Water trapped underground for more than a billion years could contain never-before-seen microbial life, researchers in the UK and Canada repored in a Nature letter.

"Fluids trapped as inclusions within minerals can be billions of years old and preserve a record of the fluid chemistry and environment at the time of mineralization," the team wrote in the report. In one such instance, fluids found 2.8 km below the surface in a South African gold mine in 2006 yielded chemoautotrophic microbes - organisms that obtain energy by oxidizing electrons found in their environment - that were tens of millions of years old.

Now, the researchers said, they have found deep fracture fluid in a mine in Timmins, Ontario, that they say has likely been undisturbed since the Precambrian era 1.5 billion years ago. The team measured changes in xenon isotopes and other noble gases in the fluid samples to calculate their age. "Together, the different noble gases show that ancient pockets of water can survive the crustal fracturing process and remain in the crust for billions of years," the team added.

Lancaster University's Greg Holland, the report's lead author, told NPR the samples could be even older, as 1.5 billion years is the lower age limit. This is the oldest water ever found on the planet, he added, and is likely to have come from an ancient ocean.

Importantly, the discovery of such an ancient and isolated system means there could be bacteria present that evolved differently from bacteria on the surface of the Earth, NPR says. The samples also contain hydrogen, indicating that any microbes present could be hydrogen-eating, similar to other organisms found deep underground or far down in the ocean, NPR adds. Holland's team is testing the samples for evidence of life, and they hope the results will be ready to publish within a year.

This discovery could even indicate how life on other planets with atmospheres similar to these underground systems has evolved, NPR says. NASA research scientist Carl Stoker told NPR that because the Earth and Mars looked very much alike a few billion years ago, the discovery in Timmins could give scientists some insight as to where to look for Martian life, or may help explain why life began on Earth, but not on Mars.

Source: G Holland, BS Lollar, L Li, et al. Deep Fracture Fluids Isolated in the Crust Since the Precambrian Era. Nature. 2013. 2013.