The gases which make up the earth's atmosphere and probably its oceans are an import from outer space, says a new study.
Scientists from the Universities of Manchester and Houston (US) said that age-old beliefs like volcanoes being the source of our earliest atmosphere must now be discarded.
Using futuristic analytical techniques, the team of Greg Holland, Martin Cassidy and Chris Ballentine tested volcanic gases to uncover the new evidence. The research was funded by Natural Environment Research Council (NERC).
“We found a clear meteorite signature in volcanic gases,” said Manchester’s Greg Holland, who headed the project. “From that we now know that the volcanic gases could not have contributed in any significant way to the earth's atmosphere.”
“Therefore, the atmosphere and oceans must have come from somewhere else, possibly from a late bombardment of gas and water rich materials similar to comets,” he added.
“Until now, no one has had instruments capable of looking for these subtle signatures in samples from inside the earth - but now we can do exactly that.”
The techniques enabled the team to measure tiny quantities of the non-reactive volcanic trace gases Krypton and Xenon, which revealed an isotopic 'fingerprint' matching that of meteorites which is different from that of ‘solar’ gases.
The study is also the first to establish the precise composition of the Krypton present in the Earth's mantle, said a Manchester release.
Project director Chris Ballentine of Manchester University concluded that “many people have seen artist's impressions of the primordial earth with huge volcanoes in the background spewing gas to form the atmosphere. We will now have to redraw this picture.”
These findings were published in Science.