Researchers from Canada and the United Kingdom led by Prof Chris Ballentine from the University of Manchester have discovered ancient water pockets that have been isolated deep underground for more than a billion years.

The scientists analyzed water pouring out of boreholes from a mine 1.5 miles (2.4 km) beneath Ontario, Canada.

According to their study published in the journal Nature, this water could be some of the oldest on Earth and may even contain life. The similarity between the rocks that trapped it and those on Mars raises the hope that comparable life-sustaining water could lie buried beneath the Red planet’s surface.

The team found that the water is rich in dissolved gases like hydrogen, methane and isotopes of noble gases such as helium, neon, argon and xenon. Indeed, there is as much hydrogen in the water as around hydrothermal vents in the deep ocean, many of which teem with microscopic life. The hydrogen and methane come from the interaction between the rock and water, as well as natural radioactive elements in the rock reacting with the water. These gases could provide energy for microbes that may not have been exposed to the sun for billions of years.

The crystalline rocks surrounding the water are thought to be around 2.7 billion years old. But no-one thought the water could be the same age, until now. Using ground-breaking techniques, the researchers show that the fluid is at least 1.5 billion years old, but could be significantly older.

“We’ve found an interconnected fluid system in the deep Canadian crystalline basement that is billions of years old, and capable of supporting life. Our finding is of huge interest to researchers who want to understand how microbes evolve in isolation, and is central to the whole question of the origin of life, the sustainability of life, and life in extreme environments and on other planets,” Prof Ballentine said.

Before this discovery, the only water of this age was found trapped in tiny bubbles in rock and is incapable of supporting life. But the water found in the Canadian mine pours from the rock at a rate of nearly two liters per minute. It has similar characteristics to far younger water flowing from a mine 1.7 miles (2.8 km) below ground in South Africa that was previously found to support microbes.

The researchers don’t yet know if the underground system in Canada sustains life.

“Our Canadian colleagues are trying to find out if the water contains life right now. What we can be sure of is that we have identified a way in which planets can create and preserve an environment friendly to microbial life for billions of years. This is regardless of how inhospitable the surface might be, opening up the possibility of similar environments in the subsurface of Mars,” explained first author Dr Greg Holland of Lancaster University.

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Bibliographic information: G. Holland et al. 2013. Deep fracture fluids isolated in the crust since the Precambrian era. Nature 497, 357–360; doi: 10.1038/nature12127