life are hiding," said Schultz in a news release. "On Mars they're probably not going to come out screaming in the form of a plant, but we may find traces of organic compounds, which would be really exciting."

The findings are published in the journal Geology.

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