Yellowstone National Park is all gassed up.
Vast stores of helium that have accumulated in the Earth’s crust for up to 2 billion years are escaping through volcanic rocks beneath the national park, a new study published in the journal Nature, suggests. The helium, which is being released at about 60 tons per year, is due to the advent of volcanic activity in the region over the past 2 million years.
"That might seem like a really, really long time to people, but in the geologic time scale, the volcanism is a recent phenomenon," study coauthor Bill Evans, a research chemist at the U.S. Geological Survey office in Menlo Park, Calif., told the Los Angeles Times.
Helium, the second most-abundant element in the universe, is formed by the decay of radioactive elements in rocks. Researchers measured two helium isotopes at Yellowstone: Helium-3 and Helium-4. While the hydrothermal system at the park has a relatively high amount of the former, scientists found the amount of Helium-4 far exceeds the amount they expected to find. They attribute the unusually high amount to a pocket of the Earth’s crust formed during the Archaean eon that contains uranium among other radioactive materials. This allowed helium to accumulate underground. About 2 million years ago this hotspot penetrated the ancient rocks and began releasing Helium-4 and Helium-3, the Smithsonian Magazine reports.
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While Yellowstone is known to have geysers like Old Faithful, caldrons of boiling mud and hot springs -- scientists were surprised to discover just how much helium is being released from the rocks below.
"The amount of crustal helium coming out is way more than anyone would have expected," Jacob Lowenstern, lead study author and scientist-in-charge at the U.S. Geological Survey's Yellowstone Volcano Observatory, told NBC News.
Researchers collected helium samples using plastic funnels, tubes and probes that they stick in the ground. The gases were analyzed in a lab. While the helium can't be given an exact date, scientists could determine it has been there a long time by comparing its density levels with other areas.
"This really isn't a volcano story," Lowenstern said. "But it reveals how the Earth's crust behaves on a long time frame. The crust 'holds its breath' for long periods of time, and then releases it during tectonically and volcanically active bursts."
Despite the large amount of helium at Yellowstone, researchers say it's not an ideal location to extract the element.
"It's a national park, so you'd never set up an extraction industry there," Evans said. "But even if that weren't the case, it would still be difficult to capture this helium and purify it. It just wouldn't be economical."