More than 3 kilometers inside the Earth’s crust, scientists were able to tap into an ancient underground water source. After dating it, they found it is at least two billion years old. Strikingly, the researchers found sulphate, which organisms can use for energy, was made in situ as a result of chemical reactions between the water and the rock. This means that a whole new biodome is waiting for science to describe it beneath the crust. A whole new world of life far grander than anyone imagined — maybe.
University of Toronto researchers have been exploring the Kidd Mine in Ontario, Canada, since 2013. This is deepest metal mine in the world and it proved an excellent opportunity to probe for ancient water trapped miles underground. Copper, zinc, and gold have gotten more expensive in the last five years so companies are mining deeper than ever around Ontario. But one man’s corporate playground is another man’s perfect science experiment.
Initially, the researchers found a pocket of water 2.4 kilometers (1.5 miles) below the surface, which turned out to be 1.5 billion years old. They dug deeper though and eventually got to 3.1 kilometers (1.9 miles) below the surface. It is here that they hit the jackpot.
They found a source that’s at least half a billion years more ancient. It wasn’t some drops seeping out of cracks either — “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,” Professor Barbara Sherwood Lollar from the University of Toronto told BBC News.
Ancient gases like helium, neon, argon, and xenon were still trapped in the water, and this is how the researchers were able to date the water following an isotopic analysis.
The most striking find, however, was the discovery of sulphate, the chemical left behind by organisms that once lived in the water.
“By looking at the sulphate in the water, we were able to see a fingerprint that’s indicative of the presence of life,” said Prof Sherwood Lollar.
“And we were able to indicate that the signal we are seeing in the fluids has to have been produced by microbiology – and most importantly has to have been produced over a very long time scale.
“The microbes that produced this signature couldn’t have done it overnight. This isn’t just a signature of very modern microbiology.”
“This has to be an indication that organisms have been present in these fluids on a geological timescale.”
Though no actual microbes were found yet, the geochemical conditions suggest it’s possible that these ancient waters which are completely cut out from the surface can sustain life.
“Most life lives on sunlight, but these deep subsurface microbes seem to live on the limited energy they can only get inside the water trapped in these ancient rocks, ” says Long Li, assistant professor in the University of Alberta’s Department of Earth and Atmospheric Sciences.
Finding energy-rich waters like this is indicative that a whole new kind of life is presented miles beneath the crust. The findings also suggest there’s a good chance life is presented beneath Mars’ surface where there might be water of similar age and mineralogy. Stripped of its atmosphere, Mars’ surface is bombarded with radiation and UV light. There’s little chance any life can survive in these conditions but if there are any organisms on the red planet, you’ll find them underground.
“The wow factor is high,” says Li. “If geological process can naturally supply a steady energy source in these rocks, the modern terrestrial subsurface biosphere may expand significantly both in breadth and in depth.”
“Because this is a fairly common geological setting in early Earth as well as modern Mars, we think that as long as the right minerals and water are present, likely kilometers below the surface, they can produce the necessary energy source to support the microbes. I’m not saying that these microbes definitively exist, but the conditions are right to support microbial life on Mars,” he added.