Earth's birth: Inert gases provide clues

"Our findings throw into uncertainty a recent conclusion that gases . . . were solely delivered by meteorites crashing into the planet," said Mark Kendrick from School of Earth Sciences - University of Melbourne.

The study shows atmospheric gases are mixed in the mantle inside Earth's interior, during the process called 'subduction', when tectonic plates collide and submerge beneath volcanoes in subduction zones, the journal Nature Geoscience reports.

"This finding is important because it was previously believed that inert gases inside the Earth had primordial origins and were trapped during the formation of the solar system," Kendrick said, according to a Melbourne statement.

Because the composition of neon in Earth's mantle is very similar to that in meteorites, it was recently suggested by scientists that most of the Earth's gases were delivered by meteorites that also generated visible craters on its moon.

"Our study suggests a more complex history in which gases were also dissolved into the Earth while it was still covered by a molten layer, during the birth of the solar system," Kendrick said.