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Meteorite impacts could preserve ancient environments

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Researchers have discovered asteroid impacts might actually preserve ancient ecosystems, after finding complex organic material encased in material thrown out of a crater.

According to new findings published recently in the journal Nature Geoscience, rainforest and swamp survived extreme pressures and temperatures during a meteorite impact in Western Tasmania, by being incorporated in glassy material that formed from newly melted rock.

Professor Phil Bland, co-author and planetary scientist from the Department of Applied Geology, Curtin University, said when large meteorites strike the Earth at incredibly high speeds of up to 18 kilometres per second, the energy released causes solid rocks to melt and blast into the air.

The droplets of molten rock then rain down over large areas of Earth, solidify in flight, forming glass fragments known as “impact glasses”.

“Inside these glasses the research team found tiny spheres of carbon bearing organic matter sourced from the ancient rainforest and swamp present at the time of impact,” Professor Phil said.

“Seeing well-preserved biomarkers in these very tough glasses is really exciting.

“Impact glasses are thrown a long way from the crater – even off-planet. Potentially you could find evidence for ancient terrestrial ecosystems on the Moon.”

Dr Kieren Howard, lead researcher and mineralogist based at Kingsborough Community College, The City University of New York, said researchers had long assumed any organic molecules, such as amino acids would not survive a meteorite impact, whether they were on the meteorite or already on the planet.

“We were surprised by our discovery. The evidence we have now supports an old hypothesis that impacts might have delivered the building blocks of life to early Earth,” Dr Howard said.

The team studied the Darwin Crater in Western Tasmania. The tiny fragments of glass formed during the impact are known as Darwin Glass.

Impact glasses do not change very much over time and they contain an oxygen-poor environment so any molecules trapped within them are protected from degradation.

Professor Bland said this made them great time capsules, giving an idea what environments were like millions of years ago.

“On planets like Mars, impact glasses may survive billions of years, possibly providing evidence for long extinct Martian organisms,” Professor Bland said.

“Impact glasses from Mars might be a great place to look for evidence of past life.”

The team also consisted of researchers from the United Kingdom’s University of Surrey, Imperial College, Open University and The Natural History Museum.

View the paper, “Biomass preservation in impact melt ejecta”.

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