Dinosaur Doomsday Crater Became an Ocean Oasis for 700,000 Years

Around 66 million years ago, an asteroid between six and ten miles (10 to 15 kilometers) wide slammed into what is now the Gulf of Mexico, leaving behind a massive 90-mile-wide (150 kilometers) crater. The impact killed all non-avian dinosaurs and decimated marine creatures—but may have also boosted life in a peculiar way.

A team of international researchers suggests that the asteroid impact created a hydrothermal system within the Chicxulub crater, as it’s officially known, which may have nurtured a unique marine environment in the ocean above it for at least 700,000 years. The study, published Tuesday in Nature Communications, shows how a highly destructive event might eventually become a catalyst for life.

“After the asteroid impact, the Gulf of Mexico records an ecological recovery process that is quite different from that of the global ocean,” Honami Sato, lead author in the study and a geologist from Kyushu University, said in a University of Texas at Austin statement.

In the Gulf of Mexico, hydrothermal activity takes place when water seeps into the seafloor. Heated by Earth’s interior, the water mixes with chemicals (among other materials) in the oceanic crust and then rises back into the ocean. The hydrothermal fluid, as it’s called, cools quickly in the deep, cold water. The chemicals separate from the fluid and deposit along the seafloor.

Some deep-sea microbes eat the chemicals churned up by hydrothermal activity. The microbes are themselves eaten by other organisms, which are in turn eaten by other organisms, and so on, sustaining a whole deep-sea food chain dependent on hydrothermal vents.

In 2016, a scientific drilling expedition to the Gulf of Mexico extracted approximately 2,720 feet (829 meters) of core from the ancient crater. By analyzing this core, Sato and her colleagues found evidence of an ancient hydrothermal system that, in the wake of the impact, pulled up a chemical element called osmium from the oceanic crust.

“The impact event created a porous and permeable structure in the Chicxulub impact structure that was an ideal host for the hydrothermal fluid system,” the researchers wrote in the study.

Osmium is associated with the composition of asteroids. In other words, the researchers suggest that hydrothermal activity pulled osmium from buried asteroid remnants on the seafloor and carried it into the Gulf waters, where it eventually settled into the sediment layers—something they observed in the core samples.

The team found that the kind of marine life that existed during this time was different from that which took hold after the hydrothermal activity ceased to release osmium. Specifically, plankton associated with high-nutrient environments thrived during the release of osmium. When osmium levels returned to normal, the habitat shifted to favor plankton adapted to low-nutrient conditions.

This suggests that, by then, the ecosystem was no longer reliant on the chemical nutrients churned up by the hydrothermal system—potentially because the hydrothermal vents had become completely buried beneath millions of years worth of sediment layers, according to the researchers.

While earlier research showed that life in the crater rebounded quickly, the team’s findings suggest that hydrothermal systems created by the impact and asteroid debris may have helped fuel that recovery.

“We are increasingly learning about the importance of impact-generated hydrothermal systems for life,” Gulick said. “This paper is a step forward in showing the potential of an impact event to affect the overlying ocean for hundreds of thousands of years.”

In other words, the researchers may have found the most striking silver lining of all—life springing from a mass extinction crater.