Samples of water collected from deep below Earth's surface suggest our planet had water ever since becoming a planet.
Published in the journal Science, the new study details samples of water trapped in glass compartments in the Earth's mantle some 20 micrometers wide.
"The measurements are extremely difficult to make. Only in the past few years has the technology developed enough to measure such low concentrations of water inside such small amounts of material," study lead author Lydia Hallis, a cosmochemist at the University of Hawaii, told Discovery News.
The researchers had to view the samples through an instrument called an ion microprobe, a highly sensitive spectrometer ideal for analyzing complex minerals. In this case, the researchers were looking at microscopic samples encased in a tiny compartment.
They found the samples in rocks containing a mineral called olivine on Padloping Island, which lies east of Baffin Island in Northeastern Canada.
"The Baffin Island rocks were collected back in 1985, and scientists have had a lot of time to analyze them in the intervening years. As a result of their efforts, we know that they contain a component from Earth's deep mantle," Hallis said in a press release. "On their way to the surface, these rocks were never affected by sedimentary input from crustal rocks, and previous research shows their source region has remained untouched since Earth's formation. Essentially, they are some of the most primitive rocks we've ever found on Earth's surface, and so the water they contain gives us an invaluable insight into Earth's early history and where its water came from.
"We found that the water had very little deuterium, which strongly suggests that it was not carried to Earth after it had formed and cooled. Instead, water molecules were likely carried on the dust that existed in a disk around our Sun before the planets formed. Over time this water-rich dust was slowly drawn together to form our planet."
