'Sleeping Giant' of ancient life-sustaining water found in Earth's crust
Friday, December 19, 2014, 10:44 AM - A Canadian-led team of researchers has discovered that Earth's crust holds a vast repository of ancient water, potentially billions of years old, that may be supporting a vast underground biosphere.
These new findings, published this week in the journal Nature and reported at the 2014 American Geophysical Union meeting in San Francisco, have important implications towards how life started on Earth, how it may have survived during times when the surface was being bombarded by asteroids, and even for whether life may exist on worlds such as Mars.
According to University of Toronto geoscientist Barbara Sherwood Lollar, wherever on Earth her team examined the planet's oldest rock formations - either by drilling deep into the ground or exploring mines - they found water. While this isn't unusual, as water can trickle far down through soil and rock, what was surprising was the large quantity of the water, how old some of it is - millions to billions of years old - and the energy locked up in the water, in the form of dissolved hydrogen gas.
This hydrogen gas in the water is important as a food source for chemolithotrophic, or 'rock-eating' microbes, as it can sustain them even when they're locked away from other energy sources, like the Sun (the ultimate source of energy for life on Earth's surface).
"This is a vast quantity of rock that we've sometimes overlooked both in terms of its ability to tell us about past processes - the rocks are so ancient they contain records of fluid and the atmosphere from the earliest parts of Earth's history," Sherwood Lollar said, according to BBC News. "But simultaneously, they also provide us with information about the chemistry that can support life. And that's why we refer to it as 'the sleeping giant' that has been rumbling away but hasn't really been characterized until this point."
In addition to the implications for life here on Earth, this discovery may give renewed hope for finding life on Mars.
"If the ancient rocks of Earth are producing this much hydrogen, it may be that similar processes are taking place on Mars," Sherwood Lollar said in a University of Toronto press release.
Hints of Earth's self-sufficiency?
In another study being presented at the AGU meeting this week, Ohio State researchers have examined how this ancient subsurface water may be cycled between Earth's oceans, crust and possibly deeper into the semi-molten mantle. Their findings give some indication that the timeline of this circulation may be very long, indeed.
"If all of the Earth’s water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years," Ohio State researcher Wendy Panero said in a press release. "But if mantle circulation is also part of the water cycle, the total cycle time for our planet’s water has to be billions of years."
If this turns out to be true, it may reveal that, rather than the planet receiving its vast supply of water from asteroids or comets, it may have been much more self-sufficient, producing and recycling its own initial supply of water even up to the present day.