Hydrothermal vents are among the strangest ecosystems on Earth: eerie places where the planet’s deep heat and chemicals mingle with ocean water to support thriving networks of bizarre lifeforms that don’t need sunlight to survive.
Stranger still, sometimes short-lived versions of these ecosystems form when asteroids slam into Earth—including the space rock that killed off non-avian dinosaurs 66 million years ago. New evidence published in Communications Earth & Environment suggests that this impact created a hydrothermal vent system that lasted far longer than scientists thought was possible—perhaps as long as eight million years.
Previous research based on modeling had indicated that the impact site, called Chicxulub, likely did host hydrothermal vents after the asteroid hit, but for just two million years. Now, researchers have analyzed samples taken from within the structure itself—specifically, the peak-ring crater, an inner ring that forms when an impact produces enough debris that it forms a mound in the center of the crater that later collapses.
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Annemarie Pickersgill, was one of a team of scientists who, in 2016, drilled into the crater left behind by the Chicxulub impact, along the coast of Mexico’s Yucatan Peninsula, according to a statement. The researchers snagged four samples from within the peak-ring crater from depths ranging from 2,316 to 2,480 feet (706 to 756 meters) below the sea floor. Then, they compared the ratios of two different isotopes of argon—this provides a chemical fingerprint that scientists can use to estimate the age of minerals in the rocks, and thus the hydrothermal system.
The analyses revealed a long span of hydrothermal activity at the site—with the oldest samples dating to around 66 million years ago and, the freshest to about 58 million years ago. It’s not clear whether that long-lived activity was localized to where the researchers got their samples, or if it was true across the structure more generally. Still, they posit the peak ring may have been particularly suited to supporting hydrothermal vents.
That’s intriguing for scientists, given how vibrant hydrothermal vent ecosystems can be. “The porous, fractured rocks created by impacts create microenvironments where micro-organisms can be protected from radiation and extreme temperatures,” Pickersgill, a scientist at the SUERC Centre for the Isotope Sciences, which is a collaboration of the Universities of Glasgow and Edinburgh, said in a statement. “Those conditions give life the chance to take hold and flourish.”
As intriguing as the results are for understanding the surprising potential for life in the aftermath of Earth’s most infamous cataclysm, Pickersgill and her team are considering whether the findings have extraterrestrial applications, too. It’s possible that similar phenomena may have unfolded on Mars, which could have offered an opportunity for any life on that planet to blossom at exotic hydrothermal vents.
“As we look to the future of space exploration, these findings could help future missions to other planets determine which impact craters might have been most likely to sustain life,” Pickersgill said.
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