You wouldn't want to shower in it, but researchers have discovered pockets of water in a deep reservoir in Canada that may be up to 2.64 billion years old.
Researchers extracted the fluid from ancient rocks in a mine 1.5 miles underground in the area of Timmins, Ontario. In other mines, water has been found to support life, but scientists are still working to determine if there is life in this particular location. They say this is the oldest water found in such an environment.
We spoke with Chris Ballentine, professor of geochemistry at the University of Manchester in the United Kingdom, and senior author on this study, which published in the journal Nature. Here is an edited version of our email Q&A:
CNN: How did you find this ancient water?
Ballentine: My colleague in Toronto, Barbara Sherwood Lollar, project co-director, has been working on understanding the chemistry of these waters for many years. She suspected the water was very old because of the high levels of helium (which takes a long time to build up) contained in the water. I am developing new techniques to date underground water (an essential component when making safety cases for CO2 burial) and we decided to work together to put a proper age on these waters.
CNN: Do we think that there was life on Earth at that time?
Ballentine: Life was established on Earth by 3.5 billion years ago (Earth itself is 4.56 billion years old). The rocks containing the water we have analysed are about 2.7 billion years old. The Earth's surface would be teaming with very simple life - the ancestors of bacteria. Complex single-celled and multicelled organisms did not evolve until about 1.9 billion to 2.1 billion years ago. The water we have found is between 1.5 billion and 2.6 billion years in age.
CNN: Does this have any implications for life on other planets?
Ballentine: The system we have found is truly ancient and can support simple life. Our work tells us that Earth had a refuge for life during its earliest stages of formation - if life started there was a way for it to be preserved during continuing bombardment by meteorites that would make the surface of Earth barren - and could push back the time when life could have formed on Earth.
Equally on somewhere like Mars, any life that formed could have found its way into similar pockets of water in the Martian crust, and our work shows that these pockets of water can survive and provide a place for the life to have survived long after the surface of Mars lost its water and became sterile.
CNN: Can you describe the environment in which this was found?
Ballentine: These are waters that come out of the rock from exploration boreholes deep in the copper-zinc mine. The samples we have collected pour out of only some boreholes, but they can flow for months. The environment is dark, dusty, very noisy and hot.
CNN: Is it drinkable?
Ballentine: Alas not. The water is crystal clear when it first comes out of the rock and looks very tempting, bubbling with gas. But actually it is too salty to drink (it is a brine), and the gas instead of carbon dioxide is a mixture of methane, hydrogen, nitrogen and helium!
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