Water trapped inside rocks for billions of years

Scientists have found evidence that water was trapped for up to billions of years inside rocks deep in an African gold mine.

"It's really exciting," said Barbara Sherwood Lollar, a University of Toronto geologist who co-authored the study published in the February issue of Chemical Geology. "Nobody has ever identified a billion-year-old component within water before."

She noted that the Earth itself has only existed for around 4.5 billion years.

The study led by Johanna Lippmann-Pipke of the Helmholtz-Zentrum Dresden-Rossendorf in Leipzig, Germany, looked at groundwater in crevices deep under South Africa's Witwatersrand Basin.

"They are like pockets of water that are interconnected," Sherwood Lollar told CBC's Quirks & Quarks in an interview that was to air Saturday.

The researchers analyzed the water and the elements dissolved init and found that onaverage, they were25 million years old.

But the very oldest was thedissolved neon gas.

"By looking at both how much is there and at the nature of the neon in particular something called the isotope composition we can get sense of how long these systems have been there," Sherwood Lollar said.

The neon showed evidence of having been there sincethe last time the rocks were heated to an extremely high temperature by geologic activity two billionto 2.7 billion years ago. At that time, water containing dissolved neon, salts and other componentswastrapped in microscopic pockets in the rock.

Over time, the rock fractured and some ofthat waterhad leaked into the rock crevices, where it could be detected and analyzed.

The researchers werelooking for water deep underground inhopes offinding life there, andthey succeeded in that goal also. Theydiscovered that microbes living in the rock three kilometres underground show many similarities to microbes that live at the bottom of the ocean, Sherwood Lollar said.

According to the paper, the life found in the mine represents the deepestmicrobial ecosystems on Earth ever described by scientists.

The team is hoping to hunt for water in ancient rocks at other locations around the globe, including Sudbury, Ont., and the Fennoscandian Shield in northern Europe.