Meteor hit Oklahoma 100 million years later than previously thought

A geological map noting the types of rock that make up the Ames impact structure. The locations of oil and gas wells are noted with arrows. Credit: Catlos et al

Researchers at The University of Texas at Austin have rewritten a small part of Oklahoma's geologic history with global implications for ancient life. Below the surface of the small town of Ames, Oklahoma, a meteor impact site spans miles. The crater is buried by sedimentary strata in the subsurface, but it remains an important marker of Oklahoma's ancient past and present-day economy; the Ames impact structure is a major oil and gas producer.

It's also part of a series of significant meteor impacts across North America with ages that center around 467.5 million years ago—it's called the Ordovician Meteor Event. The sheer number of impact sites that exist from this time period has led researchers to theorize that Earth might have had a Saturn-like ring of asteroid debris around it during the Middle Ordovician.

UT researchers, however, have recently discovered that the Ames impact structure is nearly 100 million years younger than previously believed. By dating zircon crystals found in impacted granites at the site, researchers have found that a meteorite hit Ames in Late Devonian times about 370 million years ago, not 467 million years ago in the Ordovician.

"No matter what technique we used, it was coming back to this younger signal," said lead author Elizabeth Catlos, associate professor at UT's Department of Earth and Planetary Sciences.

The research was published in July in Meteoritics & Planetary Science.

Ancient teeth gave a misleading date

The Ames meteor impact site had previously only been dated biochronologically; researchers found the teeth of an ancient eel-like creature called a conodont in the rock, which were around during the older Ordovician age. However, the teeth were likely already millions of years old when the asteroid struck Ames, and likely just got jumbled around in the mix of the impact, remaining preserved, Catlos said.

This new radiometric date from the zircon from the Ames impact shows that it could not have been part of the Ordovician Meteor Event, but squarely fits into the timing of the Frasnian-Famennian mass extinction event, which occurred about 372 million years ago, and led to the extinction of a huge percentage of marine life on Earth.

A map of upper North America shows the approximate area and location of impact structures from about 486-360 million years ago. Credit: Catlos et al

Danny Stockli, dean of the Jackson School of Geosciences and a co-author of the study, said that zircon U-Pb dating is not only the most accurate way to tell when events like this occurred in Earth's history, but that microstructures in zircon can record the shock pressures of impacts.

"These small crystals allow us to go back in time and learn about the major changes to Earth's ancient landscapes," Stockli said. "It would be great to do this for more of the meteor impact sites across the continent so we could get a more accurate timeline for these major events."

Crystals retain the impact's signature

To prove that the zircons they dated were in fact impacted by the meteor, the research team worked with NASA to image the crystals using cathodoluminescence and electron backscatter diffraction. When a zircon is hit by an impact like this, it recrystallizes in a very specific way, which they can see through these methods.

Catlos said that having a more accurate timeline for mass extinction events and other big moments in Earth's history is crucial for understanding how our planet works. It matters whether these extinctions were driven by an extraterrestrial force such as this one, or an interior force such as a series of massive volcanic eruptions, she said.

"With this research, we're basically taking a major pawn out of the Ordovician Meteor Event and dumping it into the Frasnian-Famennian event, and saying, "This is where this impact belongs,'" she said.

This research was instigated by former Jackson School of Geosciences graduate student Andrew Parisi, who graduated in 2018 and has since passed away. He went to Oklahoma to collect the Ames rock core from the Oklahoma Geological Survey, extracted the zircons and helped to date them.

Co-author Michael Brookfield, an affiliated researcher at the school, also passed away before the paper was published. Research Professor Sean Gulick and Professor Emeritus Mark Cloos at the Jackson School also contributed to this research.

More information

Elizabeth J. Catlos et al, The Ames impact structure, Oklahoma: New radioisotopic constraints and implications for North American impact chronology, Meteoritics & Planetary Science (2026). DOI: 10.1111/maps.70191

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