Deep-Earth Carbon Offers Clues to Origins of Life

Researchers learning more about deep-Earth carbon, the stuff that makes precious diamonds, are finding that it can offer clues to the origins of life, according to a new study.

Deep-Earth carbon is located 100 miles below the Earth's surface and can exist at temperatures up to 2,100 degrees Fahrenheit (1,148 Celsius). Scientists have long known that this element plays a vital role at the planet's crust, as well as sparks the formation of diamonds, but now they believe it can even become food for microbial life.

"It is a very exciting possibility that these deep fluids might transport building blocks for life into the shallow Earth," lead author and geochemist Dimitri Sverjensky, of Johns Hopkins University, said in a statement. "This may be a key to the origin of life itself."

Based on Sverjensky's theoretical Deep Earth Water model, he and his team were able to determine the chemical makeup of fluids in Earth's mantle - chemicals that are discharged from descending tectonic plates. Some of the fluids - those in equilibrium with mantle peridotite minerals - contained carbon dioxide and methane, compounds already known to exist in Earth's subterranean environment. But others - those in equilibrium with diamonds and eclogitic minerals - contained dissolved organic carbon species including a vinegar-like acetic acid.

The existence of dissolved carbon species in such high concentrations deep beneath Earth's surface suggests to the Johns Hopkins team that carbon might have influenced the history of life on the planet.

But in what way? The dissolved species may help to transport large amounts of carbon from Earth's deep subduction zone into the shallower overlying mantle wedge, where they are likely to alter the mantle and affect the cycling of elements back into Earth's atmosphere.

The researchers plan to continue learning more about Earth's carbon through a 10-year global project, called the Deep Carbon Observatory. Their recent findings were published in the journal Nature Geoscience.