Deep saline groundwater in South Africa’s Witwatersrand Basin may have remained isolated for many thousand – maybe even millions – of years say researchers who found neon dissolved in the water
Witwatersrand National Park – home to the oldest water on Earth Credit Chris Eason
The area is also home to the deepest known microbial ecosystem on Earth, who survive on chemical energy originating in the rock, rather than sunlight.
Researchers from the University of Toronto found the noble gas neon dissolved in water in three-kilometre deep crevices. The unusual neon profile, along with the high salinities and other unique chemical signatures is very different from anything seen in molten fluid and gases rising from beneath the Earth’s crust.
“We know that this specific neon isotope signature was produced and trapped within the rock at least two billion years ago. We can still find them there today,” said professor Barbara Sherwood Lollar. “The study show some of the neon found its way outside of the rock minerals, gradually dissolving into, and accumulating in, fluids in crevices.”
“This could only happen in waters that have indeed been cut off from the surface for extremely long time periods.”
The microorganisms found in the areas have a genetic similarity to those found in hydrothermal vents, Sherwood Loller said, suggesting these are not a separate origin of life, but arrived from elsewhere to colonise the rocks in ancient times.
“Clearly the long period of isolation affected their evolution,” she said, “This is one area we hope to explore with continuing research with our microbiology colleagues.”