University of Toronto scientists can lay claim to having found the world’s oldest water, which has been dated at roughly two billion years old. The water comes from the Kidd Creek Mine, a copper, zinc and silver mine in Timmins, Ontario, at a depth of nearly three kilometres.

In results recently presented at the American Geophysical Union Fall Meeting in San Francisco, researchers described how the new find is at least 500 million years older than a previous discovery from the same mine, and that contrary to the presumption that water at that depth must be contained in rock formations, this water was freely flowing.

“When people think about this water they assume it must be some tiny amount of water trapped within the rock,” says Barbara Sherwood Lollar, geochemist at U of T and lead author of the new study, in conversation with the BBC. “But in fact it’s very much bubbling right up out at you. These things are flowing at rates of litres per minute – the volume of the water is much larger than anyone anticipated.”

The water found coming out of boreholes in the ground was determined to be full of dissolved gases like hydrogen and methane, showing that it likely supported microbial life, a find that changes our conceptions of where life can exist on Earth – and may also provide clues as to how and in what capacity microbial life may be proliferating below the surface of Mars.

The world’s oldest water has been dated at roughly two-billion years old…

“For many years we still thought that life was really just a thin veneer on the surface of the planet, that life was largely dependent just on the sun’s energy,” says Lollar, who also spoke to the Australian Broadcasting Corporation (ABC). “What we have learnt since then through work done at the hydro thermal vents, the ocean bottoms and caves and in the sub-surfaces, is in fact there is life on this planet as well in the deep dark places.”

Because Mars -on the surface, at least- is less than hospitable for life as it’s understood from a terrestrial perspective, scientists are keen to look underground on the Red Planet, to see what possibilities might exist for life. Professor Simon George of the Department of Earth and Planetary Sciences at Macquarie University in Sydney spoke to ABC news about the significance of finding water rich in gases so far below Earth’s surface. “The work that’s been published recently here has now shown the possibility of this deep biosphere really working quite separately from the atmosphere of a planet,” says George. “It is quite an incredible geological process that’s been explored there.”

Analyzing the ancient water, researchers found chemical traces of single-celled organisms, ones that existed long ago. “By looking at the sulphate in the water, we were able to see a fingerprint that’s indicative of the presence of life,” says Lollar. “The microbes that produced this signature couldn’t have done it overnight. This isn’t just a signature of very modern microbiology.”

The research team was able to date the water by studying the concentration of xenon gas isotopes within it, finding that this water sample contains a high amount of lighter isotopes of xenon, an indication that it was around when these lighter isotopes were themselves more prevalent in Earth’s atmosphere, billion of years ago.

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